Method for producing improved vitamin A acetic ester

Abstract

The invention provides an improved preparation method for vitamin A acetate, which adopts a route of C15+C5 with Wittig reaction as characteristics, namely, using a carbon 15 phosphonic acid dialkyl ester and a C 5-aldehyde to react under the function of alkali to generate the vitamin A acetate. The invention is characterized in that a mixture of toluene and pyridine (or the methyl substitutes of pyridine) is used as a reaction solvent to enable the reaction to be carried on in an environment close to a room temperature and to reach the yield that can be achieved only under extremely low temperature, which greatly reduces the energy consumption and the difficulties of production operation and is beneficial to industrial production.

Description

technical field

[0001] The invention relates to the field of organic chemistry, in particular to a preparation method of conjugated polyene unsaturated carbon frame compounds, in particular to a preparation method of vitamin A acetate. Background technique

[0002] Vitamin A and its derivatives are important medicines for the treatment of night blindness, dry eyes, corneal softening, and dry skin. an important feed additive. Commonly used vitamin A derivatives are its alkyl esters, such as acetate, propionate, palmitate, etc., and its structure is shown in the following formula (R 1 for alkyl):

[0003]

[0004] Among the many derivatives of vitamin A, acetate is the most commonly used. At present, the technical route of synthesizing vitamin A acetate mainly contains following 3 kinds: 1, the C that is characterized by Grignard reaction 14 +C 6 Route: Using β-ionone as raw material, it is completed through six steps of Darzens reaction, Grignard reaction, hydrogenati...

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