JP4870995B2 - Method for producing amine oxide - Google Patents

Description

  The present invention relates to a method for producing an amine oxide, and more specifically, production of an amine oxide capable of efficiently producing a high quality amine oxide excellent in handling property, pH stability and color tone stability in a short reaction time. Regarding the method.

  Amine oxide has been widely used as a surfactant with little irritation to the skin for body detergents such as kitchen detergents, residential detergents, shampoos and body shampoos, cosmetics and cosmetics.

  As a method for producing an amine oxide, for example, a method of reacting a tertiary amine and hydrogen peroxide is known. In such a method for producing an amine oxide, a long reaction time is required. Deterioration of odor and color tone due to decomposition of the obtained amine oxide has been a drawback.

Various studies have been made on such drawbacks. For example, as a technique for producing amine oxides with a good odor, a technique is proposed in which a tertiary amine and hydrogen peroxide are reacted and then the pH after the reaction is adjusted to 9 to 13 by adding an alkali and a chelating agent. (See Patent Document 1). However, this does not improve the color tone, and has the disadvantage of requiring a long reaction time.
Further, as a technique for preventing the deterioration of the color tone, amine and hydrogen peroxide are reacted in a liquid solvent (solvent / reaction mixture <1/2) in the presence of carbon dioxide and 50% by mass or less of the reaction mixture. There has been proposed a technique for minimizing discoloration by producing an oxide in the presence of an inert gas at least equal to the amount of oxygen dioxide (see Patent Document 2). However, this is a technique related to the production of a high solid (high concentration product), which requires the use of an organic solvent.
In addition, as a technique for obtaining high-quality amine oxide, a technique for suppressing gelation during the reaction by dropping stearyldimethylamine while blowing carbon dioxide into citric acid, water, and hydrogen peroxide has also been proposed. (See Patent Document 3). However, this increases the viscosity of the solution at room temperature after the reaction, and particularly in a high concentration region, the liquidity may be deteriorated. As a result, the handling property and the production efficiency are deteriorated. .

  Therefore, the development of an amine oxide production method capable of efficiently producing an amine oxide having excellent color tone stability in a short reaction time is still desired.

Japanese Patent Laid-Open No. 10-168052 JP-A-3-264560 JP 11-92444 A

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide a method for producing an amine oxide capable of efficiently producing a high quality amine oxide excellent in handling property, pH stability and color tone stability in a short reaction time. To do.

As a result of intensive studies to solve the above problems, the present inventors can proceed the reaction in a short time by using carbon dioxide during the reaction between the tertiary amine and hydrogen peroxide. By removing the reaction heat generated during the reaction, deterioration of the color tone of the product can be suppressed, and by controlling the temperature of the heat transfer medium during the reaction, gelation during the reaction is suppressed, It has been found that a reduction in heat removal efficiency of reaction heat can be prevented.
Furthermore, the present inventors dilute the solution after the reaction of the tertiary amine and hydrogen peroxide as necessary, improve the liquidity by lowering the viscosity, and then add an acid to near neutrality. By adjusting the pH of the solution, the handleability of the resulting amine oxide is improved, and the dissolved bicarbonate ion is released as carbon dioxide gas, thereby improving the pH stability and color stability. As a result, the present invention has been completed.

This invention is based on the said knowledge by this inventor, and as a means for solving the said subject, it is as follows. That is,
<1> The following general formula (I):
[In the formula, R ¹ is an ester group may be any of the amide group and an ether group are inserted, a straight-chain or branched alkyl or alkenyl group of 6 to 22 carbon atoms, R ² and R ³ represents each of an alkyl group having 1 to 3 carbon atoms and a hydroxyalkyl group,
A is
R ⁴ represents a linear or branched alkylene group having 2 to 4 carbon atoms, and n represents 0 or 1]
A process for producing an amine oxide represented by
(A) The following general formula (II):
[In the formula, R ¹ is an ester group may be any of the amide group and an ether group are inserted, a straight-chain or branched alkyl or alkenyl group of 6 to 22 carbon atoms, R ² and R ³ represents each of an alkyl group having 1 to 3 carbon atoms and a hydroxyalkyl group,
A is
R ⁴ represents a linear or branched alkylene group having 2 to 4 carbon atoms, and n represents 0 or 1]
A step of reacting a tertiary amine represented by the following formula with hydrogen peroxide in the presence of carbon dioxide; and (B) adding an acid to the post-reaction solution obtained by the step (A), Adjusting the pH of the solution;
It is a manufacturing method of the amine oxide characterized by including.
<2> The amine oxide production according to <1>, wherein the reaction in the step (A) is performed by adding hydrogen peroxide after adding carbon dioxide to a raw material amine solution containing a tertiary amine. Is the method.
<3> The method for producing an amine oxide according to any one of <1> to <2>, wherein the reaction in the step (A) is performed at 30 to 80 ° C.
<4> The reaction in step (A) is performed in a reactor equipped with a cooling jacket, and the reaction temperature is controlled by controlling the temperature of the heat transfer medium circulating in the cooling jacket. <1> To <3>. The method for producing an amine oxide according to any one of <3>.
<5> The amine oxide according to <4>, wherein the temperature of the heat transfer medium circulating in the cooling jacket is set to 25 to 50 ° C. when the addition ratio with respect to the total amount of hydrogen peroxide is 0 to 50% by mass. It is a manufacturing method.
<6> The amine according to any one of <1> to <5>, wherein step (B) is a step of adjusting the pH of the post-reaction solution obtained in step (A) to 6.6 to 7.4. It is a manufacturing method of an oxide.
<7> A step of further diluting the post-reaction solution by adding a solvent to the post-reaction solution obtained by the step (C) (A) between the step (A) and the step (B),
The method for producing an amine oxide according to any one of <1> to <6>.
<8> The method for producing an amine oxide according to <7>, wherein the step (C) is a step of diluting the post-reaction solution obtained in the step (A) so that the viscosity becomes 30 to 150 mPa · s. is there.
<9> The method for producing an amine oxide according to any one of <1> to <8>, wherein a bicarbonate ion concentration in the produced amine oxide is 0 to 300 ppm.
<10> An amine oxide produced by the method for producing an amine oxide according to any one of <1> to <9>.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of an amine oxide which can manufacture efficiently the high quality amine oxide excellent in handling property, pH stability, and color tone stability in a short reaction time can be provided.

  Below, the manufacturing method of the amine oxide of this invention is demonstrated in detail.

(Method for producing amine oxide)
The method for producing an amine oxide of the present invention is a method for producing an amine oxide according to the following reaction formula: (A) a step of reacting a tertiary amine and hydrogen peroxide in the presence of carbon dioxide; B) It includes at least a step of adjusting the pH of the post-reaction solution by adding an acid to the post-reaction solution obtained in the step (A), and, if necessary, (C) the step (A) and Between the step (B), the method includes a step of adding a solvent to the post-reaction solution obtained in the step (A) to dilute the post-reaction solution, and further includes other steps as necessary. .

In the above reaction formula, R ¹ represents a linear or branched alkyl group or alkenyl group having 6 to 22 carbon atoms into which any of an ester group, an amide group and an ether group may be inserted, and R ² And R ³ each represents an alkyl group having 1 to 3 carbon atoms or a hydroxyalkyl group, and A is
R ⁴ represents a linear or branched alkylene group having 2 to 4 carbon atoms, and n represents 0 or 1.

<(A) Step of reacting tertiary amine and hydrogen peroxide in the presence of carbon dioxide>
In the step (A), a tertiary amine and hydrogen peroxide are reacted in the presence of carbon dioxide. By the presence of carbon dioxide, the reaction between the tertiary amine and hydrogen peroxide is promoted, and the amine oxide can be efficiently produced in a short reaction time.
The method for performing the reaction is not particularly limited and may be appropriately selected depending on the purpose. For example, after adding and mixing carbon dioxide with a raw material amine solution containing a tertiary amine, It is preferable to carry out by adding hydrogen peroxide to the obtained mixed solution.

-Tertiary amine-
The tertiary amine is represented by the following general formula (II).

In the general formula (II), R ¹ represents a linear or branched alkyl or alkenyl group having 6 to 22 carbon atoms into which any of an ester group, an amide group and an ether group may be inserted. , R ² and R ³ each represent one of an alkyl group having 1 to 3 carbon atoms and a hydroxyalkyl group,
A is
R ⁴ represents a linear or branched alkylene group having 2 to 4 carbon atoms, and n represents 0 or 1.

  Specific examples of the tertiary amine are not particularly limited as long as they are represented by the general formula (II), and can be appropriately selected according to the purpose. For example, dimethyldodecylamine, dimethyloctyl Amine, dimethyldecylamine, dimethyltetradecylamine, dimethylhexadecylamine, dimethyloctadecylamine, dimethylcocoalkylamine, dimethyl-cured tallow alkylamine, diethyldodecylamine, N, N-bis (2-hydroxyethyl) dodecylamine, N , N-dimethylaminopropyloctylamide, N, N-dimethylaminopropyldecylamide, N, N-dimethylaminopropyldodecylamide, N, N-dimethylaminopropyltetradecylamide, dodecyloxypropyldimethylamine, tetradecyloxy B pills dimethylamine, de siloxy dimethylamine, hexadecene siloxy dimethylamine, dimethylaminoethyl dodecyl ester, dimethylaminoethyl tetradecyl ester, dimethylaminoethyl decyl ester, such as dimethyl aminoethyl hexadecyl ester.

