Method for preparing symmetrical acid anhydride

A symmetrical, acid anhydride technology, applied in the preparation of carboxylic acid anhydrides, organic chemical methods, chemical instruments and methods, etc., can solve the problems of unstable catalysts, low reaction yields, severe conditions, etc., and achieve good promotion and application prospects and advanced process routes. , the effect of mild reaction conditions

Inactive Publication Date: 2011-08-31
ZHEJIANG UNIV OF TECH
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AI Technical Summary

Problems solved by technology

The above method more or less has the following disadvantages: the raw material is expensive, the reaction yield is low, the conditions are relatively severe, the catalyst is unstable, and the reaction reagent is highly toxic and highly toxic. The reagent is not friendly to the environment
Reagents such as thionyl chloride, phosphorus pentoxide, and phosgene are all chemical weapons stipulated by the United Nations. There are relatively large safety and environmental risks in the production, transportation, and use of them, and their use is also strictly controlled.
In the process of use, waste gas that is difficult to treat, such as sulfur dioxide, is often produced, and the pollution of the three wastes is serious
In addition, there are also reports in the literature that BTC is used to prepare acid anhydrides. In the literature, triethylamine is used as the acid scavenger, and the required amount is equimolar to the reactant, and the reaction yield is low.
Triethylamine reacts with hydrogen chloride to form triethylamine hydrochloride, which is difficult to separate from the solid product, and post-processing is troublesome

Method used

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  • Method for preparing symmetrical acid anhydride
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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Embodiment 1: the preparation of propionic anhydride

[0024] The amount ratio of the feed material is carboxylic acid RCOOH: bis(trichloromethyl)carbonate: the catalyst is 1:0.17:0.01, RCOOH is propionic acid, the catalyst is N,N-dimethylformamide, and the organic solvent is ethyl acetate , its dosage is 3 times of the mass of carboxylic acid.

[0025] In a 250mL three-necked flask equipped with a thermometer, a reflux condenser and mechanical stirring, add 7.4g (100mmol) of propionic acid, 5.0g (17mmol) of bis(trichloromethyl)carbonate, 22.2ml of ethyl acetate and N,N - Dimethylformamide 0.07 g (1 mmol). After the addition was completed, the temperature was raised to 60-65° C., and the reaction was kept for 6 hours. After the reaction was completed, the solvent was evaporated under reduced pressure, and then 6.3 g of propionic anhydride was obtained by high vacuum distillation. The product yield was 97.0%, and it was an oily substance. 1 H-NMR (400MHz, CDCl 3 ): 1....

Embodiment 2

[0026] Embodiment 2: the preparation of benzoic anhydride

[0027] The amount ratio of feed material carboxylic acid RCOOH: two (trichloromethyl) carbonate: catalyst is 1:0.17:0.005, and RCOOH is benzoic acid, and catalyst is N, N-dimethylformamide, and organic solvent is toluene, and The dosage is twice the mass of carboxylic acid.

[0028] In a 250mL three-necked flask equipped with a thermometer, a reflux condenser and a mechanical stirrer, add 12.2g (100mmol) of benzoic acid, 17g (17mmol) of bis(trichloromethyl)carbonate, 24.4ml of toluene and N,N-dimethyl 0.04 g (0.5 mmol) of methyl formamide. After the addition was completed, the temperature was raised to 70-75°C, and the temperature was kept for 5 hours. After the reaction, the solvent was evaporated under reduced pressure, and the residue was recrystallized with cyclohexane to obtain 11.0 g of benzoic anhydride. The product yield was 97.0%, and it was a solid. Melting point: 43-44°C. 1 H-NMR (400MHz, CDCl 3 ): 8.12...

Embodiment 3

[0029] Embodiment 3: the preparation of o-chlorobenzoic anhydride

[0030] Replace benzoic acid with o-chlorobenzoic acid, the reaction solvent is dichloromethane, the reaction temperature is 40~45°C, and the reaction time is 10h. The operation process is the same as in Example 2 to obtain o-chlorobenzoic anhydride with a yield of 94%, solid . Melting point: 79-81°C. 1 H-NMR (400MHz, CDCl 3 ): 8.04 (dd, 2H, J=2, 16Hz), 7.54-7.48 (4H, m), 7.42-7.26 (2H, m); IR (KBr, cm -1 ): 1780, 1718; MS(EI): m / z(%)=259(M+1, 56), 141(39), 139(100), 113(17), 111(44), 75(18 ). 13 C NMR (100MHz, CDCl 3 ): 160.34, 135.1, 134.2, 132.6, 131.6, 127.8, 126.9.

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Abstract

The invention discloses a preparation method for symmetric anhydride, which comprises the following steps: raw materials are corresponding carboxylic acid RCOOH and bis(trichloromethyl) carbonic ester, which react in organic solvent under the action of catalyst for 1 to 10h under the temperature of 40 to 100 DEG C. The reacted mixture is post-processed, and the symmetric anhydride indicated in formula (II) is obtained. The catalyst is tertiary amine with N-formyl group, and the molar ratio of the carboxylic acid, bis (trichloromethyl) carbonic ester and the catalyst is 1:0.17-0.19:0.005-0.1. The preparation method has the advantages of advanced technical route, mild reaction condition, high reaction yield, low three-waste, low catalyst consumption, and the like, and is the preparation method for symmetric anhydride with good popularization and application prospect.

Description

(1) Technical field [0001] The invention relates to a preparation method of a symmetrical acid anhydride. (2) Background technology [0002] Acid anhydride is an important acylating reagent, which is widely used in organic synthesis. The common ones such as acetyl anhydride can be used in the industry to manufacture chemical intermediates such as cellulose acetate, fuel and spices. Phthalic anhydride is widely used in synthetic dyes, polyester resins, alkyd resins, plasticizers, polyester, etc. [0003] Symmetrical anhydrides are usually also used to prepare unsymmetrical anhydrides. In addition, it is also widely used in the preparation of medicines. [0004] Before the present invention provides, the synthetic method of existing acid anhydride mainly is corresponding carboxylic acid and dehydration reagent such as P 2 o 5 , DCC, Ph 3 P / COCl 2 , Thionyl chloride and other effects in the system. The above method more or less has the following disadvantages: the raw ma...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C51/56C07B41/10
Inventor 陈志卫苏为科
Owner ZHEJIANG UNIV OF TECH
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