nalkyl

N-alkyl, commonly written as n-alkyl or described as a straight-chain alkyl group, refers to a substituent derived from an alkane by removing one hydrogen from a terminal carbon, resulting in an unbranched, linear chain. The prefix n- (for normal) signals the absence of branching, distinguishing these groups from iso-, sec-, and tert-alkyl isomers.

In naming, n-alkyl groups are often listed as n-propyl, n-butyl, n-pentyl, and so on, corresponding to chains of three, four, or more carbon atoms. The general formula for an n-alkyl substituent of length n is CnH2n+1. While modern IUPAC usage frequently omits the n- prefix in favor of simple straight-chain names, the term remains in use to emphasize unbranched structure, especially in older literature and in contrast to branched alkyl groups.

N-alkyl groups are widely encountered as substituents on various core molecules. When attached to nitrogen, the groups are referred to as N-alkyl, as in N-ethylmorpholine or N-methylpiperidine. They also appear on oxygen or sulfur in alkyl ethers and thioethers, and as part of larger organics such as alkylated amines, amides, and heterocycles. The physical properties of n-alkyl groups depend on chain length; increasing the chain length generally raises boiling points and hydrophobicity and can influence the solubility and reactivity of the parent compound.