Carboxylic acid | Structure, Properties, Formula, Uses, & Facts
carboxylic acid, any of a class of organic compounds in which a carbon (C) atom is bonded to an oxygen (O) atom by a double bond and to a hydroxyl group (―OH) by a single bond. A fourth bond links the carbon atom to a hydrogen (H) atom or to some other univalent combining group. The carboxyl (COOH) group is so-named because of the carbonyl group (C=O) and hydroxyl group.
The chief chemical characteristic of the carboxylic acids is their acidity. They are generally more acidic than other organic compounds containing hydroxyl groups but are generally weaker than the familiar mineral acids (e.g., hydrochloric acid, HCl, sulfuric acid, H2SO4, etc.).
Carboxylic acids occur widely in nature. The fatty acids are components of glycerides, which in turn are components of fat. Hydroxyl acids, such as lactic acid (found in sour-milk products) and citric acid (found in citrus fruits), and many keto acids are important metabolic products that exist in most living cells. Proteins are made up of amino acids, which also contain carboxyl groups.
Compounds in which the ―OH of the carboxyl group is replaced by certain other groups are called carboxylic acid derivatives, the most important of which are acyl halides, acid anhydrides, esters, and amides.
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