| Dicyclohexyl disulfide is an important fine chemical intermediates. It is the key intermediate of N-Cyclohexylthiophthalimide for rubber anti-scorcher and widely used in food, medicine, dyes, pesticides, organic synthesis and so on. In recent years, with the continuous development of rubber industry, the market demand of dicyclohexyl disulfide is increasing year by year, causing the extensive attention in domestic. Commissioned by Sanmenxia Aoke Chemical Co. Ltd., a new synthesis process of dicyclohexyl disulfide was carried out in our study. With the bromocyclohexane and chlorocyclohexane as the raw material, the synthesis technology, mechanism and kinetics for the synthesis of dicyclohexyl disulfide was studied in this paper, which had important theoretical significance and industrial application prospect.First, we explored a new synthesis technology of dicyclohexyl disulfide with sodium sulfide nonahydrate, sublimed sulfur and bromocyclohexane as raw materials under mild conditions and phase transfer catalysis in the experiment.The product was characterized and confirmed by FT-IR and 1HNMR. Through the single-factor experiment, we got the optimal technology conditions:tetrabutyl ammonium bromide as catalyst, the amount of catalyst was 2%, the reaction temperature was 75℃, the reaction time was 10h, n(Na2S-9H2O):n(S):n(C6H11Br)=1:0.8:1.4, the mass fraction of sodium disulfide solution was 10%.Then, the technology was further optimized by orthogonal experiment, we got the optimal synthesis technology conditions:tetrabutyl ammonium bromide as catalyst, the amount of catalyst was 1%, the reaction temperature was 75℃, the reaction time was 11h, n(Na2S-9H2O):n(S):n(C6H11Br)=1:0.8:1, the mass fraction of sodium disulfide was 5%. In order to get closer to the actual situation of the enterprise industrial production, the experiment were repeated three times with the industrial sodium sulfide as the raw material and the average yield could reach 77.25%. Through the cost accounting of the synthetic technology, the results showed that the economic benefit of the technology was better.Besides, We explored the synthesis technology of dicyclohexyl disulfide with sodium sulfide, sublimed sulfur and chlorocyclohexane as raw materials under mild conditions and phase transfer catalysis. Through the single-factor experiment, we got the optimal technology conditions:tetrabutyl ammonium bromide as catalyst, the amount of catalyst was 2%, the reaction temperature was 95℃, the reaction time was 10h, n(Na2S):n(S):n(C6H11Cl)=1:0.8:0.8, the mass fraction of sodium disulfide was 10%.Finally, the kinetics of the process were studied in this experiment. The experimental results showed that the reaction was single-molecule nucleophilic substitution reaction and the reaction rate was only related to the concentration of bromocyclohexane. By fitting the experimental data, the apparent kinetic equation of the reaction was derived:rA=-dcA/dt= 814638.72exp(-6377.54/T)CA. |
