Study On The New Technology Of Synthesis Of Isooctyl Mercaptoacetate

Isooctyl mercaptoacetate (TGB) as an important fine chemical products widely used in non-toxic PVC heat stabilizers such as the preparation of thiols tin, antimony, ester-based tin, and antimony. TGB on a yearly basis of industrial demand. As a result of the current production process of TGB,there is a high investment, high costs and serious environmental pollution, and many other issues. the development of low cost, low investment and a good environment for the safety of TGB as a necessary synthesis of new technology.In the base of the successful synthesis of TGA by electricity reducing process .There were four aspects of the study were included. The first was the establishment of product qualitative and quantitative analysis method. Second, the optimization of TGA extraction. Third and last, the technological conditions optimization and apparent kinetics etc. The results had a significance of academic theories and a better prospect for industrial applications.A method was presented for the simulatneous determination of TGA and TGB in the reaction liquid by high performance liquid chromatography (HPLC). The analysis was performed on a C₁₈ column (150 mm×4.6 mm i.d) with 70 : 30 acetonitrile-water as the mobile phase (adjusted to pH = 3.0 with phosphoric acid) at a flow rate of 1.0 rnL/min. The samples were detected at 210 nm with UV detector and the column temperature was 30°C. It was found that TGA and TGB could be well separated under the chromatograph condition. The maximum relative standard deviations were 0.53% and 0.46% and the detection limits were 2.03×10^-3 g/L and 6.11×10^-3 g/L for TGA and TGB. The recoveries for TGA and TGB were 98.97%～100.76% and 99.10%～100.69% respectively.From the synthesis of TGA with electrochemical reduction ,the liquid contains about 7.1% of TGA, at the same time contains a lot of impurities in inorganic acids and salts. In this paper, with ensuring a higher total yield and purity conditions, the three-step counter-flow was carried out. Under the experimental conditions of isooctanol as extractant and the phase ratio was 1.5, the purity of TGA can be greater than 17 percent and the yield can get not less than 88%.Through the improvement of the original electrochemical reduction of DTDGA, we found that when the initial concentration of solution is high,it is beneficial for the use of change operations instead of the maintenance of current electro-reduction reaction process with higher rate and higher current efficiency. On the basis of the foregoing,using mono-factor experiment, the optimum technological conditions were found as follows: Self-made solid superacid (DMN) as catalyst and toluene as water entrainer; the mass fraction of catalyst and water entrainer in reactant were 2wt% and 50% respectively; the reaction time was 2 hours and temperature is 120°C. The results indicated that more than 98% yield and 92.5% purity could be obtained with the following optimal reaction. Infrared spectra of products in line with the standard spectra.The apparent kinetics of synthesis for TGB was investigated and obtained: the reaction order of the synthesis was n=2, and the apparent activation energy was Ea=68.072 KJ/mol, frequency factor was A =1.005×10⁷L/ (mol·min) . And the reliability was verified. The operating condition which is suitable for the industrialization production choice has provided the foundation data.