Preparation method of methyltin mercaptide

Abstract

The invention discloses a preparation method of methyltin mercaptide. The method comprises the following steps: adding water in methyltin chloride to stir and fully dissolve, adding an inorganic alkaline substance, controlling the pH value to 6-8, stirring to react at 30-60 DEG C for 3-5 hours and obtain a white turbid solution; and then adding isooctyl mercaptoacetate, controlling the reaction temperature to 40-80 DEG C to react for 2-5 hours, stopping stirring to ensure that the reaction solution is divided into an upper layer and a lower layer, rinsing the lower reaction solution, filtering, and performing reduced pressure distillation on the filtrate to dewater and obtain methyltin mercaptide, wherein the methyltin chloride is methyltin trichloride, dimethyltin dichloride, or the mixture of methyltin trichloride and dimethyltin dichloride; and the mass ratio of methyltin chloride to isooctyl mercaptoacetate is 1: (1.5-3.0). The method adopts two steps, hydrogen chloride gas can not escape in the reaction process, the method is green and environmentally-friendly; and the methyltin chloride can fully react, the reaction speed can be increased and the yield can be effectively increased.

Description

(1) Technical field [0001] The invention relates to a preparation method of a PVC heat stabilizer methyltin mercaptide. (2) Background technology [0002] Methyl tin mercaptide (a mixture of isooctyl tin monomethyl trimercaptoacetate and isooctyl tin dimethyl dimercaptoacetate) is a widely used PVC heat stabilizer with excellent performance. Its synthesis method was as early as seven There are patent reports in the ten years, such as U.S. Pat. The tin solution is reacted, and the product is post-treated to obtain the product. This method is more complicated, and a large amount of solvent must be added. It is necessary to invest in a solvent recovery device and increase the production cost of the product. [0003] In order to overcome the above drawbacks, relevant scientific research institutions have begun to focus on the preparation process of methyltin mercaptide, and have achieved certain results. Chinese patent CN1439670A proposes to adopt the direct synthesis method, ...

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Problems solved by technology

Chinese patent CN1439670A proposes to adopt the direct synthesis method, but the process equipment conditions and energy consumption required by this method are relatively high. Under the vacuum degree and temperature conditions of this method, the raw material isooctyl thioglycolate will also have a certain degree of loss.

Chinese patent CN11177495A proposes that the raw material intermediate is dissolved in isooctyl thioglycolate, and ammonia water is added dropwise to make the pH value neutral. The reaction time is 1-5 hours, and the reaction temperature is 30-80° C., but this method Hydrogen chloride is continuously produced, and the reaction is carried out in an acidic environment, which may easily cause excess intermediates and insufficient reaction

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