L(+)-Potassium hydrogen tartrate
[CAS# 868-14-4]

Identification

• Classification: Pharmaceutical intermediate >> Heterocyclic compound intermediate >> Pyridazine
• Name: L(+)-Potassium hydrogen tartrate
• Synonyms: Potassium hydrogen tartrate; Potassium bitartrate; Tartaric acid monopotassium salt
• Molecular Formula: C₄H₅KO₆
• Molecular Weight: 188.17
• CAS Registry Number: 868-14-4 (35-04-1)
• EC Number: 212-769-1
• SMILES: C(C(C(=O)[O-])O)(C(=O)O)O.[K+]

Properties

• Density: 1.954
• Melting point: 210-212 °C
• Flash point: 210 °C
• alpha: 32.5 ° (c=10, 1N NaOH)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319-H335
• Safety Statements: P261-P305+P351+P338

Discovery and Applications

Potassium L(+)-tartrate dates back to ancient winemaking. The compound forms as a crystalline residue in wine barrels during the fermentation process. Also known as "lees," this residue was first recognized for its usefulness in the Middle Ages. However, its isolation and purification as a unique chemical only made significant progress in the 18th century. In 1769, Swedish chemist Carl Wilhelm Scheele isolated tartaric acid from these wine residues. Subsequent research identified various tartrate salts, including potassium bitartrate. Its L(+) form is a naturally occurring isomer derived from the natural enantiomer of tartaric acid, which is compatible with human biological systems and ideal for culinary and pharmaceutical uses.

Potassium L(+)-tartrate (C4H5KO6) or potassium bitartrate is a white crystalline powder with a slightly sour taste. It is soluble in water, and its ability to stabilize and act as a buffer stems from its acidic and potassium-rich composition. These properties make it valuable in many applications.

In the kitchen, potassium L(+)-tartrate is essential in baking. In combination with baking soda, it acts as a leavening agent, producing carbon dioxide gas, which helps doughs and batters rise. This reaction is essential for creating a light, fluffy texture in baked goods such as cakes and cookies.

Potassium bitartrate is also used to stabilize egg whites and whipped cream. When added to egg whites, it increases their heat resistance and volume, making them ideal for making meringues and soufflés. In whipped cream, it prevents the formation of large ice crystals, maintaining a smooth texture. Another culinary application is in confectionery, where it helps prevent syrups from crystallizing, ensuring that candies and frostings have a smooth, shiny surface.

Potassium L(+)-tartrate is used in pharmaceuticals to adjust the pH of medications. Its buffering capacity helps maintain the stability and effectiveness of a variety of medications, especially in formulations where precise control of pH is critical.

In industrial settings, potassium L(+)-tartrate acts as a chelating agent, binding to metal ions and preventing adverse reactions. This property is useful in processes where metal contamination can affect product quality, such as in the production of adhesives and detergents.

Potassium(+)-tartrate is also used in electroplating to help deposit an even layer of metal on a surface, enhancing the performance and appearance of the finished product.

In traditional medicine, potassium bitartrate is used as a mild laxative and antacid. Its potassium content can help offset low potassium levels, but such use should be done with caution and under the advice of a physician.

Potassium(+)-tartrate can be used as a mild abrasive and stain remover. It is effective in cleaning metal surfaces and can be combined with other substances, such as lemon juice, to remove stains from cookware and countertops.

References

2023. Scientific and technological research on the use of wine lees. Food Production, Processing and Nutrition, 5(1).
DOI: 10.1186/s43014-023-00137-0

2023. Effect of Whole Cluster Fermentation on Phenolics in Cold-Hardy Hybrid Wines. Food and Bioprocess Technology, 16(8).
DOI: 10.1007/s11947-023-03010-7

2023. Effects of Pichia kluyveri on the flavor characteristics of wine by co-fermentation with Saccharomyces cerevisiae. European Food Research and Technology, 249(6).
DOI: 10.1007/s00217-023-04224-x