  The tertiary amine is preferably used in such an amount that 20 to 40% by mass of the amine oxide as a reaction product is contained in the post-reaction solution obtained after completion of the step (A). More preferably, it is used in such an amount that it is contained in an amount of ˜36% by mass, particularly preferably in an amount that is contained in an amount of 30-35% by mass.

-Raw material amine solution-
Here, as described above, the tertiary amine is preferably used as a raw material amine solution which is a mixed solution with a solvent.
As the solvent, water is generally used, but a water-soluble solvent may be further used for the purpose of adjusting the viscosity of the raw material amine solution. Examples of the water-soluble solvent include lower alcohols such as methanol, ethanol, 2-propanol, ethylene glycol, and propylene glycol.

The mass ratio of the tertiary amine to the solvent in the raw material amine solution is preferably tertiary amine / solvent = 10/1 to 2/3, and preferably 10/3 to 5/6. More preferred is 2/1 to 1/1.
If the amount of the solvent used is less than 1/10 times the amount of the tertiary amine used, gelation occurs in the reaction with hydrogen peroxide, making it difficult to continue the reaction. If the mass ratio exceeds 3/2 times, the hydrogen peroxide concentration will be relatively high in the reaction with hydrogen peroxide, so the color and odor of the reaction product will deteriorate, and water will be added. The reaction temperature may increase with decreasing amount. On the other hand, when the amount of the solvent used is within a range of 1/2 to 1/1 times by mass ratio with respect to the amount of tertiary amine used, the gelation during the reaction is suppressed, and more This is advantageous in that the reaction can proceed smoothly and the color tone and odor deterioration of the reaction product can be suppressed.

-Hydrogen peroxide-
There is no restriction | limiting in particular as said hydrogen peroxide, According to the objective, it can select suitably. For example, a hydrogen peroxide solution containing 3% by mass or more of hydrogen peroxide can be used. Among them, a hydrogen peroxide solution containing 30 to 60% by mass of hydrogen peroxide is generally easy to obtain. The hydrogen peroxide solution containing 35 to 50% by mass of hydrogen peroxide is more preferable.
Further, for the purpose of avoiding gel formation in the reaction with the tertiary amine, the hydrogen peroxide can be further diluted with water or an organic solvent. Examples of the organic solvent include ethanol, 2-propanol, ethylene glycol, propylene glycol and the like.

The amount of the hydrogen peroxide used is preferably 1.00 to 1.50 mol, more preferably 1.00 to 1.30 mol, and 1.00 to 1.10 with respect to 1 mol of the tertiary amine. Mole is particularly preferred.
If the amount of hydrogen peroxide used is less than 1.00 mol with respect to 1 mol of the tertiary amine, the reaction may not be completed. If it exceeds 1.50 mol, A large amount of unreacted hydrogen peroxide remains, and deterioration of color tone or the like due to decomposition of hydrogen peroxide may occur during storage of the recovered reaction product. On the other hand, when the amount of hydrogen peroxide used is in the range of 1.00 to 1.10 moles with respect to 1 mole of the tertiary amine, the reaction with the tertiary amine is more sufficiently performed. This is advantageous in that deterioration of color tone due to unreacted hydrogen peroxide can also be suppressed.

-In the presence of carbon dioxide-
As described above, in the step (A), the tertiary amine and hydrogen peroxide are reacted in the presence of carbon dioxide. The method for performing the reaction in the presence of carbon dioxide is not particularly limited and may be appropriately selected depending on the intended purpose. However, as described above, prior to the reaction between a tertiary amine and hydrogen peroxide, A method of adding carbon dioxide to the raw material amine solution containing a tertiary amine is preferred.

The method for adding carbon dioxide to the raw material amine solution is not particularly limited and may be appropriately selected depending on the intended purpose.For example, a method of substituting the gas phase in the reactor with carbon dioxide, Examples thereof include a method of supplying carbon dioxide into the raw material amine solution, a method of supplying carbon dioxide into the water or organic solvent, and a method of adding carbon dioxide by pressurization. The target to which carbon dioxide is added may be either a gas phase or a liquid phase.
Here, carbon dioxide is contained in the raw material amine solution so that the amine-converted acid value represented by the following formula (1) of the raw material amine solution is 1.6 to 15 (mg · KOH / g-amine). It is preferable to be added, more preferably 2.0 to 10.0 (mg · KOH / g-amine), and 3.0 to 6.0 (mg · KOH / g-amine). It is particularly preferable to add such that
If the amine-converted acid value is less than 1.6 (mg · KOH / g-amine), the reaction between the tertiary amine and hydrogen peroxide may be slow, and 15 (mg · KOH / g- If it exceeds (amine), economic loss and time loss due to excessive supply of carbon dioxide increase, and large excess of carbon dioxide dissolves in the reaction solution, which may cause foaming. On the other hand, when the amine-equivalent acid value is in the range of 3.0 to 6.0 (mg · KOH / g-amine), the reaction between the tertiary amine and hydrogen peroxide is performed more rapidly, and This is advantageous in that undesirable foaming is also suppressed.
Carbon dioxide may be continuously added during the reaction between a tertiary amine and hydrogen peroxide, which will be described later, within a range where foaming does not become intense.

* 1: The unit is mg · KOH / g-amine.

As shown in the formula (1), the amine-equivalent acid value of the raw material amine solution can be obtained by measuring the acid value of the raw material amine solution.
Here, as for the acid value of the raw material amine solution, for example, 1 to 5 g of the raw material amine solution is weighed, put into a 200 to 300 mL beaker, about 100 ml of 2-propanol is added, and the mixture is stirred with a stirrer. Subsequently, it can be measured by titrating with an automatic titration apparatus using a 0.1 N · KOH aqueous solution and calculating the number of KOH (mg) per 1 g of the sample from the inflection point.

The temperature at which carbon dioxide is added to the raw material amine solution is preferably 15 to 65 ° C, more preferably 20 to 50 ° C, and particularly preferably 25 to 40 ° C.
When the temperature is less than 15 ° C., the carbon dioxide absorption rate in the raw material amine solution is increased, but excessively dissolved carbon dioxide may cause foaming or gelation in the subsequent reaction. If it exceeds, carbon dioxide is difficult to dissolve, so that excess carbon dioxide is required, and the raw material amine solution may flow out of the reaction system with the introduction of carbon dioxide. On the other hand, when the temperature is in the range of 25 to 40 ° C., carbon dioxide can be more appropriately dissolved in the raw material amine solution to form an amine bicarbonate, which adversely affects the subsequent reaction. This is advantageous in that it is not given.
As a method for adjusting the temperature, for example, when carbon dioxide is added to the raw material amine solution in a reactor provided with a cooling jacket or a cooling coil, heat transfer properties circulating in the cooling jacket or the cooling coil are used. There is a method in which the temperature of the medium is adjusted to a desired temperature, and the temperature in the container and the temperature of the raw material amine solution are set to substantially the same temperature as the heat transfer medium.

-Reaction of tertiary amine and hydrogen peroxide-
The method for reacting the tertiary amine and the hydrogen peroxide is not particularly limited and may be appropriately selected depending on the intended purpose. For example, carbon dioxide is preferably added as described above. A method in which the hydrogen peroxide is added little by little to the raw material amine solution having an amine equivalent acid value and stirred while temperature control is preferred.

The reaction temperature between the tertiary amine and the hydrogen peroxide is preferably 30 to 80 ° C, more preferably 35 to 75 ° C, and particularly preferably 40 to 70 ° C. When the reaction temperature is less than 30 ° C., the reaction rate becomes slow, and thus the production efficiency may be lowered. When the reaction temperature exceeds 80 ° C., coloring of the reaction solution, deterioration of odor, and decomposition of hydrogen peroxide. May occur. On the other hand, when the reaction temperature is in the range of 40 to 70 ° C., the reaction proceeds more rapidly, which is advantageous in that the production efficiency is excellent and the decomposition of hydrogen peroxide does not occur. .
The method for adjusting the reaction temperature within a desired range is not particularly limited and may be appropriately selected depending on the intended purpose.However, the reaction is performed in a reactor equipped with a cooling jacket and a cooling coil. It is preferable to adjust the reaction temperature by removing the heat of reaction caused by the addition of hydrogen peroxide by adjusting the temperature of the heat transfer medium circulating in the cooling jacket or cooling coil.

As the reactor provided with the cooling jacket, for example, a reactor in which a circulation means capable of circulating the heat transfer medium at least in the cooling jacket and a temperature control means of the heat transfer medium are connected to the outside of the reaction tank. And can be appropriately selected from known jacketed reactors.
Moreover, as a reactor provided with the said cooling coil, the reactor by which the circulation means which can circulate a heat transfer medium to the cooling coil inside a reaction tank, and the temperature control means of the said heat transfer medium are connected, for example And can be appropriately selected from known reactors with cooling coils.
The reactor is preferably further provided with a means for adding hydrogen peroxide dropwise, a means for stirring the reaction solution, a thermometer, and the like. There is no restriction | limiting in particular as a means to stir the said reaction liquid, According to the objective, it can select suitably, For example, a turbine blade, three oval retreating blades, a full zone blade, a paddle blade, etc. are mentioned.

  There is no restriction | limiting in particular as said heat conductive medium, According to the objective, it can select suitably, For example, water, ethylene glycol, etc. are mentioned, Among these, water is preferable.

