High Accuracy Measurements of OH Reaction Rate Constants and IR Absorption Spectra: Substituted 2-Propanols
Vladimir L. Orkin, Victor Khamaganov, Michael J. Kurylo III
Rate constants for the gas phase reactions of OH radicals with 2-propanol and three fluorine substituted 2-Propanols, (CH3)2CHOH (k0), CF3)2COH (k1), (CF3)2C(OH)CH3 (k2), and (CF3)3COH (k3) were measured using a flash photolysis resonance-fluorescence technique over the temperature range 220 K to 370 K. The Arrhenius plots were found to exhibit noticeable curvature for all four reactions. The temperature dependences of the rate constants can be represented by the following expressions: k0(T) = 1.4610-11exp(-883/T) + 1.3010-12exp(+371/T) cm3 molecule-1 s-1, k1(T) = 1.1910-12exp(-1207/T) + 7.8510-16exp(+502/T) cm3 molecule-1 s-1, k2(T) = 1.6810-12exp(-1718/T) + 7.3210-16exp(+371/T) cm3 molecule-1 s-1, k3(T) = 3.0010-20(T/298)11.3exp(+3058/T) cm3 molecule-1 s-1, The atmospheric lifetimes due to reactions with tropospheric OH were estimated to be 2.4 days and 1.9, 6.3, and 46 years, respectively. UV absorption cross-sections were measured between 160 nm and 200 nm. The IR absorption cross-sections of the three fluorinated compounds were measured between 450 cm 1 and 1900 cm-1 and their global warming potentials were estimated.