CarboxylOH

CarboxylOH, commonly referred to as the carboxyl group, is a functional group in organic chemistry characterized by the chemical formula –COOH. It consists of a carbonyl group (C=O) bonded to a hydroxyl group (–OH) on the same carbon atom, rendering it a versatile and highly reactive moiety. The structure allows the carboxyl group to undergo various acid–base reactions, with the ability to donate a proton from the hydroxyl hydrogen to form carboxylate anions (–COO⁻). This property gives carboxylic acids a characteristic acidity, typically ranging from pKa values of 2 to 5, depending on the electronic environment of the substituents attached to the carbon skeleton.

In biochemistry, carboxyl groups are found in a multitude of fundamental biomolecules. They are integral to the side chains of acidic amino acids such as aspartic acid and glutamic acid, and they constitute the core functional groups of vitamins like ascorbic acid and vitamin B₁₂, as well as important metabolic intermediates such as citric acid, acetic acid, and lactic acid. The covalent attachment of a carboxyl group to sugars or lipids can significantly alter their solubility and reactivity, and in polymers, carboxyl functionalities can serve as sites for crosslinking or chain-end modifications.

CarboxylOH groups participate in a variety of chemical transformations. Esterification, where the hydroxyl hydrogen is substituted by an alkyl or aryl group, yields esters. In amidation, the hydroxyl group is replaced with an amide linkage, forming amides common in peptide bonds. Reduction processes, such as with lithium aluminium hydride, convert carboxyl groups into primary alcohols. These reactions underpin synthetic strategies in pharmaceuticals, materials science, and agrochemicals, making the carboxyl group one of the most frequently exploited functional groups in organic synthesis.

The presence of CarboxylOH groups in both naturally occurring and synthetic compounds underscores their importance in chemistry and related fields. Their ability to form hydrogen bonds, participate in acid–base equilibria, and engage in covalent modifications makes them pivotal in understanding molecular behavior from a mechanistic perspective to practical applications in industry.