Here, when the temperature of the heat transfer medium becomes high, the heat removal ability of the heat transfer medium becomes low, and it becomes necessary to stop the addition of hydrogen peroxide and cool the reaction solution, so the reaction time becomes long, Along with a decrease in production efficiency, it may cause deterioration of the color tone and odor of the reaction product. On the other hand, if the temperature of the heat transfer medium is too low, local gelation occurs in the cooled portion of the reaction solution, resulting in a decrease in heat transfer efficiency, resulting in a decrease in heat removal efficiency.
Therefore, the heat removal is preferably performed while controlling the temperature of the heat transfer medium according to the progress of the reaction, that is, according to the addition rate with respect to the total amount of hydrogen peroxide as described below. .

  When the addition rate with respect to the total amount of hydrogen peroxide is 0 to 50% by mass, the temperature of the heat transfer medium circulating in the cooling jacket and / or the cooling coil is preferably 25 to 50 ° C., 30 -45 ° C is more preferred. When the temperature is less than 25 ° C., local gelation occurs in the cooling portion of the reaction solution, heat transfer efficiency is lowered, and as a result, heat removal efficiency may be lowered, and when it exceeds 50 ° C. Since the heat removal capability of the heat transfer medium is reduced and the reaction solution needs to be cooled by stopping the addition of hydrogen peroxide, the reaction time becomes longer, the production efficiency decreases, the color tone of the reaction product and May cause odor degradation. On the other hand, when the temperature is within the more preferable range, it is advantageous in that the formation of a gel is avoided to avoid a decrease in heat removal efficiency, and a high-quality amine oxide can be efficiently produced. .

  On the other hand, after the addition rate of the hydrogen peroxide exceeds 50% by mass, the generation of reaction heat becomes small, so that the heat transfer medium circulating in the cooling jacket and / or the cooling coil is reduced. The temperature is not particularly limited, and can be appropriately selected so that, for example, the reaction temperature between the tertiary amine and the hydrogen peroxide in the reactor is within the desired range described above.

  As described above, in the step (A), the post-reaction solution containing the amine oxide as a reaction product can be obtained by reacting the tertiary amine and the hydrogen peroxide in the presence of carbon dioxide. In the amine oxide production method, the obtained post-reaction solution is subjected to the following step (B).

<(B) Step of adjusting pH by adding acid>
In the step (B), an acid is added to the post-reaction solution obtained in the step (A) to adjust the pH of the post-reaction solution. By adjusting the pH, dissolved carbon dioxide can be removed from the solution after the reaction, and the pH stability and color stability of the resulting amine oxide can be improved.

-Acid-
The acid is not particularly limited and may be appropriately selected depending on the intended purpose. For example, sulfuric acid, hydrochloric acid, mineral acid, p-toluenesulfonic acid, citric acid, lactic acid, succinic acid, tartaric acid, hydroxyethane diphosphone Examples thereof include organic acids such as acids, and acidic amino acids such as aspartic acid and glutamic acid. Among these, sulfuric acid, hydrochloric acid, citric acid, lactic acid, and hydroxyethane diphosphonic acid are preferable from the viewpoint of versatility.
There is no restriction | limiting in particular also in the form of the said acid, According to the objective, it can select suitably, For example, organic solvent solutions, such as aqueous solution and ethanol, powder, etc. are mentioned.

The said acid may be used individually by 1 type, and may use 2 or more types together.
There is no restriction | limiting in particular as the usage-amount of the said acid, For example, it can select suitably so that pH of the said solution after the reaction after pH adjustment with the said acid may exist in the desired range as mentioned later.

-Acid addition method (pH adjustment method)-
The method for adding the acid to the post-reaction solution is not particularly limited and may be appropriately selected depending on the purpose. For example, the method for gradually adding the acid while stirring the post-reaction solution, Examples thereof include a method of adding the post-reaction solution while stirring the acid, a method of adding the post-reaction solution and the acid into a container at the same time, and stirring.

There is no restriction | limiting in particular in the temperature of the said post-reaction solution at the time of adjusting the pH by adding the said acid, Although it can select suitably according to the objective, 15-75 degreeC is preferable. If the temperature is less than 15 ° C., it may take time to cool or thicken and gel, and if it exceeds 75 ° C., the solvent evaporates and the concentration of amine oxide increases. And the color tone and odor may deteriorate.
In particular, when the post-reaction solution has a high concentration of 35% by mass or more and contains an amine oxide as a reaction product, the temperature of the post-reaction solution when adjusting pH is 15 to 30 ° C. and 40 to 40 ° C. It is more preferably within a range of 60 ° C., and particularly preferably within a range of 15 to 30 ° C. When the temperature is in the range of more than 30 ° C. and less than 40 ° C., the viscosity of the post-reaction solution may increase and a gel may be generated. On the other hand, when the pH adjustment temperature is in the range of 15 to 30 ° C., it is advantageous in that the viscosity of the post-reaction solution can be kept lower.
As a method for adjusting the temperature, for example, as in the temperature adjusting method at the time of the reaction between the tertiary amine and the hydrogen peroxide, for example, a heat transfer medium circulating in the cooling jacket or cooling coil in the reactor is used. Examples include a method of adjusting the temperature to a desired temperature, and setting the temperature of the solution after the reaction to substantially the same temperature as that of the heat transfer medium.

  The pH of the post-reaction solution after pH adjustment with the acid is preferably 6.6 to 7.4, more preferably 6.8 to 7.3, and particularly preferably 7.0 to 7.3. When the pH exceeds 7.4, the color tone stability may be deteriorated, and when it is less than 6.6, the viscosity may be increased and the liquidity may be deteriorated. On the other hand, when the pH is in the range of 7.0 to 7.3, it is preferable in that the liquid property is good and the color tone stability is more excellent.

<(C) Step of diluting solution after reaction>
In the production method of the amine oxide, a solvent is added to the post-reaction solution obtained in the step (A) between the step (A) and the step (B) as necessary. And diluting the solution after the reaction. By diluting the post-reaction solution, the viscosity of the post-reaction solution can be lowered, and handling properties can be improved.

-Solvent-
As the solvent, water is generally used, but a water-soluble solvent may be further used for the purpose of further reducing the viscosity of the solution after the reaction. Examples of the water-soluble solvent include lower alcohols such as methanol, ethanol, 2-propanol, ethylene glycol, and propylene glycol.
There is no restriction | limiting in particular as the usage-amount of the said solvent, For example, it can select suitably so that the viscosity of the said post-reaction solution after diluting with the said solvent may become in the desired range as mentioned later.

The viscosity of the post-reaction solution after the dilution is preferably 30 to 150 mPa · s, more preferably 40 to 100 mPa · s, and particularly preferably 50 to 80 mPa · s.
If the viscosity is less than 30 mPa · s, the amount of solvent may increase and the amine oxide concentration may decrease. If the viscosity exceeds 150 mPa · s, a neutralization reaction may occur during pH adjustment in the step (B). May become difficult to proceed, and it may take a long time for pH adjustment, or may be difficult to disappear when carbon dioxide dissolved in the reaction solution is generated as bubbles. On the other hand, when the viscosity is 50 to 80 mPa · s, it is advantageous in that the pH can be adjusted more rapidly and undesirable bubbles are likely to disappear.

  The content of amine oxide in the post-reaction solution after dilution is preferably 20 to 35% by mass, and more preferably 25 to 34% by mass. If the content is less than 20% by mass, it may be economically disadvantageous, and if it exceeds 35% by mass, a gel layer may be formed near the liquid surface and the concentration may be non-uniform. On the other hand, when the content is within the more preferable range, it is advantageous in that the liquid property is good and the handling property is excellent.

<Other processes>
The manufacturing method of the said amine oxide further includes other processes other than said (A)-(C) as needed. There is no restriction | limiting in particular as said other process, According to the objective, it can select suitably, For example, an amine oxide ripening process, the process of reducing an unreacted tertiary amine, and the residual hydrogen peroxide are decomposed | disassembled. The process etc. are mentioned.

-Amine oxide ripening process-
In the amine oxide ripening step, after the addition of the hydrogen peroxide to the raw material amine solution in the step (A) is completed, the reaction is further continued, whereby an unreacted tertiary amine and hydrogen peroxide. This is a step of reducing the amount of. The method for performing the amine oxide ripening step is not particularly limited and may be appropriately selected depending on the purpose. For example, as described above even after the addition of the hydrogen peroxide to the raw material amine solution is completed. And a method in which stirring is continued while maintaining a preferable reaction temperature between the tertiary amine and the hydrogen peroxide.

-Step of reducing unreacted tertiary amine-
The step of reducing the unreacted tertiary amine is not particularly limited and may be appropriately selected depending on the purpose. For example, the post-reaction solution obtained in the step (A) is further peroxidized. Examples include a method of adding hydrogen to continue the reaction.

-Decomposing the remaining hydrogen peroxide-
The step of decomposing the remaining hydrogen peroxide is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a reducing agent or excess is added to the post-reaction solution obtained in the step (A). Examples include a method of decomposing hydrogen peroxide by adding a substance that decomposes hydrogen oxide (for example, hydrogen peroxide decomposing enzyme), and a method of continuing the reaction by adding the tertiary amine. .

<Amine oxide>
It is represented by the following general formula (I) by the method for producing an amine oxide including the step (A) and the step (B), the step (C) as necessary, and the other step as necessary. Can be obtained. The amine oxide obtained here is in the state of an aqueous amine oxide solution.

