A Norrish reaction, named after Ronald George Wreyford Norrish, is a photochemical reaction taking place with ketones and aldehydes. Such reactions are subdivided into Norrish type I reactions and Norrish type II reactions.[1] While of limited synthetic utility these reactions are important in the photo-oxidation of polymers such as polyolefins,[2] polyesters, certain polycarbonates and polyketones.