Where does HHC come from and how is it produced

07. 03. 2024

How is HHC created?

HHC is found in the cannabis plant, but only in trace concentrations. Extraction from the plant would be so costly that it is not worthwhile. Even the resulting price of products with HHC would be unreasonably high. Therefore, hexahydrocannabinol is produced in the laboratory.

While the cannabinoid CBN (to which many beneficial effects on the human body are attributed) is produced as a consequence of the ageing of THC, more precisely by its gradual degradation by oxygen (oxidation), and its chemical structure differs from THC by having a higher number of double bonds, HHC is its opposite. The chemical structure of HHC and THC is very similar, the only difference being that HHC has no double bonds.

All double bonds in its structure are broken and replaced by hydrogen. With exaggeration, one could say that HHC is to THC what margarine is to butter. As with vegetable oils, the conversion of THC to HHC involves the process of hydrogenation.

Although the resulting difference is slight, not only the geometry of the molecule changes during hydrogenation, but also its binding affinity to the endocannabinoid receptors CB1 and CB2 and the pain receptor TRP. This subtle change makes the molecule much more stable. This is reflected in particular by a longer shelf life.

Because the chemical structure becomes saturated during hydrogenation, the compound is much less susceptible to oxidation and decomposition, and can withstand storage errors such as exposure to heat or UV light. Compared to other cannabinoids, HHC can withstand harsh conditions and remains effective for long periods of time.

How is HHC produced?

Producers must find ways to get to HHC without using tetrahydrocannabinol (THC), which is still banned in most countries. They therefore concentrate on legal methods so as not to break any laws. There are several ways to produce HHC. Older methods used synthetic gastric juices to convert THC into HHC, more modern ones use a terpene called citronellal or a hydrogenation process using catalysts such as palladium. An interesting alternative to avoid THC is the conversion of CBD (cannabidiol) to HHC - again using synthetic gastric juices. This produces two isomers of HHC (9α-OH-HHC and 8-OH-iso-HHC) and delta 9 THC (but this must be separated and eliminated from the final product).

Hydrogenation of THC to HHC

Theoretically, any isomer of THC - including delta 8, delta 9 and delta 10 THC - can be used to produce HHC by hydrogenation, but in practice in most countries, THC handling is not allowed by law and other methods must be used.

Most of the processes described convert THCA (tetrahydrocannabinolic acid) into HHC. THC exposed to high pressure, hydrogen atoms, and a catalyst containing inert metals such as iridium, palladium, rhodium, nickel, ruthenium, platinum, or rhenium will cause a reaction and break the double bond in the THC structure, causing the THC to lose its stability. In order for the compound to regain it, a hydrogen molecule is added (the aforementioned hydrogenation) and HHC is formed.

Chemist Mark Scialdone has recently patented a new process to create hydrogenated cannabis oil (HCO). The process has several stages:

• THCA-rich cannabis extract dissolves in ethanol
• Add palladium/carbon catalyst (10 %), mix (must be a consistent mixture)
• The mixture is exposed to hydrogen gas for several hours
• During filtration, the catalyst is removed and the solvent is eliminated by rotary evaporation

This procedure is easier than the other alternative, the hydrogenation of THC to HHC using an Adams catalyst, i.e. platinum dioxide. The latter has high environmental requirements. In the production of HHC, it can ignite on contact with oxygen in the air. This method is carried out exclusively under vacuum and with an inert gas. It should only be attempted by experienced chemists with the necessary equipment.

Conversion of CBD to HHC using artificial gastric juice

An older method outlined a procedure for the conversion of CBD to 9α-OH-HHC, 8-OH-iso-HHC and 9-tetrahydrocannabinol using artificial gastric juice. A 2007 study reported that in this type of conversion, both types of HHC showed effects strikingly similar to THC when tested in mice, but at a much lower potency.

Hydrogenation of terpenes to HHC

HHC can be obtained, as described by the researchers who used this method in 2008, from citronellal terpenes using the so-called hetero-Diels-Alder reaction or via L-carvone, using a so-called Wilkinson catalyst (tris-triphenylphosphine rhodium chloride). Both methods require the use of catalysts, high temperatures, pressure and hydrogen atoms. However, a more detailed explanation of the production process would be the subject of a separate article.

Summary

Hexahydrocannabinol is a semi-synthetic cannabinoid. It occurs naturally in cannabis plants, but in such small quantities that it is not worth extracting from the plants. It is therefore produced in the laboratory by various chemical processes, which we have tried to outline in this article. Interested in learning more about HHC? Read one of our other articles.