Mass-Spectrometric Investigation of the Reactions of Atomic Hydrogen with Acetylene

The reactions of hydrogen atoms with acetylene have been investigated in a flow system, using a mass spectrometer for the determination of the concentrations of the stable and of the transient species. The disappearance of atomic hydrogen can be described by the mechanism H+C2H2=C2H3*, k1=2.4×1010 cc mole−1·sec−1,C2H3*=C2H2+H,C2H3*+M=C2H3+M,k2/k3=2.6×10−8 mole cc−1(M=H2),C2H3+H=C2H2+H2,k4≥1012 cc mole−1·sec−1,C2H3+H2=products,k5≤2×10−4 k4.All values of the rate constants refer to a temperature of about 40°C.