DL-Tartaric acid

Chemical properties

DL-Tartaric acid is a water- and alcohol-soluble colorless crystalline solid with a characteristic acid taste and a melting temperature of 170°C(338°F). Naturally occurring tartaric acid is generally of the L-configuration (based on the absolute configuration of D-glyceric acid). The L-forms of tartrates are dextrorotatory in solution and thus are designated as L(+)-tartrates. It is also known as dihydroxy succinic acid. Tartaric acid is used as a chemical intermediate and a sequestrant,as well as in tanning, effervescent beverages, baking powder, ceramics, photography, textile processing,mirror silvering,and metal coloring.

Occurrence

d-Tartaric acid occurs in many fruits or other parts of the plant, free or combined with potassium, calcium or magnesium. It is also reported found in raw, lean fish, white wine, red wine and port wine.

The Uses of DL-Tartaric acid

DL-Tartaric acid is a synergist for antioxidants, emulsifier, sequestrant and flavoring agent. It is also added with citric acid to prepare effervescent salts, thereby enhancing the taste of oral medications. It is also utilized in pigments, processing aids, ink, toner and colorant products. It acts as a chelating agent in metal and farming industries. Further, it is used as a lubricant and grease. It is mixed with sodium bicarbonate and used as a leavening agent in food preparation. In the pharmaceutical industry, it is used in preparing tartar emetic, which is used in cough syrup as an expectorant. It can be used in the Debus–Radziszewski reaction as a weak acid for synthesising imidazolium ionic liquid. As an additive in electrochemical deposition technique for synthesising bismuth thin films to be used as X-ray absorbers. As a complexing agent for synthesising nano-crystalline indium tin oxide (ITO) powder. As a dopant for synthesising polyaniline nanofibers and nanotubes by oxidation polymerization.

Preparation

The tartrates used in commerce are obtained as a by-product of wine manufacture and have the L(+) configuration. Produced from argols or wine lees, which are formed in the manufacture of wine by extracting the potassium acid tartrate, transforming this into the calcium salt and then acidifying with dilute sulfuric acid; also by oxidation of d-glucose with nitric acid. The dl-tartaric acid is obtained by boiling the d-tartaric acid with an aqueous solution of NaOH or by oxidation of fumaric acid. The l- and the meso-tartaric acid are also known, but are less important.

Definition

DL-Tartaric acid is a tetraric acid that is butanedioic acid substituted by hydroxy groups at positions 2 and 3. It is a conjugate acid of a 3-carboxy-2,3-dihydroxypropanoate. It has a role as a human xenobiotic metabolite and a plant metabolite.