Clinical data
ATC code none
Legal status
Legal status
CAS Number 117-51-1 YesY
PubChem (CID) 8334
ChemSpider 8031 YesY
UNII 450N174F9W YesY
Chemical and physical data
Formula C22H32O2
Molar mass 328.488 g/mol
3D model (Jmol) Interactive image

Parahexyl (Synhexyl, n-hexyl-Δ3THC) is a synthetic homologue of THC, which was invented in 1949 during attempts to elucidate the structure of Δ9-THC, one of the active components of cannabis.[1][2]

Parahexyl is similar in both structure and activity to THC, differing only in the position of one double bond, and the lengthening of the 3-pentyl chain by one CH2 group to n-hexyl.[3] Parahexyl produces classic cannabis agonist effects in animals. It has a somewhat higher oral bioavailability than THC itself but is otherwise very similar.[4] Presumably it acts as a CB1 agonist in the same way as THC but as there has been no research published using Parahexyl since the discovery of the CB1 receptor this has not been definitively confirmed.

Parahexyl was made illegal under UN convention in 1982 on the basis of its structural similarity and similar effects profile to THC, despite never having had any recorded instances of recreational use by humans or illicit sale. Parahexyl was placed into the most restrictive Schedule 1 as a compound with no medical use.


7 double bond isomers of parahexyl and their 30 stereoisomers
Dibenzopyran numbering Monoterpenoid numbering Number of stereoisomers Natural occurrence Convention on Psychotropic Substances Schedule
Short name Chiral centers Full name Short name Chiral centers
Δ6a,7-parahexyl 9 and 10a 3-hexyl-8,9,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-1-ol Δ4-parahexyl 1 and 3 4 No unscheduled
Δ7-parahexyl 6a, 9 and 10a 3-hexyl-6a,9,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-1-ol Δ5-parahexyl 1, 3 and 4 8 No unscheduled
Δ8-parahexyl 6a and 10a 3-hexyl-6a,7,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-1-ol Δ6-parahexyl 3 and 4 4 No unscheduled
Δ9,11-parahexyl 6a and 10a 3-hexyl-6a,7,8,9,10,10a-hexahydro-6,6-dimethyl-9-methylene-6H-dibenzo[b,d]pyran-1-ol Δ1,7-parahexyl 3 and 4 4 No unscheduled
Δ9-parahexyl 6a and 10a 3-hexyl-6a,7,8,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-1-ol Δ1-parahexyl 3 and 4 4 No unscheduled
Δ10-parahexyl 6a and 9 3-hexyl-6a,7,8,9-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-1-ol Δ2-parahexyl 1 and 4 4 No unscheduled
Δ6a,10a-parahexyl 9 3-hexyl-7,8,9,10-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-1-ol Δ3-parahexyl 1 2 No Schedule I

Note that 6H-dibenzo[b,d]pyran-1-ol is the same as 6H-benzo[c]chromen-1-ol.

See also


  1. Adams R, Harfenist M, Loewe S (1949). "New Analogs of Tetrahydrocannabinol. XIX". J. Am. Chem. Soc. 71 (5): 1624–1628. doi:10.1021/ja01173a023.
  2. Ask Dr. Shulgin Online March 7, 2001
  3. Ono M, Shimamine M, Takahashi K, Inoue T (1974). "[Studies on hallucinogens. VII Synthesis of parahexyl]". Eisei Shikenjo hōkoku. Bulletin of National Institute of Hygienic Sciences (in Japanese). 49 (92): 46–50. PMID 4477495.
  4. Fairchild MD, Jenden DJ, Mickey MR, Yale C (1980). "EEG effects of hallucinogens and cannabinoids using sleep-waking behavior as baseline". Pharmacol. Biochem. Behav. 12 (1): 99–105. doi:10.1016/0091-3057(80)90422-0. PMID 6102770.
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