Formation of acyldisulfide ions from the reaction of sulfur with thiocarboxylate ions, and reactivity towards acyl chlorides in N,N-dimethylacetamide
作者:Julie Robert、Meriem Anouti、Jacky Paris
DOI:10.1039/a606701h
日期:——
The reactivity of sulfur towards thiocarboxylate ions
RC(O)S- a (R = Ph 1, Me 2,
But 3) has been studied by
spectroelectrochemistry in
N,N-dimethylacetamide. For
2a–3a, two parallel and partial reactions, for which equilibrium
constants have been determined, led to: (i)
[RC(O)]2S2- b species and
S3·-/S82-
polysulfide ions and (ii) RC(O)S2 ions c;
only traces of 1c were detected by voltammetry. As previously observed
with thiolate ions, our results are consistent with an initial
monoelectronic transfer between RC(O)S- ions and
S2 molecules in equilibrium with S8, followed by
concurrent couplings of RC(O)S˙ and
S2·-
radicals. On a preparative scale, when sulfur was added to
RC(O)S- ions 1a,3a the enhanced reactivity of
RC(O)S2- ions towards acyl chlorides RC(O)Cl
(R = C6H5 and
But, respectively) only yielded diacyl
disulfides 1b,3b.
硫对硫羧酸盐离子 RC(O)S- 的反应性(R = Ph 1, Me 2, But 3)通过在N,N-二甲基乙酰胺中的光谱电化学进行了研究。对于2a–3a,进行了两个平行的部分反应,已确定平衡常数,导致: (i) 产生 [RC(O)]2S2- 物种及 S3·-/S82- 多硫离子; (ii) 产生 RC(O)S2 离子 c;通过伏安法仅检测到微量的 1c。正如之前观察到的与硫醇离子的行为相一致,我们的结果表明,RC(O)S- 离子与与 S8 处于平衡的 S2 分子之间发生了初步的单电子转移,随后 RC(O)S˙ 和 S2·- 自由基发生了并行偶联。在制备规模上,当硫加入到 RC(O)S- 离子 1a,3a 时,RC(O)S2- 离子对酰氯 RC(O)Cl(R = C6H5 和 But, 分别)的增强反应性仅生成二酰基二硫化物 1b,3b。