Norrish’ type I and II reactions and their role in the building of photochemical science

The highly inspiring work by Professor Norrish has exerted a consistent influence on chemistry and, in particular, on photochemistry, where he was one of the first scientists, along with Gilbert N. Lewis, able to develop a viable concept of excited states and their rate of reaction. However, having him listed among the authors of two name reactions, known as Norrish Type I and Type II, plus a subcase of the latter that is the Yang cyclization, is not coherent. Indeed, Norrish had no interest in organic synthesis, while this is a required feature of name reactions. And, at any rate, Professors Ciamician and Paternò had arrived at the same conclusions with the same compounds much earlier, except for the measurement of quantum yields. Things are too long away now for introducing any change, but one should remember that using Norrish name here is a mistake, while it would be appropriate to add the name of Ciamician for a different name reaction, the 2 + 2 cycloaddition of alkenes and conjugated carbonyls. In 1968, such an attribution was proposed by Professor Schömberg, but this had no effect and the present assignment has become a habit. The most important thing, however, is that the 2 + 2 reaction has become one of the most popular reactions in synthetic photochemistry.