Hypervalent iodine oxides and chloride for the conversion of light alkanes to mono-functionalized products: A radical-based process for selective partial oxidation

Abstract

A process for the partial oxidn. of light alkanes to mono-functionalized products in high conversion and yield has been highly sought after. With mixts. of iodine oxide and chloride salts in trifluoroacetic acid solvent, light alkanes are converted to alkyl esters in good yields (40-50%) and selectivity. The reactions can be driven thermally or photolytically. While the process exhibits similarities to radical chlorination and oxychlorination chem., the obsd. selectivity for the mono-functionalized product is unique to the iodine oxide and chloride process. The elucidation of the reaction mechanism has involved studies with adamantane as a model to examine the selectivity and kinetic isotope effect of the reaction vs. radical chlorination. The extent of the protecting effect of the ester group of the product has been investigated for MeX and EtX species. The exptl. study, supported by calcns., indicates that a radical-based reaction pathway which is catalytic in chloride results in the formation of alkyl esters that are protected from over-oxidn. These findings have enabled the extension of this system to alternative oxidants.

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