In the general formula (I), R ¹ represents a linear or branched alkyl group or alkenyl group having 6 to 22 carbon atoms into which any of an ester group, an amide group and an ether group may be inserted. , R ² and R ³ each represent any of an alkyl group having 1 to 3 carbon atoms and a hydroxyalkyl group, and A is
R ⁴ represents a linear or branched alkylene group having 2 to 4 carbon atoms, and n represents 0 or 1.

In the method for producing amine oxide, the reaction rate (conversion rate) of the tertiary amine to amine oxide is preferably 98 mol% or more, and more preferably 99 mol% or more.
In addition, the content of the unreacted tertiary amine in the amine oxide aqueous solution obtained by the method for producing amine oxide is less than 0.5% by mass with respect to the total amount of the obtained amine oxide aqueous solution. Is preferable, it is more preferable that it is less than 0.3 mass%, and it is especially preferable that it is less than 0.2 mass%. When the content is 0.5% by mass or more, the detergency of amine oxide may be reduced, the color tone, odor, etc. may be deteriorated, or skin irritation may be increased. On the other hand, when the content is less than 0.2% by mass, it is advantageous in that it becomes a high-quality amine oxide having more excellent color tone and odor.
Further, the content of the unreacted hydrogen peroxide in the aqueous amine oxide solution is preferably less than 0.10% by mass and less than 0.05% by mass with respect to the total amount of the obtained aqueous amine oxide solution. More preferably. When the content is 0.10% by mass or more, when a composition is prepared using an amine oxide solution, other components may be decomposed or altered. On the other hand, when the content is less than 0.05% by mass, it is advantageous in that when used as a composition, it does not affect other components and the amount of oxygen generated is small even when self-decomposing.

When the reaction between a tertiary amine and hydrogen peroxide is performed in the presence of carbon dioxide, the carbon dioxide dissolves in the amine oxide solution and changes from dissolved carbon dioxide gas to carbon dioxide to bicarbonate ions (and carbonate ions). . And it is thought that it is mainly bicarbonate ion in the neutral to weak alkaline region of the aqueous amine solution.
Here, the bicarbonate ion concentration in the amine oxide (amine oxide aqueous solution) obtained by the amine oxide production method is preferably 300 ppm or less, more preferably 150 ppm or less, and 50 ppm or less. Is particularly preferred.
If the bicarbonate ion concentration exceeds 300 ppm, color tone stability may deteriorate, pH stability may deteriorate, and pH adjustment may take time. On the other hand, when the bicarbonate ion concentration is 50 ppm or less, it is advantageous in that it is more excellent in color tone stability and pH stability.
The bicarbonate ion concentration can be measured by, for example, capillary electrophoresis.

<Effect / Use>
Since the reaction of the tertiary amine and hydrogen peroxide is performed in the presence of carbon dioxide, the amine oxide can be efficiently produced in a short reaction time. Moreover, since acid is added after reaction and pH is optimized, the high quality amine oxide excellent in pH stability and color tone stability can be obtained. Moreover, since the manufacturing method of the said amine oxide adds and dilutes a solvent after reaction as needed, it can improve liquid property and can improve handling property.
The amine oxide production method preferably reduces the reaction temperature when the tertiary amine and hydrogen peroxide are reacted, thereby suppressing deterioration of the color tone of the resulting amine oxide. In addition, since the temperature of the heat transfer medium in the cooling jacket provided in the reactor is controlled according to the progress of the reaction, gelation in the reaction can also be suppressed.
Therefore, the method for producing amine oxide is extremely useful as an industrial method for producing amine oxide because high-quality amine oxide can be efficiently produced.
In addition, the amine oxide obtained by the method for producing amine oxide of the present invention is of high quality and has low irritation to the skin, and is used for detergents for the body such as kitchen detergents, residential detergents, shampoos and body shampoos, perfumes. It can be suitably used for a wide range of applications such as cosmetics and cosmetics.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Through the following examples and comparative examples, the amine oxide content measurement method, viscosity measurement method, color tone measurement method, and bicarbonate ion measurement method are as follows.
<Method for Measuring Content of Dimethyldodecylamine Oxide and Dimethyl Coco Alkylamine Oxide>
After weighing 1 to 2 g of sample and dissolving in 100 mL of 2-propanol, titrate with 0.1N hydrochloric acid-2-propanol solution using an automatic titrator (manufactured by Hiranuma Sangyo Co., Ltd.) and obtain from the inflection point. It was.
<Viscosity measurement method>
A 300 g sample was placed in a 500 mL beaker and measured with a B-type viscometer (manufactured by Tokyo Keiki Seisakusho). The rotor is no. 2 was used, and the viscosity was measured 1 minute after the start of rotation at 60 rpm. When the viscosity was high, the measurement was performed by changing the number of rotations to 30 rpm and 15 rpm.
<Measurement method of color tone>
The sample was measured with a color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd.).
<Measurement method of bicarbonate ion>
The bicarbonate ion concentration was measured by capillary electrophoresis.
Capillary electrophoresis apparatus: CAPI-3100 (Otsuka Electronics Co., Ltd.)
Electrophoresis solution for organic acid analysis: 1M trishydroxymethylaminomethane aqueous solution was added to a solution of 20 mM quinolinic acid (manufactured by Wako Pure Chemical Industries, Ltd.), 0.25 mM hexadecyltrimethylammonium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.), The pH was adjusted to 6.0.
Capillary: inner diameter 75 μm, total length 725 mm (effective length 600 mm)
Electrophoresis temperature: 25 ° C
Running time: 10 min
Detection method: Indirect UV method Voltage: -15 kV
The standard solution used was an aqueous solution of sodium hydrogen carbonate (manufactured by Kanto Chemical Co., Inc.).

Example 1
450 g (2.09 mol) of dimethyldodecylamine (in Tables 1 to 3, C12) (trade name: Armin DM12D, manufactured by Lion Akzo Co., Ltd.) and 450 g of distilled water were charged into the reactor, An amine solution (dimethyldodecylamine aqueous solution) was prepared. Carbon dioxide was added to the raw material amine solution by stirring the raw material amine solution at 30 ° C. while flowing carbon dioxide into the gas phase in the reactor.
In addition, as the reactor, a 2 L separable flask equipped with a cooling jacket, a hydrogen peroxide solution dropping device, a stirring device, a thermometer, a cooling tube, and a squid type blade and wound with a heat insulating material was used. During the addition, the temperature of the heat transfer medium (water) circulating in the cooling jacket was 31 ° C. Moreover, 20 degreeC tap water was poured into the cooling pipe.

  After the addition of carbon dioxide to the raw material amine solution, the acid value of the raw material amine solution in the reactor was measured and found to be 2.2 (mg · KOH / g), which was determined according to the following formula (1) The converted acid value was 4.4 (mg · KOH / g-amine).

* 1: Unit is mg · KOH / g-amine

The heat transfer medium circulating in the cooling jacket was heated to 51 ° C., the temperature of the raw material amine solution was heated to 50 ° C., the heat transfer medium was removed, and the inside of the cooling jacket was once emptied.
Next, 450.5 g of hydrogen peroxide containing 16.0% by mass of hydrogen peroxide so that the molar ratio of hydrogen peroxide to dimethyldodecylamine is hydrogen peroxide / dimethyldodecylamine = 1.010 ( 2.11 mol) was dropped into the raw material amine solution over 2 hours using the hydrogen peroxide dropping device, and reacted.
The temperature of the heat transfer medium is kept until the added amount of hydrogen peroxide is 50% by mass with respect to the total added amount so that the temperature of the reaction solution in the reactor is maintained at 60 to 65 ° C. Controlled to 25-35 ° C. After the addition amount of hydrogen peroxide reached 50% by mass or more with respect to the total addition amount, the temperature of the heat transfer medium was set to 55 to 65 ° C., and the temperature of the reaction liquid in the reactor was maintained at 65 ° C.

  After all hydrogen peroxide was dropped into the raw material amine solution, stirring was continued for 2.5 hours while maintaining the temperature of the reaction solution at 65 ° C. as an amine oxide ripening step, and the reaction was continued.

Analysis of the resulting post-reaction solution revealed that an aqueous dimethyldodecylamine oxide solution having an unreacted tertiary amine content of 0.25% by mass and a residual hydrogen peroxide content of 0.08% by mass was obtained. I understood.
Moreover, the reaction rate (conversion rate) of dimethyldodecylamine to dimethyldodecylamine oxide was 99.2 mol%, and the content of amine oxide in the solution after the reaction was measured. As a result, it was 36.2 mass%. .

  When the appearance of the obtained solution after the reaction was observed, it was slightly turbid because of the high viscosity of the liquid, and bubbles were entrained in the liquid. When the temperature of the solution after the reaction was lowered while stirring, the viscosity increased. When allowed to stand at 50 ° C., a gel layer was formed near the liquid surface, resulting in a heterogeneous system. When the gel was dispersed by stirring, bubbles were entangled and the viscosity could not be measured. Further, the pH could not be adjusted. However, when the temperature was further lowered, the viscosity decreased. When the viscosity at 30 ° C. was measured, it was as high as 168 mPa · s.

  20.9 g of water was added to 400 g of the resulting post-reaction solution and stirred and mixed to obtain a diluted solution having a dimethyldodecylamine oxide content of 34.4% by mass. When the viscosity of 30 degreeC was measured about the obtained dilution liquid, it was 65 mPa * s and the viscosity was falling. Since the viscosity of the liquid decreased, bubbles in the liquid decreased and the liquid became transparent.

