Principle and recent development of photochemical reactions which are
applicable to organic syntheses are interpreted. Special emphasis is p
laced on the new types of heterogeneous photoinduced reactions, e.g.,
semiconductor photocatalytic reactions, photoreactions of solid, and t
hose of incorporated or intercalation compounds. Some industrialized p
hotoreactions, e.g. photonitrosation of cyclohexane, or photochlorinat
ion of pyridines are also reviewed in order to see the perspective for
application of photoreactions.