Process for producing 2, 3, 5, 6-tetrachloro-1, 4-benzenedicarboxylic acid

Inactive Publication Date: 2001-09-27
SDS BIOTECH CO LTD
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Benefits of technology

0043] In the present invention, 2,3,5,6-tetrachloro-1,4-benzenedicarboxyl-ic acid that is useful as a herbicide precursor can be produced with a high yield by a simple operation comprising hydrolyzing readily procurable cheap 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile as a feedstock in sulfuric acid (preferably, sulfuric acid containing fuming sulfuric acid) in the presence of water whose amount is smaller than the stoichiometric value of the hydrolysis. Furthermore, in the process of the present invention, from the 2,3,5,6-tetrachloro-1,4-benzenedicarboxam-ide which, in the presence of water whose amount is not smaller than the stoich

Problems solved by technology

However, this process has a drawback in that by-products such as hexachlorobenzene are formed in a

Method used

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  • Process for producing 2, 3, 5, 6-tetrachloro-1, 4-benzenedicarboxylic acid
  • Process for producing 2, 3, 5, 6-tetrachloro-1, 4-benzenedicarboxylic acid
  • Process for producing 2, 3, 5, 6-tetrachloro-1, 4-benzenedicarboxylic acid

Examples

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example 1

[0045] Preparation of 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid (compound 2) from 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide (compound 1)

[0046] 6.04 g (0.02 mol) of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide and 17.65 g of sulfuric acid, consisting of 12.43 g of 96.3% sulfuric acid (containing 0.0256 mol of water) and 5.22 g of 26% fuming sulfuric acid (containing 0.017 mol of SO.sub.3), were charged into a reactor, and a hydrolysis of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide was performed at 180.degree. C. for 6 hr under atmospheric pressure. The amount of water which was present prior to the reaction was 0.0086 mol because the SO.sub.3 in fuming sulfuric acid and the water in sulfuric acid were converted to sulfuric acid according to the formula (IV). After the completion of the reaction, precipitated crystals were collected by filtration, washed with water, and dried. As a result, 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid was obtained.

[0047] Yield: 5.8 g (is...

example 2

[0050] Preparation of 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid (compound 2) from 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide (compound 1)

[0051] 6.04 g (0.02 mol) of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide and 17.64 g of sulfuric acid, consisting of 10.82 g of 96.3% sulfuric acid and 6.82 g of 26% fuming sulfuric acid, were charged into a reactor, and a hydrolysis of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide was performed under atmospheric pressure. The temperature and reaction time were as specified in Table 1. After the completion of the reaction, the same processing as in Example 1 was conducted. As a result, 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid was obtained.

[0052] Yield: 5.9 g (isolation yield 97%), and

[0053] IR (KBr): same as in Example 1.

example 3

[0054] Preparation of 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid (compound 2) from 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide (compound 1)

[0055] 6.04 g (0.02 mol) of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide and 17.65 g of sulfuric acid, consisting of 4.64 g of 96.3% sulfuric acid and 13.01 g of 26% fuming sulfuric acid, were charged into a reactor, and a hydrolysis of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide was performed under atmospheric pressure. The temperature and reaction time were as specified in Table 1. After the completion of the reaction, the same processing as in Example 1 was conducted. As a result, 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid was obtained.

[0056] Yield: 4.1 g (isolation yield 68%), and

[0057] IR (KBr): same as in Example 1.

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Abstract

A process for producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid, comprising heating 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide together with sulfuric acid exhibiting an acidity function (-Ho) of 10.27 to 14.44 in the presence of water contained in an amount smaller than a stoichiometric value of hydrolysis at 110 to 190° C. This process efficiently produces 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid which is a precursor of dimethyl 2,3,5,6-tetrachloro-1,4-benzenedicarboxylate useful as a herbicide.

Description

[0001] The present invention relates to a process for producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid. More particularly, the present invention relates to a process for producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid, wherein the formation of reaction by-products is less than in the conventional processes to thereby enable efficiently to produce 2,3,5,6-tetrachloro-1,4-benzenedica-rboxylic acid.[0002] Dimethyl 2,3,5,6-tetrachloro-1,4-benzenedicarboxylate is widely and in a large amount used as an agricultural or horticultural herbicide.[0003] A common process for producing dimethyl 2,3,5,6-tetrachloro-1,4-ben-zenedicarboxylate comprises chlorinating benzene-1,4-dicarbonyl chloride to thereby obtain 2,3,5,6-tetrachloro-1,4-benzenedicarbonyl chloride and converting the same to a dimethyl ester with the use of methanol. However, this process has a drawback in that by-products such as hexachlorobenzene are formed in a large amount.[0004] Therefore, there is a deman...

Claims

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Application Information

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IPC IPC(8): C07B61/00C07C51/06C07C51/08C07C63/72B01J27/02
CPCC07C51/06C07C63/30
Inventor MATSUSHITA, UTAROSANO, KIMITOSHIKOMATSUBARA, KENICHIISHII, TERUHIKO
Owner SDS BIOTECH CO LTD
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