  To 400 g of the obtained diluted solution, sulfuric acid (manufactured by Kanto Chemical Co., Inc., used by diluting to 50% by mass with water) was added to adjust the pH to 7.40. The liquid property of the obtained aqueous dimethyldodecylamine oxide solution after pH adjustment was good. The bicarbonate ion concentration was measured and found to be 132 ppm. When the pH was measured after 20 hours, there was almost no change to pH 7.42.

  Moreover, the color tone of the obtained aqueous dimethyldodecylamine oxide solution after pH adjustment was 5 (APHA). It was 30 (APHA) when it preserve | saved for 8 days at 70 degreeC with a 50 mL screw mouth bottle, and the color tone after a preservation | save was measured. The reaction conditions and results are shown in Table 1.

(Example 2)
Using the same reactor as in Example 1, the same amount of dimethyldodecylamine and distilled water as in Example 1 were added to the reactor to prepare a raw material amine solution.
Carbon dioxide was added in the same manner as in Example 1 except that the temperature of the heat transfer medium circulating in the cooling jacket was kept at 26 ° C. and the raw material amine solution was 25 ° C.
After completion of the addition of carbon dioxide to the raw material amine, the acid value of the raw material amine solution in the reactor was measured in the same manner as in Example 1. The result was 2.7 (mg · KOH / g), and the formula ( The amine-converted acid value determined according to 1) was 5.4 (mg · KOH / g-amine).

Then, in the same manner as in Example 1, the same amount of hydrogen peroxide as in Example 1 was added dropwise over 2 hours.
The temperature of the heat transfer medium is kept at 25 until the amount of hydrogen peroxide added reaches 50% by mass with respect to the total amount so that the temperature of the reaction solution in the reaction vessel is 60 to 65 ° C. Controlled to ~ 35 ° C. After the added amount of hydrogen peroxide water reached 50% by mass or more, the temperature of the heat transfer medium was set to 55 to 65 ° C., and the temperature of the reaction liquid in the reactor was maintained at 65 ° C.

After completion of the dropwise addition of hydrogen peroxide, stirring was continued for 2.5 hours while maintaining the temperature of the reaction solution at 65 ° C. as an amine oxide ripening step, and the reaction was continued.
Analysis of the resulting post-reaction solution revealed that an aqueous dimethyldodecylamine oxide solution having an unreacted tertiary amine content of 0.22% by mass and a residual hydrogen peroxide content of 0.07% by mass was obtained. I understood.
The reaction rate (conversion rate) of dimethyldodecylamine to dimethyldodecylamine oxide was 99.3 mol%, and the content of dimethyldodecylamine oxide in the solution after the reaction was 36.3% by mass.

  When the appearance of the obtained solution after the reaction was observed, it was slightly turbid because of the high viscosity of the liquid, and bubbles were entrained in the liquid. When the temperature of the solution after the reaction was lowered while stirring, the viscosity increased. When the viscosity at 30 ° C. was measured, it was as high as 172 mPa · s.

  20.9 g of water was added to 400 g of the resulting post-reaction solution and stirred and mixed to obtain a diluted solution having a dimethyldodecylamine oxide content of 34.5% by mass. With respect to the obtained diluted solution, the viscosity at 30 ° C. was 67 mPa · s. Since the viscosity of the liquid decreased, the amount of bubbles decreased and the liquid became transparent.

  To 400 g of the obtained diluted solution, sulfuric acid (manufactured by Kanto Chemical Co., Inc., used by diluting to 50 mass% by adding water) was added to adjust the pH to 7.20. The liquidity was good. The bicarbonate ion concentration was measured and found to be 45 ppm. When the pH was measured after 20 hours, the pH was almost unchanged at 7.21.

  The color tone of the obtained aqueous dimethyldodecylamine oxide solution after pH adjustment was 5 (APHA). It was 20 (APHA) when it preserve | saved for 8 days at 70 degreeC with a 50 mL screw mouth bottle, and the color tone after a preservation | save was measured. The reaction conditions and results are shown in Table 1.

(Example 3)
Using the same reactor as in Example 1, the same amount of dimethyldodecylamine and distilled water as in Example 1 were added to the reactor to prepare a raw material amine solution.
Carbon dioxide was added in the same manner as in Example 1 except that the temperature of the heat transfer medium circulating in the cooling jacket was maintained at 36 ° C and the raw material amine solution was set at 35 ° C.
After the addition of carbon dioxide to the raw material amine was completed, the acid value of the raw material amine solution in the reactor was measured in the same manner as in Example 1. The result was 2.1 (mg · KOH / g), and the formula ( The amine-converted acid value determined according to 1) was 4.2 (mg · KOH / g-amine).

Next, 481.3 g of hydrogen peroxide solution containing 14.9% by mass of hydrogen peroxide so that the molar ratio of hydrogen peroxide to dimethyldodecylamine is hydrogen peroxide / dimethyldodecylamine = 1.010 ( 2.11 mol) was dropped into the raw material amine solution over 2 hours using the hydrogen peroxide dropping device, and reacted.
The temperature of the heat transfer medium is kept at 25 until the amount of hydrogen peroxide added reaches 50% by mass with respect to the total amount so that the temperature of the reaction solution in the reaction vessel is 60 to 65 ° C. Controlled to ~ 35 ° C. After the added amount of hydrogen peroxide water reached 50% by mass or more, the temperature of the heat transfer medium was set to 55 to 65 ° C., and the temperature of the reaction liquid in the reactor was maintained at 65 ° C.

After completion of the dropwise addition of hydrogen peroxide, stirring was continued for 2.5 hours while maintaining the temperature of the reaction solution at 65 ° C. as an amine oxide ripening step, and the reaction was continued.
Analysis of the resulting post-reaction solution revealed that an aqueous dimethyldodecylamine oxide solution having an unreacted tertiary amine content of 0.24% by mass and a residual hydrogen peroxide content of 0.06% by mass was obtained. I understood.
The reaction rate (conversion rate) of dimethyldodecylamine to dimethyldodecylamine oxide was 99.3 mol%, and the content of dimethyldodecylamine oxide in the solution after the reaction was 35.3 mass%.

  When the appearance of the solution after the reaction was observed, it was transparent because the viscosity of the liquid was lower than in Examples 1 and 2, and the amount of bubbles in the liquid was small. When the temperature of the solution after the reaction was lowered while stirring, the viscosity slightly increased. When the viscosity at 30 ° C. was measured, it was as low as 82 mPa · s.

  To 400 g of the obtained post-reaction solution, 15.3 g of water was added and stirred and mixed to obtain a diluted solution having a dimethyldodecylamine oxide content of 34.0% by mass. When the viscosity of the obtained diluted solution was measured at 30 ° C., the viscosity of the solution was as low as 56 mPa · s and it was easy to handle.

  Sulfuric acid (manufactured by Kanto Chemical Co., Inc., used by diluting to 50% by mass of water) was added to 400 g of the obtained diluted solution under the condition of 22 ° C. to adjust to pH 7.00. Although the viscosity of the liquid increased, the liquid was transparent. The bicarbonate ion concentration was measured and found to be 0 ppm. When the pH was measured after 20 hours, there was almost no change to pH 7.01.

  The color tone of the obtained aqueous dimethyldodecylamine oxide solution after pH adjustment was 5 (APHA). It was 20 (APHA) when it preserve | saved for 8 days at 70 degreeC with a 50 mL screw mouth bottle, and the color tone after a preservation | save was measured. The reaction conditions and results are shown in Table 1.

Example 4
Using the same reactor as in Example 1, the same amounts of dimethyldodecylamine and distilled water as in Example 1 were added to the reactor to prepare a raw material amine solution.
Carbon dioxide was added in the same manner as in Example 1 while maintaining the temperature of the heat transfer medium circulating in the cooling jacket at 31 ° C. and the raw material amine solution at 30 ° C.
When the acid value of the aqueous dimethyldodecylamine solution in the reactor was measured in the same manner as in Example 1 after the addition of carbon dioxide to the raw material amine solution, it was 2.5 (mg · KOH / g), The amine-converted acid value determined according to the formula (1) was 5.0 (mg · KOH / g-amine).

Next, 521.4 g of hydrogen peroxide solution containing 13.8% by mass of hydrogen peroxide so that the molar ratio of hydrogen peroxide to dimethyldodecylamine is hydrogen peroxide / dimethyldodecylamine = 1.010 ( 2.11 mol) was dropped into the raw material amine solution over 2 hours using the hydrogen peroxide dropping device, and reacted.
The temperature of the heat transfer medium is kept at 25 until the amount of hydrogen peroxide added reaches 50% by mass with respect to the total amount so that the temperature of the reaction solution in the reaction vessel is 60 to 65 ° C. Controlled to ~ 35 ° C. After the added amount of hydrogen peroxide water reached 50% by mass or more, the temperature of the heat transfer medium was set to 55 to 65 ° C., and the temperature of the reaction liquid in the reactor was maintained at 65 ° C.

After completion of the dropwise addition of hydrogen peroxide, stirring was continued for 2.5 hours while maintaining the temperature of the reaction solution at 65 ° C. as an amine oxide ripening step, and the reaction was continued.
Analysis of the obtained post-reaction solution revealed that an aqueous dimethyldodecylamine oxide solution having an unreacted tertiary amine content of 0.21% by mass and a residual hydrogen peroxide content of 0.06% by mass was obtained. I understood.
The reaction rate (conversion rate) of dimethyldodecylamine to dimethyldodecylamine oxide was 99.3 mol%, and the content of dimethyldodecylamine oxide in the solution after the reaction was 34.2 mass%.

