The decomposition of n-butyl acetate on charcoal was studied at 365" and 385"C, and isobutyl acetate at 394" and 419.5"C. Isobutene and acetic acid were the principal products from the is0 ester, and n-butenes and acetic acid from the normal ester. Other primary and secondary reactions exceeded 20% in most experiments. The principal primary product from the normal ester was 1-butene which isomerized subsequently to 2-butenes; iso-butene from the is0 ester did not isomerize.For both esters the activity of the charcoal decreased rapidly, the conversion decreasing linearly with time. Linear correlations were used to estimate the conversion at zero time, and data at zero time were used to evaluate constants of a rate equation. Fouling was attributed to reactions of olefins which produced carbonaceous residues.as-phase pyrolyses of butyl acetates are clean c first-order reactions yielding butenes plus acetic acid. An intramolecular mechanism involving a sixcenter-ring intermediate explains many aspects of the d e c o r n p~s i t i o n~~*~~~) .The butenes produced, as well as the rates, seem to be largely determined by the position and number of P-hydrogens in the butyl group. Activation energies are in the range 167 to 201 kJ/mol. Previous papers from this laboratory have described the decomposition of butyl acetates on c h a r~o a l '~' and on zeolitic molecular sievesc6'. For the secondary ester on charcoal the rate was proportional to the amount of adsorbed ester. The composition of butenes, 49 to 55% 1-butene, was similar to that obtained in the gas phase. The butenes did not isomerize to an appreciable extent in the ester decomposition on charcoal. The activation energy of the rate constant for ester decomposition on charcoal was 137 kJ/mol.