Method for synthesizing beta-carotene from vitamin A through one-pot method

Abstract

The invention discloses a method for synthesizing beta-carotene from vitamin A through a one-pot method. The synthesis method comprises the following steps that firstly, a vitamin A triphenyl phosphine salt reaction solution is obtained, wherein triphenyl phosphine is added in an organic solvent, acid is slowly dropwise added, after dropwise adding is completed, heat preservation is conducted, then vitamin A or a derivative of the vitamin A and alkali 1 are added, a heat preservation reaction continues, and the vitamin A triphenyl phosphine salt reaction solution is obtained; secondly, all-trans beta-carotene is obtained, wherein an acidic medium oxidizing agent and alkali 2 are dropwise added under a low-temperature condition, after the heat preservation reaction is completed, the reaction temperature is increased, the reaction continues, a beta-carotene reaction solution is obtained, a beta-carotene crude product is obtained after post-treatment, and the all-trans beta-carotene is obtained after the beta-carotene crude product is subjected to thermal isomerization. The obtained beta-carotene is crystal solid from red to dark red, the content is larger than 95%, and the yield is 55% or above.

Description

technical field [0001] The invention relates to the synthesis of beta-carotene, in particular to a vitamin A one-pot method for synthesizing beta-carotene. Background technique [0002] Beta-carotene is a known compound whose structural formula is as follows: [0003] [0004] β-carotene is a carotenoid, which has been widely used in nutrition fortifiers and food coloring agents, and many synthesis reports have been reported. These methods include the preparation of β-carotene from vitamin A acetate or 2,7-dimethyl-2,4,6-octatriene-1,8-dialdehyde as raw materials, and the methods involve various reaction routes. Among them, the synthetic route disclosed in U.S. Patent No. 3,367,985 is: vitamin A acetate is saponified to obtain vitamin A alcohol, and then vitamin A aldehyde and vitamin A triphenylphosphine salt are prepared respectively, and vitamin A aldehyde and vitamin A triphenylphosphine salt are processed by Wittig The reaction gives β-carotene. Among them, the ox...

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Problems solved by technology

Among them, the oxidation of vitamin A alcohol to vitamin A aldehyde requires an oxidant whose general structural formula is CrO 3 ·NR1R2R3·HX, the oxidant is not only difficult to prepare, but also contains heavy metals, which pollutes the environment. The preparation of divalent titanium is not only costly, but also difficult to apply, and it is difficult to realize industrial production

[0007] The synthetic route disclosed in Chinese patent CN101041631A is: Vitamin A alcohol and triphenylphosphine synthesize vitamin A triphenylphosphine salt, and then use hypochlorite coupling oxidation under alkaline conditions to beta-carotene, but due to hypochlorite Acid salts have strong oxidative properties under alkaline conditions, and easily oxidize the product β-carotene, resulting in low yields

Since the coupling reaction in this process is a two-phase reaction, the vitamin A triphenylphosphine salt is dissolved in the organic phase, and the oxidant and alkali are in the water phase, and the reaction intermediate vitamin A triphenylphosphine ylide cannot be converted into the product β in time -carotene, resulting in low yield

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