Method for preparing 2, 4, 5-trifluoro-phenylacetic-acid
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A technology of trifluorophenylacetic acid and trifluorobenzyl chloride, applied in 2 fields, can solve the problems of unsuitable industrialization, difficult operation, poor environmental friendliness, etc., and achieve the effects of mild reaction conditions, strong operability, and good product purity
Active Publication Date: 2010-03-03
ZHEJIANG YONGTAI TECH CO LTD
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Problems solved by technology
In this route, chlorosulfonic acid has a very strong pungent smell, poor safety, and the phase transfer catalyst is difficult to recycle, the atom economy is poor, the production cost is greatly increased, and the environmental friendliness is poor, so it is not suitable for industrialized production
Chinese patent 200810187895.9 reports that trifluorobenzyl halides are used to make Grignard reagents, and then react with carbon dioxide to obtain 2,4,5-trifluorophenylacetic acid. This method requires high anhydrous conditions, difficult operation, poor safety, and is not suitable for industrialization.
[0003] 2,4,5-Trifluorophenylacetonitrile needs to be hydrolyzed after separation and purification, and the separation and purification of products has always been a difficult problem in synthetic chemistry. Extraction and separation with water is only suitable for hydrophilic products, and distillation technology is not suitable for low-volatility products. products, the use of organic solvents can cause cross-contamination
With the improvement of people's awareness of environmental protection, the voice of green chemistry is getting higher and higher all over the world, and the traditional solvent extraction technology needs to be improved urgently.
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Embodiment 1
[0037] Embodiment 1: the preparation of 2,4,5-trifluorobenzyl chloride
[0038] Add 100ml of 98% sulfuric acid into a 250ml four-necked reaction flask, cool down to 20°C, add 21.3g of paraformaldehyde (equivalent to 0.71mol of monomeric formaldehyde), 44.8g of sodium chloride (0.766mol), and finally add 1,2 , 50.8g (0.385mol) of 4-trifluorobenzene, 40 DEG C heat preservation reaction for 10 hours, the reaction solution was poured into ice water, the organic layer was separated, washed with water until neutral, dried and then distilled under reduced pressure to obtain 2, 58.8g of 4,5-trifluorobenzyl chloride, content 99.8%, yield 84.7%. In the accompanying drawings figure 1 It is the hydrogen spectrum spectrum of 2,4,5-trifluorobenzyl chloride.
[0041] Embodiment 2: the preparation of 2,4,5-trifluorobenzyl chloride
[0042] According to Example 1, 57.1 g (0.766 mol) of potassium chloride was used instead of sodium chloride to obtain 55.1 g of 2,4,5-trifluorobenzyl chloride with a content of 98.2% and a yield of 79.3%.
Embodiment 3
[0043] Embodiment 3: the preparation of 2,4,5-trifluorobenzyl chloride
[0044] According to Example 1, 100 ml of hydrochloric acid was used instead of sulfuric acid to obtain 47.6 g of 2,4,5-trifluorobenzyl chloride with a content of 98.6% and a yield of 68.5%.
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Abstract
The invention provides a method for preparing 2, 4, 5-trifluoro-phenylacetic-acid. The method adopts 1, 2, 4-trifluoro-benzene to react with polyformaldehyde and chlorinating agent to obtain 2, 4, 5-trifluoro-benzyl chloride, and adopts the 2, 4, 5-trifluoro-benzyl chloride to react with cyaniding agent in ionic liquid to obtain 2, 4, 5-trifluoro-benzyl cyanide, and then the 2, 4, 5-trifluoro-benzyl cyanide is hydrolyzed in acid or alkalic conditions to obtain the 2, 4, 5-trifluoro-phenylacetic-acid. The preparation method for preparing 2, 4, 5-trifluoro-phenylacetic-acid requires cheap and available materials, and has moderate reaction conditions, less three-wastes and better safety; industrialized production can be easily realized, the product purity is high, and quality is stable, thuscompletely meeting the using requirement of 2, 4, 5-trifluoro-phenylacetic-acid as a pharmaceutical intermediate.
Description
technical field [0001] The invention relates to the technical field of preparation methods of 2,4,5-trifluorophenylacetic acid. Background technique [0002] 2,4,5-Trifluorophenylacetic acid is a key intermediate in the synthesis of Sitagliptinphosphate / Januvia (trade name), a drug for treating type II diabetes. US Patent No. 068,141 reported that 2,4,5-trifluorobromobenzene and diethyl malonate were reacted under basic conditions to obtain 2,4,5-trifluorophenylacetic acid after hydrolysis. This route requires high reaction conditions, poor atom economy, and is not suitable for industrial production. U.S. Patent No. 6,870,067 reported that 2,4,5-trifluorobromobenzene was made into Grignard reagent, reacted with allyl bromide, and then oxidized with periodic acid under the catalysis of ruthenium trichloride to obtain 2,4,5 - Trifluorophenylacetic acid. The Grignard reaction in this method often adopts low-boiling-point volatile solvents such as ether, which are prone to ex...
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