Synthetic method of trans-4-acetoxyl-2-methyl-2-butene-1-aldehyde

Abstract

The invention discloses a synthetic method of trans-4-acetoxyl-2-methyl-2-butene-1-aldehyde. The method comprises the steps that 3,4-diacetoxy-1-butene and synthetic gas are used as raw materials, a formylation reaction is carried out at the temperature of 85-100 DEG C and pressure of 85-100 kg under the effects of a rhodium catalyst and an additive, the synthetic gas is mixed gas of nitrogen and carbon monoxide, and 3-formoxyl-1,2-butanediol diethyl ester is prepared; the 3-formoxyl-1,2-butanediol diethyl ester is subjected to a decarboxylic reaction at the temperature of 85-120 DEG C through an acid catalyst, and the trans-4-acetoxyl-2-methyl-2-butene-1-aldehyde is obtained. By adding the additive in the formylation reaction and adjusting the mass ratio of the additive to rhodium in the rhodium catalyst, the formylation selectivity is greatly improved, and the formylation reaction pressure is lowered; no solvent is needed, the loss caused by solvent recycling can be lowered, the production cost and production difficulty are reduced, and the raw material utilization rate is improved.

Description

technical field [0001] The invention relates to the field of medicine and chemical industry, in particular to a synthesis method of trans 4-acetoxy-2-methyl-2-butene-1-aldehyde. Background technique [0002] Vitamin A acetate belongs to the category of drugs, and its main function is to maintain the normal metabolism of animals and humans, maintain the stability and development of cell membranes, and maintain the normal functions of the reproductive system. And trans-4-acetoxy-2-methyl-2-buten-1-al is the key intermediate for the chemical synthesis of vitamin A acetate, and its research has never been interrupted, and the methods are not the same, Among them, there is a kind of method to synthesize the key intermediate with the ester compound of butenediol as the starting material. U.S. Patent No. 3,732,287 reports that 3,4-diacetoxy-1-butene is used as the raw material to synthesize 3-formyl-1 , 2-butanediol diethyl ester, the process is as figure 1 shown. But this paten...

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Problems solved by technology

[0004] Although this patent solves the difficult problem of separation, the raw material utilization rate of this route is low, and the problem that the reaction also requires relatively high pressure still exists. Patent US4124619 reports that 1,4-butenediol diethyl ester is used as raw material to synthesize trans 4-acetoxy-2-methyl-2-buten-1-al, the route is as Figure 5 shown

[0005] This patent solves the selectivity problem of formylation, but in order to obtain the desired effect, the pressure requirement of the formylation reaction is still very high, and hydroisomerization must be carried out. During isomerization, only 61% of the formula 6 was converted, and among the converted products, the target product only accounted for 80%, and the yield was also 48%.

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