Gluconic acid
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| General | ||||||||||||||||||||||
| Surname | D -gluconic acid | |||||||||||||||||||||
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| Molecular formula | C 6 H 12 O 7 | |||||||||||||||||||||
| Brief description |
syrupy liquid, crystalline in the pure state |
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| properties | ||||||||||||||||||||||
| Molar mass | 196.16 g mol −1 | |||||||||||||||||||||
| Physical state |
firmly |
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| density |
1.24 g cm −3 |
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| Melting point |
131 ° C |
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| boiling point |
417 ° C |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | ||||||||||||||||||||||
D -gluconic acid is a carboxylic acid from the group of fruit acids . In the system of compounds derived from carbohydrates, it is assigned to the group of onic acids . It differs from D-glucose in the oxidation state on the first carbon, where a carboxy group is presentinstead of an aldehyde group . Gluconate is the anion of gluconic acid.
Occurrence
Gluconic acid occurs in small amounts in numerous fruits and wine and is responsible for a slightly sour, refreshing taste. Also Kombucha (a drink made from fermented tea), honey and Bionade contain gluconic.
Extraction and presentation
D- gluconic acid can be obtained in a synthetic chemical way by mild oxidation of the D - glucose with bromine water or with iodine in an alkaline solution . It is also the by-product in the quantitative determination of reducing sugars ( Luff-Schoorl method ). Copper (II) sulfate oxidizes the D- glucose to D- gluconic acid, with copper (II) being reduced to copper (I).
In addition to Gluconobacter oxydans (the taxonomic group also contains Acetobacter suboxydans and Gluconobacter suboxydans ), the fermentation of glucose to gluconic acid can also be effected by Aspergillus niger , various Acetobacter , mixtures of the preceding microorganisms or by adding the enzymes glucose oxidase and catalase .
In industry, only the biochemical route of fermentation is used to produce gluconic acid.
Chemical properties
In the acidic medium, or when attempting to isolate the free acid from solutions formed from D -Gluconsäure easily dehydration D -gluconolactone (gluconic acid δ-lactone). D- gluconic acid is therefore only available commercially in the form of aqueous solutions or in the form of its salts.
use
Food
Gluconic acid (E 574) and its salts are used in foods as an artificial acidity regulator , as a stabilizer or, like calcium gluconate (E 578) or calcium lactate gluconate, as a source of calcium . Iron gluconate (E 579) is used to color black olives more intensely . D- gluconolactone is used as a food additive E 575. The commercially available soft drink " Bionade " contains gluconic acid as the product of a fermentation process . Excessive consumption of gluconic acid or products containing gluconic acid can have a laxative effect.
technology
Gluconic acid is used as a mild acid in metal pickling agents.
medicine
Iron gluconate is found in some medicines for iron deficiency . Other metal gluconates are also contained in corresponding preparations, e.g. B. zinc gluconate . Gluconate is well absorbed (absorbed) by the body. The anion "drags" the trace element bound as a cation into the body and enables it to be absorbed efficiently. This effect can also be seen on the skin: after hydrofluoric acid burns, a calcium gluconate gel is massaged into the skin. The gluconate facilitates the absorption of calcium, which renders the toxic soluble fluoride harmless in the body by forming the insoluble calcium fluoride.
Web links
- Entry to gluconic acid . In: P. J. Linstrom, W. G. Mallard (Eds.): NIST Chemistry WebBook, NIST Standard Reference Database Number 69 . National Institute of Standards and Technology , Gaithersburg MD
- ChemSub Online: Gluconic Acid
Individual evidence
- ↑ Entry on GLUCONIC ACID in the CosIng database of the EU Commission, accessed on June 30, 2020.
- ↑ Entry on E 574: Gluconic acid in the European database for food additives, accessed on June 30, 2020.
- ↑ a b c Entry on D- gluconic acid. In: Römpp Online . Georg Thieme Verlag, accessed on April 9, 2014.
- ↑ Entry Gluconic Acid at www.chemicalland21.com
- ↑ OECD : Screening Information Dataset (SIDS) Initial Assessment Report (SIAR) for D-Gluconic acid , accessed on November 6, 2014.
- ↑ a b Data sheet D-Gluconic acid solution from Sigma-Aldrich , accessed on April 3, 2011 ( PDF ).
- ^ A b Christoph Syldatk, Rudolf Hausmann: Organic acids . In: Hermann Sahm, Garabed Antranikian, Klaus-Peter Stahmann & Ralf Takors (eds.): Industrial microbiology . Springer Spectrum, Berlin, Heidelberg 2013, ISBN 978-3-8274-3039-7 , chap. 5 , p. 92-107 , doi : 10.1007 / 978-3-8274-3040-3 .
- ^ National Center for Bioinformatics Information Taxonomy Browser: Gluconobacter oxydans
- ↑ DEPATIS: Patent DE000004406087C1 by Dieter Leipold and Sigrid Peter.