Deprenyl is a racemic compound a mixture of two isomers called enantiomers. In contrast to THC, CBN has no double bond isomers nor stereoisomers. This racemic mixture can be separated into its optical isomers&colon; levoamphetamine and dextroamphetamine. Racemic adrenaline is a 1&colon;1 mixture of the two isomers of adrenaline. Chromium also has two metastable nuclear isomers. Azobenzene (and derivatives) undergo photoisomerization of trans and cis isomers. Molecular H exists a two spin isomers, i.e. compounds with two nuclear spin states. At least 21 metastable nuclear isomers exist. There are two isomers of propanol. The chemical and physical properties of xylene differ according to the respective isomers. Dronabinol does not include any other tetrahydrocannabinol (THC) isomers or any cannabidiol. It is one of the four isomers of butanol. It is one of the isomers of heptane. The more desirable isomers were selected or synthesized. It is one of several isomers of amyl alcohol.