JPS6337780B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for purifying crude ketazine solutions. Hydrazine is used as a raw material for oxygen scavengers or blowing agents, and ketazine is a compound useful as an intermediate in the production of hydrazine. The latter, ketazine, is known to be produced by reacting hydrogen peroxide, ketone, and ammonia in the presence of nitriles (Japanese Patent Publication No. 51-33083
issue). However, with this method, the inventors' patent application
A side reaction occurs as described in No. 53-35833,
Ketoxime is produced as a by-product. According to the invention, this side reaction can be suppressed and ketazine can be obtained in high yield, but it is still difficult to completely eliminate the by-product of ketoxime. For this reason, in the step of separating ketazine from the reaction solution using a known method and hydrolyzing it to form hydrazine hydrate, this by-product ketoxime accompanies ketazine and gradually accumulates, causing harm to the hydrolysis and further is mixed into the product hydrazine hydrate in the form of ketoxime or hydroxylamine, causing a decrease in product quality. It is also known that, as another method for producing hydrazine, hydrazine was obtained by reacting hydroxylamine-O-sulfonic acid with ammonia. (US Pat. No. 2,935,378, May 3, 1960) The products of this process are a large amount of salt (ammonium sulfate) and a low concentration of hydrazine. In order to efficiently separate hydrazine from the reaction mixture, a ketone can be added to the reaction mixture to convert it to ketazine, and after this ketazine is isolated, it can be hydrolyzed to hydrazine hydrate, but even with this method, Hydroxylamine is produced as a by-product through a side reaction in which hydroxylamine-O-sulfonic acid is partially hydrolyzed, and this hydroxylamine is converted to ketoxime by the ketone, so it has the same drawbacks as the above-mentioned method. As described above, it is strongly desired by those skilled in the art to develop a method for efficiently and economically separating and removing contaminated ketoxime from crude ketazine solutions, but so far there have been no effective means to satisfy this desire. was unknown. The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems related to impurities, that is, ketoxime by-products, and have found that ketazine and ketoxime can be distilled in the presence of ketones in a very simple and efficient manner. The desired ketazine was successfully separated, thus completing the method for purifying a crude ketazine solution according to the present invention. That is, the present invention is based on the general formula () General formula () containing a ketoxime represented by [wherein R ₁ and R ₂ are the same or different alkyl groups having 1 to 3 carbon atoms] By distilling a crude solution of ketazine represented by the formula [wherein R ₁ and R ₂ are the same as above] in the presence of a ketone of the type corresponding to the ketazine and an alkali selected from caustic alkali or alkali carbonate. ,
The present invention relates to a method for purifying a crude ketazine solution containing ketoxime, which is characterized by distilling ketazine together with ketone and leaving ketoxime behind. The features of the present invention include the following points. (b) Ketoxime impurities can be efficiently separated and removed by simple operations. (b) A ketazine solution substantially free of ketoxime is obtained. (c) Ketazine can be efficiently hydrolyzed using a purified ketazine solution. (d) The hydrazine hydrate or hydrazine salt obtained by hydrolysis is of high quality. (e) Impurity ketoxime can also be isolated and recovered and used effectively. In the method of the present invention, the mechanism by which ketazine is selectively distilled out together with ketones by distillation in the presence of ketones has not been completely elucidated at present, but it is presumed to be due to the following reasons. be done. Ketazine and ketoxime have similar boiling points and behave similarly towards water, so
When distilled, both ketazine and ketoxime are easily distilled out in an aqueous system, and separation by fractional distillation is difficult. However, when distillation is carried out in the presence of a ketone as in the method of the present invention, the ketone disrupts the azeotropic relationship of the three-component system of ketazine-ketoxime-water, moderately suppresses the amount of water distilled out, and the ketone and ketazine is probably distilled out selectively. Ketazine can be easily separated from the distilled ketone-ketazine solution (fraction) by ordinary fractional distillation. In addition, in the method of the present invention, it is possible to rectify more effectively by distilling in the presence of an alkali, but this is because ketoxime is an amphoteric substance, so it forms a weak bond with the alkali as shown in the example of the following formula, and the ketoxime is dissolved in the liquid phase. This is probably due to the fact that it tends to remain. (R ₁ and R ₂ have the above-mentioned meanings. M means an alkali metal.) However, this bond is weak, and when steam distilled, the ketoxime is also distilled and recovered, and the remaining aqueous alkali solution is left as it is or concentrated. Since it can be recycled and reused, it is extremely advantageous in terms of resource conservation. Next, embodiments of the present invention will be described in detail. The crude ketazine solution containing ketoxime as an impurity, which is the raw material used in the present invention, is as follows:
