Citric acid

Citric acid
Zitronensäure Kristallzucht.jpg
Names
Preferred IUPAC name
2-Hydroxypropane-1,2,3-tricarboxylic acid
Identifiers
  • 77-92-9 checkY
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.973
EC Number
  • 201-069-1
E number E330 (antioxidants, ...)
KEGG
RTECS number
  • GE7350000
UNII
  • OC(=O)CC(O)(C(=O)O)CC(=O)O
Properties
C6H8O7
Molar mass 192.123 g/mol (anhydrous), 210.038 g/mol (monohydrate)
Appearance Crystalline white solid
Odor Odorless
Density 1.665 g/cm3 (anhydrous)
1.542 g/cm3 (18 °C, monohydrate)
Melting point 156 °C (313 °F; 429 K)
Boiling point 310 °C (590 °F; 583 K) decomposes from 175 °C
117.43 g/100 mL (10 °C)
147.76 g/100 mL (20 °C)
180.89 g/100 mL (30 °C)
220.19 g/100 mL (40 °C)
382.48 g/100 mL (80 °C)
547.79 g/100 mL (100 °C)
Solubility soluble in acetone, alcohol, ether, ethyl acetate, DMSO
insoluble in C
6H
6, CHCl3, CS2, toluene
Solubility in ethanol 62 g/100 g (25 °C)
Solubility in amyl acetate 4.41 g/100 g (25 °C)
Solubility in diethyl ether 1.05 g/100 g (25 °C)
Solubility in 1,4-Dioxane 35.9 g/100 g (25 °C)
log P −1.64
Acidity (pKa) pKa1 = 3.13
pKa2 = 4.76
pKa3 = 6.39, 6.40
1.493–1.509 (20 °C)
1.46 (150 °C)
Viscosity 6.5 cP (50% aq. sol.)
Structure
Monoclinic
Thermochemistry
Std enthalpy of
formation ΔfHo298		 −1548.8 kJ/mol
Std enthalpy of
combustion ΔcHo298		 −1960.6 kJ/mol
−1972.34 kJ/mol (monohydrate)
Standard molar
entropy So298		 252.1 J/(mol·K)
Specific heat capacity, C 226.51 J/(mol·K) (26.85 °C)
Pharmacology
A09AB04 (WHO)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 skin and eye irritant
GHS labelling:
GHS07: Exclamation mark
Warning
H319
P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
1
0
Flash point 155 °C (311 °F; 428 K)
345 °C (653 °F; 618 K)
Explosive limits 8%
Lethal dose or concentration (LD, LC):
3000 mg/kg (rats, oral)
Safety data sheet (SDS) HMDB
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Infobox references
Citric acid crystals, magnified about 200 times, seen through a polarizing filter.

Citric acid is a weak organic acid. It can be found in citrus fruits. It is used by organisms for Krebs cycle. It acts like a preservative when added to food. It is also used to add a sour (acidic) taste to foods and soft drinks. In the European Union it is known as E 330, as a food additive.

Carl Wilhelm Scheele was the first who could extract citric acid from lemons, in 1782. The substance was probably known to alchemists, perhaps with a different name. The Arabian alchemist Geber is said to have discovered citric acid in the 9th century. Citric Acid contains 6 Carbon atoms, 8 Hydrogen atoms and 7 Oxygen atoms. Its chemical formula is C6H8O7.

Main uses

References

  1. ↑ CID 22230 from PubChem
  2. 1 2 3 4 5 6 7 "citric acid". chemister.ru. Archived from the original on 2014-11-29. Retrieved 2019-02-05.
  3. 1 2 3 4 5 CID 311 from PubChem
  4. ↑ "Data for Biochemical Research". ZirChrom Separations, Inc. Retrieved January 11, 2012.
  5. ↑ "Ionization Constants of Organic Acids". Michigan State University. Retrieved January 11, 2012.
  6. 1 2 3 Citric acid in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD), http://webbook.nist.gov (retrieved 2014-06-02)

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