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Preparation method of low-carbon chain symmetric anhydride

A low-carbon chain, carbon-chain carboxylic acid technology, applied in the preparation of carboxylic acid anhydrides, etc., can solve the problems of less side reactions, low yield, complicated operation, etc., and achieve the effects of less by-products, high yield and high purity

Active Publication Date: 2012-09-19
NANJING ACCELEDEV TECH DEV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Technical problem to be solved: In order to solve the defects of low yield and cumbersome operation of the existing preparation method of low carbon chain symmetric acid anhydride, the present invention provides a high-purity low carbon chain symmetric acid anhydride with less side reactions, high yield and easy operation Methods

Method used

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  • Preparation method of low-carbon chain symmetric anhydride

Examples

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Embodiment 1

[0017] Embodiment 1: the preparation of acetic anhydride.

[0018]

[0019] Keep the temperature at 20°C, in 98% concentrated sulfuric acid (98kg, 1000mol), add acetic acid (30kg, 500mol) and phosphorus pentoxide (17.8kg, 125mol) in turn while stirring, and continue stirring for 0.5h to make it fully mixed , reacted at 80°C for 3h, and collected fractions at 140°C by atmospheric distillation to obtain 22.8kg of acetic anhydride with a yield of 89.4% and a purity (GC) of 98.6%.

Embodiment 2

[0020] Example 2: Preparation of fluoroacetic anhydride (2-fluoroacetic anhydride).

[0021]

Embodiment 3

[0022] Keeping the temperature at 20°C, in 98% concentrated sulfuric acid (196g, 2.0mol), add 2-fluoroacetic acid (78g, 1.0mol) and phosphorus pentoxide (35.5g, 0.25mmol) successively while stirring, and continue stirring for 0.5 After h, make it fully mixed, react at 100°C for 3 hours, and collect fractions by distillation under reduced pressure to obtain 59.2 g of 2-fluoroacetic anhydride, yield 85.8%, purity Example 3: Difluoroacetic anhydride (2,2- Preparation of difluoroacetic anhydride)

[0023]

[0024] Referring to the method in Example 2, the reaction time was 5 hours, and the fraction at 124-127°C was collected, with a yield of 90.5% and a purity (GC) of 97.9%.

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Abstract

The invention discloses a preparation method of low-carbon chain symmetric anhydride (I). The preparation method comprises the following steps of: taking low-carbon chain carboxylic acid (II) as a raw material, performing reaction by concentrated sulfuric acid and phosphorus pentoxide, and distilling to obtain the high-purity low-carbon chain symmetric anhydride (I). The preparation method of the low-carbon chain symmetric anhydride, disclosed by the invention, only comprises one-step reaction, has the advantages of few reaction byproducts, high yield and simplicity and convenience in operation, and is suitable for industrial production; and the obtained low-carbon chain symmetric anhydride is high in purity.

Description

technical field [0001] The invention relates to the field of chemical synthesis, in particular to a preparation method of a low carbon chain symmetrical acid anhydride. Background technique [0002] Acid anhydrides are widely used in the fields of chemical industry and medicine. There are many methods for synthesizing acid anhydrides that have been reported so far. The acid anhydrides can be prepared by reacting acid chlorides and carboxylic acids, but generally it is necessary to prepare acid chlorides first and then react with carboxylic acids. This two-step method The preparation process is relatively cumbersome, so this method is often used to synthesize asymmetric anhydrides. The preparation of symmetrical acid anhydrides reported in the literature mainly uses corresponding carboxylic acids as raw materials, using (1) acetic anhydride dehydration method: this method uses acetic anhydride as a dehydrating agent, and the reaction with carboxylic acids is a common reaction...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/56
Inventor 王奇邓一成
Owner NANJING ACCELEDEV TECH DEV
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