A kind of Grignard process for preparing ws series cooling agent intermediate menthyl carbonate

Abstract

The invention discloses a Grignard technology for preparing a WS series cooling agent intermediate (menthyl carbonate), and relates to the technical field of organic synthesis. The Grignard technologycomprises the following steps of using industrial bromoethane, industrial tetrahydrofuran and magnesium chip as raw materials, and dripping chlorinated menthol to generate a Grignard reagent withoutthe inert gas protection; standing the generated Grignard reagent (menthyl chloride), settling, and separating, so as to obtain a supernatant; leading carbon dioxide gas, absorbing carbon dioxide, anddripping hydrochloric acid, so as to obtain menthyl carbonate. The Grignard technology has the advantages that the reaction time is short, any side product is not produced, the utilization rate of the magnesium chip of the raw material is high, the final chlorinated menthol is fully converted into menthyl carbonate, the yield rate of the WS series cooling agent intermediate is increased, and theloss rate of the raw material is reduced; the amount of solvent is reduced, the requirement on the Grignard reaction conditions is not strict, and the drainage of waste liquid is avoided.

Description

Technical field: [0001] The invention relates to the technical field of organic synthesis, in particular to a Grignard process for preparing menthol-based carbonic acid intermediates of WS series cooling agents. Background technique: [0002] As a cooling agent, natural menthol has very important uses in daily chemicals, food, medicine and cigarette products. However, due to the high volatility and irritation of menthol, its cooling effect is short and strong, and it is even harmful to human skin and skin. Eyes are harmful, and its special mint smell limits its wide application in daily chemical products. [0003] New cooling agent WS-3 (N-ethyl-2-isopropyl-5-methyl-cyclohexanecarboxamide), cooling agent WS-5 (N-(ethoxycarbonylmethyl)-p-alkane -3-formamide), WS-12 (N-(4-methoxyphenyl)-p-menthyl-3-carboxamide) are characterized by refreshing, long-lasting, fresh, non-irritating spicy taste, and no bitterness , can be widely used in chewing gum, toothpaste, candy, jelly, jam...

AI Technical Summary

Problems solved by technology

[0005] In the process of preparing menthyl carbonate, because menthyl chloride is not active enough, it is difficult to cause grittiness reaction, which affects the amount of magnesium chips used.

In the prior art, dry ice or carbon dioxide is directly added to the prepared menthyl chloride Grignard reagent, and the Grignard reagent is destroyed after each Grignard reaction, resulting in the need to prepare a new Grignard reagent next time.

However, the newly prepared formatted reagent has strict requirements on the conditions, and it is easy to fail the preparation. It takes a long time to prepare the formatted reagent each time, and the prepared formatted reagent is not active enough, which is easy to cause waste of magnesium scraps.

And because there are many by-products in the Menthyl Chlorine Grignard reaction, the Grignard reaction is not thorough, which has a greater impact on the absorption of carbon dioxide in the next step, thereby causing the yield to decrease and affecting the output.

[0006] The traditional format synthesis process requires the removal of surface oxides on the raw material magnesium chips, and the use of a unique method for drying the solvent. Large-scale use of bulk raw materials is not possible, which greatly increases the cost of raw materials; moreover, magnesium chips cannot fully participate in the format reaction. As a result, a large amount of magnesium scrap remains after the format is completed, and the discarded magnesium scrap can only be stored as solid waste, which increases the risk of production. Every time the format reagent is prepared, a new input of 1,2-dibromoethane is required, which reduces the ws of the cooling agent. Profit space, ws overall yield is 40-50%