Term: photochemical reaction
https://doi.org/10.1351/goldbook.P04585

Definition:
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 @A00093@ barriers in a short period of time, and allow reactivity otherwise inaccessible by thermal methods.

Related Terms:
1) activation (http://doi.org/10.1351/goldbook.A00093).
2) ultraviolet (http://doi.org/10.1351/goldbook.UT07492).
3) visible (http://doi.org/10.1351/goldbook.VT07496).
4) infrared (http://doi.org/10.1351/goldbook.IT07399).
5) photo-fries rearrangement (http://doi.org/10.1351/goldbook.P04614).

Source: PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 386 (https://doi.org/10.1351/pac200779030293)

Citation: 'photochemical reaction' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.P04585

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