Karboksilik

Karboksilik refers to the carboxyl group or compounds that contain this functional group. The carboxyl group has the structure -COOH, consisting of a carbonyl group (C=O) attached to a hydroxyl group (−OH) on the same carbon. When R represents a hydrocarbon or other substituent, the general form is R−COOH, and such compounds are collectively known as carboxylic acids. The carboxyl group is highly characteristic for reactivity and acidity in organic chemistry.

Acidity and resonance are central to karboksilik chemistry. In aqueous solution, carboxylic acids donate a proton to form a carboxylate anion (R−COO−), which is stabilized by resonance between two oxygen atoms. This stabilization explains the relatively low pKa values typical for simple aliphatic carboxylic acids, usually around 4–5, making them weak acids compared with strong mineral acids. In their deprotonated form, carboxylates can participate in a range of salt- and ester-forming reactions.

Carboxyl-containing compounds give rise to several important derivative families, including esters, anhydrides, amides, and acyl chlorides, all derived from the carboxyl group. Common reactions include esterification with alcohols to form esters, formation of acid chlorides from carboxylic acids, dehydration to anhydrides, and reduction to primary alcohols. Decarboxylation, decarbonylation, and various condensation reactions also occur under suitable conditions.

Biology and industry heavily rely on karboksilik chemistry. Carboxyl groups are present in amino acids, fatty acids, and many metabolites, enabling protein synthesis, energy storage, and signaling. They also underpin polymer chemistry (polyesters), flavor and fragrance chemistry, and pharmaceutical synthesis. Naming typically labels the compound as a carboxylic acid when R is not hydrogen.