The reactions of H and D atoms with H2CO (H + H2CO → H2 + HCO (1.1), D + H2CO → HD + HCO (2.1), and D + H2CO → H + HDCO (2.2)) have been studied in the temperature range 296 K ≤ T ≤ 780 K in an isothermal discharge flow reactor with EPR detection of D and H atoms and LIF detection of HCO. Simultaneous measurements of the absolute concentration−time profiles of the three species established the occurrence of the D/H isotope exchange reaction (2.2) in addition to the H atom abstraction channel (2.1). The rate constants for the three reactions could be represented by the Arrhenius expressions k 1.1(T) = (8.7 ± 1.9) × 1012 exp[−(14.5 ± 0.7) kJ mol-1/RT] cm3 mol-1 s-1, k 2.1(T) = (1.2 ± 0.5) × 1013 exp[−(15.8 ± 0.8) kJ mol-1/RT] cm3 mol-1 s-1, and k 2.2(T) = (5.9 ± 1.5) × 1012 exp[−(14.7 ± 1.0) kJ mol-1/RT] cm3 mol-1 s-1. A mechanistic analysis of reaction 2.2 using the unimolecular rate theory gave these estimates for the classical potential energy barrier heights in the addition of D and H atoms to H2CO:  ΔE 0(D + H2CO) = 1360 ± 100 cm-1 and ΔE 0(H + H2CO) = 1540 ± 150 cm-1.

The kinetics of the homogeneous gas phase reaction OH + CH2CO → products (1) has been investigated at room temperature and pressures between 1.4 mbar ≤ p ≤ 2.5 mbar using the discharge flow method. Reactors with Teflon wall coatings and with different surface‐to‐volume ratios were employed to exclude effects of heterogeneous reactions. OH radicals were generated via the reaction F + H2O. Their concentration‐versus‐time decay profiles were followed under pseudo‐first‐order conditions, [CH2CO] → [OH]0 with a Far Infrared Laser Magnetic Resonance (FIR‐LMR) spectrometer. The rate constant of the title reaction was found to be k1, (296 K) = (7.2 ± 2.0)·1012 cm3/mol·s.

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The kinetics of the reactions of CH2 (X̄3B1) with selected alkenes R = ethylene (1), tetramethylethylene (2), cycloheptatriene (3), and 1,3‐butadiene (4) were studied at temperatures between 296 K≤T≤728 K. Rate constants were measured for reactions (2–4) using the discharge flow technique with Far‐Infrared Laser Magnetic Resonance (FIR–LMR) detection of 3CH2. The experimental data can be described by the rate expressions (±2σ) These data and results for reaction (1) obtained earlier were analyzed to separate the contributions to the CH2 (X̄) depletion by reactive channels versus collisional excitation to the ã1A1 state of CH2 followed by reactions of CH2 (ã). The rate expressions (±2σ) for the reactive pathways of CH2 (X̄) were found to be .