Production method of 2-methyl-3(5 or 6)-methylthio pyrazine

Abstract

The invention discloses a production method of 2-methyl-3(5 or 6)-methylthio pyrazine. The method comprises the following steps: adding solvents dichloroethane and triethylamine into a reaction kettle, sealing the reaction kettle, introducing chlorine to control the pressure in the kettle at 0.02-0.03 MPa, pumping a methylpyrazine solution into the reaction kettle by using a metering pump, controlling the temperature at 45-60 DEG C, reacting, and transferring reaction liquid(containing the chlorine)in the kettle into a dichloroethane turnover tank through filter pressing for recycling after the reaction is finished; dissolving the residual 2-methyl-3(5 or 6)-chloropyrazine hydrochloride solid in the reaction kettle with water, adjusting the neutrality, and layering to obtain a 2-methyl-3(5or 6)-chloropyrazine crude product; and dropwise adding thechloropyrazine crude product is into sodium methyl mercaptide, performing reflux reaction , and after reaction liquid is extracted, adding an aid into an organic phase to generate a hydrochloride for separating the non-pyrazine product from the product to greatly improve the aroma quality of the obtained product. The product grade is improved, and the whole production process is safe and environmentally friendly.

Description

technical field [0001] The invention relates to a production method of 2-methyl-3(5 or 6)-methylthiopyrazine, which belongs to the technical field of food additive production. Background technique [0002] 2-Methyl-3(5 or 6)-methylthiopyrazine (Methylthiopyrazine) is a pyrazine fragrance. It has the aroma of popcorn, roasted almonds, hazelnuts, peanuts and cashews, and has the green smell of seafood such as crabs and shells. Type and baking flavor food flavor. 2-Methyl-3(5 or 6)-methylthiopyrazine can also be used as a pharmaceutical raw material or a pharmaceutical intermediate. [0003] 2-Methyl-3(5 or 6)-methylthiopyrazine, the molecular formula is C 6 h 8 N 2 S, the structural formula is as follows. At present, the mixture of the following three isomers is generally used as food flavor. [0004] [0005] At present, there are relatively few synthetic research reports on 2-methyl-3 (5 or 6)-methylthiopyrazine, and the current synthetic method is: reacting methyl...

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Problems solved by technology

[0008] 1) The chlorination reaction operation is carried out under normal pressure. A large amount of chlorine gas escapes during the reaction process, which not only wastes raw materials, but also causes environmental pollution. After the chlorination reaction is completed in addition, the chlorine in the reaction system is all hydrolyzed, neutralized and processing, which wastes raw materials and increases the difficulty of operation

[0009] 2) In the existing 2-methyl-3(5 or 6)-methylthiopyrazine production process, the design of the post-treatment process is unreasonable, the composition of the product is relatively complicated, the product purity is low, and the aroma of the product is poor

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