According to the inventions of Japanese Patent Publication No. 51-33083 and Japanese Patent Application No. 53-35833, a reaction solution obtained by reacting hydrogen peroxide, ketone, and ammonia in the presence of nitriles, etc., is directly used. Or special public service 1977-
A ketazine solution containing ketoxime obtained by distillation by the method of No. 12684, etc., or a ketoxime converted to ketazine by adding a ketone to a reaction solution obtained by the method of U.S. Pat. Any solution containing ketoxime as an impurity in the ketazine solution can be used. Further, even if the raw material solution contains inorganic salts, ammonia, nitriles, etc., they hardly interfere with the selective distillation effect of ketazine. Usually, the crude ketazine solution contains 0.01 to 1.0 mole of ketoxime per mole of ketazine, but it can be used as a raw material even outside this range. As for the form of the solution, an aqueous solution is generally preferred. Specific examples of ketazine represented by the general formula () include dimethylketazine, diethylketazine, methylethylketazine, methylisopropylketazine, and the like. In addition, the ketoxime represented by the general formula () is as follows:
Examples include acetone oxime, diethyl ketone oxime, methyl ethyl ketone oxime, methyl isopropyl ketone oxime and the like. Furthermore, specific examples of ketones used in the present invention include acetone, diethyl ketone, methyl ethyl ketone,
Examples include methyl isopropyl ketone. Usually, the ketone is used in such a manner that it is maintained at 1% by weight or more based on the raw material crude ketazine solution during distillation, and the ketone can be supplied batchwise or continuously. When the amount of ketone used decreases, the effect of the present invention becomes poor and the separation of ketoxime and ketazine deteriorates.On the other hand, when the amount of ketone used is excessive, the distillation ratio of ketazine to ketone decreases, resulting in thermoeconomic problems. It will be disadvantageous. For this reason, preferably 3 to 20% by weight based on the raw material crude ketazine solution.
It is best to supply the ketones so that they are present. Since ketazine may be partially hydrolyzed to ketone hydrozone or hydrazine by heating, it is also possible to supply ketone to the crude ketazine solution as a raw material and allow sufficient reaction time to recombine with the ketone and convert it to ketazine. It's advantageous. The distillation operation of the present invention can be carried out at a temperature corresponding to the working pressure, from reduced pressure to increased pressure of about 5 kg/cm ² , but usually reduced pressure to normal pressure is used. If pressure increases, ketazine tends to be more easily hydrolyzed and its separation from ketoxime becomes worse, and a polymerization reaction of ketones and ketazine occurs, increasing the loss of ketones and ketazine, so excessive pressure should not be used. It is disadvantageous. If the distillation operation is carried out in the presence of an alkali, the separation of ketazine and ketoxime will be carried out advantageously, probably for the reason explained in reference to the reaction formula (2) above. In this case, specific examples of the alkali include sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate. The amount of alkali used is not particularly limited, but is preferably 1 to 20 moles per mole of ketoxime. The alkali is used in the form of a solid or aqueous solution, which can be added beforehand to the crude ketazine solution or fed batchwise or continuously during the extraction or distillation. There is no particular limitation on the apparatus for carrying out the distillation of the present invention.
In addition to the usual simple distillation apparatus, a fractionating column having several theoretical plates can also be used, and either a continuous method or a batch method can be used. The residual liquid remaining after ketazine is distilled off by the process of the present invention contains ketoxime, and this ketoxime can be effectively utilized as it is or after being isolated by steam distillation. Furthermore, the alkali-containing residual liquid remaining after the ketoxime has been removed can be used repeatedly in the method of the present invention either as it is or after being concentrated. The present invention will be specifically explained below with reference to Examples, but these are merely for illustration and do not mean a limitation on the idea of the present invention. Example 1 100 ml of an aqueous solution containing 6.20 g (6.20 w/V%) of dimethyl ketazine, 2.30 g (2.30 w/V%) of acetone oxime, and 1.50 g (1.5 w/V%) of acetone,
The mixture was placed in a 200 ml branched distillation flask equipped with a dropping funnel, and distillation was carried out while supplying acetone from the dropping funnel at a rate of 50 ml/hour while adjusting the heating noise to keep the liquid volume in the flask constant. After distilling off the first 50 ml of distillate (Fraction 1), the next 50 ml of distillate (Fraction 2) was distilled off, and the acetone supply and distillation were stopped. The results of analysis of the distillate and the residual liquid in the flask were as follows.

