Tartaric Acid

Cas Number


Other Names

Tartaric acid

2,3-Dihydroxysuccinic acid

Threaric acid

Racemic acid

Uvic acid

Paratartaric acid

The formula



Tartaric acid is a white crystalline organic acid that occurs naturally in many plants, most notably in grapes. 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 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.

Physical and Chemical Properties
Molar mass 150.087 g/mol
Appearance white powder
Density 1.79 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)
Solubility in water 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
Magnetic susceptibility (χ) -67.5·10−6 cm3/mol