Naphthenic acid by a general formula CH O, where "n" indicates the carbon number and "z" specifies a homologous series. The "z" is equal to 0 for saturated, acyclic acids and increases to 2 in monocyclic naphthenic acids, to 4 in bicyclic naphthenic acids, to 6 in tricyclic acids, and to 8 in tetracyclic acids. Salts of naphthenic acids, called naphthenates, are widely used as hydrophobic sources of metal ions in diverse applications.Aluminium salts of naphthenic acid and palmitic acid were combined during World War II to produce napalm. The word "napalm" is derived from the words naphthenic acid and palmitic acid.
Non-proteinogenic amino acids a methylene group. Diaminopimelic acid is both used as a bridge in peptidoglycan and is used a precursor to lysine (via its decarboxylation). In meteorites and in prebiotic experiments (e.g. Miller–Urey experiment) many more amino acids than the twenty standard amino acids are found, several of which at higher concentrations than the standard ones: it has been conjectured that if amino acid based life were to arise in parallel elsewhere in the universe, no more than 75% of the amino acids would be in common. The most notable anomaly is the lack of aminobutyric acid. The genetic code has been