Organic superbase-catalyzed oxidation of alkanethiols to dialkyl disulfides by elemental sulfur

Abstract

Under atmospheric pressure and solvent-free conditions, organic superbase (SB) catalyzed the oxidation of alkanethiols (RSH) to dialkyl disul de (R 2 S 2 ) by using sulfur as oxidant was investigated. The results showed that amidines (DBU, DBN) and guanidines (BTMG, MTBD, TMG) exhibited signi cantly higher catalytic activity than common organic bases. Under the condition of 3.0 molar ratio of RSH/S (50 mol% excess of RSH), 99~100% yield of (n-C 8 H 17 ) 2 S 2 could be obtained with 0.1 mol% SB and more than 95% yield of (n-C 8 H 17 ) 2 S 2 could be also obtained even if with 0.001 mol% SB. The yield of target product R 2 S 2 (R = alkyl, phenyl) was still obtained above 90% when the molar ratio of RSH/S was 2.1 (5 mol% excess of RSH). R 2 S 3 was the only by-product, and no R 2 S 4 was generated. The deprotonation ability of SB to RSH is signi cantly higher than that of common organic bases, and RS − is the key active species in the catalytic reaction. This synthetic method has the advantages of operational simplicity, inexpensive, and the applicability to 20-30 g scale synthesis strengthen its potential applications for preparing disul de at an industrial scale.

In situ sulfonated mesoporous polydivinylbenzene as a solid acid catalyzed the condensation of phenol and acetone

“…Figure 3 showed the N 2 adsorption isotherm and pore size distribution of the two samples. Both PDVB and PDVB-SO 3 H-IS showed type IV isotherms with distinct hysteresis loops in the P/P 0 range of 0.7-0.95, indicating the existence of mesoporous structure [35,36]. 1 showed the speci c surface area, pore volume, and average pore size of PDVB and PDVB-SO 3 H-IS samples.…”