The isomerisation of N-methylpyrrole to 2-methylpyrrole has been inves
tigated experimentally by means of a single pulse shock tube over the
temperature range 1000 to 1350 K and theoretically by ab initio calcul
ations. Between 1000 and 1100 K the isomerization is found to occur vi
a an intramolecular methyl shift. The experimental rate constant for t
his rearrangement was found to be k(iso) = 10(12.8(+/- 0.4)) exp[-56.2
(+/- 2.0) kcal mol-1/RT] s-1. Ab initio calculations gave Arrhenius pa
rameters for the methyl shift in good agreement with the experimental
values. Methyl shifting produces the intermediate 2-methyl-2H-pyrrole
which undergoes a hydrogen shift of low activation energy to form the
product of isomerisation, 2-methylpyrrole. Above about 1240 K there is
a competing free-radical process which produces methane, pyrrole and
traces of higher molecular weight products.