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The electrophilicity of the H atom in hydrogen abstraction reactions was studied by the CNDO/2 method. The origin of the electrophilicity of the H atom was well understood using the stabilization energy due to the delocalization of electrons (SEDE) between the radical and substrate; this energy was calculated along the reaction path. The electrophilic energy (SEDE from the substrate to the radical) governs the relative reactivities of substrates, CH4

The reactivities of hydrogen atoms of aliphatic amino acids toward hydroxyl radicals in the hydrogen atom abstraction reaction have been studied in terms of the energy required for stretching the C–H bond which is attacked. The energy required for stretching the C–H bond by 0.5 Å from the equilibrium bond length has been calculated by the INDO method and compared with the partial rate constants experimentally assigned to the hydrogen atoms of aliphatic amino acids. The energy required has been correlated only with the partial rate constants of the hydrogen atoms on the ß-carbon atom. For the hydrogen atoms on the a-carbon atom, although data was insufficient a similar situation has been observed. The reactivities of the hydrogen atoms on the ? and d-carbon atom failed to correlate with the stretching energy. The reasons are discussed in terms of the effect raised by the configuration of amino acid molecules in solution. The stretching energy has also been found to be consistent with the electrophilicity observed in the hydrogen abstraction reaction by hydroxyl radical.

The electrophilicity of the hydroxyl radical in hydrogen abstraction from methane was studied by the CNDO/2 method. The stabilization energy due to the delocalization of the electrons (SEDE) between methane and the radical at a close distance was calculated. The electrophilicity defined by the SEDE from methane to the hydroxyl radical was larger than the nucleophilicity defined by that from the hydroxyl radical to methane. This result is consistent with the electrophilicity observed in hydrogen abstraction by the hydroxyl radical from a series of substituted methanes. For sulfhydryl radical, the electrophilicity was also suggested by the calculation for hydrogen abstraction from methane. The calculations were also carried out for various radicals which have low electron affinity (hydrogen atom and methyl radical), and the SEDE from methane to the radical was found to be large compared with that from the converse case.

The electrophilicity of the CF3radical in hydrogen abstraction reactions was studied theoretically by the CNDO/2 method. The activation energy for hydrogen abstraction by the CF3radical from aliphatic hydrocarbons decreases with an increase in the electron density on the hydrogen atom to be abstracted. The origin of the electrophilicity of the CF3radical can be well understood by the stabilization energy due to delocalization of electrons (SEDE) between the radical and substrate. The electrophilic stabilization energy denned by the SEDE from substrate to the radical governs the relative reactivities of aliphatic hydrocarbons, CH4

The transfer of singlet energy in p-terphenyl crystal was measured as a function of the dopant (tetracene) concentration and the temperature. The simple hopping model yields a value of 3×10-14s. This value is believed to be correct within a factor of 5. In the low temperature phase of the crystal, the energy transfer is temperature dependent with an activation energy of 66 cm-1in undeuterated p-terphenyl and 90 cm-1in perdeuterated p-terphenyl. It seems probable that in the low temperature phase the freedom of the conformational change of the molecule plays an important role in the energy migration.

The polarities (nucleophilicity and electrophilicity) of free radicals in abstraction reactions were studied by the comparison of the stabilization energies due to delocalization of electrons (SEDE) between a radical and a substrate. The stabilization energies were calculated by the CNDO/2 method for several substrate–radical systems. For the reactions of the methyl radical with chlorinated methanes, the nucleophilicity of the radical was well interpreted by the SEDE from the radical to the substrate. Similarly, the nucleophilicity of the hydrogen atom in chlorine abstraction from chlorinated methanes was indicated by the SEDE from the hydrogen atom to the substrate. In an electrophilic reaction such as hydrogen abstraction by the methyl radical from aliphatic hydrocarbons, the activation energy was found to decrease linearly with an increase in the SEDE from the substrate to the radical. This result is consistent with the electrophilic tendency of the reaction. The SEDE calculated for the reactions of a radical with a series of substrate thus indicates the polarity of the free radical in the abstraction reactions.

The energy required to stretch a C–H bond of alkanes by 0.5 Å from an equilibrium bond length was calculated by the INDO method, and it was found that this energy has a relation with the delocalizability, DrR, of hydrogen atoms in alkanes, and with the activation energy for the hydrogen-abstraction reaction of the methyl radical from alkanes. The reactivities of hydrogen atoms in aliphatic alcohols and carboxylate ions, as defined by this energy were found to correlate with the partial reactivities of hydrogen atoms, just as was proposed by Anbar et al., i.e., the rate constants for the hydrogen-abstraction reaction of aliphatic compounds with hydroxyl radicals can be well explained by a summation of the partial reactivities assigned to primary, secondary, and tertiary hydrogen atoms bound to a- or ß- (for ?-CH and d-CH the same value as for ß-CH was used) carbon atoms.

The end-to-end dimerization of acrylonitrile was effected with a ruthenium trichloride trihydrate catalyst under a hydrogen atmosphere, thus obtaining a mixture of cis- and trans-1, 4-dicyano-1-butene as the main products. Under nitrogen, however, only very small amounts of these products were formed. The reaction occurred at temperatures of 120–200°C under moderate hydrogen pressures in alcoholic media such as ethanol. The effects of various salts or electron-donating compounds on the catalysis were examined.