Vitamin A has a variety of physiological functions to promote growth, reproduction, maintenance of bones, epithelial tissues, vision and normal secretion of mucosal epithelium, etc. Vitamin A and its analogs have the effect of preventing precancerous lesions. Deficiency is manifested as growth retardation, dark adaptation ability is reduced and the formation of night blindness.

Because of the epidermis and mucous membrane epithelial cell dryness, desquamation, hyperkeratosis, lacrimal secretion is reduced, thus dry eye disease occurs, and in severe cases, the cornea is softened, perforation and blindness. Respiratory epithelial cells keratinization and loss of cilia, so that the resistance to reduce easy infection. China's adult vitamin A recommended intake (RNI) for men 800ug retinol activity equivalent per day, women 700ug retinol activity equivalent per day.

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Synthesis of Vitamin A

While vitamin A can be extracted from animal tissues, the resources are relatively dispersed, the steps are cumbersome, and the cost is high, so the commercial vitamin A are all chemically synthesized products. The industrial synthesis of vitamin A at home and abroad, there are mainly two synthetic process routes of Switzerland Roche and Germany BASF.

The former takes β-violet ketone as the starting material, characterized by Grignard reaction, and completes the synthesis of vitamin A acetate by DArzens reaction, Grignard reaction, selective hydrogenation, hydroxyl bromination and debromination of hydrogen;

The latter is typically characterized by Wittng reaction, which is characterized by Grignard reaction with β-violet ketone as the starting material and acetylene to generate acetylene-β- Violet alcohol, selective hydrogenation to obtain ethylene-β-violet alcohol, and then after the Wittng reaction, with sodium alcohol as a catalyst, and C 5 aldehyde condensation to produce vitamin A acetate.

Baidu Encyclopedia - Vitamin A