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Process for preparing DL-ortho-chloro mandelic acid

A technology of o-chloromandelic acid and o-chlorobenzaldehyde, applied in the field of preparation of DL-o-chloromandelic acid, can solve the problems of high production cost and low yield, and achieve the effect of increasing yield and reducing production cost

Inactive Publication Date: 2007-04-11
四川省天然气化工研究院
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the use of anhydrous hydrocyanic acid in this method, the production cost is high and the yield is low, only 41%.

Method used

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  • Process for preparing DL-ortho-chloro mandelic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] In the 250ml three flasks that have thermometer, condensing tube, agitator, add 42.9 grams of o-chlorobenzaldehyde (mass percentage content is 98.5%), water 6 grams, catalyst sodium hydroxide 5.7 grams (mass percentage content is 5%) , at a temperature of -5°C, add 10.1 grams of aqueous hydrocyanic acid solution (80% by mass) dropwise within 30 minutes. gram (mass percentage content is 31%) is hydrolyzed, and after dropwise addition, after insulation reaction 1 hour, add 240ml toluene, heat up and make toluene and water azeotropic dehydration, ammonium chloride is separated out in the reaction solution, and filter removes ammonium chloride, filtrate Cooling, crystallization, filtration to get the crude product DL-o-chloromandelic acid, the crude product DL-o-chloromandelic acid was dissolved in 360ml toluene and recrystallized to obtain 39.5 grams of qualified white DL-o-chloromandelic acid crystals, content 99.2%, melting point 82.8~ 83.5°C, yield 67%.

Embodiment 2

[0027] Carry out feeding operation by embodiment 1, difference is that the product recrystallization mother liquor among the example 1 is used as dehydrating agent. The crude product DL-o-chloromandelic acid was dissolved in 380ml of toluene for recrystallization to obtain 40.6 grams of qualified DL-o-chloromandelic acid with a content of 99.3%, a melting point of 83-83.6°C, and a yield of 72%.

Embodiment 3

[0029] Carry out feeding operation by embodiment 1, difference is that 10.1 gram mass percent content in example 1 is that 80% hydrocyanic acid aqueous solution is changed into 30 gram mass percent content and is 30% hydrocyanic acid aqueous solution, obtains qualified DL-o Chloromandelic acid 40.1 g, content 99.2%, melting point 82.9-83.5°C, yield 71.1%.

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Abstract

The process of preparing DL-ortho-chloro mandelic acid includes the following steps: 1. the cyanidation reaction of o-chloro benzaldehyde and hydrocyanic acid in the molar ratio of 1 to 0.9-1.5 to produce o-chloro mandelonitrile at the temperature of -20 to +20 deg.c and in the presence of alkaline catalyst; 2. hydrolyzing the product via adding inorganic acid and heating to 20-120 deg.c; 3. eliminate ammonium chloride through adding toluene into the hydrolysate, heating for azeotropic dehydration to separate out ammonium chloride and filtering out ammonium chloride; and cooling the filtrate to crystallize and filtering to obtain crude DL-ortho-chloro mandelic acid product; and 4. refining crude DL-ortho-chloro mandelic acid product through dissolving in toluene and re-crystallizing to obtain qualified DL-ortho-chloro mandelic acid product. The present invention has lowered production cost and high yield.

Description

Technical field: [0001] The present invention is related to the preparation method of DL-o-chloromandelic acid. Background technique: [0002] The existing methods for preparing DL-o-chloromandelic acid mainly include the following two methods. [0003] 1. O-chlorobenzaldehyde phase transfer catalytic method: [0004] In this method, o-chlorobenzaldehyde is mixed with bromoform or chloroform under alkaline conditions, and reacted in the next step under the action of a phase transfer catalyst to obtain DL-o-chloromandelic acid. product. The reaction yield of this method is low, and the production cost is high. [0005] 2. O-chlorobenzaldehyde cyanation method: [0006] The method for preparing DL-o-chloromandelic acid with hydrocyanic acid as a cyanating agent has been reported in the document "Journal of the American Chemical Society" (J Am Chem.Soc) S.S.Jenking 1931.53.3241. Water hydrocyanic acid reacts to generate o-chloromandelonitrile, and o-chloromandelonitrile is...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/08C07C59/56C07C59/50
Inventor 周伟罗克俊高含
Owner 四川省天然气化工研究院
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