[Table] As shown in the table above, the ratio of acetone oxime to dimethylketazine in the raw materials is (weight ratio =)
While it was 2.70, it was 9.91 for fraction 1,
The proportion of dimethylketazine has increased significantly, and the purity of dimethylketazine has increased significantly. Fraction 2
The ratio of dimethyl ketazine to acetone oxime is almost the same as the raw material. On the other hand, the proportion of acetone oxime in the flask residual liquid is large. Example 2 The composition of Example 1 was further added with sodium hydroxide.
The distillation operation was carried out in exactly the same manner except that 7.5 g was added. The results of analysis of each fraction were as follows.

[Table] As shown in the table above, by adding sodium hydroxide,
A better purification result was obtained compared to the previous example, and fraction 1
is not contaminated with acetone oxime at all. Next, the residual liquid in the flask was subjected to steam distillation, and 400 ml of distillate was collected. This distillate was an aqueous solution containing 2.21 g of acetone oxime. The residual liquid after recovering this acetone oxime is essentially an aqueous sodium hydroxide solution, which is concentrated and recycled for use. Example 3 Methyl ethyl ketazine 1.50g (1.50w/V%),
Methyl ethyl ketone oxime 0.60g (0.60w/V
%), and 2.0g of methyl ethyl ketone (2.0w/V
%) was placed in a 200 ml Claisen-type distillation flask equipped with a dropping funnel and a vacuum device, and 15 ml of the concentrated sodium hydroxide solution recovered in Example 2 (sodium hydroxide
(containing 7.0 g) was added, and while supplying methyl ethyl ketone from the dropping funnel at a rate of 50 ml/hour, the flask was heated to maintain a constant liquid volume at 200 mmHg.
Distilled under reduced pressure. First, 50 ml (fraction 1) and then 50 ml (fraction 2) of the distillate were distilled off, and the supply of methyl ethyl ketone and distillation were stopped. The results of analysis of the distillate and the residual liquid in the flask were as follows.

[Table] As shown in the above table, good results were obtained in fraction 1, in which methyl ethyl ketone azine substantially free of methyl ethyl ketoxime was obtained.

Claims (1)

[Claims] 1 General formula () General formula () containing a ketoxime represented by [wherein R ₁ and R ₂ are the same or different alkyl groups having 1 to 3 carbon atoms] By distilling a crude solution of ketazine represented by the formula [wherein R ₁ and R ₂ are the same as above] in the presence of a ketone of the type corresponding to the ketazine and an alkali selected from caustic alkali or alkali carbonate. ,
A method for purifying a crude ketazine solution containing a ketoxime, characterized by distilling ketazine together with a ketone and leaving a ketoxime. 2. The method according to claim 1, wherein the crude ketazine solution is an aqueous solution containing 0.01 to 10 moles of ketoxime per mole of ketazine. 3. The method according to claim 1, wherein the ketone is present in an amount of 1% by weight or more based on the raw material crude ketazine solution during distillation. 4. The method according to claim 1, wherein the caustic alkali is sodium hydroxide or potassium hydroxide, and the alkali carbonate is sodium carbonate or potassium carbonate.