Preparation method of crotonic acid

Abstract

The invention provides a preparation method of crotonic acid, and belongs to the technical field of organic synthesis. The preparation method comprises the following steps: in the presence of a molecular sieve catalyst, mixing crotonaldehyde, an organic solvent and oxidizing gas, and carrying out catalytic oxidation reaction to obtain crotonic acid. The molecular sieve is used as a catalyst for catalyzing crotonaldehyde oxidation to prepare crotonic acid, so that the cost is low; the molecular sieve is a solid-phase catalyst, can be well separated from the oxidation reaction liquid and recycled, and is green and environment-friendly; the molecular sieve catalyst is used for catalytic oxidation reaction, in the process of oxidizing crotonaldehyde into crotonic acid, the molecular sieve can adsorb a large amount of oxygen, sufficient oxidation of crotonaldehyde is guaranteed, the conversion rate of crotonaldehyde is increased, and meanwhile the yield of crotonic acid is increased; and it is shown that the yield of the crotonic acid prepared by the preparation method provided by the invention is 85.3-94%, and the purity of the crotonic acid is 99.1-99.5%.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, in particular to a preparation method of crotonic acid. Background technique [0002] Crotonic acid, also known as 2-butenoic acid, is an unsaturated fatty acid containing 1 double bond and 1 carboxyl group with strong reactivity. value chemicals. There are two main methods for the preparation of crotonic acid: one is the catalytic thermal depolymerization-3-hydroxybutyrate (PHB) method; the other is the catalytic oxidation of crotonaldehyde. At present, the catalytic oxidation of crotonaldehyde method is mostly used, and the synthetic route is as follows: [0003] [0004] In the catalytic oxidation of crotonaldehyde, noble metals, metal oxides or strong acids are generally used as catalysts. For example, in 1993, Lin Jing et al. reported the use of active manganese dioxide, copper acetate-cobalt acetate as catalysts in "Selective Oxidation of Crotonaldehyde" published in "Journa...

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Problems solved by technology

[0005] In the patent CN 1415594, precious metal silver is selected as the catalyst, and the oxidation reaction of crotonaldehyde is carried out in the oxidation tower to prepare crotonic acid, but the catalytic cost of the precious metal is relatively high

[0006] In 2005, Jiang Zhenwu and others reported in "Crotonaldehyde Oxidation to Crotonic Acid" published in "Light Industry Science and Technology" that phosphoric acid was used as a catalyst, and the yield of crotonic acid obtained was 78-80%, but the acidity of phosphoric acid is strong, It is not conducive to recycling and waste liquid treatment, and will bring greater pressure to the environment. At the same time, due to the volatilization of crotonaldehyde gas due to incomplete reaction, it will cause greater damage to the environment and operators.

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