JPS6154014B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing carbonic acid esters of secondary or tertiary alcohols, and more specifically, the present invention relates to a method for producing carbonic acid esters of secondary or tertiary alcohols, and more specifically, by reacting secondary or tertiary alcohols with chlorocarbonic acid esters, secondary or tertiary alcohols can be produced. The present invention relates to a method for producing carbonic esters, characterized in that a finely ground anhydrous solid alkaline substance is used. Known methods for producing alcohol carbonate esters include a method using carbonate and alcohol, a method in which alcohol and chlorocarbonate ester are reacted with an aqueous alkali solution, and a method in which alcohol and chlorocarbonate ester are reacted with an organic base. In the alcohol exchange reaction with carbonate, the reactivity of alcohol is in the order of primary≫secondary≫tertiary;
and tertiary alcohols are difficult to form carbonate esters. When carbonate esters are synthesized by the reaction of chlorocarbonate esters and alcohol, they are synthesized using an aqueous solution of caustic soda or an amine base. The present inventors attempted to produce a carbonate ester of a secondary or tertiary alcohol from a secondary or tertiary alcohol and a chlorocarbonate. The target carbonate ester of secondary or tertiary alcohol is represented by the following general formula (), () or (), where () and () are used as a fragrance, and () is used as an intermediate. It is an important compound as

