Atmospheric chemistry of diazomethane – an experimental and theoretical study

Abstract

The kinetics of the O 3 , OH and NO 3 radical reactions with diazomethane were studied in smog chamber experiments employing long-path FTIR and PTR-ToF-MS detection. The rate coefficients were determined to be k CH2NN+O3 = (3.2 ± 0.4) × 10 −17 and k CH2NN+OH = (1.68 ± 0.12) × 10 −10 cm 3 molecule −1 s −1 at 295 ± 3 K and 1013 ± 30 hPa, whereas the CH 2 NN + NO 3 reaction was too fast to be determined in the static smog chamber experiments. Formaldehyde was the sole product observed in all the reactions. The experimental results are supported by CCSD(T*)-F12a/aug-cc-pVTZ//M062X/aug-cc-pVTZ calculations showing the reactions to proceed exclusively via addition to the carbon atom. The atmospheric fate of diazomethane is discussed.

Atmospheric Chemistry of N-Methylmethanimine (CH3N═CH2): A Theoretical and Experimental Study

“…The present results clearly demonstrate that high barriers block this route. In addition, a recent experimental and theoretical study of the atmospheric chemistry CH 3 NC shows CH 3 NCO as the only product …”

“…Further MMI and TMT photo-oxidation experiments were carried out in the Oslo 240 L stainless steel Smog Chamber employing FTIR and high-resolution PTR-ToF-MS detection; the system was recently described in detail (in the present experiments the PTR drift tube was operated at 107 Td). 22 MMI was added to the evacuated chamber by heating a TMT sample to 180 °C and trapping impurities and TMT in two dry ice cold-traps on the fly. TMT and an OH-radical precursor were added to the chamber by injection in a constant stream of replenishment air compensating for the PTR sampling.…”

Atmospheric Chemistry of Methyl Isocyanide–An Experimental and Theoretical Study

“…The M06-2X hybrid functional locates the D 3h structure as a saddle point and the two C 2v structures as local energy minima. 39 BHandHLYP calculations also locate the D 3h structure as a saddle point and the (2s1l) C 2v structure as a minimum; the (1s2l) C 2v structure is found to be a saddle point. Table S1 in the Supporting Information summarizes the results obtained for the D 3h and the two C 2v structures.…”

“…Several frequently employed DFT methods, such as the B3LYP and B98 functionals, predict D 3h structures as global minima, whereas others, including M06-2X and BHandHLYP, also show symmetry breaking. The M06-2X hybrid functional locates the D 3h structure as a saddle point and the two C 2v structures as local energy minima . BHandHLYP calculations also locate the D 3h structure as a saddle point and the (2 s 1 l ) C 2v structure as a minimum; the (1 s 2 l ) C 2v structure is found to be a saddle point.…”

Atmospheric Chemistry of 2-Amino-2-methyl-1-propanol: A Theoretical and Experimental Study of the OH-Initiated Degradation under Simulated Atmospheric Conditions

“…The m / z 73.065 ion signal has quantified contributions from protonated AMP and AMPNO 2 , and the profile leaves little evidence for an additional contribution that by necessity is time correlated to AMPNO 2 . 2-Diazopropane is expected to react equally fast with OH as diazomethane does, k OH+CH 2 NN = 1.7 × 10 –10 cm 3 molecule –1 s –1 , and it will therefore not build up during the present photo-oxidation experiments. The observed signal at m / z 71.049 neither displays any skewness toward higher values nor a transient profile.…”