An isopentyl group is a subset of the generic pentyl group. The free radical pentyl was studied by Pacansky and Gutierrez in 1983. Replacement of the piperidinyl by pentyl or a heptyl chain gave the compounds agonistic properties. For instance, the substituents methyl (-CH) and pentyl (-CH). It is referred to as pentyl valerate or amyl pentanoate using classical nomenclature. Notice the pentyl group substituted onto the nitrogen atom of the indole ring. In THC, CBD, and CBN, this side-chain is a pentyl (5-carbon) chain. Ethyl valerate and pentyl valerate are used as food additives because of their fruity flavors. Notice the 5 membered pentyl chain on the 3-position of the indene ring. In older literature, the common non-systematic name amyl was often used for the pentyl group. The ester formed from 1-pentanol and butyric acid is pentyl butyrate, which smells like apricot. Notice the pentyl group on the nitrogen atom of the pyrrole ring of the molecule. In the most common homologue, the pentyl chain is replaced with a propyl (3-carbon) chain. Major metabolic reactions included pentyl hydroxylation, hydroxylation followed by oxidation (ketone formation), and glucuronidation. In organic chemistry, pentyl is a five-carbon alkyl functional group (substituent) with chemical formula -CH.