【formula】

【formula】

[Formula] Here, R ₁ is hydrogen or a methyl group, and R ₂ is

It is an isoprenoid group (n is an integer of 1 to 10) represented by the formula, a double bond-transferred isoprenoid group, a cyclized isoprenoid group, or a partially or completely hydrogenated product thereof. R ₃ represents a straight-chain alkyl group or a branched alkyl group, R ₄ , R ₅ , and R ₆ represent hydrogen, a straight-chain alkyl group,
It indicates a branched alkyl group, an alkenyl group, etc. In the method of synthesizing these carbonate esters of secondary or tertiary alcohols, the inventors found that when chlorocarbonate and an alkaline aqueous solution are used, the yield of the carbonate ester produced is only 50% or less. I learned that there isn't. Also, chlorocarbonate and aliphatic amines such as triethylamine,
Even if triethylenediamine, diethylaniline as an aromatic amine, pyridine, quinoline, etc. as an alicyclic amine are used alone or in combination, the desired product cannot be obtained at all, or
Even if it were obtained, the yield would be only low and it was judged that it could not be used as an industrial synthesis method. These known methods result in lower yields of tertiary alcohol carbonate because the hydrolysis rate of chlorocarbonate is faster than when it reacts with alcohol, or because stable salts are created when amines are used. It is likely that there will be no improvement. Therefore, we tried a non-aqueous reaction, but when a solid alkali was used, the salt formed during the reaction covered the alkali surface, and the reaction did not occur sufficiently, resulting in the desired product being obtained only in a low yield. I learned that.
When the solid alkali was pulverized in a solvent or pulverized during the reaction, surprisingly, the desired carbonate ester of a secondary or tertiary alcohol could be produced easily and in high yield. The present invention was achieved by discovering that the present invention can be obtained at a high rate. The gist of the present invention is to provide a method for producing a carbonic acid ester of a secondary or tertiary alcohol, in which solid anhydrous caustic alkali is made into fine particles, and a secondary or tertiary alcohol and a chlorocarbonic ester are added to the solid anhydrous caustic alkali into fine particles. The method is characterized in that the reaction is carried out by adding a solid anhydrous caustic alkali into fine particles in the reaction medium. In order to make the alkaline substance into fine particles, it can be pulverized using a homomixer such as Polytron (trade name) or a ball mill in a liquid medium that does not dissolve the substance and is inert to the substance. In this way, the alkaline substance can be pulverized into fine particles with a particle size of 50 μm or less without absorbing water. As the solvent that can be used in the present invention, general organic solvents can be used, but saturated aliphatic hydrocarbons, aromatic hydrocarbons, aliphatic ketones, etc. are particularly preferred. These solvents include pentane, hexane, octane, benzene, xylene, Toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone and the like are preferred. The amount of these solvents used is secondary or tertiary.
It is preferably 2 to 15 times the amount of alcohol, preferably 3 to 10 times. If the amount is less than twice that of the secondary or tertiary alcohol, the reaction system will become gel-like when reacting with finely ground caustic alkali, reducing the efficiency of heat removal stirring and reducing the yield of the desired carbonate ester. decreases. In addition, using more than 15 times the amount of solvent improves the yield of carbonate ester, but decreases the yield of the target product relative to the reaction volume, and also reduces the efficiency of the reaction due to post-treatment, recovery, and reuse of a large amount of solvent. It cannot be said that it is industrially preferable. The caustic alkali used in this reaction includes alkali hydroxide, alkaline earth hydroxide, alkali and alkaline earth carbonate, etc. These are preferably those that can be easily pulverized because they are used as fine particles. Particularly preferred are sodium hydroxide, potassium hydroxide, etc., which can be easily pulverized in an organic solvent using a homomixer or the like, and from an industrial standpoint, sodium hydroxide is preferred. The amount of caustic alkali used is 1 to 1 times the molar ratio of chlorocarbonate.
The range is 15 times, preferably 1.5 times to 10 times. If it is less than 1 mole, it is secondary or tertiary.
The reaction rate of the grade alcohol is low, and a large amount of raw alcohol needs to be recovered and reused, which is not preferable.
Moreover, if it is used in excess of 15 times the mole, not only will the treatment of excess caustic alkali after the reaction be complicated, but also the cost of raw materials will increase, which is not preferable. Examples of chlorocarbonate include methyl, ethyl,
It has a saturated straight chain alkyl or saturated branched alkyl group such as n-propyl, i-propyl, n-butyl, etc., and the amount used is 0.5 to 5 times the molar ratio of secondary or tertiary alcohol. times, preferably in the range of 1 to 3 times. If it is less than 1 mole, the amount of unreacted secondary or tertiary alcohol will be recovered and reused, and if it is more than 5 moles, chlorocarbonate will remain as unreacted, which is industrially disadvantageous. The method of the present invention can be carried out at a reaction temperature between -20°C and 50°C, but the preferred reaction temperature is between -10°C and 20°C. If the temperature is lower than -20°C, the reaction rate is slow and it takes a long time to complete the reaction, and if the temperature is higher than 50°C, side reactions occur, causing a decrease in yield. The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to the examples. Example 1 500 ml of toluene was placed in a reaction vessel equipped with a 1-volume homomixer, and 80 ml of granular anhydrous caustic soda was added.
g was added and pulverized for 30 minutes at 3000 rpm to obtain a toluene suspension in caustic soda. Then, the mixture was cooled to 5° C., 61 g of dehydrolinalool was added, and a solution of 60 g of chloroethyl carbonate dissolved in 100 ml of toluene was added dropwise through a separating funnel for reaction. During the dropwise addition, stirring was continued and the mixture was cooled to maintain the reaction temperature at 5 to 10°C. The dropwise addition time required 3 hours, and the reaction was continued for 30 minutes at the same temperature after the dropwise addition was completed. Then, the alkali was removed with a large amount of 10% brine and water, the organic layer was separated, the toluene was expelled, and the residue was removed. Rectification was carried out under reduced pressure to obtain 69 g of a fraction having a temperature of 88-91°C (2 mmHg). The yield is 77% based on the dehydrolinalool used.
%, and it was confirmed by infrared analysis, mass spectrometry, NMR analysis, etc. that it had the structure of dehydrolinalyl ethyl carbonate. Comparative Example 1 Put 80 ml of toluene, 61 g of dehydrolinalool, and 65 g of chloroethyl carbonate into a reaction container and heat at 5°C.
A concentrated stock solution of 80 g of sodium hydroxide dissolved in 90 g of water was added dropwise with stirring over 1.5 hours. During this time, the mixture was cooled to maintain the temperature at 5 to 10°C, and after the dropwise addition was completed, the reaction was continued at the same temperature for an additional 30 minutes. After the completion of the reaction, the aqueous layer was separated, and the organic layer was washed with 10% brine until the alkali was removed.The obtained organic layer was rectified after expelling toluene in the same manner as in Example 1 to obtain 38 g of dehydrolinalyl ethyl carbonate. Ta. This was a yield of 42% based on the dehydrolinalool used. Example 2 In order to examine the pulverizing effect of caustic soda under the conditions of Example 1, a reaction was carried out while changing the rotation speed of the pulverizer, and the results shown in Table 1 were obtained.

