Synthesis method of zinc pyrithione

Abstract

The invention discloses a synthesis method of zinc pyrithione. The method comprises the following steps: (1) nitrogen oxidation of 2-chloropyridine: adding 2-chloropyridine, a solvent and a catalyst into a reactor, dropwise adding hydrogen peroxide for reacting, and after the reacting, filtering to obtain a 2-chloropyridine nitrogen oxide solution; (2) sulfhydrylation: adding a sulfhydrylation reagent into the reactor, dropwise adding the 2-chloropyridine nitrogen oxide solution, and after the reacting, adjusting the pH value, and decolorizing with active carbon to obtain a 2-chloropyridine nitrogen oxide mercapto sodium salt solution; and (3) chelation to obtain salt: adding a zinc salt solution into the reactor, dropwise adding the 2-chloropyridine nitrogen oxide mercapto sodium salt solution, and after the reacting, filtering, washing the filter cake with deionized water, and drying to obtain zinc pyrithione. In the zinc pyrithione prepared by the method disclosed by the invention, the total yield is increased to 92%, and the product purity is increased to over 98%; the nitrogen oxidation reaction yield is increased to over 97%, and the catalyst can be regenerated for use; and moreover, the whole process is simple to operate and generates relatively few three wastes.

Description

technical field [0001] The invention belongs to the field of chemistry, and in particular relates to a method for synthesizing zinc pyrithione. Background technique [0002] Pyrithione zinc (Pyrithionc Zinc, ZPT), aliases: omadine zinc, pyrithione zinc, CAS number is 13463-41-7, molecular formula is C 10 h 8 N 2 o 2 S 2 Zn, the molecular weight is 317.7, the pure product is off-white fine powder, and the common dosage form is 50% emulsion. [0003] Zinc pyrithione, as an antibacterial and bactericide with excellent performance and broad-spectrum environmental protection, is widely used in daily chemical, paint, paint and other industries. It is mainly used in shampoo, which can effectively care for hair and delay hair aging. It is the best additive with anti-dandruff and anti-itch functions in hair shampoo products to control the occurrence of white hair and hair loss. [0004] The existing synthesis technique of zinc pyrithione mainly contains following 3 kinds: [0...

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Problems solved by technology

[0010] ②Using glacial acetic acid as the medium, since the subsequent mercaptolation reaction must be carried out under alkaline conditions, before the mercaptolation reaction, either distill and recover acetic acid, or use alkali to neutralize, the former is complicated to operate and difficult to distill completely, and the latter is A large amount of saline wastewater is added; in addition, the presence of acetic acid greatly increases the requirements for reaction equipment, which increases product costs in disguise;

[0011] ③ The amount of hydrogen peroxide is large, at least double the excess, the utilization rate of hydrogen peroxide is low, and the residual hydrogen peroxide in the reaction system needs to be quenched after the reaction is completed, otherwise it will affect the subsequent mercaptolation reaction

[0012] In addition, in the patent CN201210219748, it is mentioned in the patent CN201210219748 that molecular sieves are catalyzed and oxidized to prepare 2-chloropyridine nitrogen oxides, and a good yield is obtained, but the catalyst is prepared separately, and its stability and reusability need to be verified by long-term experiments. Secondly, the The catalyst uses MCM-41 mesoporous molecular sieve as the carrier. The carrier has a large pore size and relatively low catalytic activity. In addition, its pore wall has an amorphous structure and poor hydrothermal stability. The third point is that its hydrogen peroxide and 2-chloro The molar ratio of pyridine is close to 1.5:1, the excess is too much, the utilization rate of hydrogen peroxide is too low, and the reaction time is as long as 7h, which also shows that the activity of the catalyst prepared by it is low