When the appearance of the solution after the reaction was observed, the amount of bubbles in the liquid was small because the viscosity of the liquid was low. When the viscosity at 30 ° C. was measured, it was as low as 58 mPa · s.
To 400 g of the obtained post-reaction solution, sulfuric acid (manufactured by Kanto Chemical Co., Inc., used after being diluted to 50% by mass with water) was added to adjust the pH to 6.80. Although the viscosity of the liquid increased, the liquid was transparent. The bicarbonate ion concentration was measured and found to be 0 ppm.
When the pH was measured after 20 hours, the pH was almost unchanged at 6.79.

  The color tone of the obtained aqueous dimethyldodecylamine oxide solution after pH adjustment was 5 (APHA). It was 20 (APHA) when it preserve | saved for 8 days at 70 degreeC with a 50 mL screw mouth bottle, and the color tone after a preservation | save was measured. The reaction conditions and results are shown in Table 1.

(Example 5)
In Example 4, sulfuric acid (manufactured by Kanto Chemical Co., Inc., diluted with water to 50% by mass) was added to 400 g of the post-reaction solution obtained after the amine oxide ripening step under the condition of 22 ° C., and pH 6 Adjusted to .50. The viscosity of the liquid increased and air bubbles were entangled. When the viscosity at 30 ° C. was measured, it was 997 mPa.s. It was high with s.
Therefore, 8.4 g of water was added to 400 g of the post-reaction solution obtained in Example 4 and stirred and mixed to obtain a diluted solution having a dimethyldodecylamine oxide content of 33.5% by mass. When the viscosity of the obtained diluted solution was measured at 30 ° C., the viscosity of the solution was reduced to 51 mPa · s, the number of bubbles was small, and the solution was easy to handle.

To 400 g of the obtained diluted solution, sulfuric acid (manufactured by Kanto Chemical Co., Inc., used by diluting to 50 mass% by adding water) was added to adjust the pH to 6.50. Although the viscosity of the liquid increased, the liquid was transparent. When the viscosity at 30 ° C. was measured, it was 277 mPa.s. s.
The bicarbonate ion concentration was measured and found to be 0 ppm. When the pH was measured after 20 hours, there was almost no change to pH 6.48.

  The color tone of the obtained aqueous dimethyldodecylamine oxide solution after pH adjustment was 5 (APHA). It was 20 (APHA) when it preserve | saved for 8 days at 70 degreeC with a 50 mL screw mouth bottle, and the color tone after a preservation | save was measured. The reaction conditions and results are shown in Table 1.

(Example 6)
Using the same reactor as in Example 1, 242.5 g of dimethyldodecylamine as in Example 1 and 125.0 g of dimethyltetradecylamine (trade name: Armin DM14D, manufactured by Lion Akzo Co., Ltd.) 400 g (1.76 mol) of dimethylcocoalkylamine (in Tables 1 to 3, Coco) having a pseudo-palm composition consisting of 32.5 g of dimethylhexadecylamine (trade name: Armin DM16D, manufactured by Lion Akzo Co., Ltd.) and distillation 500.0 g of water was added to prepare a raw material amine solution.
Carbon dioxide was added in the same manner as in Example 1 while maintaining the temperature of the heat transfer medium circulating in the cooling jacket at 31 ° C. and the raw material amine solution at 30 ° C.
After completion of the addition of carbon dioxide to the raw material amine, the acid value of the raw material amine solution in the reactor was measured in the same manner as in Example 1. The result was 2.3 (mg · KOH / g), and the formula ( The amine-converted acid value determined according to 1) was 5.0 (mg · KOH / g-amine).

Then, 16.9% by mass of hydrogen peroxide-containing hydrogen peroxide solution 358.% so that the molar ratio of hydrogen peroxide to dimethylcocoalkylamine is hydrogen peroxide / dimethylcocoalkylamine = 1.010. 7 g (1.78 mol) was dropped into the raw material amine solution over 2 hours using the hydrogen peroxide dropping device, and reacted.
The temperature of the heat transfer medium is kept at 25 until the amount of hydrogen peroxide added reaches 50% by mass with respect to the total amount so that the temperature of the reaction solution in the reaction vessel is 60 to 65 ° C. Controlled to ~ 35 ° C. After the added amount of hydrogen peroxide water reached 50% by mass or more, the temperature of the heat transfer medium was set to 55 to 65 ° C., and the temperature of the reaction liquid in the reactor was maintained at 65 ° C.

After completion of the dropwise addition of hydrogen peroxide, stirring was continued for 2.5 hours while maintaining the temperature of the reaction solution at 65 ° C. as an amine oxide ripening step, and the reaction was continued.
The obtained post-reaction solution was analyzed, and an aqueous dimethylcocoalkylamine oxide solution having an unreacted tertiary amine content of 0.26% by mass and a residual hydrogen peroxide content of 0.08% by mass was obtained. I understood it.
The reaction rate (conversion rate) of dimethylcocoalkylamine to dimethylcocoalkylamine oxide was 99.3 mol%, and the content of dimethylcocoalkylamine oxide in the solution after the reaction was 35.1% by mass. It was.

  When the appearance of the solution after the reaction was observed, the viscosity of the liquid was high, so that the amount of bubbles in the liquid was large and a slight gel was observed on the liquid surface. When the temperature of the solution after the reaction was lowered while stirring, the viscosity gradually increased. When the viscosity at 30 ° C. was measured, it was as high as 153 mPa · s.

  33.2 g of water was added to 400 g of the obtained solution after the reaction, and the mixture was stirred and mixed to obtain a diluted solution having a dimethylcocoalkylamine oxide content of 32.5% by mass. When the viscosity of the obtained diluted solution was measured at 30 ° C., the viscosity of the solution was as low as 76 mPa · s and it was easy to handle.

  To 400 g of the obtained diluted solution, sulfuric acid (manufactured by Kanto Chemical Co., Inc., used by diluting to 50% by mass by adding water) was added to adjust the pH to 7.30. Although the viscosity of the liquid increased, the liquid was transparent. The bicarbonate ion concentration was measured and found to be 85 ppm. When the pH was measured after 20 hours, it was not changed to pH 7.30.

  The color tone of the obtained pH-adjusted dimethylcocoalkylamine oxide aqueous solution was 5 (APHA). It was 20 (APHA) when it preserve | saved for 8 days at 70 degreeC with a 50 mL screw mouth bottle, and the color tone after a preservation | save was measured. The reaction conditions and results are shown in Table 1.

(Example 7)
Using the same reactor as in Example 1, the same amount of dimethyldodecylamine and distilled water as in Example 1 were added to the reactor to prepare a raw material amine solution.
Carbon dioxide was added in the same manner as in Example 1 except that the temperature of the heat transfer medium circulating in the cooling jacket was kept at 26 ° C. and the raw material amine solution was 25 ° C.
After completion of the addition of carbon dioxide to the raw material amine, the acid value of the raw material amine solution in the reactor was measured in the same manner as in Example 1. The result was 2.3 (mg · KOH / g), and the formula ( The amine-converted acid value determined according to 1) was 4.6 (mg · KOH / g-amine).

Then, in the same manner as in Example 1, the same amount of hydrogen peroxide as in Example 1 was added dropwise over 2 hours.
The temperature of the heat transfer medium is kept at 25 until the amount of hydrogen peroxide added reaches 50% by mass with respect to the total amount so that the temperature of the reaction solution in the reaction vessel is 60 to 65 ° C. Controlled to ~ 35 ° C. After the added amount of hydrogen peroxide water reached 50% by mass or more, the temperature of the heat transfer medium was set to 55 to 65 ° C., and the temperature of the reaction liquid in the reactor was maintained at 65 ° C.

After completion of the dropwise addition of hydrogen peroxide, stirring was continued for 2.5 hours while maintaining the temperature of the reaction solution at 65 ° C. as an amine oxide ripening step, and the reaction was continued.
Analysis of the resulting post-reaction solution revealed that an aqueous dimethyldodecylamine oxide solution having an unreacted tertiary amine content of 0.24% by mass and a residual hydrogen peroxide content of 0.06% by mass was obtained. I understood.
The reaction rate (conversion rate) of dimethyldodecylamine to dimethyldodecylamine oxide was 99.3 mol%, and the dimethyldodecylamine oxide content in the solution after the reaction was 36.4% by mass.

  When the appearance of the obtained solution after the reaction was observed, it was slightly turbid because of the high viscosity of the liquid, and bubbles were entrained in the liquid. When the temperature of the solution after the reaction was lowered while stirring, the viscosity increased. When the viscosity at 30 ° C. was measured, it was as high as 173 mPa · s.

  56.4 g of water was added to 800 g of the obtained solution after the reaction, and the mixture was stirred and mixed to obtain a diluted solution having a dimethyldodecylamine oxide content of 34.0% by mass. With respect to the obtained diluted solution, the viscosity at 30 ° C. was 56 mPa · s. Since the viscosity of the liquid decreased, the amount of bubbles decreased and the liquid became transparent.

  Hydrochloric acid (manufactured by Kanto Chemical) was added to 150 g of the obtained diluted solution under the condition of 22 ° C. to adjust the pH to 7.20. The liquidity was good. The bicarbonate ion concentration was measured and found to be 52 ppm.

