CN1113887C

CN1113887C - Preparation of tin methyl mercaptide

Info

Publication number: CN1113887C
Application number: CN99105326A
Authority: CN
Inventors: 张麟; 张天恩
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-04-19
Filing date: 1999-04-19
Publication date: 2003-07-09
Anticipated expiration: 2019-04-19
Also published as: CN1270961A

Abstract

The present invention discloses a method for preparing methyl stannum mercaptide, which adopts a two-step method. Step one, intermediate body dimethyltin dichloride and trichloromethylstannane are prepared; step two, the intermediate body as raw materials and thioglycolic acid isooctyl fat react and generate an end product, wherein the reaction of a step one uses amine salt as a catalyst, metallic tin is firstly added, and methyl chloride gas is led. Temperature is controlled to 160 to 250 DEG C, pressure is from 0.8 to 1.5MPa, reaction time is from 2 to 5 hours, a proper amount of tin tetrachloride is added to carry out recombination reaction, and time is from 1 to 2 hours. The method can be used for preparing the intermediate body under middle and low pressure, product safety is improved, and production cost is decreased.

Description

Process for preparing methyl tin mercaptide mixture

The invention relates to the technical field of preparation of a PVC heat stabilizer methyltin mercaptide mixture and raw material intermediates dimethyltin dichloride and monomethyltin trichloride.

Organotin compounds are mainly used as a heat stabilizer in PVC resins, and there are many U.S. patents, mainly butyltin and octyltin, in which propyltin is odorous and ethyltin is toxic and substituted.

Methyl tin bis (isooctyl) thioglycolate (TM-181) developed by Morton chemical company in the United states is a widely-used efficient heat stabilizer, the tin content of the heat stabilizer is 19% -20%, which is obviously higher than butyl tin and octyl tin (the tin content is about 16%), and TM-181 has good compatibility with other additives, so that the transparency of the product can be improved, and the initial colorability of the product is better due to a certain proportion of methyl tin.

The preparation method of methyl tin bis-mercaptoacetic acid isooctyl ester is many, but the technical process is relatively complex and the recovery cost is high. In order to solve the problems, the Chinese patent application laid-open Specification No. 94109586, X uses dimethyl sulfone as a catalyst, the reaction pressure is 6.0-7.0MPa and the reaction time is 1-8 hours at the temperature of 150-250 ℃, and a mixture intermediate of dimethyl tin dichloride and methyl tin trichloride is generated through the first step of reaction; the second step of reaction is to dissolve the raw material intermediate into isooctyl thioglycolate, and dropwise add ammonia water to make the pH value neutral, wherein the reaction time is 1-5 hours and the reaction temperature is 30-80 ℃. However, the preparation method still needs to synthesize an intermediate under a high-pressure state, has high process requirements and higher preparation cost. It has another disadvantage that the second reaction is carried out in an acidic environment, which easily causes an excess of raw material intermediates and an insufficient reaction.

The invention aims to adopt a novel catalyst to react and synthesize a raw material intermediate under a medium-low pressure state, improve the production safety and reduce the production cost.

Another object of the present invention is to provide a method for producing a final product by carrying out the second reaction in an alkaline environment, which can make full use of the starting intermediate.

The purpose of the invention is realized by the following technical scheme: the preparation method of methyl tin mercaptide mixture adopts a two-step method, and the first step is used for preparing raw material intermediates of dimethyl tin dichloride and monomethyl tin trichloride; and the second step is to react the raw material intermediate with isooctyl thioglycolate to generate a final product, wherein the first step adopts amine salt as a catalyst, metallic tin is firstly added, chloromethane gas is introduced, the temperature is controlled to be 160-ion and 250 ℃, the pressure is 0.8-1.5MPa, the reaction time is 2-5 hours, and a proper amount of tin tetrachloride is added for recombination reaction for 1-2 hours.

The preparation of the catalyst amine salt is that trimethylamine and chloromethane are mixed and reacted in absolute ethyl alcohol solvent at the temperature of 80-115 ℃ and the pressure of 0.4-1.0MPa for 24-36 hours, and then the mixture is cooled and filtered to obtain light yellow or white crystal finished products.

As a further improvement of the invention, the second step of reaction is to dissolve isooctyl thioglycolate in petroleum ether, add sodium bicarbonate aqueous solution, then drop the raw material intermediate aqueous solution, control the reaction to proceed in alkaline environment, make the final PH value neutral, the reaction time is 1-3 hours, the reaction temperature is 30-80 ℃.

The preparation method of the mixture of the raw material intermediate dimethyltin dichloride and the monomethyltin trichloride adopts the amine salt and the quaternary ammonium salt as the catalyst, so that the reaction can be carried out in a medium-low pressure state, the process is simple, the production safety is good, the production cost can be reduced, the mixture ratio of the prepared raw material intermediate dimethyltin dichloride and the monomethyltin trichloride is about 80: 20, the conversion rate reaches 99%, the recovery rate of the final product reaches more than 98%, and the impurity trimethyltin chloride is not more than 0.6%.

The second step is reaction in alkaline environment, and the reaction product hydrogen chloride can be neutralized in time, so that the reaction is promoted to be carried out towards the direction of generating a final product, the reaction speed is accelerated, and the raw material intermediate can be fully utilized.

The present invention will be further described with reference to the following examples.

