Hexadecyl

Hexadecyl is a univalent alkyl substituent consisting of 16 carbon atoms, commonly represented as C16H33− when considered as a substituent. It is derived from hexadecane by removing a hydrogen atom; in many chemical contexts the straight-chain form is referred to as n-hexadecyl, whereas "hexadecyl" alone may denote the generic 16-carbon chain.

Chemically, hexadecyl is a saturated, nonpolar hydrocarbon chain. As such it is insoluble in water and soluble in many organic solvents. It behaves as a typical alkyl group in reactions, enabling formation of hexadecyl halides, hexadecyl esters, ether derivatives, and related surrogates.

Hexadecyl is widely encountered in industry, especially in cosmetics and surfactants. The long C16 chain is a common feature of cetyl esters and cetyl alcohol, and the term cetyl is often used in commercial ingredient names to denote the hexadecyl moiety. Surfactants such as cetyltrimethylammonium chloride and other hexadecyl-containing quaternary ammonium salts rely on the 16-carbon chain to provide hydrophobic character and surface activity.

Nomenclature and variants: The "n-" prefix specifies the unbranched chain, i.e., n-hexadecyl. Branched isomers would have different names (for example isohexadecyl). The hexadecyl group forms a wide range of derivatives, including hexadecyl chloride, hexadecyl sulfate, and hexadecyl esters such as hexadecyl palmitate used as cosmetic emollients.