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| Formula | C23H32O3 |
| Molar mass | 356.506 g·mol−1 |
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THC-O-acetate (THC acetate ester,O-acetyl-THC,THC-O,AcO-THC) is theacetateester ofTHC. The termTHC-O-acetate is commonly used for two different isomers of this substance, dependent on which isomer of THC it is synthesized from. The difference between Δ8-THC and Δ9-THC is the location of the double bond within thecyclohexene ring system. In naming the esters of THC, the "-O-" is superfluous.
THC acetate ester (THC-O or THCOA) can be synthesized fromTHC,[1][2] or fromTHCA.The acetylation of THC does not change the properties of the compound to the same extent as with other acetate esters, as the parent compound (THC) is already highlylipophilic, but potency is nonetheless increased to some extent. While the acetate ester of Δ9-THC is the best studied, the acetate esters of other isomers, especiallyΔ8-THC but alsoΔ10-THC are also known, as are other esters such as THC-O-propionate,THC-O-phosphate,THC hemisuccinate, THC hemiglutarate,THC morpholinylbutyrate, THC piperidinylpropionate,[3] THC naphthoyl ester (THC-NE),[4] andTHC-VHS, as well as the hydrogenated derivativeHHC-O-acetate and the ring-expandedAbeo-HHC acetate, as well as related compounds such asTHC methylcarbonate.
It is a metabolicpro-drug, with its subjective effects being felt around 30 minutes after ingestion.[1][5][better source needed]
In a 2023 study, anecdotal claims surrounding THC-O-acetate's supposed ability to initiatepsychedelic experiences were shown to not be significant. Answers using the Mystical Experience Questionnaire (MEQ) were under the threshold of a true experience, and those who had used classical psychedelics such asLSD orpsilocybin consistently scored lower on the MEQ. When asked directly, 79% of the participants said it was either "not at all" or "a little" like a psychedelic experience.[6]
This substance was investigated as a possible non-lethal incapacitating agent as part of theEdgewood Arsenal experiments at some point between 1949 and 1975. It was noted to have about twice the capacity to produceataxia (lack of voluntary coordination of muscle movements) as didTHC when administered todogs.[7]
Author D. Gold provided synthesis instructions for this compound (calling it "THC acetate") in his 1974 bookCannabis Alchemy: Art of Modern Hashmaking, in which it is described as follows;[1]
"The effect of the acetate is more spiritual and psychedelic than that of the ordinary product. The most unique property of this material is that there is a delay of about thirty minutes before its effects are felt."
The U.S.DEA first encountered THC-O-acetate as an apparentcontrolled substance analogue of THC in 1978. It was made in an analogous manner to how aspirin (acetylsalicylic acid) was first made from willow bark extract (which is mostlysalicylic acid) in the 1800s.[8] The incident was described by Donald A. Cooper of the DEA thus:
Given the world wide ready availability of marijuana, it is somewhat difficult to produce a viable argument for making [controlled substance analogs (CsA's)] ofcannabinoids. However, ten years ago (1978) an attempt to produce CsA's fromcannabis extracts was encountered in theJacksonville, Florida area. In this case a concentrated extract of cannabis had been obtained by asoxhlet extraction. The extract had beenacetylated withacetic anhydride, and in the final step, the excess acetic anhydride removed bydistillation (reference is unretrievable due to its appearance in an underground periodical). The product contained neither quantities of nonderivatized cannabinoid nor any identifiable plant fragments. Since this single instance, no acetylated cannabinoid samples have been reported by a DEA laboratory. Therefore, this instance is assumed to represent an isolated occurrence and as such, will serve to terminate our discussion of cannabinoid CsA's.
A similar case reported in June 1995 in theUnited Kingdom.The description of that case appears to indicate the convicted manufacturer was using D. Gold's bookCannabis Alchemy as a guide.[9] THC acetate was also reported to have been found byNew Zealand police in 1995, again made by acetylation of purified cannabis extracts with acetic anhydride.[10]
With passage of the2018 United States farm bill[11] (which eased legal restrictions on the cultivation of industrialhemp), ∆8-THC-O-acetate basedvaporizers andedibles have become increasingly available in the United States and are now commonly sold atconvenience stores andgas stations.[12]
In 2022, researchers at Portland State University used ane-nail to vaporizeCBD-acetate,CBN-acetate, and THC-O-acetate (referred to simply as "THC acetate") to screen for the presence of ketene formation when vaporizing. They reported that just likeVitamin E acetate, all three of these cannabinoid acetates producedketene gas when heated.[13] For this reason, the inhalation of THC-O-acetate based products could be hazardous to health.[14]
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THC-O-acetate is a Class B drug in theUnited Kingdom.[15]
The legal status of THC-O is in dispute within the United States. Since 2023, theDrug Enforcement Administration has held the position that it is a controlled substance because "delta-9-THCO and delta-8-THCO do not occur naturally in the cannabis plant and can only be obtained synthetically".[16] In September 2024, being the first court case specifically addressing this issue, theUnited States Court of Appeals for the Fourth Circuit rejected the foregoing DEA position and "set a legal hemp standard" by holding that THC-O is legal.[17] The issue of THC-O legality has not been addressed by other circuits or by the Supreme Court and there remains a "hazy legal landscape" for hemp derived psychotropic products.[18]
On 27 June 2024, following the Ban of HHC, THC-O-Acetate was added to both the annex ofNew Psychoactive Substances Act (NpSG) and theNarcotic Drugs Act (BtMG) since it was not a naturally occurring cannabinoid.
Manufacture, sale and possession of the cannabinoid has since been fully outlawed.
From study number 7: "N-benzylacetamide formation [sign of ketene formation] was observed for all cannabinoids studied... Vaping cannabinoid acetates leads to ketene emissions. Vaping these products thus could be putting users at risk."
