Method for preparing methyl pyridine nitrogen oxide

Abstract

The invention discloses a method for preparing a methyl pyridine nitrogen oxide. The method comprises the following steps of: (1) mixing methyl pyridine and catalyst in a mass ratio of 1: (0.05-0.5), stirring, and adding hydrogen peroxide for reacting at the temperature of between 40 and 90 DEG C, wherein the molar ratio of the hydrogen peroxide to the methyl pyridine is (0.8-3.5): 1; and (2) keeping the temperature unchangeable, reacting for 3 to 10 hours with stirring, cooling to normal temperature, filtering to obtain methyl pyridine nitrogen oxide filtrate, concentrating, and thus obtaining a finished product of the methyl pyridine nitrogen oxide, wherein an MCM-41 mesoporous molecular sieve is used as a carrier of the catalyst. By adopting the preparation method, the reaction conversion rate of the methyl pyridine reaches 100 percent, the yield of the methyl pyridine nitrogen oxide is over 98 percent, and the content of the methyl pyridine nitrogen oxide is improved from 95-96 percent to over 98 percent.

Description

technical field [0001] The invention relates to the field of organic synthesis, in particular to a preparation method of pyridine nitrogen oxide. Background technique [0002] The picoline nitrogen oxides generally include 2-picoline nitrogen oxides, 3-picoline nitrogen oxides and 4-picoline nitrogen oxides, among which: [0003] (1) 2-methylpyridine nitrogen oxide [0004] English name: 2-Methylpyridine-N-oxide [0005] Molecular formula and molecular weight: C6H7NO=109.13 [0006] Properties: Melting point 46-50°C. The boiling point is 259-261°C. Flash point 143°C. Water-soluble soluble. [0007] (2) 3-methylpyridine nitrogen oxide [0008] English name: 3-Methylpyridine-N-oxide [0009] Molecular formula and molecular weight: C6H7NO=109.13 [0010] Properties: Melting point 38-40°C. The boiling point is 150°C (15mmHg). Flash point 143°C. Water-soluble soluble. [0011] (3) 4-methylpyridine nitrogen oxide [0012] English name: 4-Methylpyridine-N-oxide [00...

AI Technical Summary

Problems solved by technology

[0026] In these documents, different catalysts are used to oxidize with hydrogen peroxide in acetic acid medium to generate picoline-N-oxide and pyridine nitrogen oxides, so there are several same problems: one is that the reaction is not complete, and the process requires Recover picoline; the second is to use acetic acid medium, because the mercaptolation reaction will be carried out under alkaline conditions, before mercaptolation, acetic acid must be recovered by distillation or neutralized with a large amount of alkali, and the operation is complicated to increase a large amount of saline waste water; It is difficult to recycle the catalyst. Recycling will increase the production cost. Failure to recycle will affect the subsequent reaction yield and affect the final product quality. Fourth, there is a large excess of hydrogen peroxide, and the excess is more than 1.5 times.

For subsequent reactions, the excess hydrogen peroxide must be destroyed, otherwise it is easy to cause dangers such as punching