Synthetic method for 2-thiopheneacetic acid

A synthesis method and technology of thiopheneacetic acid, applied in the direction of organic chemistry, etc., can solve the problems of lowering yield, lowering yield, decomposing sodium cyanide and other problems, and achieves the promotion of generation and yield, reduction of damage degree and utilization rate of raw materials. high effect

CN104327040AInactive Publication Date: 2015-02-04EAST CHINA NORMAL UNIVERSITY
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2015-02-04
Estimated Expiration
Not applicable · inactive patent

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Abstract

A disclosed synthetic method for 2-thiopheneacetic acid comprises: adding concentrated hydrochloric acid, thiophene, paraformaldehyde and acetone in a reaction kettle, reacting at a low temperature, and dropwise adding phosphorus trichloride to maintaining the saturation concentration of an acid in the reaction solution, so as to obtain 2-2-(chloromethyl)thiophene, reacting with an aqueous solution of sodium cyanide under catalysis of acetone to obtain 2-thiopheneacetonitrile, and performing basic hydrolysis to obtain the target product 2-thiopheneacetic acid. The synthetic method has the advantages of simple operation, low production cost, high raw material utilization rate, recyclable raw materials, friendliness to environment, and the like.
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Description

technical field

[0001] The invention relates to a synthesis method of fine chemicals, in particular to a synthesis method of 2-thiopheneacetic acid. Background technique

[0002] 2-thiophene derivatives are widely used in the synthesis of medicines, pesticides, dyes, chemical reagents and polymer additives, etc. Among them, 2-thiopheneacetic acid is currently the most used 2-thiophene derivative, and the global consumption is about 1000t / a. The molecular formula for 2-thiopheneacetic acid is C 6 h 4 Q 2 S; molecular weight is 142; its structural formula is as follows:

[0003]

[0004] In the prior art, the synthesis method of 2-thiopheneacetic acid is relatively simple. For example, the first two-step reaction disclosed in document (1) (Chloromethylation of thiophene WO020094806A1): thiophene, methyl isobutyl ketone, concentrated hydrochloric acid, and paraformaldehyde are put in at one time, and react at 0-5°C for 6 hours, during which the Add hydrogen chloride gas...

Examples

Embodiment 1

[0040] (1) Synthesis of 2-chloromethylthiophene:

[0041] Add 140 grams of 30% hydrochloric acid and 84 grams of thiophene to a 500 milliliter reaction bottle at one time, and when it is cooled to below 8° C., add 50 milliliters of acetone and 30 grams of paraformaldehyde. Immediately after the addition, phosphorus trichloride was added dropwise, and the internal temperature was controlled at 5-8°C. The drop was completed in about 3.5 hours, and then kept at 6-7°C for 1 hour.

[0042] Post-processing: After the reaction, the mixture was left standing to separate layers, and the lower organic phase was separated and washed once with 30-40 ml of ice water to obtain 110 g of crude 2-chloromethylthiophene in the lower layer, with a yield of 83%. used directly in the next reaction.

[0043] (two) the synthesis of 2-thiophenecetonitrile:

[0044]Add 40 g of solid sodium cyanide and 70 ml of water to a 500 ml reaction bottle at one time, stir until completely dissolved, then add 40...

Embodiment 2

[0050] (1) Synthesis of 2-chloromethylthiophene:

[0051] Add 70 grams of 30% hydrochloric acid and 42 grams of thiophene to a 250 milliliter reaction bottle at one time, and when it is cooled to below 8° C., add 25 milliliters of acetone and 15 grams of paraformaldehyde. Immediately after the addition, phosphorus trichloride was added dropwise, and the internal temperature was controlled at 5-8°C. The drop was completed in about 3.5 hours, and then kept at 6-7°C for 1 hour.

[0052] Post-processing: after the reaction, the mixture was left to stand for separation, and the organic phase of the lower layer was separated, washed once with 15-20 ml of ice water to obtain 58 g of the crude product of the lower layer, 2-chloromethylthiophene, with a yield of more than 85%. used directly in the next reaction.

[0053] (two) the synthesis of 2-thiophenecetonitrile:

[0054] Add 20 g of solid sodium cyanide and 35 ml of water to the 250 ml reaction bottle at one time, stir until it ...