The heat of formation of the acetonyl radical VLPP studies of acetonyl bromide, isopropenylmethylether, and hexanedione‐2,5 in a search for acetonyl stabilization energy

The decomposition of acetonyl bromide, isopropenylmethylether, and hexanedione‐2,5 was studied using the very‐low‐pressure pyrolysis (VLPP) technique. The acetonyl radical is a product of each reaction. Arrhenius parameters determined are or acetonyl bromide ← acetonyl + Br: and for isopropenylmethylether ← acetonyl + CH 3 : These lead to values of acetonyl stabilization energy (SE) of 0.8 and −4.0 kcal/mol, respectively. Comparison of the pyrolyses of hexanedione‐2,5 and 2,5‐dimethylhexane indicate a value of SE ∼ 2 kcal/mol. The total of these results is taken, along with previous work, to indicate that 0 ≲ SE ≲ 2 kcal/mol.