The Ghost in the Bottle — How CBD Turns Itself Into THC, HHC and CBN

Human stomach acid sits somewhere between pH 1.5 and pH 3.5. That is not a coincidence for this article — it is close to the exact range a team of South Korean researchers chose when they set out to answer a question the CBD industry has mostly avoided asking directly: what actually happens to cannabidiol when it sits in an acidic environment for a while? Not in a clandestine lab with a hydrogen tank and a palladium catalyst, but in the ordinary acidic conditions a CBD product might encounter — a citrus-flavoured gummy, a vinegar-preserved tincture, a bottle that got warm in transit, or simply a stomach after being swallowed.

The answer, published in the Journal of Food and Drug Analysis in 2023 by a team from Kyung Hee University, Kookmin University and Woosuk University, is not reassuring. Isolated CBD dissolved in ethanol and mildly acidified with hydrochloric acid began converting — on its own, at temperatures as low as 30°C — into a small chemistry set of psychoactive compounds. Delta-9 THC. Delta-8 and delta-10 THC. Cannabinol. Cannabichromene. And a family of alkoxy-substituted compounds the researchers themselves describe as HHC analogs.

Why CBD to HHC Conversion Matters for Cannabis Processors

We have written before about hexahydrocannabinol and the vape-shop version of the "legal high" argument — a semi-synthetic cannabinoid made by hydrogenating CBD under a metal catalyst and high pressure, deliberately, in an industrial setting. This study asks a different and in some ways more unsettling question: does CBD need a lab to start moving in that direction at all? The double bond that commercial HHC producers saturate with hydrogen gas turns out to be reactive enough that it will also react with whatever solvent it happens to be sitting in, given nothing more than acid and time. No catalyst required. No intent required.

The Acid Degradation Pathway: How CBD Converts to THC and HHC

The transformation is not random. It follows a small number of well-defined chemical pathways, all starting from the same first step: acid activates the double bond in CBD's side chain, forming a positively charged carbon centre that is desperate to react with something.

The pH Threshold: At What Acidity Does CBD Degrade?

Of everything the study measured, acidity turned out to matter more than heat or time. At pH 5.0, essentially no degradation occurred, regardless of how hot or how long the reaction ran. At pH 3.5, degradation became measurable within five to ten hours. At pH 2.0, it was fast: roughly ninety-five percent of the CBD was gone within five hours at 70°C, and none remained detectable by the ten-hour mark. Delta-9 THC itself followed the same arc — it rose quickly, peaked around the five-hour point, and then began falling as it was further converted into ethoxy-HHCs, isomerised THCs and other products. A product tested once, early, would show clean CBD. Tested again later in its shelf life, it might not.

8 Psychoactive By-Products Formed from CBD Acid Degradation

At the most acidic, hottest, longest condition tested — pH 2.0, 70°C, twenty-four hours — the researchers identified eight distinct transformed products in a single reaction. Cannabichromene, delta-9 THC, and two ethoxy-HHC isomers were the major components. Delta-8 THC, delta-10 THC, cannabinol and a hydroxy-HHC derivative showed up as minor components. Across the full study, including parallel experiments on whole cannabis extract, the team catalogued sixteen cannabinoids in total — among them eight compounds structurally classed as THC isomers, all considered potentially psychoactive, alongside CBN and the methoxy- and ethoxy-HHC analogs.

Some of these were confirmed against authentic reference standards — THC isomers, CBC and CBN all matched known compounds exactly on retention time and mass spectrum. The HHC analogs and the hydroxy-HHC derivative were identified more tentatively, by matching chromatographic behaviour and interpreting their fragmentation patterns, because no commercial reference standards exist for them yet. That is itself a telling detail: these are compounds well-resourced analytical labs cannot buy a certified standard for, let alone the average processor trying to test a finished product.

Best Practices for CBD Processing and Storage to Prevent Degradation

None of this is abstract chemistry for growers who stop at flower. But for anyone extracting, formulating, bottling or storing CBD products — which is an increasing share of the South African cannabis economy — this study has direct, practical teeth.

What the Study Does Not Resolve

The authors are candid about the limits of their own data. The ethoxy-HHC, methoxy-HHC and hydroxy-HHC identifications are tentative — inferred from retention behaviour and mass spectral interpretation rather than confirmed against authentic standards, because none exist commercially for these specific compounds. The psychoactivity of the ethoxy-HHC derivatives specifically is, in the authors' own words, still controversial and not fully studied; their pharmacological profile has not been directly tested in the way delta-9 THC's has.

The experiments also used isolated CBD at fairly high purity, dissolved in pure ethanol or methanol — a simplified system, not a direct stand-in for the complex matrix of a real gummy, beverage or emulsified tincture, where other ingredients could accelerate, slow, or otherwise change these reactions. And while the pH and temperature ranges tested were chosen to be systematic, they are a controlled screen, not a simulation of any one product's actual storage history. What the study firmly establishes is that the chemistry is real and follows predictable, mechanistically explainable pathways — not whether any specific commercial CBD product on a shelf right now has crossed into psychoactive territory.

What it does put to rest is the idea that CBD is chemically inert once it leaves the plant. Given the wrong pH, it very much is not — and the compounds it becomes are not obscure novelties. They are the same THC isomers, the same CBN, and structural cousins of the same HHC that the market has spent the last few years arguing about.