Naphthenic acid (
CAS: ) (NAs)is the name for an unspecific mixture of several
cyclopentyl and
cyclohexyl carboxylic acids with molecular weight of 120 to well over 700
atomic mass units. The main fraction are carboxylic acids with a carbon backbone of 9 to 20 carbons. McKee et al. claim that "naphthenic acids (NAs) are primarily cycloaliphatic carboxylic acids with 10 to 16 carbons." Salts of naphthenic acids, which are naphthenates, are widely used as hydrophobic sources of metal ions in diverse applications.