chromogen

{{More citations needed|date=February 2022}}{{Short description|Chemical compound that can be converted into a dye or pigment}}

In chemistry, the term chromogen refers to a colourless (or faintly coloured) chemical compound that can be converted by chemical reaction into a compound which can be described as "coloured" (a chromophore).{{cite book|last1=Burkinshaw|first1=Stephen M.|url=https://books.google.com/books?id=4SjdCQAAQBAJ&q=chromogen+chemistry&pg=PA75|title=Physico-chemical Aspects of Textile Coloration|date=2016|publisher=John Wiley & Sons|isbn=9781118725696|page=75|language=en|oclc=1038053293|access-date=2020-11-05|archive-date=2022-02-24|archive-url=https://web.archive.org/web/20220224103523/https://books.google.com/books?id=4SjdCQAAQBAJ&q=chromogen+chemistry&pg=PA75|url-status=live}}{{cite book |last1=Cain |first1=John Cannell |last2=Thorpe |first2=Jocelyn Field |title=The Synthetic Dyestuffs and the Intermediate Products from which They are Derived |date=1905 |publisher=C. Griffin, limited |pages=[https://archive.org/details/syntheticdyestuf00cainuoft/page/38 38]-40 |url=https://archive.org/details/syntheticdyestuf00cainuoft |quote=chromogen classification. |access-date=2 September 2018 |language=en}} There is no universally agreed definition of the term. Various dictionaries give the following definitions:

• A substance capable of conversion into a pigment or dye.
• Any substance that can become a pigment or coloring matter, a substance in organic fluids that forms colored compounds when oxidized, or a compound, not itself a dye, that can become a dye.
• Any substance, itself without color, giving origin to a coloring matter.

In biochemistry the term has a rather different meaning. The following are found in various dictionaries.

• A precursor of a biochemical pigment
• A pigment-producing microorganism
• Any of certain bacteria that produce a pigment
• A strongly pigmented or pigment-generating organelle, organ, or microorganism.{{Citation needed|date=February 2022}}