Quantum chemical investigation of the 1‐methyl‐ and 1‐neopentyl‐2‐methoxydiazene‐1‐oxides thermal decomposition mechanisms

Abstract

The thermolysis mechanism of two members of the 2-alkoxydiazene-1-oxide class of compounds -1-methyl-2-methoxydiazene-1-oxide (1) and 2-methoxy-1-neopentyldiazene-1-oxide (2) was studied by quantum chemical methods. Calculations were performed using coupled clusters method at the CCSD and CCSD(T) level using the aug-cc-pVDZ and aug-cc-pVTZ basis sets. It was shown that the mechanism of thermal decomposition of compounds 1 and 2 is similar and occurs via two competing channelsvia homolytic N-OCH 3 bond cleavage and via intramolecular nucleophilic substitution at the methoxyl carbon atom. The calculated values of the activation enthalpies for both compounds are close (ΔН а ‡ is in the range of 200-210 kJ/mol) and practically coincide with the experimental activation energies obtained earlier. The main thermolysis products predicted theoretically correspond to the thermal decomposition products of compounds 1 and 2 that have been observedexperimentally.