An FT-IR study of the isomerization of 1-butoxy radicals under atmospheric conditions

Abstract

Relative rate-studies of the reactions of 1-butoxy radicals have been carried out using a 47 L static reactor with detection of end products by FT-IR spectroscopy. Experiments were performed at 700 torr total pressure and over the temperature range 253–295 K. The chemistry of 1-butoxy is characterized by a competition between reaction with oxygen CH 3CH 2CH 2CH 2O + O 2 → n-C 3H 7CHO + HO 2 (R2), which yields butanal and isomerization CH 3CH 2CH 2CH 2O → CH 2CH 2CH 2CH 2OH (R3), to form a hydroxylated carbonyl-product. A reference spectrum attributed to the product of 1-butoxy isomerization was obtained and used to determine the competition between 1-butoxy isomerization versus reaction with oxygen. The results indicate that isomerization is the dominant fate of 1-butoxy radicals at ambient temperature and pressure and that its importance decreases with decreasing temperature. The rate-coefficient ratio k 3/ k 2 (molecule cm −3) = 5.5 × 10 23 exp[(−25.1 ± 0.9 kJmol −1)/RT] was obtained. This agrees with other estimates based on methods without monitoring of the isomerization product.