+

Acetone vapour fragments to acyl and methyl radicals at high temperature.

Chapter 4-1: Acids and Bases. Table 4-2 Scale of Acidities, pp 99. S.H.Pine, Organic Chemistry, McGraw-Hill, 1987

Reaction defined as:
Decomposition by Heat (Pyrolysis)
Radical Cleavage
Thermolysis of Acetone