Borate-assisted liquid-phase selective oxidation of n-pentane

Abstract

Oxidation of n-pentane with molecular oxygen to sec-pentanols was performed in the presence of a free radical initiator (di-tert-butyl peroxide) and a boron compound (sec-butyl metaborate), with in situ adsorption of water on molecular sieve 3A. Kinetics of the reaction was studied in a laboratory-scale batch reactor over a broad range of conditions (130‒150°C, 20‒30 bar, 5‒10 vol% "O" _"2" ) in order to establish the optimum parameters for maximising the selectivity and yield of sec-pentanols. Results show that the initiator markedly improves the rate of oxidation, and hence yield, compared to thermal oxidation without an initiator, while the boron species enhances the selectivity to sec-pentanols. Under the conditions investigated, maximum sec-pentanol selectivity is 56% with an alcohol-to-ketone ratio of 3.6:1 for the borate-assisted oxidation compared to 33% and 1.1:1, respectively, for the oxidation without borate. This work demonstrates the feasibility of oxyfunctionalization of n-pentane with industrially relevant selectivity and yield.