Tributylammonium Halochromates/silica Gel: Simple Reagents for Oxidative Coupling of Thiols to Symmetrical Disulfides

Abstract

New orange solid tributylammonium halochromates, (C 4 H 9 ) 3 N ＋ CrO 3 X -, TBAXC (X＝F, Cl) are easily synthesized by the reaction of tributylammonium fluoride and chloride with CrO 3 in a 1∶1 molar ratio in the presence of HF and HCl. Tributylammonium halochromates(VI) are versatile reagent for the effective and selective oxidation of organic substrates. Silica gel supported TBAFC and TBACC are versatile reagents for the effective and selective oxidation of organic substrates, in particular, thiols, under mild conditions. Considerable improvements are observed in the presence of the absorbent, making the work-up much more convenient.

Immobilizing Triphenylamine with Photoredox Inert Sr2+ Forming Sr‐MOF with Controlled Electron Migration for Photocatalytic Oxidation of Thiols to Disulfides

“…Disulfides possessing covalent S—S bond with outstanding redox properties play critical roles in the field of biological systems, pharmaceuticals, agro‐chemicals, etc . [ 1‐3 ] Thiols as one category of organic sulfur compounds in coals, have unpleasant odor and release SO 2 after the coal combustion, exhibiting serious negative effects on human health and natural environment. [ 4‐7 ] The oxidation of thiols to disulfides can not only effectively solve the above problems, but also generate the high value‐added chemicals, displaying important environmental and industrial significance.…”

In situ generated hypoiodous acid in an efficient and heterogeneous catalytic system for the homo-oxidative coupling of thiols

“…The conversion of thiols to the corresponding disulfides is an important and interesting transformation in organic chemistry due to the central importance of this functional group in diverse areas of chemistry and biology, [6][7][8][9][10][11] and oxidation is the most common methodology used for their preparation because of the commercial availability of thiols. A variety of oxidants have been reported for the conversion of thiols into disulfides, such as tributylammonium halochromates/ /silica gel, 12 Fe(HSO 4 ) 3 or Fe(HSO 4 ) 3 /DMSO, 13 Al(NO 3 ) 3 ⋅9H 2 O/SiO 2 -OSO 3 H, 14 (C 3 H 7 ) 3 NH[CrO 3 X], (X = F or Cl)/Al 2 O 3 , 15 N-bromosuccinimide, 16 poly(4-vinylpyridinium nitrate), 17 H 2 O 2 /NaI, 18 urea-hydrogen peroxide/maleic anhydride, 19 ethylenebis(N-methylimidazolium) chlorochromate, 20 manganese(III) 174 GHORBANI-CHOGHAMARANI, NIKOORAZM and AZADI Schiff-base complexes, 21 Au/CeO 2 , 22 Co(II) and Mn(II) salts of 4-aminobenzoic acid supported on silica gel 23 and Zn(II)-Al(III) double layer hydroxide with intercalated [Mo VI O 2 (O 2 CC(S)Ph 2 ) 2 ] 2-. 24 Some of these procedures suffer from one or more disadvantages, such as long reaction times, overoxidation, tedious work-up, low yields of the products, heavy metal contamination, harsh conditions, and expensive reagents or catalysts.…”

Microwave Assisted, Synthesis of Symmetrical Disulfides with Triethylammonium Halochromates, (C2H5)3NH+[CrO3X]-(X=F, Cl)

“…Sweetening of catalyst poisons thiols to low volatile disulfides in oil industries and also industrial applications of disulfides in vulcanization of rubbers and elastomers led us to investigate the introduction and applications of new member of this category of reagents in oxidation of thiols to the corresponding disulfides. This conversion has been accomplished using reagents such as molecular oxygen, [1] metal ions, [2] Bu3SnOMe/FeCl3, [3]nitric oxide, [4] halogens, [5][6][7] sodium perborate, [8]borohydride exchange resin (BER)-transition metal salt system, [9] a morpholine iodine complex, [10] pyridinium chlorochromate (PCC), [11] ammonium persulfate, [12] KMnO4 / CuSO4, [13] and Tributylammonium Halochromates [14]. There are some disadvantages in these reagents such as availability of the reagent, cumbersome procedure, high cost of the reagent, over oxidation or oxidation of other functional groups presented in thiols.…”