Tartaric acid

Tartaric acid[1]
Tartaric acid.svg
Preferred IUPAC name
2,3-Dihydroxybutanedioic acid
Other names
Tartaric acid
2,3-Dihydroxysuccinic acid
Threaric acid
Racemic acid
Uvic acid
Paratartaric acid
3D model (JSmol)
ECHA InfoCard100.121.903
C4H6O6 (Basic formula)
HO2CCH(OH)CH(OH)CO2H (Structural formula)
Molar mass150.087 g/mol
AppearanceWhite powder
Density1.79 g/mL (H2O)
Melting point 171 to 174 °C (340 to 345 °F; 444 to 447 K) (L or D-tartaric; pure)
206 °C (DL, racemic)
165–166 °C (meso-anhydrous)
146–148 °C (meso-hydrous)[3]
  • 1.33 kg/L (L or D-tartaric)
  • 0.21 kg/L (DL, racemic)
  • 1.25 kg/L ("meso")
Acidity (pKa)L(+) 25 °C :
pKa1= 2.89, pKa2= 4.40
meso 25 °C:
pKa1= 3.22, pKa2= 4.85


Conjugate baseBitartrate
−67.5·10−6 cm3/mol
R-phrases (outdated)R36
Related compounds
Other cations
Monosodium tartrate
Disodium tartrate
Monopotassium tartrate
Dipotassium tartrate
Butyric acid
Succinic acid
Dimercaptosuccinic acid
Malic acid
Maleic acid
Fumaric acid
Related compounds
Cichoric acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes, but also in bananas, tamarinds, and citrus.[4] Its salt, potassium bitartrate, commonly known as cream of tartar, develops naturally in the process of winemaking. It is commonly mixed with sodium bicarbonate and is sold as baking powder used as a leavening agent in food preparation. The acid itself is added to foods as an antioxidant E334 and to impart its distinctive sour taste.

Tartaric is an alpha-hydroxy-carboxylic acid, is diprotic and aldaric in acid characteristics, and is a dihydroxyl derivative of succinic acid.


Tartaric acid has been known to winemakers for centuries. Written record of its extraction from wine-making residues was made circa 800 AD, by the alchemist Jābir ibn Hayyān.[5] The chemical process for extraction was developed in 1769 by the Swedish chemist Carl Wilhelm Scheele.[6]

Tartaric acid played an important role in the discovery of chemical chirality. This property of tartaric acid was first observed in 1832 by Jean Baptiste Biot, who observed its ability to rotate polarized light.[7][8] Louis Pasteur continued this research in 1847 by investigating the shapes of sodium ammonium tartrate crystals, which he found to be chiral. By manually sorting the differently shaped crystals, Pasteur was the first to produce a pure sample of levotartaric acid.[9][10][11][12][13]