Kinetics of disproportionation–combination reactions between the n-propoxyl radical and nitric oxide, and of the pyrolysis of the O–O bond in di-n-propyl peroxide in the gas phase

Abstract

A study of the reactions of the n-propoxyl radical, from the gas-phase pyrolysis of di-n-propyl peroxide at 100–150°, with nitric oxide shows that the disproportionation–combination ratio Δ=k_i/k_ii is 0·40–0·45, and is temperature- PrⁿO·+ NO → HNO + EtCHO (i), PrⁿO·+ NO → PrⁿONO (ii) independent with k₁= A_i= 5–6 × 10¹⁰ mole^–1 cm.³ sec.^–1. The pyrolysis of the O–O bond in the peroxide is of the first order with k₁= 9·1 × 10¹⁴ exp (–35,000/RT) sec.^–1, from which it is shown that k₁ for the reverse of this pyrolysis, i.e., recombination of n-propoxyl radicals, is 4·7 × 10¹¹ mole^–1 cm.³ sec.^–1. From E₁ and the calculated value of ΔH_f° for the peroxide, ΔH_f° for the n-propoxyl radical is found to be –10·3 kcal. mole^–1.