JPS6223739B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides γ-
The present invention relates to a method for producing chlorocarboxylic acid ester. γ-chlorocarboxylic acid esters are particularly preferred intermediates for the production of cyclopropanecarboxylic acids and their esters.

Many methods for producing γ-chloro fatty acid esters are known. That is, from butyrolactone and alcohol, in the presence of hydrogen chloride, omega-chlorobutyrate methyl-, -ethyl-, -propyl- and butyl esters are produced, but in this case, the lactones 2-
Higher esters are also produced from 3 moles. In the case of methyl esters, this amount of highly condensed esters is greater than 50%. By adding _ZnCl2 , the amount of highly condensed esters is reduced, but in this case, for example ω-
The theoretical yield of chlorobutyric acid methyl ester is 50.4.
It is only %. The yield of ethyl ester is 57.6% (Reppe, Ann. 596, pp. 163-224). Furthermore, the reaction of γ-valerolactone with absolute ethanol and HCl gas is known. In this case 4
- Chlorovaleric acid ethyl ester is obtained in a yield of 55% of theory (Julia et al, Bull.Soc.Chirnie
France 1960, p. 306). If such a mixture is saturated with HCl-gas for several hours, the yield increases to 79% of theory. It is also known to synthesize α-methyl-γ-chlorobutyric acid ethyl ester in a two-step process. According to this study, α-methylbutyrolactone was prepared using HCl and SOCl ₂ with a yield of 68%.
Conversion to methyl-γ-butyryl chloride, which is then reacted with anhydrous alcohol, yields the desired α-methyl ester in 84% yield. The overall yield is 57.1% of theory (Cannon et al. Am.
Soc, Vol. 81, pp. 1664 et seq.).

The yields achieved by the known methods are therefore very unsatisfactory. This drawback is eliminated by the present invention, which has succeeded in obtaining γ-chlorocarboxylic acid esters with a yield of over 90%.

The present invention has the general formula: [In the formula, R, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ may be the same or different and represent a straight or branched alkyl group having 1 to 4 carbon atoms, and In producing the γ-chlorocarboxylic acid ester represented by [Other than R can also represent a hydrogen atom], starting from the corresponding optionally substituted butyrolactone, alcohol and thionyl chloride (SOCl ₂ ), and optionally substituted butyrolactone is dissolved in anhydrous alcohol, reacted with at least an equivalent amount of thionyl chloride (SOCl ₂ ), and subsequently isolated from the SO ₂ formed by known methods. This invention relates to a method for producing chlorocarboxylic acid ester.

Since the reaction starts already at a low temperature, it is recommended to keep the temperature between about 20 and -60° C. by cooling during the thionyl chloride addition. After the addition of thionyl chloride is completed, the addition is desirably continued for several hours, e.g. 1 to 2 hours.
Post-stirring is carried out at a low temperature, for example from -20°C to about 5°C. Next, it is preferable to carry out further post-stirring for 1 to 2 hours, for example at room temperature.

Thionyl chloride is particularly used in an amount such that the molar ratio of lactone to thionyl chloride is about 1:1. However, advantageously the thionyl chloride is e.g. 25%
Used in excess amount. Usually 1:1-1:
3, in particular between 1:1.1 and 1:1.25.

Alcohols which can be used in the process of the invention include in particular methanol and ethanol, but also propanol and butanol, ie all alcohols having 1 to 4 carbon atoms.

After the end of the reaction or during post-stirring at a slightly elevated temperature, the SO ₂ formed is removed from the solution, which can take place together with the removal of the alcohol. For example, a vacuum can be applied or an inert gas, for example nitrogen, can be introduced. However, it is also possible to neutralize with SO ₂ -acceptors, such as lye or carbonates. However, it is also possible to pour the reaction mixture into water. In this case, the chlorocarboxylic acid ester is separated, but with SO ₂ and possibly HCl
remains dissolved in water.

The product is then distilled, for example in vacuo, for purification.

