Research On Synthesis Of Di-sec Butyl Disulfide With Sodium Sulfide Method Under Phase Transfer Catalysis

Di-sec butyl disulfide is a symmetrical disulfide. As an important pharmaceutical intermediate and chemical material, it can be used to synthesize a variety of pesticides dyes and medcine. In recent years, di-sec butyl disulfide has a good market demand with its deep realization and development of down-stream products. But its scale of production is very low at home and abroad. So the study on production technology of di-sec butyl disulfide is very significative. Commissioned by Sanmenxia Aoke Chmical Engineering Co. Ltd, synthesis of di-sec butyl disulfide was carried out in this study. The work was as follows.The solubility of sodium sulfide in water and methanol-water, ethanol-water, dimethyl formamide-water, dimethylsulfoxide-water, tetrahydrofuran-water,1, 4-dioxane-water had been determined by synthetic method. It can be observed that the solubility in selected solvents follow the order DMF-water> water> methanol-water>1,4-dioxane-wate>DMSO-water> ethanol-water on the whole. By using Apelblat three parameters solubility equation to correlate the experimental data, and comparing the calculated value with experimental value, the related deviations were within 4.7%.2-brombutane and sodium sulfide, sulfur as materials were used. The optimal technology conditions were obtained by single-factor and orthogonal designs. The effects of mole ratio of sodium sulfide to sulfur, the amount of catalysis, the amount of solvent, temperature on the result of reaction were studied. The optimal technology conditions of single-factor were:the amount of catalysis 2%, the mole ratio of sodium sulfide to sulfur 1.25:1, the mole ratio of sodium disulfide to 2-brombutane 1:1.8, the reaction temperature 25℃, the drop time 4 hours, the reaction time 10 hours and the yield 91.64%. The factors followed the order the amount of catalysis> the mole ratio of sodium disulfide to sulfur>the reaction temperature>the mole ratio of sodium disulfide to 2-brombutan>the drop time. And the optimal technology conditions of orthogonal designs were:the amount of catalysis 0.5%, the mole ratio of sodium disulfide to sulfur 1:0.5, the reaction temperature 25℃, the mole ratio of sodium disulfide to 2-brombutan 1:1.75 and the drop time 0 hour. The selectivity and purity of di-sec butyl disulfide is up to 95% and 99.5% respectively. The average yield was 92.04% under the optimal conditions. The process is applicable to the industrial preparation of di-sec butyl disulfide.The inorganic phase solution could be recycled three times in reaction. So the amount of waste water and catalyst were on the decrease. The economic technology conditions were obtained by material accounting and cost accounting. The optimal technology conditions by orthogonal designs were more suitable for industrial production due to low consumption of raw materials and low cost.The structure of di-sec butyl disulfide prepared was charactered by IR and 1HNMR.The result showed that the structure of product was in good agreement with the authentic sample. And GC was used for the measurement of crude di-sec butyl disulfide and monitoring the progress of the reaction.