Phoooxidation mechanism of 2,4,4-trimethyl-1-pentanol in gas phase

Santiago

Congreso; 25th InterAmerican Photochemical Society Meeting (25th IAPS Meeting); 2016

IAPS (InterAmerican Photochemical Society)

Alcohols have biogenic and anthropogenic emissions and play an important role in the troposphere chemistry. The photooxidation mechanism of volatile organic compounds (VOCs) is initiated by their reaction with OH radicals. However, the chlorine atoms´ reaction with VOCs is considered to be of potential importance in the marine troposphere because, in this zone, it is present in significant concentration.Rate constants and the photo-oxidation mechanism for alcohols, for example methanol, ethanol, 1-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, and 2-pentanol, has been determined by several authors. However, the available information for alcohols of longer and substituted carbonated chains is minor. In this study, we present the determination of the relative rate constant for the reaction between chlorine atoms and 2,4,4, trimethyl 1-pentanol, along with its photo-oxidation mechanism.Kinetics studies were carried out using a relative method employing 1-pentanol as reference. Photolyses were carried out in a photo-reactor using black lamps. The identification and quantification of reactants and products were performed by infrared spectroscopy. The identity of some products was confirmed by the use of a gas chromatograph/mass spectrometer (GC/MS).The rate constant measured for 2,4,4-trimethyl-1-pentanol with chlorine atoms agrees with the theoretical values (2.55 x 10-10 cm3 molecule-1 s-1) calculated by using available data from the bibliography.The identification of products and the kinetics analysis lead to the conclusion that the chlorine atom could attack the molecule in five sites, causing the formation of pivalaldehyde, acetone, 3,3-dimethyl butanal, and 4,4-dimethyl pentan-2-one. The photooxidation mechanism of 2,4,4-trimethyl-1-pentanol is also presented.