By this method, γ-chlorocarboxylic acid ester can be obtained in high yield and without generating significant amounts of by-products.

Example 1 γ-Butyrolactone in a 3-necked flask from 1.
Mix 258 g (=3 mol) with 500 ml of anhydrous methanol. Cool the mixture to 0°C. 380 g of thionyl chloride are then slowly added dropwise with good stirring, keeping the temperature below +5.degree. Mixture at 0℃
for 2 hours at 20°C, then 2 hours at 20°C, and then evacuated. SO ₂ and CH ₃ OH are then pumped out. The residue is distilled in vacuo. Boiling point 62℃/10
Converts to ω-chlorobutyric acid methyl ester at mmHg. Amount: 374g, equivalent to 91.3% of the theoretical value.

Example 2 Valerolactone (=γ-methyl-γ-butyrolactone, produced from levulinic acid by hydrogenation)
Add 300 g to 500 ml of absolute ethanol. 380 g of thionyl chloride are added to the mixture at 0.degree. C. and stirred for 2 hours at this temperature, followed by evacuation of _SO.sub.2 with nitrogen at 10-20.degree. The residue is distilled in vacuo. Boiling point 84-85
3-chlorovaleric acid ethyl ester is distilled out at ℃/15 mmHg. Amount: 462.6g, equivalent to 93.7% of the theoretical value.

Example 3 400 g of thionyl chloride are added to 300 g of α-methyl-γ-butyrolactone in 500 ml of absolute ethanol at 0° C. and subsequently stirred for 4 hours at 0° C. and 2 hours at 20° C., during which the sulfurous acid is liberated with nitrogen. The crude product is poured into water, neutralized with NaOH, then taken up with methylene chloride, dried and evaporated under vacuum. The product is rectified in a rectifier under vacuum. Boiling point 78℃/10mmHg
α-methyl-ω-chlorobutyric acid ethyl ester is distilled out. Amount: 443.5g = 89.9% of theoretical value.

Example 4 500 g of β-methylbutyrolactone was mixed with 1 part of anhydrous methanol, cooled to -20°C, then 750 g of thionyl chloride was slowly added under stirring for 2 hours.
Stir at 20 to -10°C and then bring to room temperature. After 6 hours, the mixture is evaporated in a rotary pressure cooker at 40°C and 20 Torr. The residue is distilled on a 1 m Vigreux column under vacuum. After a short period of time, boiling point 67-68
β-Methyl-γ-chlorobutyric acid methyl ester is distilled out at ℃/10mmHg. Amount: 674.1g, theoretical value
Equivalent to 89.6%.

γ-Butyrolactone in the three-necked flask of Comparative Example 1
Mix 258 g with 500 ml of absolute methanol. Introduce HCl gas until saturation under sufficient cooling, then
Leave it at 20℃ for 4 hours.

The post-treatment consisted of 45.8 g of ω-chlorobutyric acid methyl ester (theoretical value) along with the main amount of unreacted butyrolactone.
11.2%).

Claims (1)

[Claims] 1. General formula: [In the formula, R, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ may be the same or different and represent a straight or branched alkyl group having 1 to 4 carbon atoms, and A method for producing a γ-chlorocarboxylic acid ester represented by [Other than R can also represent a hydrogen atom] from the corresponding optionally substituted butyrolactone using an alcohol and thionyl chloride, which may be substituted. 1. A process for producing γ-chlorocarboxylic acid ester, which comprises dissolving butyrolactone in anhydrous alcohol, reacting it with at least an equivalent amount of thionyl chloride, and subsequently separating the SO ₂ formed by a method known per se. 2. The method of claim 1, wherein thionyl chloride is added at a temperature below about 20°C. 3. Molar ratio of lactone to thionyl chloride is 1:1~
The method according to claim 1 or 2, wherein the ratio is maintained between 1:3. 4. The method according to claim 1, wherein an anhydrous alcohol having 1 to 4 carbon atoms is used.