Photopolymerization four-center

Hasegawa, M. Four-Center Photopolymerization in the Crystalline State. Vol. 42, pp. 1 —49. 

Hasegawa, M. Four-Center Photopolymerization in the Crystalline State. Vol. 42, pp. 1-49. Hatano, M. Induced Circular Dichroism in Biopolymer-Dye System. Vol. 77, pp. 1-121. 

A typical reaction of four-center photopolymerization is that of 2,5-distyrylpyrazine (DSP), which was reported by the author in 1967. 

Four-center photopolymerization in the crystalline state is a general term for the reactions in which conjugated diolefin crystals are photochemically converted in a step-... 

Only a few review articles concerning this type of topochemical polymerization have been published so far8,11 from the viewpoint of a specific field, though extensive work has been done in recent years. This article is the first review of a four-center photopolymerization and related problems which covers all the results obtained from a variety of... 

These two discoveries of the new type of crystalline state photopolymerization prompted polymer chemists to study the generality of this type of polymerization. In consequence, a large number of diolefinic compounds have been found to photopoly-merize to linear high molecular weight polymers by a four-center photopolymerization in the crystalline state. All the diolefinic monomer crystals investigated so far have been found to undergo no detectable polymerization upon prolonged irradiation with y- or X-rays. 

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