Addition of C3H8to slowly reacting mixtures of hydrogen and oxygen at 480°C

Abstract

Analysis has been made of the reaction products formed when 1 % of C₃H₈ is added to slowly reacting mixtures of H₂+O₂ at 480°C. Three H₂+O₂ mixtures of widely varying composition have been examined in detail, and others in less detail. By determining the initial value of d[C₃H₆]/d[C₂H₄], the ratio of OH attack at primary and secondary C—H bonds has been estimated, as well as the ratio k_25p/k_27p= 1.2 × 10³ l. mol^–1. CH₃CH₂CH₂= CH₃+C₂H₄(27p) CH₃CH₂CH₂+O₂= C₃H₆+HO₂(25p) From the published value of k27_p, k_25p= 3.7 × 10⁷ l. mol^–1 s^–1. The corresponding values for the reactions of n-C₃H₇ radicals with O₂ to give propene oxide and to give C₂H₅CHO, are estimated as 2.9 × 10⁶ and 1.3 × 10⁵ l. mol^–1 s^–1, respectively. Mechanisms for the formation of the other products, which include prop-2-en-1-al, CH₃CHO, CH₄ and HCHO, are also discussed.