Experimental and theoretical study of the isomerisation of N-methylpyrrole

Article abstract of DOI:10.1016/0009-2614(94)00267-3

The isomerisation of N-methylpyrrole to 2-methylpyrrole has been investigated experimentally by means of a single pulse shock tube over the temperature range 1000 to 1350 K and theoretically by ab initio calculations.Between 1000 and 1100 K the isomerization is found to occur via an intramolecular methyl shift.The experimental rate constant for this rearrangement was found to be k_iso = 1E12.8(+/-0.4) exp<-56.2(+/-2.0) kcal mol^-1/RT> s^-1.Ab initio calculations gave Arrhenius parameters 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.