THC-OTHC-O-acetate (Δ9-tetrahydrocannabinol acetate)

(6aR,10aR)-6,6,9-trimethyl-3-pentyl-6a,7,8,10a-tetrahydro-6H-benzo[c]chromen-1-yl acetate

Aliases.THC-O-A · THC acetate · ATHC

A THC prodrug sold as "THC-O". "EVALI"-like pulmonary toxicity documented in 2021.

Updated on 1 May 2026

Level of detail

Harm-reduction warning

No characterised human dose: animal / in vitro data only. Effect profile, safety margin and acute toxicity are not documented in human clinical practice. Extremely potent compound: severe effects, seizures and deaths reported in the literature.

Identifiers

Formula: C₂₃H₃₂O₃
Molar mass: 356.50 g·mol⁻¹
CAS: 23132-17-4
PubChem CID: 198013
First described: 1949
Origin: Semi-synthesis (acetylation of THC)
InChIKey: DEWSJDIJFWQLOA-RTBURBONSA-N

In plain terms

THC-O-acetate is a modified version of THC sold in some American vape shops. Several cases of severe lung injury have been documented (close to the EVALI syndrome of 2019-2020). Best avoided.

Receptors and activity

CB1
via hydrolyse → THCPartial agonist
CB2
Partial agonist

Agonist
Partial agonist
Antagonist
Modulator
Inverse agonist

Hover over a row for the precise value (Ki, EC50…)

Subjective signature

Hover over an axis to read its definition.

Calm
50
Clarity
25
Sleep
75
Appetite
80
High
90

Editorial estimate, not clinical.

Pharmacology

THC-O-acetate (Adams, JACS 1949) is the acetate ester of Δ9-THC on the phenolic hydroxyl. A prodrug: it is hydrolysed to active THC after inhalation or ingestion, which explains the delayed onset (≈ 30-45 min) and the subjectively "stronger" effect (~ 3× THC according to users). Critical point: when vaped, the compound undergoes partial pyrolysis producing **ketene** (OC=CH₂) - a powerfully lung-irritant gas associated with the EVALI syndrome (Munger et al., Chem Res Toxicol 2023, PMID 37449873). France: captured by the **ANSM Decision of 22 May 2024** (benzo[c]chromene clause).

Key sources.