THC acetate ester (THC-O-acetat; THC acetate) is the acetate ester of THC. It has been reported to be approximately two times as potent as THC to approximately three times as potent as THC with a unique psychedelic high described as follows.
"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."
THC acetate ester can reportedly be synthesized from THC or from THCA. 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 highly lipophilic, but potency is nonetheless increased to some extent. This derivative of THC is notable in that it is one of the few analogues of THC to have been encountered as a recreational drug sold and used in a highly pure smokable form.
THC acetate ester was investigated as a possible non-lethal incapacitating agent as part of the Edgewood Arsenal experiments at some point between 1949 and 1975. It was noted to have about twice the capacity to produce ataxia (lack of voluntary coordination of muscle movements) as did THC when administered to dogs.
Author D. Gold provided synthesis instructions for this compound (calling it "THC acetate") in his 1974 book Cannabis Alchemy: Art of Modern Hashmaking.
The U.S. DEA first encountered THC-O-acetate as an apparent controlled substance analogue of THC in 1978. It was apparently made in an analogous manner to how heroin is made from morphine. 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)] of cannabinoids. However, ten years ago (1978) an attempt to produce CsA's from cannabis extracts was encountered in the Jacksonville, Florida area. In this case a concentrated extract of cannabis had been obtained by a soxhlet extraction. The extract had been acetylated with acetic anhydride, and in the final step, the excess acetic anhydride removed by distillation (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 acetalaced 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 was reported in June 1995 in the United Kingdom, and THC-O-acetate was ruled to be a Class A drug in that case. The description of that case appears to indicate the convicted manufacturer was using D. Gold's book Cannabis Alchemy as a guide.
THC-O-acetate is not scheduled at the federal level in the United States, but it could be considered an analog of THC, in which case purchase, sale, or possession could be prosecuted under the Federal Analog Act.