  The color tone of the obtained aqueous dimethyldodecylamine oxide solution after pH adjustment was 5 (APHA). It was 20 (APHA) when it preserve | saved for 8 days at 70 degreeC with a 50 mL screw mouth bottle, and the color tone after a preservation | save was measured. The reaction conditions and results are shown in Table 2.

(Example 8)
In Example 7, 150 g of diluted solution obtained by adding water to the solution after the reaction was adjusted to 50% by mass of citric acid (manufactured by Wako Pure Chemicals, water added to anhydrous citric acid under the condition of 22 ° C. Used) and adjusted to pH 7.20. The liquidity was good. The bicarbonate ion concentration was measured and found to be 0 ppm.

  The color tone of the obtained aqueous dimethyldodecylamine oxide solution after pH adjustment was 5 (APHA). It was 15 (APHA) when it preserve | saved for 8 days at 70 degreeC with a 50 mL screw mouth bottle, and the color tone after a preservation | save was measured. The results are shown in Table 2.

Example 9
In Example 7, hydroxyethanediphosphonic acid (in Table 2, HEDP) (60% solution, manufactured by Wako Pure Chemical Industries, Ltd.) was added to 150 g of the diluted solution obtained by adding water to the solution after the reaction under the condition of 22 ° C. Was adjusted to pH 7.20. The liquidity was good. The bicarbonate ion concentration was measured and found to be 0 ppm

  The color tone of the obtained aqueous dimethyldodecylamine oxide solution after pH adjustment was 5 (APHA). It was 10 (APHA) when it preserve | saved for 8 days at 70 degreeC with a 50 mL screw mouth bottle, and the color tone after a preservation | save was measured. The results are shown in Table 2.

(Example 10)
In Example 7, lactic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 150 g of a diluted solution obtained by adding water to the post-reaction solution at 22 ° C. to adjust the pH to 7.20. The liquidity was good. The bicarbonate ion concentration was measured and found to be 0 ppm

  The color tone of the obtained aqueous dimethyldodecylamine oxide solution after pH adjustment was 5 (APHA). It was 20 (APHA) when it preserve | saved for 8 days at 70 degreeC with a 50 mL screw mouth bottle, and the color tone after a preservation | save was measured. The results are shown in Table 2.

(Example 11)
In Example 7, 150 g of diluted solution obtained by adding water to the solution after the reaction was added with tartaric acid (manufactured by Wako Pure Chemicals, adjusted to 50% by mass using water) at 22 ° C. PH was adjusted to 7.20. The liquidity was good. The bicarbonate ion concentration was measured and found to be 0 ppm

  The color tone of the obtained aqueous dimethyldodecylamine oxide solution after pH adjustment was 5 (APHA). It was 25 (APHA) when it preserve | saved for 8 days at 70 degreeC with a 50 mL screw mouth bottle, and the color tone after a preservation | save was measured. The results are shown in Table 2.

(Comparative Example 1)
Using the same reactor as in Example 1, the same amounts of dimethyldodecylamine and distilled water as in Example 1 were added to the reactor to prepare a raw material amine solution.
Carbon dioxide was added in the same manner as in Example 1 except that the temperature of the heat transfer medium circulating in the cooling jacket was kept at 26 ° C. and the raw material amine solution was 25 ° C.
After completion of the addition of carbon dioxide to the raw material amine solution, the acid value of the raw material amine solution in the reactor was measured in the same manner as in Example 1. The result was 2.8 (mg · KOH / g), The amine-converted acid value determined according to (1) was 5.6 (mg · KOH / g-amine).

Next, the heat transfer medium circulating in the cooling jacket was heated to 51 ° C., the temperature of the raw material amine solution was raised to 50 ° C., the heat transfer medium was removed, and the inside of the cooling jacket was emptied once. Next, the same amount of hydrogen peroxide as in Example 1 was dropped into the reaction vessel.
Since the temperature of the reaction solution increased with the addition of hydrogen peroxide, the temperature of the heat transfer medium was controlled to 15 to 20 ° C. so that the temperature of the reaction solution became 65 ° C. or less. A gel was formed on the contact surface with the jacket, the heat removal efficiency was lowered, and the temperature of the reaction solution exceeded 65 ° C. Therefore, the cooling water was once drained, and the dropwise addition of hydrogen peroxide was interrupted until the temperature of the reaction solution reached 62 ° C., and then the addition of hydrogen peroxide and the circulation of the heat transfer medium were resumed. When the reaction temperature reached 65 ° C, the addition of hydrogen peroxide was stopped, and the temperature of the reaction solution was maintained at 60 to 65 ° C while repeating the operation of removing the heat transfer medium. After the temperature rise of the reaction liquid was not observed, the temperature of the heat transfer medium was set to 55 to 65 ° C, and the temperature in the reactor was kept at 65 ° C. For this reason, it took 3.4 hours to finish dropping hydrogen peroxide.

After completion of the dropwise addition of hydrogen peroxide, stirring was continued for 2.5 hours while maintaining the temperature of the reaction solution at 65 ° C. as an amine oxide ripening step, and the reaction was continued.
Analysis of the resulting post-reaction solution revealed that an aqueous dimethyldodecylamine oxide solution having an unreacted tertiary amine content of 0.22% by mass and a residual hydrogen peroxide content of 0.07% by mass was obtained. I understood.
The reaction rate (conversion rate) of the obtained dimethyldodecylamine to dimethyldodecylamine oxide was 99.3 mol%, and the content of dimethyldodecylamine oxide in the solution after the reaction was 36.4% by mass.

  When the appearance of the obtained solution after the reaction was observed, the gel floated on the liquid surface and bubbles were entrained in the liquid. When the temperature of the solution after the reaction was lowered while stirring, the viscosity increased. When the viscosity at 30 ° C. was measured, it was as high as 173 mPa · s.

  The pH of the obtained post-reaction solution was 7.65. The bicarbonate ion concentration was measured and found to be 435 ppm. When the pH was measured after 20 hours, it was changed to pH 7.75.

  The color tone of the obtained pH-unadjusted dimethyldodecylamine oxide aqueous solution was 5 (APHA). When it was stored in a 50 mL screw cap bottle at 70 ° C. for 8 days and the color tone after storage was measured, it was deteriorated to 35 (APHA). The reaction conditions and results are shown in Table 3.

(Comparative Example 2)
Using the same reactor as in Example 1, the same amounts of dimethyldodecylamine and distilled water as in Example 1 were added to the reactor to prepare a raw material amine solution.
Carbon dioxide was added in the same manner as in Example 1 while maintaining the temperature of the heat transfer medium circulating in the cooling jacket at 31 ° C. and the raw material amine solution at 30 ° C.
After completion of the addition of carbon dioxide to the raw material amine solution, the acid value of the raw material amine solution in the reactor was measured in the same manner as in Example 1. The result was 2.9 (mg · KOH / g), and the above formula The amine-converted acid value determined according to (1) was 5.8 (mg · KOH / g-amine).

Next, 521.4 g of hydrogen peroxide solution containing 13.8% by mass of hydrogen peroxide so that the molar ratio of hydrogen peroxide to dimethyldodecylamine is hydrogen peroxide / dimethyldodecylamine = 1.010 ( 2.11 mol) was dropped into the raw material amine solution over 2 hours using the hydrogen peroxide dropping device, and reacted.
The temperature of the heat transfer medium is kept at 25 until the amount of hydrogen peroxide added reaches 50% by mass with respect to the total amount so that the temperature of the reaction solution in the reaction vessel is 60 to 65 ° C. Controlled to ~ 35 ° C. After the added amount of hydrogen peroxide water reached 50% by mass or more, the temperature of the heat transfer medium was set to 55 to 65 ° C., and the temperature of the reaction liquid in the reactor was maintained at 65 ° C.

After completion of the dropwise addition of hydrogen peroxide, stirring was continued for 2.5 hours while maintaining the temperature of the reaction solution at 65 ° C. as an amine oxide ripening step, and the reaction was continued.
Analysis of the resulting post-reaction solution revealed that an aqueous dimethyldodecylamine oxide solution having an unreacted tertiary amine content of 0.20% by mass and a residual hydrogen peroxide content of 0.05% by mass was obtained. I understood.
The reaction rate (conversion rate) of dimethyldodecylamine to dimethyldodecylamine oxide was 99.3 mol%, and the content of dimethyldodecylamine oxide in the solution after the reaction was 34.2 mass%.

When the appearance of the solution after the reaction was observed, the amount of bubbles in the liquid was small because the viscosity of the liquid was low. When the viscosity at 30 ° C. was measured, it was as low as 58 mPa · s.
The pH of the obtained post-reaction solution was 7.68. The bicarbonate ion concentration was measured and found to be 440 ppm. When the pH was measured after 20 hours, it was changed to pH 7.76.

  The color tone of the obtained pH-unadjusted dimethyldodecylamine oxide aqueous solution was 5 (APHA). When it was stored in a 50 mL screw cap bottle at 70 ° C. for 8 days and the color tone after storage was measured, it was deteriorated to 35 (APHA). The reaction conditions and results are shown in Table 3.

(Comparative Example 3)
Using the same reactor as in Example 1, 400 g of dimethylcocoalkylamine and 500 g of distilled water in the same amounts as in Example 6 were added to the reactor to prepare a raw material amine solution.
Carbon dioxide was added in the same manner as in Example 1 except that the temperature of the heat transfer medium circulating in the cooling jacket was kept at 31 ° C. and the raw material amine solution was changed to 30 ° C.
After completion of the addition of carbon dioxide to the raw material amine solution, the acid value of the raw material amine solution in the reactor was measured in the same manner as in Example 1. The result was 2.3 (mg · KOH / g), The amine-converted acid value determined according to (1) was 5.2 (mg · KOH / g-amine).

