Oxidation of isobutyraldehyde in aged boric-acid-coated vessels

Abstract

The oxidation of (CH₃)₂CHCHO has been studied over a wide range of mixture composition at 440°C in an aged boric-acid-coated vessel. By the use of the pressure against time profiles, rate constants k₁= 0.120 ± 0.010 dm³ mol^–1 s^–1 and k₄=(1.83 ± 0.10)× 10⁶ dm³ mol^–1 s^–1 have been obtained.,(CH₃)₂CHCHO + O₂=(CH₃)₂CHCO + HO₂(1),HO₂+(CH₃)₂CHCHO =(CH₃)₂CHCO + H₂O₂(4),HO₂(CH₃)₂CHCHO =(CH₃)C—CHO + H₂O₂(4t),OH +(CH₃)₂CHCHO =(CH₃)₂CHCO + H₂O(7),OH +(CH₃)₂CHCHO =(CH₃)₂C—CHO + H₂O(7t),(CH₃)₂C—CHO + O₂→(CH₃)₂CO + CO + OH(8),(CH₃)C—CHO + M = CH₃CHCH₂+ HCO + M(9),From the variation of the yield of (CH₃)₂CO with oxygen concentration and extent of reaction, the rate constants k^t₄=(1.4 ± 0.2)× 10⁵ dm³ mol^–1 s^–1, k^t₇/k₇= 0.70 ± 0.10 and k₉/k₈= 0.014 ± 0.002(M = N₂) have been evaluated. This value of k^t₄, which is higher than that for the t-CH bond in i-C₄H₁₀ by a factor of ≈ 4, confirms the view, indicated by corresponding rate constants for C₂H₅CHO, that C—H bonds adjacent to aldehydic groups are weaker than in alkanes. Rate constants for some of the reactions involved in the formation of propene oxide have also been determined.