HHC

HHC (hexahydrocannabinol, C₂₁H₃₂O₂) is hydrogenated THC: the C9–C10 double bond of Δ⁹-THC is reduced, yielding a saturated cyclohexane ring and greater oxidative stability. Small quantities occur naturally in cannabis pollen (Loewe, 1944, Journal of the American Pharmaceutical Association 33:47), but commercial HHC is almost entirely semi-synthetic, produced by catalytic hydrogenation of Δ⁸- or Δ⁹-THC (platinum, palladium, or nickel catalysts). Hydrogenation creates two diastereomers at C9: 9(R)-HHC (often written 9α) is the more CB1-active isomer, while 9(S)-HHC (9β) is substantially less active. Most commercial product contains a mixture, often ~2:1 in favor of the active isomer, driving variable labeled-vs-actual potency. HHC binds CB1 and CB2 with lower affinity than Δ⁹-THC but produces THC-like subjective effects in self-report surveys. Regulatory status in the US and EU has tightened rapidly since 2023. ⚠️ Limited toxicology data. → See also: THC, Synthetic cannabinoid, Delta-8 THC.