Parahexyl

Parahexyl, also known as synhexyl, is a synthetic homologue of tetrahydrocannabinol (THC) which was invented in 1941 during attempts to elucidate the structure of Δ⁹-THC, one of the active components of cannabis.

Parahexyl is similar in both structure and activity to THC, differing only in the position of one double bond and the lengthening of the 3-pentyl chain by one CH₂ group to n-hexyl. Parahexyl produces effects typical of other cannabinoid receptor agonists in animals. It has a somewhat higher oral bioavailability than THC itself but is otherwise very similar. Presumably, it acts as a CB₁ receptor agonist in the same way as THC, but as there has been no research published using parahexyl since the discovery of the CB₁ receptor, this has not been definitively confirmed.

Parahexyl was occasionally used as an anxiolytic in the mid-20th century, the dosage ranging from 5 mg to 90 mg.

Parahexyl was made illegal under UN convention in 1971 on the basis of its structural similarity and similar effects profile to THC. Parahexyl was placed into the most restrictive Schedule I as a compound with no medical use.