Reaction of hydrogen atoms with diethyldisulfide and ethylmethyldisulfide

Abstract

H atoms react with CzH5SSC;H5 to give CzH5SH as the sole retrievable product with d~ = 2.32 a t 25°C and 2.84 a t 145°C. The primary reaction is postulated to be H + CzHsSSCzH5CzH5SH + CzH5S with k l = (4.73 f 0.64to the rate constant of the H + CzH4 -CzHs reaction. The high value of the entropy of activation suggests the presence of partial hydrogen bonding in diethyldisulfide which is broken in the transition state.Ethylmethyldisulfide reacts similarly: H + CzH5SSCH3 -C2H5SH + CH3S or CHBSH + CzH5S. The thiyl radicals propagate a chain of radical exchange reactions forming the symmetrical disulfides with exposure-time-dependent quantum yields. The overall kinetics conform to a 16-step mechanism from which the rate constants of the elementary reactions could be established by computer modeling. Thiyl radicals react considerably more slowly with disulfides than H atoms.

Reaction of hydrogen atoms with diethylsulfide

“…The extent of quenching of the excited those employed in the previous studies (4,5 less than 5% in all cases. Control experiments in the range 25-188°C showed that C2H5SC,H, was thermally stable.…”

“…The were the same as before (4,5). Diethylsulfide (Eastman) was common feature that was found for these reactions purified by gc using a loft 10% tricresylphosphate on Chromois that the sulfur atom is abstracted by the hydrogen sorb W column operated between 60 and 65°C using helium as atom in a concerted single step attack on the the carrier gas.…”

“…One of these additional C2H6-producing reactions Can must be hydrogen abstraction from the substrate: [4] CZHS + C2HSSCZHS + CZH6 + C H~C H S C~H~ The site of the abstraction is most probably at the methylene moiety since the C-H bond here is weaker (-92 kcal mol-I) than in the methyl group (98 kcal m o l t ) , and moreover, MTH and DMDTO were identified among the products but the corresponding products from the expected reactions of the CH,CH2SCH2CH, radical were not. The reaction sequence is completed by the combination and disproportionation reactions [5] to [9]:…”

“…Ethylvinylthioether was not identified as a product, probably because reactions [5] and [9] are relatively slow. However, even if it were formed in small quantities, gc analysis for ethylvinylthioether in a mixture containing a large excess of C2H5SC2H5 would be difficult since the two compounds would probably have similar elution times.…”

The reactions of hydrogen atom with organosulfur compounds

“…The Hg sensitized decomposition of H 2 in the presence of C2H5SSC2H 5 yielded C2H5SH as the only retrievable product [62], similar to the case of dimethyidisulfide, indicating that the principal elementary reaction between the H atoms and the diethyldisulfide molecule is the radical displacement reaction H + C2H5SSC2H 5 ÷ C2H5SH + C2H5S (57) Temperature studies in the presence of added C2H 4 yielded the Arrhenius equation k57 = (4.73±O.64)xlO13exp[(-1710±69)/RT] cm3mol'Is -l for reaction (57), relative to that of the H + C2H 4 ÷ C2H 5 reaction.…”