nC3H7

nC3H7 refers to the normal propyl substituent, a straight-chain alkyl group with three carbon atoms and the formula C3H7. It is formed by removing one hydrogen from propane at an end of the chain, yielding the fragment -CH2-CH2-CH3 that can attach to a larger molecule as a substituent.

In chemical nomenclature, nC3H7 is one of two structural isomers that share the C3H7 formula. The other is iC3H7, the isopropyl group, which is branched and has the structure (CH3)2CH-. The prefix n- (normal) is used to distinguish the straight-chain propyl group from the branched isopropyl group.

As a substituent, the n-propyl group occurs in a wide range of organic compounds. It is found in alkyl halides such as n-propyl chloride, in esters such as propyl formate and propyl acetate, and in many other molecules where a three-carbon, linear side chain is attached to a parent structure. In systematic naming, the substituent is generally referred to simply as propyl, with the qualifier n- used when it is necessary to differentiate it from the isopropyl substituent.

Notes on interpretation: nC3H7 represents a specific connectivity and shape—three carbon atoms in a row, attached through the terminal carbon—rather than a discrete, stable molecule. The term is largely used in discussions of organic synthesis, reaction mechanisms, and chemical nomenclature to distinguish linear propyl groups from branched isomers.