Tartrate

Tartrate refers to the salts and esters of tartaric acid, a naturally occurring dicarboxylic acid found in grapes and other plants. Tartaric acid can lose protons to form tartrate, which then combines with metals to form tartrate salts or with alcohols to form tartrate esters. These salts and esters are used in chemistry, food, and industry.

In nature and industry, tartrates are notable in winemaking. Potassium bitartrate, also known as cream of tartar, precipitates from wine as it ages and can be collected as a crystalline substance. Tartrate crystals may form in wines and come out of solution during cold conditions, a phenomenon known as cold stability. Tartrate salts are also used in various culinary and laboratory applications.

Common tartrate salts include potassium bitartrate (cream of tartar), Rochelle salt (potassium sodium tartrate tetrahydrate), and ammonium tartrate. Tartrate esters, such as diethyl tartrate, are important reagents in organic synthesis and exist in enantiomeric forms used as chiral auxiliaries or ligands, notably in Sharpless asymmetric epoxidation.

Applications extend beyond chemistry and food. In cooking, cream of tartar stabilizes egg whites and prevents sugar crystallization in certain recipes, while contributing to leavening when used with baking soda. In laboratory settings, tartrates provide convenient sources of tartrate ligands and serve as tools in stereochemical and catalytic studies. Tartrates are generally regarded as safe for common culinary uses, though crystals can be gritty and may require dissolution or filtration in some applications.