JPS60156639A - Method for collecting geometric isomer of cinnamic acid compound - Google Patents

Abstract

PURPOSE:To separate the titled compound which is a raw material for producing various organic chemicals selectively by using the difference in pKa between the cis- and the trans-isomers, by converting a mixture of the cis- and the trans- isomers of cinnamic acid and a derivative thereof into a metal salt, and reacting the metal salt with a specific amount of an acid. CONSTITUTION:A mixture of the cis- and the trans-isomers of cinnamic acid and a derivative expressed by formula I (R1 and R2 are H or lower alkoxyl) is converted into an alkali metal or alkaline earth metal salt in an aqueous solution. If the mixture is scarcely dissolved, the dissolution is accelerated by heating. A mineral acid in an amount of gram equivalents corresponding to the trans-isomer content is added to the resultant solution to deposit and recover only the trans- isomer from the aqueous solution. An acid is then added to adjust the filtrate to about 1.0pH, and crystals of the cis-isomer are deposited.

Description

[Detailed Description of the Invention] The present invention is a method of extracting cinnamic acid, which is often used as a synthetic raw material in the production of various chemicals, and its mixture with high purity geometrically different bodies of cinnamic acid and its conductor. Regarding the method, 1.

According to the present invention, a cis-tris mixture of cinnamic acid and its derivatives is dissolved as a metal salt in a water bath solution. , by heating if it is difficult to dissolve.
) Dissolution is promoted. The metal salts used in this case include sodium carbonate, sodium bicarbonate, sodium salts such as sodium carbonate, sodium carbonate, potassium salts such as water and potassium oxide, barium hydroxide, barium carbonate, etc. Usually barium salts such as Next, an equivalent amount of mineral acid corresponding to the trans-containing mineral acid was added to this solution, and the mixture was stirred at 0° to room temperature for 3.0 minutes to several hours.

Then, precipitated trans-cinnamic acid and its derivatives are counted. By further adding acid to the F solution and adjusting the pH to around 1.0, cis crystals are precipitated. By filtering this, cis-cinnamic acid and its derivatives can be obtained. The purity of the obtained cis-isomer and trans-isomer is 95% or more. By repeating the above H-pi operation, almost pure cis and trans isomers can be obtained.

Conventionally, not only cinnamic acid derivatives but also a pair of geometric isomers generally have melting points between each geometric isomer.

It is known that there are differences in physical properties such as solubility. Particularly in terms of purification, fractional crystallization, which takes advantage of differences in solubility, has been used to achieve this goal.

Unlike the method of the present invention that utilizes the difference in mineral solubility, the difference in pKa between the cis and trans forms is utilized.
Since a is small, when the metal salt reacts with an acid, the reaction of the acid is controlled to selectively release only the cis form and separate it from the cis form. Examples are shown below.

Example 1 3.4-dimethoxycinnamic acid (cis:trans=70=3
032ON (0,0962 mol) and sodium carbonate 10
．． 9 (0,0945 mol) in 1,000 mol of water by heating. Add 10.1- of concentrated hydrochloric acid (12N) at room temperature and
After stirring for 0 min, filtering the precipitated crystals and drying the crystals, 5.0
#(cisnidorans=2298) is obtained. Add hydrochloric acid to solution F to adjust the pH to 1O, and filter the precipitated crystals. By drying the crystals, silas-3,4-dimethoxycinnamic acid 1
2.8 g (cis:trans=96:4) is obtained. The cis body is m1.98.2~100℃, and the trans body is m
, is 180 to 180.5°C.

Example 2 3,4-dimethoxycinnamic acid (cis:trans=64:3
6) Heat and dissolve 15.85 g (0.0762 mol) and 20.2 g (0.145 mol) of potassium carbonate in 500 ml of water. Add 40.2 ml of 6N hydrochloric acid at room temperature and
After stirring for a minute, the precipitated crystals are filtered and dried to obtain 5.2 g of trans-3,4-dimethoxycinnamic acid (cis:trans=4:96). pH of the solution at this time
is approximately 4.1. Add 6N hydrochloric acid to the filtrate to pH 1.0.
The precipitated crystals were filtered and dried to obtain 7.4 g of cis-3,4-dimethoxycinnamic acid (cis:trans=95:5). The final mother liquor was extracted with ethyl acetate, and the ethyl acetate layer was washed successively with water and saturated brine, and then dried and concentrated to obtain 3.0 g of crude crystals. This crystal also contains a large amount of trans isomer (cis: trans = 88.9:1
11).

Example 3 3,4-dimethoxycinnamic acid (cis:trans=75:2
5) 10.0g (0.048mol) and barium hydroxide 8
Hydrate 20.0 (0.063 mol) was dissolved in 500 ml of water, 15.1 ml of 6N sulfuric acid was added thereto, and the mixture was stirred at room temperature for 30 minutes. When the precipitated crystals are filtered and dried, 2.7 g of trans-3,4-dimethoxycinnamic acid (cis:trans=2:98) is obtained. The pH of the solution at this time is about 4.1. Add 6N sulfuric acid to the filtrate to pH 1.
．． Set to 0. The precipitated crystals are filtered and dried to give cis-3,4
-4.2 g of dimethoxycinnamic acid (cis:trans=96:
4) is obtained. After the mother liquor is extracted with ethyl acetate, it is concentrated to obtain 3.0 g of crude crystals (cis:trans=90:10).

Example 4 Cinnamic acid (cis:trans=78:22) 10.9(0
,0676 mol) and sodium carbonate 10.9 (0,0
943 moles) are dissolved in 1000 moles of water. Add 11.3 d (0,1658 mol) of hydrochloric acid at room temperature and stand for 5 minutes.
By pressing, filtering the precipitated crystals, and drying the crystals, trans-cinnamon rM 1.7 II (cis:trans=4296) is obtained. Add concentrated hydrochloric acid to P solution 1)
Adjust to H2.0. This solution was mixed with 100% each of ethyl acetate.
Extract twice using The ethyl acetate layer was washed with water, further washed with saturated saline, dried over magnesium chloride, and concentrated to obtain oily cis-cinnamic acid 8.0II (cis:trans=91:9).

Example 5 p-methoxycinnamic acid (cis:trans=79:21) 1
011 (0,0562 mol) and sodium carbonate 10JN
0.0943 mol) is dissolved in 1000 td of water. Add 11.0 m (0,1324 mol) of hydrochloric acid at room temperature, filter the precipitated crystals, and dry the crystals to obtain 2.8.9 trans-p-methoxycinnamic acid (cis:trans=
1187) is obtained. Add 8.3 mg of hydrochloric acid (0.1
00 mol] was added to adjust the pH to about 2.0, the precipitated crystals were allowed to pass through, and the crystals were dried to obtain 4.6 g of cis-p-methoxy cinnamon IV (cis:trans=99:1).

Further, the F solution was concentrated under reduced pressure to a concentration of about 50%, and then left to stand for 14 minutes to precipitate crystals. The crystals were filtered, dried and cis-
p-methoxycinnamic acid2. ON (cis:trans=95:
5) is obtained.

Patent applicant: Nisshin Seifun Co., Ltd.

Claims (1)

[Scope of Claims] A mixture of cinnamic acid represented by formula (1) (wherein R1 and R2 represent a hydrogen atom or a lower alkoxy group) and its cis and trans isomers in a water bath liquid. After converting the alkali into a salt of an alkaline earth metal, add p to this solution according to the trans isomer content.
) The cis- and A method for collecting trans-cinnamic acid and its v1 exclusive form.