Oxidation of (CD3)2\dotCX Radicals. III. Reaction of 2-Propanol and (CD3)2\dotC(OH) Radicals with Atomic Oxygen

Abstract

Abstract The reaction of oxygen atoms with 2-propanol was studied in a fast flow system coupled with a photoionization mass spectrometer. Radicals formed in the primary attack of O(3P) atoms on 2-propanol were photoionized by the Xe lamp and identified as the (CH3)2\dotC(OH) radical from (CH3)2CH(OH) and (CH3)2CD(OH) and the (CD3)2\dotC(OH) radical from (CD3)2CH(OH). The major primary product in the subsequent reaction of O+(CD3)2\dotC(OH) was found to be acetone, (CD3)2CO, (62±4%). Formation of 1-propen-2-ol, CD3C(OH)=CD2, by deuterium abstraction and acetic acid, CD3COOH, by oxygen addition were observed in the reaction of O+(CD3)2\dotC(OH). In the reaction of 18O+(CD3)2\dotC(OH), the acetone produced was mostly (CD3)2CO. This fact shows that acetone is produced predominantly by the hydrogen abstraction by O(3P) from the O–H in the (CD3)2\dotC(OH) radical. A part of the acetone is produced also by the addition of O(3P) to the (CD3)2\dotC(OH) radical; i.e., a small but significant signal of (CD3)2C18O was observed in the reaction of 18O+(CD3)2\dotC(OH). The competition experiment between O(3P) and O2 for the (CD3)2\dotC(OH) radical shows that (CD3)2\dotC(OH) react (0.16±0.02) times as fast with O2 as with O(3P). This result suggests that the reaction of (CD3)2\dotC(OH) with O2 is very rapid. It is proposed that the rapid reaction is hydrogen abstraction by O2 from the O–H in the (CD3)2\dotC(OH) radical to form acetone and HO2.