Next, the heat transfer medium circulating in the cooling jacket was heated to 51 ° C., the temperature of the raw material amine solution was raised to 50 ° C., the heat transfer medium was removed, and the inside of the cooling jacket was emptied once. Next, the same amount of hydrogen peroxide as in Example 1 was dropped into the reaction vessel.
Since the temperature of the reaction solution increased with the addition of hydrogen peroxide, the temperature of the heat transfer medium was controlled to 15 to 20 ° C. so that the temperature of the reaction solution became 65 ° C. or less. A gel was formed on the contact surface with the jacket, the heat removal efficiency was lowered, and the temperature of the reaction solution exceeded 65 ° C. Therefore, the cooling water was once drained, and the dropwise addition of hydrogen peroxide was interrupted until the temperature of the reaction solution reached 62 ° C., and then the addition of hydrogen peroxide and the circulation of the heat transfer medium were resumed. When the reaction temperature reached 65 ° C, the addition of hydrogen peroxide was stopped, and the temperature of the reaction solution was maintained at 60 to 65 ° C while repeating the operation of removing the heat transfer medium. After the temperature rise of the reaction liquid was not observed, the temperature of the heat transfer medium was set to 55 to 65 ° C, and the temperature in the reactor was kept at 65 ° C. For this reason, it took 3.2 hours to complete the dropwise addition of hydrogen peroxide.

After completion of the dropwise addition of hydrogen peroxide, stirring was continued for 2.5 hours while maintaining the temperature of the reaction solution at 65 ° C. as an amine oxide ripening step, and the reaction was continued.
The obtained post-reaction solution was analyzed to obtain an aqueous dimethylcocoalkylamine oxide solution having an unreacted tertiary amine content of 0.25% by mass and a residual hydrogen peroxide content of 0.09% by mass. I understood it.
The reaction rate (conversion rate) of the obtained dimethylcocoalkylamine to dimethylcocoalkylamine oxide was 99.2 mol%, and the content of dimethylcocoalkylamine oxide in the solution after the reaction was 34.9% by mass. there were.

  When the appearance of the obtained solution after the reaction was observed, the gel floated on the liquid surface and bubbles were entrained in the liquid. When the temperature of the solution after the reaction was lowered while stirring, the viscosity increased. When the viscosity at 30 ° C. was measured, it was as high as 151 mPa · s.

  To 150 g of the obtained post-reaction solution, alkaline 25% sodium hydroxide (manufactured by Kanto Chemical Co., Ltd., adjusted to 25 mass% by adding water) was added under a condition of 22 ° C. to adjust the pH to 7.80. The viscosity of the liquid was high, and the gel near the liquid surface was floating. The bicarbonate ion concentration was measured to be 393 ppm. When the pH was measured after 20 hours, the pH had changed to 7.72.

  The color tone of the obtained pH-unadjusted dimethylcocoalkylamine oxide aqueous solution was 5 (APHA). When it was stored in a 50 mL screw mouth bottle at 70 ° C. for 8 days and the color tone after storage was measured, it was deteriorated to 45 (APHA). The reaction conditions and results are shown in Table 3.

In Tables 1 to 3 below, * 1 to 5 were evaluated according to the following criteria.
* 1: Liquidity was evaluated based on the following criteria.
○: The amount of bubbles is small and no gel is observed Δ: The amount of bubbles is slightly large and the gel is slightly observed ×: The amount of bubbles is large and the gel floats when left standing * 2: Evaluation was made based on criteria.
○: The amount of bubbles is small and gel is not observed Δ: The amount of bubbles is slightly large and the gel is slightly observed ×: The amount of bubbles is large and the gel floats when left standing * 3: The pH stability is shown below Based on the criteria of the evaluation.
○: Almost no change in pH during storage (less than 0.03)
Δ: pH slightly fluctuates during storage (0.03 or more and less than 0.06)
X: pH fluctuates during storage (0.06 or more)
* 4: Color stability was evaluated based on the following criteria.
○: slight deterioration in color tone (APHA change: less than 20)
Δ: Little deterioration in color tone (APHA change: 20 or more, less than 30)
X: Deterioration of color tone is large (APHA change: 30 or more)
* 5: As a comprehensive evaluation, for the above evaluation results of * 1 to 4, x: 0 points, Δ: 1 point, ○: 2 points, the total points of the evaluation results of * 1 to 4 are as follows: Based on the evaluation.
○: 6 to 8 points Δ: 3 to 5 points ×: 0 to 2 points

From the results of Tables 1 and 3, the post-reaction solution obtained by reacting a tertiary amine and hydrogen peroxide was diluted as necessary to improve the handling property, and then an acid was added. It has been found that adjusting the pH within the range of pH 6.6 to 7.4 improves the pH stability and the color tone stability as compared with the case where the pH is not adjusted or the case where the pH is adjusted with a non-acid.
Furthermore, it was found that by adjusting the bicarbonate ion concentration to 300 ppm or less, the color tone stability was improved as compared with the case where the pH was not adjusted or the bicarbonate ion concentration was higher than 300 ppm.
Moreover, in order to suppress the temperature rise at the time of reaction with a tertiary amine and hydrogen peroxide, the temperature of the heat transfer medium in the cooling jacket is kept at a low temperature of less than 25 ° C. until the amount of hydrogen peroxide added becomes 50% by mass. It was found that when heat is removed, gelation occurs and the reaction efficiency may be lowered. In addition, when the viscosity after reaction (30 ° C.) is 150 mPa · s or more, the liquid property may be deteriorated, and the pH value after pH adjustment may be changed, but by making it less than 150 mPa · s. It was found that the liquidity was improved and there was almost no fluctuation in the pH value after pH adjustment, and the production was more efficient.
Further, from the results in Table 2, it was found that organic acids such as citric acid, hydroxyethanediphosphonic acid, and lactic acid are excellent in color tone stability and highly effective in reducing bicarbonate ions as pH adjusting acids. .

The amine oxide production method of the present invention is suitable as an industrial amine oxide production method because it can efficiently produce a high-quality amine oxide excellent in handling properties, pH stability, and color tone stability. It is. In addition, the amine oxide produced by the method for producing amine oxide of the present invention is high quality, has low irritation to the skin, and is a body cleaner such as a kitchen detergent, a household detergent, a shampoo, a body shampoo, It can be suitably used for a wide range of applications such as cosmetics and cosmetics.

Claims (9)

The following general formula (I):
[Wherein, R ¹ represents a linear or branched alkyl group or alkenyl group having 6 to 22 carbon atoms into which any of an ester group, an amide group and an ether group may be inserted, and R ² and R ³ represents either an alkyl group having 1 to 3 carbon atoms or a hydroxyalkyl group,
A is
R ⁴ represents a linear or branched alkylene group having 2 to 4 carbon atoms, and n represents 0 or 1]
A process for producing an amine oxide represented by
(A) The following general formula (II):
[Wherein, R ¹ represents a linear or branched alkyl group or alkenyl group having 6 to 22 carbon atoms into which any of an ester group, an amide group and an ether group may be inserted, and R ² and R ³ represents either an alkyl group having 1 to 3 carbon atoms or a hydroxyalkyl group,
A is
R ⁴ represents a linear or branched alkylene group having 2 to 4 carbon atoms, and n represents 0 or 1]
A step of reacting a tertiary amine represented by the following formula with hydrogen peroxide in the presence of carbon dioxide; and (B) adding an acid to the post-reaction solution obtained by the step (A), Adjusting the pH of the solution;
A process for producing an amine oxide, comprising:   The method for producing an amine oxide according to claim 1, wherein the reaction in the step (A) is performed by adding hydrogen peroxide after adding carbon dioxide to a raw material amine solution containing a tertiary amine.   (A) The manufacturing method of the amine oxide in any one of Claim 1 to 2 with which reaction of a process is performed at 30-80 degreeC.   The reaction in step (A) is performed in a reactor equipped with a cooling jacket, and the reaction temperature is controlled by controlling the temperature of the heat transfer medium circulating in the cooling jacket. The manufacturing method of the amine oxide in any one.   The method for producing an amine oxide according to claim 4, wherein the temperature of the heat transfer medium circulating in the cooling jacket is set to 25 to 50 ° C when the addition rate with respect to the total amount of hydrogen peroxide is 0 to 50% by mass. .   The method for producing an amine oxide according to any one of claims 1 to 5, wherein the step (B) is a step of adjusting the pH of the post-reaction solution obtained in the step (A) to 6.6 to 7.4. A step of further diluting the post-reaction solution by adding a solvent to the post-reaction solution obtained by the step (C) (A) between the step (A) and the step (B);
Only including,
The method for producing an amine oxide according to any one of claims 1 to 6, wherein the solvent is at least one selected from water, methanol, ethanol, 2-propanol, ethylene glycol, and propylene glycol .   The method for producing an amine oxide according to claim 7, wherein the step (C) is a step of diluting the post-reaction solution obtained in the step (A) so that the viscosity becomes 30 to 150 mPa · s.   The method for producing an amine oxide according to any one of claims 1 to 8, wherein a bicarbonate ion concentration in the produced amine oxide is 0 to 300 ppm.