Method for preparing L-pyroglutamic acid

A technology of pyroglutamic acid and pyroglutamic acid ethanol, applied in the direction of organic chemistry and the like, can solve the problems of unsuitable industrial production, difficult removal of other impurities, complicated preparation process, etc. Effect

Active Publication Date: 2014-03-26
宜兴市前成生物有限公司
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

However, the above two methods have high requirements on the dehydration temperature of L-glutamic acid, the preparation process is complicated, and other impurities are easy to be introduced and difficult to remove, so they are not suitable for industrial production.
Invention 201010214563.2 reports a method for preparing magnesium L-pyroglutamate, which discloses a method for preparing L-pyroglutamic acid by dehydration of L-glutamic acid, which needs to be separated by a cation exchange resin column from L-pyroglutamic acid and untreated magnesium. Coking L-glutamic acid, ion exchange extraction will bring a lot of sewage

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  • Method for preparing L-pyroglutamic acid

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Embodiment 1

[0018] A method for preparing L-pyroglutamic acid, including: adding 147g of L-glutamic acid, 500ml of absolute ethanol, 2ml of concentrated sulfuric acid into a 1000L three-necked flask, heating to 90℃, and maintaining at 90℃ for 4 hours. Dehydration reaction. After the reaction, the reaction solution is filtered while it is hot. The ethanol filtrate of L-pyroglutamate is concentrated under reduced pressure at a temperature of 55°C to saturation. The ethanol concentrate of L-pyroglutamate is cooled to 20°C, and a large amount of crystals are precipitated. The L-pyroglutamic acid crystals were filtered out and dried at a temperature of 55°C to obtain 115 g of L-pyroglutamic acid refined product with a yield of 89.1%.

Embodiment 2

[0020] A method for preparing L-pyroglutamic acid, including: adding 294g of L-glutamic acid, 1200ml of absolute ethanol, 2ml of concentrated sulfuric acid into a 2000L three-necked flask, heating to 92°C, and maintaining at 92°C for 5 hours. Dehydration reaction. After the reaction, the reaction solution is filtered while it is hot. The ethanol filtrate of L-pyroglutamate is concentrated under reduced pressure at a temperature of 60°C to saturation. The ethanol concentrate of L-pyroglutamate is cooled to 20°C, and a large amount of crystals are precipitated. The L-pyroglutamic acid crystals were filtered out and dried at a temperature of 60°C to obtain 233 g of L-pyroglutamic acid refined product, with a yield of 90.3%.

Embodiment 3

[0022] A method for preparing L-pyroglutamic acid, including: adding 221g of L-glutamic acid, 900ml of absolute ethanol, 2.3ml of concentrated sulfuric acid into a 2000L three-necked flask, heating to 95°C, and maintaining at 95°C for 3 hours The dehydration reaction is carried out. After the reaction is completed, the reaction solution is filtered while it is hot. The ethanol filtrate of L-pyroglutamate is concentrated under reduced pressure to saturation at a temperature of 55°C. The ethanol concentrate of L-pyroglutamate is cooled to 25°C and a large amount of crystals are precipitated. The L-pyroglutamic acid crystals were filtered out with suction, and dried at a temperature of 55°C to obtain 175g of L-pyroglutamic acid refined product, with a yield of 90.2%.

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Abstract

The invention discloses a method for preparing L-pyroglutamic acid, which comprises the following steps: placing L-glutamic acid in an ethanol system; adding a proper amount of a dehydration catalyst; heating to 88 to 100 DEG C to perform the dehydration reaction; after the reaction, carrying out filtering, concentration and crystallization; carrying out suction filtration on crystals to obtain the L-pyroglutamic acid competitive product. The method disclosed by the invention belongs to a closed process, is simple to operate and adopts a proper proportion; the L-pyroglutamic acid generated through dehydration is soluble to ethanol, the L-glutamic acid which is not dehydrated is insoluble to ethanol, the L-glutamic acid which is not dehydrated is directly removed by filtering, crystallization is carried out to obtain the high-purity L-pyroglutamic acid, and the obtained L-pyroglutamic acid has purity of over 99.5 percent and yield of over 85 percent; due to addition of the dehydration catalyst concentrated sulfuric acid, the dehydration reaction is accelerated; moreover, the reaction is performed at a lower reaction temperature, so that the L-pyroglutamic acid is prevented from generating racemization; the concentrated sulfuric acid is in a mother liquor obtained by suction filtration and can be returned together with the L-glutamic acid for next batching; the method is low in cost and is suitable for industrial production.

Description

Technical field [0001] The invention relates to a method for preparing L-pyroglutamic acid. Background technique [0002] L-Pyroglutamic acid, English name: L-Pyroglutamic acid, chemical name: L-2-pyrrolidone-5-carboxylic acid. L-pyroglutamic acid can be used as a biochemical reagent, mainly for the resolution of racemic amines. Currently, L-pyroglutamic acid is used as a cosmetic moisturizer in the field of daily chemicals. [0003] The synthesis of pyroglutamic acid on the market is mainly made by dehydrating glutamic acid as a raw material. The synthesis of L-pyroglutamic acid reported by Feng Dayan in the "Chemical World" magazine is obtained by dehydration and cyclization of glutamic acid, and the yield is generally 75.3-63.3%. This synthesis method is suitable for L-glutamic acid The dehydration reaction temperature and time have strict requirements, which should be controlled at about 150°C and maintained for 45 minutes. If the temperature is higher than 160°C, L-pyroglut...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D207/28
CPCC07D207/28
Inventor 席日新
Owner 宜兴市前成生物有限公司
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