JPS6210976B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides 3-
This invention relates to a method for producing pentenoic acid.

For the production method of 3-pentenoic acid, see Kyoritsu Shuppan
The Kagaku Daijiten (volume 1, p. 887) published by Co., Ltd. describes that it is produced by condensing malonic acid and acetaldehyde in the presence of pyridine, but the detailed conditions, yield, purity etc. There is no mention of such things. In addition, S.E. Boxer et al.
Boxer, RPLinstead, J.Org.Chem., 1931, 740
~751) gave a detailed report on the reaction between butyraldehyde and malonic acid. However, in this report, when pyridine, piperidine, triethanolamine, diethylaniline, etc. are used as the base, the purity of βγ-type acid is 70 to 100.
% of the product, but the yield is 10 to 37% (when a large amount of pyridine is used, the yield is 75 to 82%, but the purity of the βγ-type acid It has been shown that only 2% to 5% of the results are achieved.

The present inventors have conducted various studies to selectively obtain 3-pentenoic acid with high purity and high yield.
The present invention was made based on the recognition that the object could be achieved by using N-diethylbenzylamines. That is, the present invention combines propionaldehyde and malonic acid with the general formula (In the formula, R represents a lower alkyl group, and X represents a hydrogen atom or a halogen atom.)
- This is a method for producing 3-pentenoic acid by reacting it in the presence of dialkylbenzylamines.

In the method of the present invention, there is no significant difference in the effect depending on the order of addition of the raw materials, and there is no problem in adding propionaldehyde in portions or dropwise. As mentioned above, preferably about 1.2 times the mole is used, and the N,N-dialkylbenzylamine is used in an equal mole or more, preferably, in an equal mole to malonic acid, and these three are mixed, and then Stir at room temperature for several hours, preferably 2 to 4 hours. Then, malonic acid dissolves, forming a homogeneous system, and the reaction proceeds. Then, for several hours, preferably
The reaction is terminated by gradually increasing the temperature to about 100°C over 2 to 4 hours. At this time, if the temperature increase rate is too fast, propionaldehyde will be lost. Therefore, it is necessary to maintain this reaction at room temperature for several hours and then gradually raise the temperature to terminate the reaction.
Therefore, there is no particular advantage in increasing the yield to maintain the temperature even after raising the temperature to about 100°C.

After the reaction is completed, the amine is liberated by treatment with an alkaline solution and removed by separation. The recovered amine can be used repeatedly in the reaction as it is. on the other hand,
3-pentenoic acid is extracted into water as an alkali of 3-pentenoic acid, and after liquid separation, it is acidified and liberated with an acid, extracted with benzene, etc., and concentrated and distilled to obtain 3-pentenoic acid.

In addition, N,N-dialkylbenzylamines are compounds in which the substituent R is a methyl group, ethyl group or other lower alkyl group, and X is a hydrogen atom, or a chlorine atom, a bromine atom or other halogen atom. , p-chloro-N,N-diethylbenzylamine is preferably used.

The method of the present invention belongs to the so-called Knovenagel method, which is a method in which an active methylene compound is condensed with a carbonyl compound in the presence of an amine or ammonia, similar to the methods described in the above-mentioned documents. As is clear from various literature descriptions, the reaction yield was extremely low.
In contrast, in the present invention, propionaldehyde and malonic acid are reacted in the presence of N,N-dialkylbenzylamines, and in particular, the temperature is gradually raised over several hours after being kept at room temperature for several hours. By allowing the reaction to complete, we were able to obtain a highly pure product with an unexpectedly high reaction yield. Furthermore, we recovered the N,N-dialkylbenzylamines and conducted repeated reactions. This is a highly effective method, as it can be manufactured at low cost if used for this purpose.

Next, an example will be described.

Example 1 69.7 g (1.2 mol) of propionaldehyde is placed in a reaction flask equipped with a condenser, thermometer, and stirrer.
and 197.7 g (1.0 mol) of p-chloro-N,N-diethylbenzylamine are taken and mixed, and then 104.0 g (1.0 mol) of malonic acid is added, cooled in a water bath, and dissolved with vigorous stirring. At this time, heat was generated and the temperature rose to 40 to 50°C, but it was left to cool and kept for 3 hours. Then, the mixture was gradually heated while stirring, and the temperature was raised to 100°C in 4 hours. Since carbon dioxide gas is generated and propionaldehyde is refluxed, a refrigerant (methanol -10 to -20°C) is passed through the cooler to prevent it from flowing out.
Once gas is no longer generated, cool to room temperature.
When neutralized with 280 g of 15% aqueous sodium hydroxide solution to make it slightly alkaline, p-chloro-N,N-diethylbenzylamine is liberated. This is separated and removed, and the aqueous layer is cooled and neutralized with 111 g of concentrated hydrochloric acid (36%) to make it acidic (pH 2 or less), thereby liberating 3-pentenoic acid. This was extracted with benzene, the aqueous layer was extracted twice, the organic layers were combined, concentrated under normal pressure, the solvent was removed, and vacuum distillation was performed to obtain a boiling point of 82
75.0 g of 3-pentenoic acid was obtained at ~83°C/11 mmHg. The yield was 75% and the purity was 95%.

Note that the same procedure as above was carried out using the separated and collected p-chloro-N,N-diethylbenzylamine as it was, and the same results were obtained in both yield and purity.

Comparative Example When the same procedure as in Example 1 was carried out using triethanolamine instead of p-chloro-N,N-diethylbenzylamine, the yield was only 35%.

Example 2 Propionaldehyde was added to a reaction flask equipped with a condenser, thermometer, addition funnel and stirrer.
14.5g (0.25mol) and p-chloro-N,N-
Take and mix diethylbenzylamine (197.7 g (1.0 mol)), add 104.0 g (1.0 mol) of malonic acid, and dissolve while stirring vigorously. At this time, heat was generated and the temperature rose to about 60°C, but it remained as it was. After continuing stirring for 1 hour while maintaining the temperature, 58.1 g (1.0 mol) of propionaldehyde was added dropwise over 3 hours.
At the same time, the temperature was raised to 100°C. After that about 1 hour 100
℃, and after gas generation, cooled to room temperature.
The same treatment as above was carried out to obtain 75.0 g of 3-pentenoic acid. The yield was 75%.

Claims (1)

[Claims] 1. Propionaldehyde and malonic acid are represented by the general formula (In the formula, R represents a lower alkyl group, and X represents a hydrogen atom or a halogen atom.)
- A method for producing 3-pentenoic acid, which comprises reacting in the presence of dialkylbenzylamines.