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DL-amygdalic acid preparing method

A technology of mandelic acid and mandelonitrile, which is applied in the field of preparation of DL-mandelic acid, can solve the problems of difficult treatment, large amount of three wastes and high cost, and achieves the effects of high reaction conversion rate, reduction of pollutants and high production efficiency

Inactive Publication Date: 2008-07-02
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

PTC reagents have not been industrialized due to factors such as difficulty in preparation and high cost
[0004] 2. Benzene-glyoxylic acid method: In this method, glyoxylic acid is used as the starting material, and mandelic acid is obtained by one-step reaction with benzene in acetic acid medium, and the reaction liquid is subjected to post-treatment processes such as phase separation, pH adjustment, concentration, filtration, and drying. Obtain product, yield is not high and glyoxylic acid is expensive, and cost is higher
The yield of this method is low, the amount of three wastes is large, and the pollution caused by organic solvents is difficult to solve
The by-product ammonium chloride is of poor quality and difficult to further process

Method used

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  • DL-amygdalic acid preparing method

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Experimental program
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Effect test

Embodiment 1

[0028] In the 1000L reactor, add benzaldehyde (the weight percentage content is 99%) 450kg, water 450kg, the concentrated sulfuric acid catalyst 7.5kg, pass into the hydrogen cyanide gas that the weight percentage content is 8% at 70~80 ℃, flow control and Calculate the weight of hydrogen cyanide introduced. When feeding hydrogen cyanide weight to reach 120kg, stop feeding. The incubation reaction was completed in 0.5 hours. Transfer the cyanidation reaction solution to a 2000L hydrolysis reactor, slowly add 255kg of concentrated sulfuric acid at 80-90°C, and complete the addition and keep warm for 2 hours to complete the reaction. Analysis of the DL-mandelic acid content in the reaction solution is 47.2% (HPLC), add water 600L, be cooled to 10 ℃ of crystallization, centrifuge, get DL-mandelic acid crude product 630kg, water content 7%, count DL-mandelic acid content in dry basis It is 96.2% (acid-base titration), and the yield in one reaction is 88.2%. Mother liquor 1150L,...

Embodiment 2

[0031] In the 1000L reactor, add benzaldehyde (the weight percentage content is 99%) 450kg, water 450kg, the concentrated sulfuric acid catalyst 7.5kg, pass into the hydrogen cyanide gas that the weight percentage content is 8% at 70~80 ℃, flow control and Calculate the amount of hydrogen cyanide introduced. When feeding hydrogen cyanide weight to reach 120kg, stop feeding. The incubation reaction was completed in 0.5 hours. Transfer the cyanidation reaction solution to a 2000L hydrolysis reactor, slowly add 255kg of concentrated sulfuric acid at 80-90°C, and complete the addition and keep warm for 2 hours to complete the reaction. The content of DL-mandelic acid in the analyzed reaction solution was 47.2% (HPLC).

[0032] In the hydrolysis mother liquor of embodiment 1, add liquid ammonia 27.0kg, mother liquor crystallizes at 10 ℃ after concentrating under reduced pressure, centrifugation separates by-product ammonium sulfate, by-product weighs 320kg after drying, content 9...

Embodiment 3

[0035] Carry out feeding operation as in Example 2, the difference is that the liquid ammonia is changed into 140kg of 42% sodium hydroxide solution by weight percentage, after the mother liquor is concentrated, it is filtered while hot to remove sodium sulfate, and then the filtrate is cooled to 10°C for crystallization , by-product ammonium sulfate is centrifugally separated, after drying, the by-product ammonium sulfate weighs 296kg, and the content is 90%, and the remaining filtrate replaces the added clear water in the hydrolysis process for recycling, and the crystallization of the hydrolyzate obtains DL-mandelic acid crude product 660kg, with a water content of 8%, The DL-mandelic acid content is 93% on a dry basis. The average yield of DL-mandelic acid reaction was 88.4%. The mother liquor is recycled according to the above steps.

[0036] Add above-mentioned DL-mandelic acid crude product in the recrystallization mother liquor that example 2 obtains, add gac 12kg, de...

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Abstract

This invention has disclosed a kind of producing method for DL-mandelic acid; comprising the steps of: cyanidation, mix benzaldehyde with acidity or alkaline catalyst, supplement water, add cyaniding hydrogen air or hydrocyanic acid solution, react to mandelonitrile; -hydrolysis, put mineral acid into the solution and hydrolyze, form hydrolysis solution contained DL-mandelic acid and mineral acid ammonium salts after hydrolysis entirety; -crystal, supplement water and cycle mother liquor into hydrolysis solution, crystallisate by cooling, centrifugal separate to find DL-mandelic acid coarse product and mother liquor contains DL-mandelic acid and mineral acid ammonium salts; mother liquor handling, adding inorganic basic substance, crystallisate by cooling after ordinary pressure or reduction concentrating, centrifugally get rid of mineral acid ammonium salts, the rest mother liquor recycle to hydrolysis procedure; DL-mandelic acid refining, dissolve DL-mandelic acid coarse product into water, add active carbon to decolor, filtrate, crystal, centrifugation and drying to gain DL-mandelic acid finished product whose yield is high and cost is low.

Description

Technical field: [0001] The present invention is related to the preparation method of mandelic acid, especially related to the preparation method of DL-mandelic acid. Background technique [0002] The existing method for preparing mandelic acid has the following, and these methods all have weak points: [0003] 1. Benzaldehyde phase-transfer catalytic method: This method uses benzaldehyde as a starting material, mixes it with chloroform in an alkaline environment, and reacts in the next step under the action of a phase-transfer catalyst to obtain mandelic acid. The reaction solution is extracted, dried, evaporated, and reassembled. Crystallization and other post-processing products. PTC reagents have not been industrialized due to factors such as difficulty in preparation and high cost. [0004] 2. Benzene-glyoxylic acid method: In this method, glyoxylic acid is used as the starting material, and mandelic acid is obtained by one-step reaction with benzene in acetic acid me...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C59/48C07C51/00C07C51/08
Inventor 王锋罗克俊朱庆川彭琼
Owner 四川省天然气化工研究院
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