TY - JOUR
T1 - Catalytic carbon-carbon and carbon-hydrogen bond cleavage in lower alkanes. Low-temperature hydroxylations and hydroxycarbonylations with dioxygen as the oxidant
AU - Lin, Minren
AU - Hogan, Terrence E.
AU - Sen, Ayusman
PY - 1996
Y1 - 1996
N2 - RhCl3, in the presence of several equivalents of Cl- and I- ions, catalyzed the direct formation of methanol and acetic acid from methane, carbon monoxide, and dioxygen at 80-85°C in a 6:1 mixture of perfluorobutyric acid and water (approximate turnover rate: 2.9/h based on Rh). It was possible to selectively form either methanol or acetic acid by a simple change in the solvent system. As might be anticipated, ethane was more reactive than methane, and under similar reaction conditions formed methanol, ethanol, and acetic acid (approximate turnover rate: 7.5/h based on Rh). For both methane and ethane, the product alcohols were less reactive than the starting alkanes. Methyl iodide was also less reactive than methane. Most significantly, for ethane and higher alkanes products derived from C-C cleavage dominated over those derived from C-H cleavage on a per bond basis. Indeed, C-C cleavage products were virtually all that were observed with butane, isopentane, and 2,3-dimethylbutane. While the mechanism of the C-H and C-C cleavage steps remains to be elucidated, preliminary indications are that outer-sphere electron transfer or bond homolysis resulting in the formation of alkyl radicals did not occur.
AB - RhCl3, in the presence of several equivalents of Cl- and I- ions, catalyzed the direct formation of methanol and acetic acid from methane, carbon monoxide, and dioxygen at 80-85°C in a 6:1 mixture of perfluorobutyric acid and water (approximate turnover rate: 2.9/h based on Rh). It was possible to selectively form either methanol or acetic acid by a simple change in the solvent system. As might be anticipated, ethane was more reactive than methane, and under similar reaction conditions formed methanol, ethanol, and acetic acid (approximate turnover rate: 7.5/h based on Rh). For both methane and ethane, the product alcohols were less reactive than the starting alkanes. Methyl iodide was also less reactive than methane. Most significantly, for ethane and higher alkanes products derived from C-C cleavage dominated over those derived from C-H cleavage on a per bond basis. Indeed, C-C cleavage products were virtually all that were observed with butane, isopentane, and 2,3-dimethylbutane. While the mechanism of the C-H and C-C cleavage steps remains to be elucidated, preliminary indications are that outer-sphere electron transfer or bond homolysis resulting in the formation of alkyl radicals did not occur.
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U2 - 10.1021/ja953670r
DO - 10.1021/ja953670r
M3 - Article
AN - SCOPUS:0029996718
SN - 0002-7863
VL - 118
SP - 4574
EP - 4580
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 19
ER -