Gluconic acid
Template:Distinguish Template:Chembox Gluconic acid is an organic compound with molecular formula C6H12O7 and condensed structural formula HOCH2(CHOH)4CO2H. A white solid, it forms the gluconate anion in neutral aqueous solution. The salts of gluconic acid are known as "gluconates". Gluconic acid, gluconate salts, and gluconate esters occur widely in nature because such species arise from the oxidation of glucose. Some drugs are injected in the form of gluconates.
Chemical structureEdit
The chemical structure of gluconic acid consists of a six-carbon chain, with five hydroxyl groups positioned in the same way as in the open-chained form of glucose, terminating in a carboxylic acid group. It is one of the 16 stereoisomers of 2,3,4,5,6-pentahydroxyhexanoic acid.
ProductionEdit
Gluconic acid is typically produced by the aerobic oxidation of glucose in the presence of the enzyme glucose oxidase. The conversion produces gluconolactone and hydrogen peroxide. The lactone spontaneously hydrolyzes to gluconic acid in water.<ref>Template:Cite journal</ref>
Variations of glucose (or other carbohydrate-containing substrate) oxidation using fermentation.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> or noble metal catalysis.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Gluconic acid was first prepared by Hlasiwetz and Habermann in 1870<ref>Template:Cite journal</ref> and involved the chemical oxidation of glucose. In 1880, Boutroux prepared and isolated gluconic acid using the glucose fermentation.<ref>Template:Cite journal</ref>
Historical role in development of deep-tank fermentationEdit
The production of gluconic acid by deep-tank fermentation (aerated, pH controlled, and stirred >1000 L tanks) of the filamentous fungi Aspergillus niger in 1929, for use as a food acidity regulator and cleaning agent, was the first successful use of deep-tank fermentation by Pfizer.<ref name="r856">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> This expertise later led to Pfizer's successful use of deep-tank fermentation of Penicillium fungi in February 1944,<ref name="r856"></ref> to rapidly scale up penicillin production, resulting in sufficient penicillin to treat the American and British battle casualties of the June 6th Allied D-Day invasion of World War II.<ref>Template:Cite book</ref>
Occurrence and usesEdit
Gluconic acid occurs naturally in fruit, honey, and wine. As a food additive (E574<ref>Current EU approved additives and their E Numbers. Food Standards Agency.</ref>), it is now known as an acidity regulator.
The gluconate anion chelates Ca2+, Fe2+, [[Potassium|Template:Chem2]], Al3+, and other metals, including lanthanides and actinides. It is also used in cleaning products, where it dissolves mineral deposits, especially in alkaline solution.
Zinc gluconate injections are used to neuter male dogs.<ref>Julie K. Levy, P. Cynda Crawford, Leslie D. Appel, Emma L. Clifford (2008), Comparison of intratesticular injection of zinc gluconate versus surgical castration to sterilize male dogs. American Journal of Veterinary Research Vol. 69, No. 1, Pages 140–143. {{#invoke:doi|main}}</ref>
Gluconate is also used in building and construction as a concrete admixture (retarder) to slow down the cement hydration reactions, and to delay the cement setting time. It allows for a longer time to lay the concrete, or to spread the cement hydration heat over a longer period of time to avoid too high a temperature and the resulting cracking.<ref name="RamachandranLowery1992">Template:Cite journal</ref><ref name="MaLi2015">Template:Cite journal</ref> Retarders are mixed in to concrete when the weather temperature is high or to cast large and thick concrete slabs in successive and sufficiently well-mixed layers.
Gluconic acid aqueous solution finds application as a medium for organic synthesis.<ref>Template:Cite journal</ref>
MedicineEdit
In medicine, gluconate is used most commonly as a biologically neutral carrier of Template:Chem2, Template:Chem2, Template:Chem2, Template:Chem2, and Template:Chem2 to treat electrolyte imbalance.<ref>Template:Cite journal</ref>
Calcium gluconate, in the form of a gel, is used to treat burns from hydrofluoric acid;<ref name="pmid2741315">Template:Cite journal</ref><ref name="pmid17091088">Template:Cite journal</ref> calcium gluconate injections may be used for more severe cases to avoid necrosis of deep tissues, as well as to treat hypocalcemia in hospitalized patients. Gluconate is also an electrolyte present in certain solutions, such as "plasmalyte a", used for intravenous fluid resuscitation.<ref> D. Thomas, U. Jaeger, I. Sagoschen, C. Lamberti and K. Wilhelm (2009), Intra-Arterial Calcium Gluconate Treatment After Hydrofluoric Acid Burn of the Hand. CardioVascular and Interventional Radiology, Volume 32, Number 1, pages 155–158 {{#invoke:doi|main}}</ref> Quinine gluconate is a salt of gluconic acid and quinine, which is used for intramuscular injection in the treatment of malaria.
Ferrous gluconate injections have been proposed in the past to treat anemia.<ref>Paul Reznikoff and Walther F. Goebel (1937), The preparation of ferrous gluconate and its use in the treatment of hypochromic anelia in rats. Journal of Pharmacology and Experimental Therapy, volume 59 issue 2, page 182.</ref>