Pyrolysis of 3-pyrroline in the gas phase

Abstract

The pyrolysis of 3-pyrroline in the gas phase has been found to be a unimolecular first-order process, the rate constant being independent of pressure in the range 2–34 torr (267–4533 Nm^–2). Hydrogen and pyrrole in equal amounts are the only gaseous products. The rate of reaction and product yields are unaffected by the addition of significant amounts of nitric oxide.

The temperature dependence of the rate constants of the reaction over the temperature range 317–358° is given by the expression k₁=(1·9 ± 0·4)× 10¹² exp (44,600 ± 241/RT) s^–1 where R= 1·987 cal deg^–1 mol^–1(k₁=(1·9 ± 0·4)× 10¹² exp (186,600 ± 1000/RT) where R= 8·314 J deg^–1 mol^–1). When the Pyrex reaction vessel was packed with Pyrex tubes an increase in the rate constant at all temperatures was produced and it was concluded that a heterogenous process accounted for up to 5% of the reaction in the unpacked vessel. Simultataneously with the formation of pyrrole and hydrogen, a polymer, which was inactive, was produced on the cooler parts of the reaction vessel.