karboxylatgruppens

The carboxylate group, often represented as RCOO-, is the deprotonated form of a carboxylic acid. It consists of a carbonyl group (C=O) and an adjacent alkoxide group (C-O-). This anionic functional group plays a crucial role in organic chemistry and biochemistry. The negative charge is delocalized across both oxygen atoms due to resonance, making the carboxylate group relatively stable.

Carboxylate groups are commonly found in salts of carboxylic acids, such as sodium acetate. In aqueous solutions, carboxylic acids are weak acids and readily deprotonate to form carboxylate ions and protons. The acidity of carboxylic acids, quantified by their pKa values, is influenced by the nature of the R group attached. Electron-withdrawing groups generally increase acidity, leading to a higher proportion of the carboxylate form at a given pH.

In biological systems, carboxylate groups are fundamental. Amino acids, for example, possess a carboxylate group (except for proline, which has a secondary amine). This group is essential for the formation of peptide bonds and contributes to the overall charge and solubility of proteins. Fatty acids also contain a long hydrocarbon chain with a terminal carboxylate group, making them amphipathic molecules. Furthermore, many important biological molecules, like ATP, exist and function in their deprotonated carboxylate forms under physiological conditions.