Malic acid (hydroxy succinic acid, hydroxybutanedioic acid) HOOC-CH 2 -CH (OH) -COOH is a dibasic hydroxycarboxylic acid . First isolated by the Swedish chemist Carl Wilhelm Scheele (Carl Wilhelm Scheele) in 1785 from unripe apples. Salts and anions of malic acid are called malates .
| Apple acid | |
|---|---|
 | |
| General | |
| Chem. formula | C₄H₆O₅ |
| Rat formula | NOOSSN 2 CH (OH) COOH |
| Physical properties | |
| Molar mass | 134.1 g / mol |
| Thermal properties | |
| T. melt. | 100 ° C |
| Chemical properties | |
| Solubility in water | 144 g / 100 ml |
| Solubility in ethanol | 35.9 g / 100 ml |
| Classification | |
| Reg. CAS number | |
| PubChem | |
| Reg. EINECS number | |
| Smiles | |
| Inchi | |
| Codex Alimentarius | |
| Chebi | |
| ChemSpider | |
Content
- 1 Properties
- 2 In nature
- 3 Role in metabolism
- 4 Application
- 5 notes
- 6 Literature
Properties
Malic acid is a colorless hygroscopic crystals, readily soluble in water, ethyl alcohol and diethyl ether , exists in two stereoisomeric forms and in the form of a racemic mixture.
In nature
Malic acid is found in unripe apples , grapes , mountain ash , barberry , raspberries , oranges , tangerines, lemon [1] , etc. Shag and tobacco plants contain it in the form of nicotine salts. In nature, the L-form of malic acid predominates.
In citrus fruits, fruits produced in organic agriculture contain higher levels of malic acid than fruits produced in traditional agriculture [1] .
Role in Metabolism
Malate is an intermediate in the tricarboxylic acid cycle and glyoxylate cycle . In the Krebs cycle, L-malic acid is formed by hydration of fumaric acid and then oxidized by coenzyme NAD + to oxaloacetic acid .
Application
It is used as a food additive ( E296 ) of natural origin in the manufacture of fruit water and confectionery. Also used in medicine.
Notes
- ↑ 1 2 Duarte, AM, Caixeirinho, D., Miguel, MG, Sustelo, V., Nunes, C., Fernandes, MM and Marreiros, A. Organic Acids Concentration in Citrus Juice from Conventional versus Organic Farming. (English) // Acta Horticulturae (ISHS) 933. - 2012 .-- S. 601-606 .
Literature
- Gorbov A.I. Malic acid // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
- O. Ya. Neiland. Organic chemistry. - M .: High School, 1990. - 751 p. - 35,000 copies. - ISBN 5-06-001471-1 .
- Zefirov N.S. et al. 5 Tri-Yatr // Chemical Encyclopedia. - M .: Big Russian Encyclopedia, 1998 .-- 783 p. - ISBN 5-85270-310-9 .