Ambient temperature removal rate constants for singlet methylene with some nitrogen and sulphur compounds

Abstract

The technique of laser flash photolysis/laser absorption has been used to obtain absolute removal rate constants for singlet methylene, 1CH2 (ā A1), with some nitrogen and sulphur compounds at ambient temperature (298±2 K). A measurement of the removal rate constant for 1CH2 with NH3 yielded a value of (3.33±0.19)xl0−10 cm3 molecule−1 s−1 in good agreement with the only previously reported measurement. Removal rate constants for the reactants CH3NO2, CH3CH2NO2, CH3CH2CH2NO2, CH3CN, CH3CH2CH2CN, CH2=CHCN, H2S, CH3CH2SH, CH3SCH3, CH3SSCH3, and CH3COSH were measured for the first time and found to be (3.23±0.28), (3.46±0.69), (3.55±1.28), (4.51±0.21), (3.64±0.41), (4.10±0.26), (3.87±0.22), (4.77±0.25), (4.53±0.23), (5.37±0.53), and (4.59±0.32)x10−10 cm3 molecule−1 s−1 respectively. The calculated removal efficiencies (removal rate constant relative to the Lennard‐Jones collision rate constant) are indicative of reaction being the dominant process leading to loss of 1CH2. Comparisons are drawn between the reactivities of the nitrogen and sulphur functional groups and their hydrocarbon analogues, and between the sulphur compounds and their isoelectronic oxygen analogues.