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

Abstract

AbstractThe 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 channels – via homolytic N‐OCH3 bond cleavage and via intramolecular nucleophilic substitution at the methoxyl carbon atom. The calculated values of the activation enthalpies for both compounds are close (ΔНа‡ 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 observed experimentally.