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 kt4=(1.4 ± 0.2)× 105 dm3 mol–1 s–1, kt7/k7= 0.70 ± 0.10 and k9/k8= 0.014 ± 0.002(M = N2) have been evaluated. This value of kt4, 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.