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The photoreduction of 9-acetylanthracene by stannane in benzene was studied. By the analysis of UV and IR spectra of the reaction products, it was found that the carbonyl group of 9-acetylanthracene was not photoreduced, and that the addition of hydrogen atom occurred at the meso position. For several anthracene derivatives, this photoreduction reaction at the meso positions was investigated by the method of the flash photolysis. The reduction rate constants are of the order of 10^4 l mole^-1 sec^-1. The trend of the substituent effect is reverse to that found by other investigators for the photo-oxidation of anthracene derivatives. Namely, the electron donating substituents decrease the rate of the photoreduction and the electron attracting substituents increase it, The activation energy for the reaction of 9-acetylanthracene was found to be 10.4kcal/mole. The reason why the carbonyl group of 9-acetylanthracene was not photoreduced by stannane will be discussed.

The thermal bulk polymerization of butadiene was investigated at 323 to 368°K under high pressures in the range of 1100 to 5000kg/cm^2. It was observed that the polymerization reaction was not preceded by an induction period, and the polymer yields increased linearly with the reaction time throughout the comparatively long run. The rate of polymerization was accelerated by increasing the pressure and temperature. From the apparent initial rate, the activation energies, activation volumes and activation entropies were calculated and the following values were obtained ; E=15.1～-19.2kcal/mole, ΔV≠=-8.8～-17.2cm^3/mole and ΔS≒=-38.0～-24.3 e.u. The polymer obtained was insoluble in the ordinary solvents of rubbers, and it was concluded that the polymer is a crosslinked elastic polymer.

The photoreduction of 2-acetonaphthone by (Bu)_3SnH and (Bu)_3SiH were investigated by the method of flash photolysis and compared with the results obtained from the steady state method. The rate constant of the reduction by (Bu)_3SnH was found to be 1.3×10^6/mole^-1 sec^-1, which is close to that of Linschitz et al. The temperature dependence of the rate constant gives the activation energy of 1.7kcal mole^-1. The reduction by (Bu)_3SiH was found not to occur even after a long exposure to sunlight. Furthermore we discuss qualitatively about the activation energy and the reactivity of reducing agents.

Photoreduction and photoaddition reactions were investigated on those compounds, 9-CH_3CO-A, 9-CHO-A, 1-CH_3CO-A, 2-CH_3CO-A, 3-CH_3CO-P and 3-CHO-P, which are the carbonyl derivatives of anthracene (-A) or pyrene (-P). These compounds bad the ππ state as their lowest triplet states. 9-CHO-A, 1-CHO-A, 3-CH_3CO-P and 3-CHO-P underwent the above photoreactions. The other compounds were not photoreactive at all. Quantum yields of the photoreactions on the photoreactive compounds were measured, and it was found that the value for 3-CHO-P was larger than that for 9-CHO-A. The relative photoreduction rates were also obtained in several solvents. Most compounds were non-fluorescent is non-polar solvents but showed fluorescence in various degrees in polar media. In spite of the supposition that those phenomena reflected the natures of the excited states of the compounds, they had no relation to the photoreactivity. The typical examples were 1-CH_3CO-A and 1-CHO-A, both of which showed a similar solvent effect on fluorescence spectra but had a different photoreactivity; the former was non-reactive. From these results and the temperature dependence of the lowest triplet state yield, the relative positions of the several excited states of these compounds were estimated. It was supposed that the magnitudes of the decay rate of the higher excited triplet state T (nπ) determined the photoreactivity. The lifetimes of the lowest triplet state T1(ππ) were also measured on the above compounds. It was found that the compounds having the shorter lifetime of the lowest triplet state were photoreactive. Particularly the lifetime of photoreactive 9-CHO-A was much shorter than that of non-reactive 9-CH_3CO-A, which had a similar lifetime to anthracene. With the aid of the theories of Robinson and El-Sayed and the first order perturbation, it will be shown that this lifetime is correlated to the molecular structure which seems to have a close connection with the radiationless transition process and the photoreactivity of T (nπ).