Kinetic study on the synthesis of 1,4-dithiane under ultrasound and multi-site phase-transfer catalyst in liquid-liquid PTC condition

Abstract

In this work, the simple, efficient and convenient method to synthesis of 1,4-dithiane from 1,2-dibromoethane and sodium sulfide under heterogeneous liquid-liquid phase-transfer catalysis (LL-PTC) condition in the presence of ultrasound irradiation (40 kHz, 300W) and multi-site phase-transfer catalyst was reported. The multi-site phase-transfer catalyst namely 1,4-dibenzyl-1,4-diazoniabicyclo[2.2.2]octanium dibromide (MPTC) was successfully prepared and used as a superior catalyst for this synthesis. The combination of both ultrasound and multi-site phase-transfer catalyst are resulted in enhanced reaction rate and efficiency than the individual operations. The reaction was carried out under pseudo-first order condition. The kinetic aspects such as the effect of agitation speeds, ultrasound frequencies, different phase transfer catalysts, various organic solvent, volume of hexane, the amount of prepared MPTC, various temperature, the amount of water, the concentration of 1,2-dibromoethane, on the conversion of 1,2-dibromoethane and the apparent rate constant (K app ) were investigated in detail. The suitable mechanism has been proposed for reaction system.