Applications Of Ionic Liquids In The Synthesis Of Vitamins

Vitamins are very important products on the international market of medicine and health products, and now, China is one of the largest exporters in the world. The main synthesis methods of Vitamin A and Vitamin E were introduced in this paper, and several drawbacks in the production of Vitamins were pointed out, such as: the difficulty of recycling a stoichiometric amount of catalyst, which was used in the aerobic oxidation of 2,3,6-trimethylphenol;the problem of using volatile organic solvents and toxic catalysts in the synthesis of 2-methoxypropene;and the problem of using volatile organic solvents and virulent materials in the recycle of triphenylphosphine oxide. All these problems are needed to be solved by efficient method immediately.Ionic Liquids have attracted considerable interest as environmentally benign solvents or catalysts because of their excellent physical and chemical characters, and provide a new method to overcome the environmental problems in chemical productions. A novel ionic liquid [Et₃NH][CH₃COO] was used as cocatalyst in the aerobic oxidation of 2,3,6-trimethylphenol in this paper. The results show that the amount of catalyst CuCl₂ used in the oxidation reaction could be greatly decreased and the product yield was 74.2%. Also, ten quarterary ammonium ionic liquids were prepared and used as benign environmental solvents and catalysts in the synthesis of 2-methoxypropene, eliminating the need for a volatile organic solvent and additional catalyst. The good conversion and high yield can be obtained in the [Et₃NH][HSO₄] ionic liquid by 95% and 82%, respectively. In addition, triphosgene was used for the first time in the chlorination reaction of triphenylphosphine oxide instead of virulent gas phosgene, and then ionic liquids were used as solvents and catalysts in this reaction without the use of traditional volatile organic and catalysts. Comparatively, especially high yield could be obtained by 72.3% in the [Et₃NH][CH₃COO] ionic liquid.Ionic liquids used in this paper are easy to prepare from cheap amines and easy to be separated and reused. Hence these ionic liquids are used as solvents or catalysts for the mentioned reactions, eliminating the need for a volatile organic solvent or additional catalyst. The conversion and yield obtained are significantly increased in comparison with those reported in traditional organic solvents to date. Therefore, these ionic liquids provide a good alternative way for the industry chemical productions.