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Method for preparing symmetrical acid anhydride

A symmetrical, acid anhydride technology, applied in the preparation of carboxylic acid anhydrides, organic chemistry methods, chemical instruments and methods, etc., can solve the problems of unstable catalysts, troublesome post-processing, severe conditions, etc., to achieve good promotion and application prospects, and less catalyst consumption. , the effect of mild reaction conditions

Inactive Publication Date: 2009-02-04
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
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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

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Embodiment 1

[0023] Example 1: Preparation of propionic anhydride

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

[0025] In a 250mL three-necked flask equipped with a thermometer, reflux condenser and mechanical stirring, 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, the temperature is increased to 60-65°C, and the reaction is kept for 6 hours. After the reaction is completed, the solvent is evaporated under reduced pressure, and then 6.3 g of propionic anhydride is obtained by high-vacuum distillation. The product yield is 97.0% as an oily substance. 1 H-NMR (400MHz, CDCl 3 ): 1.18 (6H, t, J = 3.6 Hz), 2.50 (4H, q, J = 6.8 Hz); IR (KBr, c...

Embodiment 2

[0026] Example 2: Preparation of benzoic anhydride

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

[0028] In a 250mL three-necked flask equipped with a thermometer, reflux condenser and mechanical stirring, add 12.2g (100mmol) of benzoic acid, 17g (17mmol) of bis(trichloromethyl) carbonate, 24.4ml of toluene and N,N-dimethyl Benzamide 0.04g (0.5mmol). After the addition, the temperature is increased to 70-75°C, and the reaction is kept for 5 hours. After the reaction is completed, the solvent is evaporated under reduced pressure, and the residue is recrystallized with cyclohexane to obtain 11.0 g of benzoic anhydride, with a product yield of 97.0%, solid. Melting point: 43-44°C. 1 H-NMR (400MHz, CDCl 3 ): 8.12 (4H, d, J=8.4 Hz, ArH), 7.68-7.58 (2H, m, ...

Embodiment 3

[0029] Example 3: Preparation of o-chlorobenzoic anhydride

[0030] Use o-chlorobenzoic acid instead of benzoic acid, the reaction solvent is dichloromethane, the reaction temperature is 40~45℃, the reaction time is 10h, the operation process is the same as that of Example 2, to obtain o-chlorobenzoic anhydride, the yield is 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 method for preparing symmetric acid anhydrides. (2) Background technology [0002] Acid anhydride is an important acylating reagent, which is widely used in organic synthesis. Common ones such as acetyl anhydride can be used in industry to manufacture cellulose acetate, fuel and perfume and other chemical intermediates. Phthalic anhydride is widely used in the synthesis of dyes, polyester resins, alkyd resins, plasticizers, polyester and so on. [0003] Symmetric anhydrides are usually also used to prepare asymmetric anhydrides. In addition, it is also widely used in drug preparation. [0004] Before the present invention is given, the existing synthesis methods of acid anhydrides are mainly corresponding carboxylic acid and dehydrating reagent such as 2 O 5 ,, DCC, Ph 3 P / COCl 2 , Thionyl chloride, etc. The above method more or less has the following disadvantages: the raw materials are expensive, the reaction yield is low, t...

Claims

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Application Information

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IPC IPC(8): C07C51/56C07B41/10
Inventor 陈志卫苏为科
Owner ZHEJIANG UNIV OF TECH
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