Application Of Microstructured Reactor In Methyl Thioglycolate Esterification Reactions

Methyl thioglycolate, which as an important fine chemicals, is an important intermediates of synthetic pesticides, pharmaceuticals, tobacco spice and flavor, has a broad application in industrial production. Long time as needed for synthesis of methyl thioglycolate-mercaptoacetic acid widely used as chemical and pharmaceutical intermediates in the synthesis of polymers, low yield, high prices, and some depend on imports; at the same time the synthesis of thioglycolic acid methyl ester yields low, low, high costs. Microstructured reactor is a reactor for continuous flow of pipeline, the pipe size is far less than conventional tubular reactors, generally defined in the micrometer to millimeter size range, there are a lot of specific surface area, which brings the fundamental advantage is great efficiency and mass transfer efficiency. In other words, you can precisely control reaction temperature and the response according to the exact ratio of instantaneous mixing of materials. These are increased yields and selective reaction speed, security, and quality of critical factors.Therefore, on the basis of previous studies,first we take Thioglycolic acid and methanol for raw materials,that’s with a liquid-liquid homogeneous esterification reaction as a case study of the reaction law in the microstructured reactor,then take methyl chlorider and sodium sulfide as raw material, considered single factors experimental, Study the thioglycolic acid methyl ester yield problems of liquid-liquid two-phase synthesison in micro structure reactor, and use the microstructured reactor applied to refined products, with using its excellent of heat transfer and pass mass characteristics, improve reaction and refined of efficiency, for this, It carried out the following work. Papers with thioglycollic acid and methanol as raw material in chapter Ⅱ, in the reactor with extension tube connected to a micro-mixer and composed of micro-structure, conducted a study on preparation of methyl thioglycolate. Main inspected the effec tof pipe diameter, type of catalyst, catalyst, residence time, temperature and alkyd initial Mole ratio on esterification of synthesis of Methyl thioglycolate. The results showed ester yield is higher when with p-toluene sulphonic acid as catalyst, Channel size on product yields has a greater impact, reducing the diameter of micro-channel can significantly improve the yield of ester. As the amount of catalyst increases, Ester yields increased. When the retention time increased from8.2min to57.2min, Ester yields increase in9.5min to a14.3min ester yields significantly increase, an increase of15.82%, after this time.increasing residence time, yields are not increased. When the temperature increases from30°c to90°c, Ester yields increased, at60℃91.0%has been reached. Alkyd molar ratio is4:1, Ester yields94.64%, is more suitable for alkyd Mole ratio.In chapter Ⅲ, first we take methyl chloride and Sodium hydrosulfide for raw materials, in a traditional way reach the synthesis of methyl thioglycolate by using phase transfer catalyst, Investigation of the sodium sulfide dosage, stirring speed, reaction temperature, reaction time and catalyst dosage and kinds of several factors on the product yield of methyl thioglycolate have been done. And with iodine quantity method and gas chromatography for the product analysis, results shows that, methyl thioglycolate by optimization of the process conditions is this:mixing speed for1100r/min, and using30%of sulfur hydrogen of sodium water solution, and catalyst four butyl ammonium chloride dosage for0.6%, and reaction temperature for10℃, reaction time for2.5h, sulfur hydrogen of sodium and chlorine acetate methyl ester More than for1.1:1; received rate can reach73%(GC purity70%), but vice products clearly exist, selectivity is bad. Therefore, on the basis of the above work, the microstructured reactor was studied by phase transfer catalysis synthesis of thioglycolic acid methyl ester on the focus of the study, the total flow rate, retention time and temperature effect on the reaction. The results showed, the0.6mm, T stainless steel micro mixer and corresponding stainless steel capillary tubes micro-structured reactor, in the total flow rate of0.76ml/min, temperature of40℃, only lOmin, methyl chloride conversion rate reached34.9%, thioglycolic acid methyl ester yield can reach more than30%, selectivity higher than95%. The reaction time is greatly reduced, and almost no side reaction, is a good prospect of mercaptoacetic acid methyl ester synthesis method.