From hydrogen halides

A number of studies of H-atom transfer from hydrogen halides to free radicals, R + HX - RH + X, have been done by FPTRMS in which R was detected by photoionization, and its decay was monitored as a function of [HX] under pseudo-first-order conditions. When the rate coefficient is combined with determinations of the rate coefficient of the reverse reaction to obtain the equilibrium constant, the enthalpy of formation of the radical can be deduced. If the kinetics are accurately measured in isolation, this is a direct kinetic method which can be used to confirm (or otherwise) thermodynamic data obtained by classical, indirect kinetic methods which depend on correct mechanistic interpretation. In a number of instances free radical enthalpies of formation by these two different approaches have not been in good agreement. It is not the purpose of this short survey to discuss the differences, but rather to briefly indicate the extent to which the FPTRMS method has contributed to the kinetics of these reactions and to free radical thermochemistry. 

Isoquinolines from Hydrogen Halide Cyclization of 2-NCC6H4CH(R)CN... 

The alkenes are more reactive than the alkanes. For example, alkene molecules undergo addition reactions in which the atoms from halogen molecules or from hydrogen halides bond to the carbon atoms involved in the double bond ... 

I.r. emission has been seen from the vibrationally excited CO2 product of MPD of vinylacetic and pyruvic acids, from hydrogen halides formed by chemical reaction of CI2 with H atoms produced in the MPD of various hydrocarbons, and of HBr with F and Cl atoms formed in the MPD of CFjCl. Infrared fluorescence from CjFjCl following MPA shows emission from both discrete levels and the quasicontinuum, with efficient intramolecular vibrational redistribution out of the pumped mode evident after absorption of only 2—3 photons. Emission in the i.r. has been seen following MPA in N2p4, and has been used to study the interconversion of perfluorocyclobutene to perfluoro-butadiene isomers following MPA. Further isomerization reactions induced by CO2 lasers have been reported. 

Formation of H2 from hydrogen halides 1 Reaction with elemental group-IA metals 5,... 

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