Thiyl Radical Abstraction. A Mechanism for the Free Radical Substitution Reactions of Pentachlorobenzenesulfenyl Chloride

Abstract

The substitution reactions of pentachlorobenzenesulfenyl chloride with saturated alkanes were found to proceed by a free radical chain mechanism where the pentachlorobenzenethiyl radical is the predominant chain-carrying species. The selectivity of this radical could be determined by the investigation of the photoinitiated reactions of bispentachlorophenyl disulfide with a number of alkanes.I1 a 6t6 d6montrC que les reactions de substitution du chlorure de pentachlorobenzene-sulfenyle avec des alcanes satures se deroulent, selon un mecanisme radicalaire en chdne ou le radical pentachlorobenzene thiyle est I'agent principal de propagation de chaine. La sClectivitC de ce radical peut ttre determinee par une etude des reactions de photoinitiees des bisulfures de bis-pentachlorophenyle avec plusieurs alcanes;Can.

Free-radical reactions of fluoroalkanesulfenyl halides. 3. Reactions of fluoroalkane- and chlorofluoroalkanesulfenyl chlorides with hydrocarbons

“…The reactions of heptafluoro-2-propanesulfenyl chloride (2) gave high yields of chlorohydrocarbons, varying yields of thiol, i.e., heptafluoro-2-propanethiol (9) and disulfide, and low yields of heptafluoroisopropyl hydrocarbyl sulfides.…”

“…Very little HC1 evolution was detected during the irradiation period. A gas chromatogram contained a large peak (52.5% of the total product peak area) for -chlorotoluene, a 5% unknown peak, and an early peak (42.5%) which was not reproducible in area and which apparently represented both bis(heptafluoroisopropvl) disulfide and heptafluoro-2-propanethiol (9). Further GC studies showed that the disulfide component of this peak was small.…”

“…There collected in the first dry-ice trap 1.5-2.0 mL of liquid, which on distillation through a microstill gave about 1 mL of colorless liquid boiling at 28 °C. The infrared and and 19F NMR spectra indicated that it was largely heptafluoro-2-propanethiol (9): IR 3.85 µ (SH), 7.73, 8.08 (CF);'1H NMR b 3.06 (d, q); 19F NMR -77.03 (CFa), -147.07 ppm (CF), Jcf-H = 5.3 Hz, 5/0F3-H = 1.5 Hz, Jcf3-f = 9.5 Hz. The residue remaining after removal of the thiol was shown by GC to contain just a trace of bis(heptafluoroisopropyl) disulfide.…”

“…A solution of 15.16 g (0.0641 M) of freshly distilled heptafluoro-2-propanesulfenyl chloride (2) and 60 mL (0.555 M) of "Spectrograde" cyclohexane was irradiated as described above until the yellow color was gone (30 min). A gas chromatogram contained substantial peaks with the retention times of bis(heptafluoroisopropyl) disulfide [plus heptafluoro-2-propanethiol (9)], chlorocyclohexane, and a very small unknown peak. The thiol was removed as described in the preceding experiment.…”

The Second Isolable B12-Thiolate Complex, (Pentafluorophenylthiolato)cobalamin: Synthesis and Characterization

“…Herein we report the synthesis, isolation, and characterization of (pentafluorophenylthiolato)cobalamin, C 6 F 5 SCbl, Figure . We picked this particular RS group for these initial studies because of (i) its well-precedented H • abstracting ability (i.e., of C 6 X 5 S • radicals, X = Cl, F) due to the increased strength of C 6 F 5 S−H bond, the property that first brought the C 6 F 5 S - ligand to our attention; (ii) its anticipated stronger RS−Co bond energy; (iii) its greater resistance to protonation at S (i.e., due to the electron withdrawing C 6 F 5 - group, C 6 F 5 SH p K a 2.68 vs a typical RSH p K a of 10 26 ); and, hence, (iv) because of the expectation that properties (ii) and (iii) would make C 6 F 5 S−Cbl easier to isolate …”