Dimethylsulfoxide adducts with chlorinated Lewis acids and with chlorine : NMR investigations

Acylation Mechanisms of DMSO/[D6]DMSO with Di‐tert‐butylketene and Its Congeners

“…None of the intermediates ( 6 , 8 , or 10 ) in Scheme could be detected in situ ( 1 H and 13 C NMR analysis), but the development of HCl in parallel with the emergence of 11 and acid 3 was recognized through an increasing 1 H NMR shift of free DMSO (δ = 2.48 ppm) toward the value for DMSO · HCl24a (δ = 2.87 ppm). The much slower subsequent conversion of 11 into the sulfoxide 12 24b is known18 to be mediated by HCl.…”

“…The acylation of DMSO by 9 will again give 6 in step 1 of Scheme . The mutual interconversion of 6 and (H 3 C) 2 S–Cl + ( 10 ) in step 2 may be visualized23 as involving a sulfurane with a tetracoordinate sulfur atom; the process would be terminated above 0 °C24a presumably through an E2‐type elimination (step 3) within the ion pair23 of 10 + 7 , producing the acid 3 together with the thionium chloride 8 and finally (step 4) chloro(methylthio)methane24a,24b ( 11 ). Steps 1 and 2 were formulated as reversible processes in analogy with the main path suggested23 for the rapid acetylation of DMSO by acetyl chloride, where an experimental k H / k D estimate of approximately 5 at 30 °C had been assigned to the C–H/C–D bond‐breaking step 3, in rough accord with the values cited above14a,16 for acetic anhydride.…”

“…The occurrence of some [α‐D] 3 mentioned above can be understood through a very slow reaction of DCl (first column of Scheme ) with acid 3 (as formed in step 3), in analogy with the labeling technique reported25,26 for a related system. During storage of the mixture for some weeks at ambient temperature without workup, the sulfoxide 12 vanished slowly, with appearance27 of H 3 CS–SO 2 CH 3 24a,24c. The ester 4 is probably not generated under the reaction conditions shown in Scheme from the intermediates 6 or 8 (in contrast to Scheme ), presumably due to a shortage of bases such as 7 in this HCl‐producing system; this notion gained support in the following way: A sample (5 mg) of pure ester 4 was added to this aged solution and required significantly longer than 4 h at 55 °C for its cleavage by HCl to give 11 (2nd column of Scheme ).…”

“…Chloro(methylthio)methane (11): 24a,24b 1 H NMR (diglyme, 400 MHz): δ = 2.253 (s, 3 H, CH 3 ), 4.88 (s, 2 H, CH 2 ) ppm. 13 C NMR (diglyme, 100.6 MHz): δ = 14.66 (CH 3 ), 52.90 (CH 2 ) ppm.…”

Fast and efficient green synthesis of thiosulfonate S-esters by microwave-supported permanganate oxidation of symmetrical disulfides

“…[59] The observed 1 H and 13 C NMR spectroscopic data for the eight thiosulfonate S-esters synthesized are listed below, and all of them were found compatible with those reported in the literature. [60][61][62] …”