Formation of organic acids from the gas-phase ozonolysis of terpinolene

Abstract

Gas-phase ozonolysis of terpinolene was studied in static chamber experiments using gas chromatography coupled to mass spectrometric and flame ionisation detection to separate and detect products. Two isomers of C₇-diacids and three isomers of C₇-aldehydic acids were identified in the condensed phase after derivatisation. Possible mechanisms of formation of these acids were investigated using different OH radical scavengers and relative humidities, and were compared to those reported earlier for the ozonolysis of β-pinene. In addition, branching ratios for some of the individual reaction steps, e.g. the branching ratio between the two hydroperoxide channels of the C₇–CI, were deduced from the quantitative product yield data. Branching ratios for POZ decomposition and the stabilisation/decomposition of the C_7–CI were also obtained from measurements of the C₇ primary carbonyl product.