Generally used to describe a chemical reaction caused by absorption of
ultraviolet,
visible or
infrared radiation. There are many ground-state reactions,
which have photochemical counterparts. Among these are photochemical nitrogen extrusions,
photocycloadditions, photodecarbonylations, photodecarboxylations, photoenolizations,
photo-Fries rearrangement, photoisomerizations, photooxidations, photorearrangements,
photoreductions, photosubstitutions, etc.
Note:
Photochemical paths offer the advantage over thermal methods of forming
thermodynamically disfavoured products, overcome large
activation barriers in a short
period of time, and allow reactivity otherwise inaccessible by thermal methods.
Source:
PAC, 2007, 79, 293
(Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006))
on page 386