Laser-Induced Organic Transformation. Direct and Selective Synthesis of Diols from Methanol, Ethanol, and Their Mixture in the Presence of Hydrogen Peroxide

Abstract

Abstract The laser-induced transformation of methanol (MeOH), ethanol (EtOH), and MeOH–EtOH mixture have been investigated in the presence of H2O2. Ethylene glycol (EG) was highly selectively produced in high quantum yield (φ=0.94) by KrF-laser irradiation of the N2-saturated MeOH and the selectivity was 94% at 3.2 ml h−1 of H2O2 feeding rate (f). Butanediol (BD) and acetaldehyde (AA) were directly and selectively produced by KrF-laser irradiation of the N2-saturated EtOH. The quantum yields of BD and AA were 0.42 and 0.29, respectively, and the combined selectivity was 97% at f=3.4 ml h−1. Also, propanediols (PD) were directly produced by KrF-laser irradiation of the N2-saturated MeOH–EtOH mixture. The quantity of 1,2-PD reached the maximum at about 64 mol% of MeOH content. EG is produced through the dimerization of hydroxymethyl radicals formed by the abstraction of a hydrogen atom from MeOH by hydroxyl radical formed in high density by the laser-photolysis of H2O2. Similarly, 2,3-BD is produced by the dimerization of 1-hydroxyethyl radicals formed by the abstraction of α-hydrogen atom from EtOH by hydroxyl radical and 1,2-PD is produced by the recombination between hydroxymethyl radical and 1-hydroxyethyl radical.