作者:George C. Fortman、Nicholas C. Boaz、Dominik Munz、Michael M. Konnick、Roy A. Periana、John T. Groves、T. Brent Gunnoe
DOI:10.1021/ja502657g
日期:2014.6.11
We describe an efficient system for the direct partial oxidation of methane, ethane, and propane using iodate salts with catalytic amounts of chloride in protic solvents. In HTFA (TFA = trifluoroacetate), >20% methane conversion with >85% selectivity for MeTFA have been achieved. The addition of substoichiometric amounts of chloride is essential, and for methane the conversion increases from <1% in the absence of chloride to >20%. The reaction also proceeds in aqueous HTFA as well as acetic acid to afford methyl acetate. C-13 labeling experiments showed that less than 2% of methane is overoxidized to (CO2)-C-13 at 15% conversion of (CH4)-C-13. The system is selective for higher alkanes: 30% ethane conversion with 98% selectivity for EtTFA and 19% propane conversion that is selective for mixtures of the mono- and difunctionalized TFA esters. Studies of methane conversion using a series of iodine-based reagents [I-2, ICl, IC3, I(TFA)(3), I2O4, I2O5, (IO2)(2)S2O7, (IO)(2)SO4] indicated that the chloride enhancement is not limited to iodate.