4253-90-1Relevant articles and documents
The antioxidant activity of polysulfides: It's radical!
Chauvin, Jean-Philippe R.,Griesser, Markus,Pratt, Derek A.
, p. 4999 - 5010 (2019/05/29)
Olefin sulfurization, wherein alkenes and sulfur are heated together at high temperatures, produces branched polysulfides. Due to their anti-wear properties, they are indispensible additives to lubricants, but are also added to other petroleum-derived products as oxidation inhibitors. Polysulfides also figure prominently in the chemistry and biology of garlic and other plants of the Allium species. We previously reported that trisulfides, upon oxidation to their corresponding 1-oxides, are surprisingly effective radical-trapping antioxidants (RTAs) at ambient temperatures. Herein, we show that the homolytic substitution mechanism responsible also operates for tetrasulfides, but not trisulfides, disulfides or sulfides. Moreover, we show that this reactivity persists at elevated temperature (160 °C), enabling tetrasulfides to not only eclipse their 1-oxides as RTAs, but also hindered phenols and alkylated diphenylamines-the most common industrial antioxidant additives. The reactivity is unique to higher polysulfides (n ≥ 4), since homolytic substitution upon them at S2 yields stabilized perthiyl radicals. The persistence of perthiyl radicals also underlies the greater reactivity of polysulfides at elevated temperatures relative to their 1-oxides, since homolytic S-S bond cleavage is reversible in the former, but not in the latter. These results suggest that olefin sulfurization processes optimized for tetrasulfide production will afford materials that impart significantly better oxidation stability to hydrocarbon-based products to which polysulfides are added. Moreover, it suggests that RTA activity may contribute to the biological activity of plant-derived polysulfides.
Simple and green method for synthesis of symmetrical dialkyl disulfides and trisulfides from alkyl halides in water; PMOxT as a sulfur donor
Soleiman-Beigi, Mohammad,Mohammadi, Fariba
, p. 134 - 141 (2017/03/07)
An environmentally new, mild and efficient method has been developed for the synthesis of dialkyl disulfides and dialkyl trisulfides in aqueous conditions by a reaction between alkyl halides (and tosylate) and potassium-5-methyl-1,3,4-oxadiazole-2-thiolate (PMOxT) as a sulfur transfer reagent. The advantages of this method are that it occurs under mild reaction conditions, it is base free, it uses water as the solvent and it occurs in high yields. A variety of dialkyl disulfides and dialkyl trisulfides can be obtained in good to excellent yields up to 98%.
Oxidation of thiols to bisulfides by elemental sulfur without contamination by higher polysulfides
Shaw, James E.,McAfee, Marilyn G.
, p. 125 - 131 (2007/10/03)
Dialkyl disulfides were prepared in near quantitative yield by oxidation of alkanethiols with elemental sulfur using NaOH and ethoxylated alcohols as catalysts. Tergitol 15-S-7 was one of several ethoxylated alcohols which was used. Contamination by trisulfides was essentially eliminated in the disulfide products. The ratios of disulfide to trisulfide ranged from 100/0 to 99.6/0.4 for reactions with primary and secondary alkanethiols (100% excess) such as 1-propanethiol, 1-octanethiol, 2-propanethiol, and 2-butanethiol. The process did not work for tertiary alkanethiols such as 2-methyl-2-propanethiol where the trisulfide was greatly favored.
