文摘
The selective, oxidative functionalization of ethane, a significant component of shale gas, to products such as ethylene or ethanol at low temperatures and pressures remains a significant challenge. Herein we report that ethane is efficiently and selectively functionalized to the ethanol ester of H2SO4, ethyl bisulfate (EtOSO3H) as the initial product, with the PtII 鈥淧eriana-Catalytica鈥?catalyst in 98% sulfuric acid. A subsequent organic reaction selectively generates isethionic acid bisulfate ester (HO3S-CH2-CH2-OSO3H, ITA). In contrast to the modest 3鈥? times faster rate typically observed in electrophilic CH activation of higher alkanes, ethane CH functionalization was found to be 100 times faster than that of methane. Experiment and quantum-mechanical calculations reveal that this unexpectedly large increase in rate is the result of a fundamentally different catalytic cycle in which ethane CH activation (and not platinum oxidation as for methane) is now turnover limiting. Facile PtII-Et functionalization was determined to occur via a low energy 尾-hydride elimination pathway (which is not available for methane) to generate ethylene and a PtII-hydride, which is then rapidly oxidized by H2SO4 to regenerate PtII-X2. A rapid, non-Pt-catalyzed reaction of formed ethylene with the hot, concentrated H2SO4 solvent cleanly generate EtOSO3H as the initial product, which further reacts with the H2SO4 solvent to generate ITA.