The first embodiment is as follows: synthesis of the catalyst amine salt

Adding 4L of absolute ethyl alcohol into a small stainless steel reaction kettle, introducing 2.4Kg of trimethylamine, heating to 80 ℃ after dissolving and absorbing, stirring and introducing methyl chloride gas, controlling the temperature to be 115 ℃, the pressure to be 0.4-1.0MPa, reacting for 24 hours, cooling, centrifuging and filtering to obtain a light yellow or white crystalline compound, namely a catalyst (Cat). Preparation of raw material intermediates dimethyltin dichloride and monomethyl tin trichloride

Reaction type

Adding 3.5Kg of tin sheet and 0.1Kg of catalyst into a stainless steel pressure kettle with a stirring device, heating to 150 ℃, introducing methyl chloride gas, keeping the kettle pressure at 0.8-1.5MPa, heating to 200 ℃, intermittently adding the methyl chloride gas until the methyl chloride gas is not absorbed (namely the pressure is not reduced), reducing the pressure to 0.8MPa for about 2.5 hours, adding 1.0Kg of tin tetrachloride, measuring the temperature to be 230 ℃, the pressure to be 1.2MPa, then introducing the methyl chloride gas to continue the reaction, keeping the kettle pressure at 0.8-1.5MPa, reacting for 1.5 hours, and taking the methyl chloride gas not absorbed as a reaction end point; after cooling, the remaining chloromethane gas was vented to obtain 5.5Kg of white needle-like crystalline compound, at which point 3.5Kg of chloromethane gas was consumed in total. Theoretical calculation shows that the ratio of dimethyl tin dichloride to monomethyl tin trichloride as the raw material intermediate is 78: 22, the measured value is 77: 23, and the conversion rate is 99%. -production of the end product

Reaction type

12.6Kg of isooctyl thioglycolate is added to 15Kg of 60^#-90^#Dissolving in petroleum ether, and adding prepared sodium bicarbonate solution (5.3 KgNaHCO)₃Dissolved in 5Kg of water) 10.3Kg, stirred and then the aqueous intermediate solution (5.5Kg of intermediate dissolved in 10Kg of water, total 15.5Kg) was added dropwise in the chamberReacting at normal temperature and pressure for 2 hours, preserving the temperature at 60 ℃ by using a water bath after the reaction is finished, preserving the temperature for 1 hour, removing a lower water layer, washing the lower water layer twice by using water, raising the temperature to 100 ℃, recovering the petroleum ether solvent by using a condenser, and obtaining 15.2Kg of a transparent oily product after desolventizing for 1 hour. The recovery rate was 98%.

And (3) product physical property analysis results:

tin content: 19.4% refractive index: 1.503 specific gravity (20 ℃): 1.18 color (Pt-Co):<100

Example two:

the procedure of example one was repeated except that the first reaction step was carried out as follows: adding 3.0Kg of tin sheet and 0.1Kg of catalyst into a stainless steel pressure kettle with a stirring device, heating to 150 ℃, introducing methyl chloride gas, keeping the kettle pressure at 0.8-1.5MPa, reacting at 200 ℃, intermittently adding the methyl chloride gas until the methyl chloride gas is not absorbed (namely the pressure is not reduced), reacting for 2 hours, reducing the pressure to 0.8MPa, adding 0.9Kg of stannic chloride, introducing the methyl chloride gas, continuing the reaction, keeping the kettle pressure at 0.8-1.2MPa, reacting for 1 hour, and taking the methyl chloride gas which is not absorbed as a reaction end point; after cooling, the remaining chloromethane gas was vented to give 5.0Kg of white needle-like crystalline compound, at which point 3.0Kg of chloromethane gas was consumed in total. The ratio of dimethyl tin dichloride and monomethyl tin trichloride in the raw material intermediate is 79: 21, and the conversion rate is 99%.

Example three:

the procedure of example one was repeated except that the first reaction step was carried out as follows: adding 3.5Kg of tin sheet and 0.1Kg of catalyst into a stainless steel pressure kettle with a stirring device, heating to 150 ℃, introducing methyl chloride gas, keeping the kettle pressure at 0.8-1.2MPa, reacting at the temperature of 200-; after cooling, the remaining chloromethane gas was vented to obtain 5.6Kg of white needle-like crystalline compound, at which point 3.5Kg of chloromethane gas was consumed in total. The ratio of dimethyl tin dichloride and monomethyl tin trichloride as the raw material intermediates is 80: 20, and the conversion rate is 99%.

Claims

1. The preparation method of methyl tin mercaptide mixture adopts a two-step method, and the first step is used for preparing raw material intermediates of dimethyl tin dichloride and monomethyl tin trichloride; and the second step is to react the raw material intermediate with isooctyl thioglycolate to generate a final product, wherein the first step adopts amine salt as a catalyst, metallic tin is firstly added, chloromethane gas is introduced, the temperature is controlled to be 160-ion and 250 ℃, the pressure is 0.8-1.5MPa, the reaction time is 2-5 hours, and a proper amount of tin tetrachloride is added for recombination reaction for 1-2 hours.

2. The process for preparing methyl tin mercaptide mixture according to claim 1, wherein the amine salt as catalyst is prepared by mixing trimethylamine and chloromethane in anhydrous ethanol solvent at 80-115 deg.C under 0.4-1.0MPa for 24-36 hr, cooling, and filtering to obtain yellowish or white crystal.

3. The process for preparing a mixture of methyltin mercaptides according to claim 1, wherein said second reaction step comprises dissolving isooctyl thioglycolate in petroleum ether, adding aqueous sodium bicarbonate solution, adding dropwise said aqueous intermediate solution, and reacting in an alkaline environment to make the final pH neutral, wherein the reaction time is 1-3 hours, the reaction temperature is 30-80 ℃, and the temperature is maintained for 1 hour.

4. The process for the preparation of a mixture of methyltin mercaptides according to claim 1 wherein the temperature of the second stage is maintained at 60 ± 1 ℃.