Hexahydrocannabinol
Hexahydrocannabinol (HHC) is a hydrogenated derivative of tetrahydrocannabinol (THC). It is a naturally occurring phytocannabinoid that has rarely been identified as a trace component in Cannabis sativa, but can also be produced synthetically by hydrogenation of cannabis extracts. HHC was first synthesized in 1944 by Roger Adams using natural THC found in Cannabis sativa. HHC is a theoretical psychoactive substance with effects reportedly similar to that of THC. HHC has been openly sold at head shops and online since the early 2020s in the United States and Europe. Chemistry 
Several research groups have successfully synthesized (+)-HHC and (-)-HHC using citronellal and olivetol, as well as other related compounds. The Elucidation of HHC and related hydrogenated cannabinoid epimers were elucidated using various NMR spectroscopic techniques (ie, NOSY, COSY, 1H) and the diasteromers were isolated using LC-MS and SCFC. While similar compounds have previously been identified in cannabis, hexahydrocannabinol itself has rarely been isolated from the plant. The de Las Heras group in 2020 took lipid extract from Cannabis sativa seeds and discovered 43 cannabinoids in the crude extract; one of them being hexahydrocannabinol. It has two diastereomers at the methyl (9) position. HHC is typically made from CBD. There are no double bonds in the cyclohexyl ring like D8/D9 have—they have been removed from the structure and hydrogens have been added to the compound. Similar structural analogs of HHC have been demonstrated to bind to the CB1 receptor and produce cannabinoid effects in animals, with the 9β-HHC enantiomer being much more active than 9α-HHC. While HHC has been shown to bind to the CB1 receptor, it binds with weaker affinity than THC, which has typically been an indication that it is not as intoxicating as typical THC. Several structurally related HHC analogs have been found to be naturally occurring in Cannabis including cannabiripsol, 9α-hydroxyhexahydrocannabinol, 7-oxo-9α-hydroxyhexa-hydrocannabinol, 10α-hydroxyhexahydrocannabinol, 10aR-hydroxyhexahydrocannabinol and 1′S-hydroxycannabinol, 10α-hydroxy-Δ(9,11)-hexahydrocannabinol and 9β,10β-epoxyhexahydrocannabinol. HHC itself has been found as a degradation byproduct of THC in a similar way that Cannabinol and Delta-8-THC can be formed by the Cannabis plant from Delta-9-THC degradation. The degradation of D9-THC that forms HHC is the reduction of the double carbon bonds that would typically make up the delta isomer position on THCs structure. Delta-9-THC was discovered to partly metabolize into 11-Hydroxy-THC and alpha,10 alpha-epoxy-hexahydrocannabinol along with 1,2-epoxy-hexahydrocannabinol. Cannabidiol was discovered to partly metabolize into 9α-hydroxy-HHC and 8-hydroxy-iso-HHC inside the body. In the presence of alcohol, the methoxy or ethoxy analogs such as 9-methoxy-HHC, 10-methoxy-HHC, 9-ethoxy-HHC and 10-ethoxy-HHC can be formed. Hexahydrocannabinol should not be confused with the related compounds 9-Nor-9β-hydroxyhexahydrocannabinol (9-Nor-9Beta-HHC) or 9-Hydroxyhexahydrocannabinol (9-OH-HHC) or 11-Hydroxyhexahydrocannabinol (11-OH-HHC and 7-OH-HHC), all of which have also sometimes been referred to as "HHC". Legality 
The ANSM announced the ban (production, sale and use) of HHC and two of its derivatives, HHC-acetate (HHCO) and hexahydrocannabiphorol (HHCP), on French territory from June 13, 2023. In the United Kingdom, HHC would likely be considered illegal under the Psychoactive Substances Act 2016. Several European countries (Denmark, Belgium, Austria) also recently banned the sale of HHC. In Greece, HHC is considered legal at the moment as there is no law to restrict its usage. In Romania, HHC is also considered legal at the moment as there is no law to restrict its usage. HHC has been banned in Sweden since July 11, 2023, and in Italy since July 28, 2023. See also 
 8-Hydroxyhexahydrocannabinol
 11-Hydroxyhexahydrocannabinol
 7,8-Dihydrocannabinol
 Cannabinol
 9-Nor-9β-hydroxyhexahydrocannabinol
 9-Hydroxyhexahydrocannabinol
 H4-CBD
 Hexahydrocannabihexol
 HU-243
 Canbisol
 Delta-8-THC
 Delta-10-THC
 Delta-11-THC
 Tetrahydrocannabiphorol
 THC-O-acetate
 Delta-6-Cannabidiol

References 

Benzochromenes
Cannabinoids