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Hydroxamic acid

  A hydroxamic acid is a class of chemical compounds sharing the same functional group in which an amine is inserted into an carboxylic acid. Its general structure is R-CO-NH-OH, with an R as an organic residue, a CO as a carbonyl group, and a hydroxylamine as NH2-OH. They are used as metal chelators.

Hydroxamic acids can be synthesized from aldehydes via the Angeli-Rimini reaction. A well-known hydroxamic acid reaction is the Lossen rearrangement.

Hydroxamates are essential growth factors, or vitamins, for some microbes. They function as iron-binding compounds (siderophores) that solubilise iron and transport it into the cell.

Iron is a key component of cytochromes and iron-sulphur proteins (involved in electron transport) and is thus important in cellular respiration. In an environment, absent from oxygen (anoxic); iron will be present in the ferrous +2 oxidation state (Fe2+), which is water-soluble. Under oxic conditions; iron will be in the ferric +3 oxidation state (Fe3+), in insoluble mineral form. The powerful chelating properties of hydroxamic acid and its derivatives is exploited by bacteria to obtain ferric iron. Once the iron-hydroxamate complex has entered the cell, the iron is liberated and the hydroxamic acid can be excreted and reused for iron transport.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Hydroxamic_acid". A list of authors is available in Wikipedia.
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