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The preparation method of 3-amino-2,4-dimethylthiophene

A technology of dimethylthiophene and dimethyltetrahydrothiophene, which is applied in the field of preparation of 3-amino-2,4-dimethylthiophene, can solve the problems of difficult industrial preparation, long steps and low yield, and achieve Easy operation, mild reaction conditions and high yield

Active Publication Date: 2020-11-06
NUTRICHEM LAB CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to overcome the problems of long steps, low yield and difficulty in industrial preparation of 2,4-dimethyl-3-aminothiophene existing in the prior art, and to provide a 3-aminothiophene with simple steps and suitable for industrial preparation. -Amino-2,4-dimethylthiophene method

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0027] The preparation method of 3-amino-2,4-dimethylthiophene provided by the invention comprises the following steps,

[0028] 1) In the presence of an acid anhydride and a base, subjecting 2,5-dimethyl-3-thiadipic acid to cyclodecarboxylation to obtain 2,4-dimethyltetrahydrothiophene-3-one;

[0029] 2) Condensate 2,4-dimethyltetrahydrothiophene-3-one with hydroxylamine or its salt and then rearrange to obtain 3-amino-2,4-dimethylthiophene.

[0030] In the prior art, the ring closure is mainly carried out by heating 2,5-dimethyl-3-thiadipic acid in the presence of iron powder, iron acetate, barium hydroxide, tertiary amine, etc., but the yield of this step is low The maximum is only 70%, and the product purity is less than 95%, the operation is complicated, the reaction conditions are harsh, the by-products are many and difficult to handle, and it is difficult to realize industrial production. In contrast to this, the inventors of the present invention have found through in...

Embodiment 1

[0060] 1) Preparation of 2,5-dimethyl-3-thiadipic acid

[0061] Put 64g of sodium hydroxide and 260g of water into a 1000mL four-necked bottle, stir to dissolve and lower to room temperature (25°C). Slowly add 84.8g of thiolactic acid dropwise with violent exotherm, control the temperature of ice water to 20-25°C, and add 68.8g of 2-methacrylic acid dropwise after the drop. Heated to 104°C and refluxed for 6 hours. Transfer to 150mL concentrated hydrochloric acid, stir evenly at 35-40°C, and extract with dichloromethane twice with 200mL each time. First recover the solvent under normal pressure, and then remove the solvent under reduced pressure to obtain 2,5-dimethyl-3-thiadipic acid with a purity of 95% and a yield of 93%. Liquid mass ESI-MS: 193 (M+H) + .

[0062] 2) Preparation of 2,4-dimethyltetrahydrothiophene-3-one

[0063] Put 197.2g of 2,5-dimethyl-3-thiadipic acid prepared in step 1) into a 500mL four-neck bottle, 160mL of acetic anhydride and 40g of sodium acet...

Embodiment 2

[0067] 1) Preparation of 2,5-dimethyl-3-thiadipic acid

[0068] According to the method of step 1) of Example 1, the difference is that the extraction solvent is methyl tert-butyl ether, and 2,5-dimethyl-3-thiadipic acid is obtained in the same way with a purity of 93.45%. The rate is 88.5%. Liquid mass ESI-MS: 193 (M+H) + .

[0069] 2) Preparation of 2,4-dimethyltetrahydrothiophene-3-one

[0070] According to the method of step 2) of Example 1, the difference is that 2,5-dimethyl-3-thiadipic acid uses the 2,5-dimethyl-3- Thiadipic acid was similarly obtained to obtain 2,4-dimethyltetrahydrothiophen-3-one with a gas phase purity of 97% and a yield of 85%. Temperament EI-MS: 130(M) + .

[0071] 3) Preparation of 3-amino-2,4-dimethylthiophene

[0072] Put 52.9g of 2,4-dimethyltetrahydrothiophen-3-one prepared in step 2), 30.1g of hydroxylamine hydrochloride and 300mL of acetonitrile into a 500mL four-necked bottle, and react under reflux for 7 hours. After the reaction w...

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Abstract

The invention relates to the field of preparation of chloroacetamide, and discloses a preparation method of 3-amino-2,4-dimethylthiophene. The method comprises the following steps that 1) in the presence of an anhydride and a base, 2,5-dimethyl-3-thia-adipic acid is subjected to cyclized decarboxylation to obtain 2,4-dimethyltetrahydrothiophene-3-one; 2) after the 2,4-dimethyltetrahydrothiophene-3-one is subjected to condensation with hydroxylamine or salt of hydroxylamine, rearrangement is carried to obtain the 3-amino-2,4-dimethylthiophene. The preparation method has high yield, and easily produce the 3-amino-2,4-dimethylthiophene suitable for industrialization in large scale.

Description

technical field [0001] The invention relates to the field of preparation of chloroacetamide, in particular to a preparation method of 3-amino-2,4-dimethylthiophene. Background technique [0002] Dimethenamid is a chloroacetamide herbicide that inhibits the synthesis of very long chain fatty acids. The mode of action is primarily a soil treatment herbicide, but can also be applied post-emergence. The herbicide enters the plant through root and hypocotyl uptake, has little or no foliar activity, and has little transplantation in the plant. For the control of annual grasses and broadleaf weeds in crops such as corn, soybeans, sugar beets, potatoes and beans. [0003] Refined dimethenamid, which is the optical S body of dimethenamid, has a good market prospect in recent years. Its synthesis document is reported as US Patent No. 5,457,085. US Patent No. 5,457,085 reports two synthetic methods, one of which uses 3-amino-2,4-dimethylthiophene. [0004] There are few reports on...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D333/36
CPCC07D333/36
Inventor 吴浩黄广英杨海舰
Owner NUTRICHEM LAB CO LTD