[Table] Example 3 A reaction was carried out under the conditions of Example 1 by changing the type and amount of alkali used. Other conditions and treatments were the same, and the results in Table 2 were obtained.

[Table] Example 4 In the method of Example 1, the reaction was carried out by changing the type and amount of solvent used. The amount of sodium hydroxide used as the caustic alkali is 160g.
The chlorocarbonate was dissolved in 100 ml of the solvent used and reacted dropwise. The results are shown in Table 3. The amount of solvent used in the table is the total amount used including 100 ml of this solvent for dissolution.

[Table] Example 5 The same reaction conditions and processing operations were carried out in the method of Example 1, except that 73 g of propyl chlorocarbonate was used instead of ethyl chlorocarbonate, and 94 g of dehydrolinalyl propyl carbonate was prepared.
92 g was obtained as a fraction at ~97°C (2 mmHg). This is 81% of the amount of raw material dehydrolinalool used.
The yield is Example 6 The method of Example 1 was repeated except that 88 g of dehydronerollidol was used instead of dehydrolinalool, a polytron was used as a mixer, and sodium hydroxide was pulverized at a rotation speed of 400 rpm.
By a similar reaction, dehydronerollyl ethyl carbonate was obtained as a fraction at 139-143°C (1 mmHg).
g (yield 83%). Example 7 The reaction was carried out under the same conditions as in Example 1 except that 74 g of t-butanol was used instead of dehydrolinalool, and 61 g of t-butylethyl carbonate was obtained as a fraction at 130 to 134°C. . Example 8 A reaction was carried out under the same conditions as in Example 1 except that 74 g of sec.-butanol was used instead of dehydrolinalool, and 106 g of sec.-butylethyl carbonate was obtained as a fraction of 130 to 134°C. .

Claims (1)

[Claims] 1. In a method for producing a carbonate ester of a secondary or tertiary alcohol by reacting a secondary or tertiary alcohol with a chlorocarbonate in the presence of an alkaline substance, as the alkaline substance A method for producing a carbonate ester of a secondary or tertiary alcohol, which comprises using an anhydrous solid fine particulate alkaline substance and carrying out the reaction in a non-aqueous medium. 2. According to claim 1, the anhydrous solid fine particulate alkaline substance is micronized to a particle size of 50μ or less in a liquid that does not dissolve the alkaline substance and is inert to the alkaline substance. Method described. 3. Claim 1 or 2, in which chlorocarbonate is used in an amount of 0.5 to 5 times the molar ratio to the secondary or tertiary alcohol, and caustic alkali is used as the alkaline substance in an amount of 1 to 15 times the molar ratio to the chlorocarbonate. The method described in section. 4. The method according to claim 1, 2 or 3, wherein the obtained carbonate ester of a secondary or tertiary alcohol is represented by the following general formula. [Formula] [Formula] [Formula] (In the general formula, R ₁ is hydrogen or a methyl group, R ₂ is an isoprenoid group shown in [Formula] (n is an integer from 1 to 10), double bond transition isoprenoid group, a cyclized isoprenoid group, or a partially or completely hydrogenated product thereof, R ₃ is a straight-chain or branched alkyl group, R ₄ , R ₅ , R ₆ are hydrogen straight-chain or branched alkyl groups, (Indicates an alkenyl group.)