Trans-3-Methyl-2-hexenoic acid

trans-3-Methyl-2-hexenoic acid

Names
Preferred IUPAC name (2E)-3-Methylhex-2-enoic acid
Other names E3M2H 3M2H TMHA MHA C7:2 (Lipid numbers)
Identifiers
CAS Number	27960-21-0  Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:144845
ChemSpider	4947706  Y
ECHA InfoCard	100.225.656
PubChem CID	6443739
UNII	Q98FU4WJ65  Y
CompTox Dashboard (EPA)	DTXSID701020850
InChI InChI=1S/C7H12O2/c1-3-4-6(2)5-7(8)9/h5H,3-4H2,1-2H3,(H,8,9)/b6-5+ Y Key: NTWSIWWJPQHFTO-AATRIKPKSA-N Y InChI=1S/C7H12O2/c1-3-4-6(2)5-7(8)9/h5H,3-4H2,1-2H3,(H,8,9)/b6-5+ Key: NTWSIWWJPQHFTO-AATRIKPKSA-N
SMILES CCCC(=CC(=O)O)C
Properties
Chemical formula	C7H12O2
Molar mass	128.171 g·mol−1
Density	0.97 g/cm3
Melting point	−3.4 °C (25.9 °F; 269.8 K)
Boiling point	225.2 °C (437.4 °F; 498.3 K)
Hazards
Flash point	132 °C (270 °F; 405 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N (what is  YN ?) Infobox references

trans-3-Methyl-2-hexenoic acid (TMHA) is an unsaturated short-chain fatty acid that occurs in sweat secreted by the axillary (underarm) apocrine glands of Caucasians and some Asians. ^[1]

Hexanoic acids such as TMHA have a hircine odor. Of the fatty acids contributing to Caucasian men's underarm odor, TMHA has the most prominent odor. ^[2]

Schizophrenia odor

It has long been claimed that schizophrenia patients exhibit a particular peculiar body odor, and it has been postulated the odor may be caused by underlying metabolic abnormalities associated with the condition, among other factors. ^{[3] [4]} Initial studies identified the causal component as TMHA, ^[5] however, subsequent studies failed to reproduce such results, ^{[3] [6]} with subsequent researchers suggesting the initial research may have had misidentified impurities in samples as TMHA due to poor methodology. ^[3] However, a 2007 study found schizophrenia patients to have reduced olfactory sensitivity to TMHA, possibly indicating sensory habituation; the decreased ability to smell the substance due to the presence of the substance as a constant component of subjects' own sweat and body odor. Furthermore, the researchers noted a positive association between reduced ability to smell TMHA and greater severity of disorganised and negative symptoms. ^[4]

An allusion to TMHA and its purported link to the smell of the mentally ill is made in the 1996 David Foster Wallace novel, Infinite Jest , ^[7] the 1988 Thomas Harris novel The Silence of the Lambs ,^{[ citation needed ]} and the 2025 comic book Absolute Martian Manhunter #2 by Deniz Camp and Javier Rodríguez. ^[8]

References

1. Akutsu, T.; Sekiguchi, K; Ohmori, T; Sakurada, K (2006). "Individual Comparisons of the Levels of (E)-3-Methyl-2-Hexenoic Acid, an Axillary Odor–Related Compound, in Japanese". Chemical Senses. 31 (6): 557–63. doi: 10.1093/chemse/bjj060 . PMID   16690870.
2. Sun, Lixing; Williams, Wendy A.; Avalos, Corinna (2005). Human sweaty smell does not affect women's menstrual cycle. pp. 308–312. doi:10.1007/0-387-25160-X_34. ISBN   978-0-387-25159-2.
3. Perry, Thomas L.; Melançon, Serge B.; Lesk, Donna; Hansen, Shirley (December 1970). "Failure to detect trans-3-methyl-2-hexenoic acid in the sweat of schizophrenic patients". Clinica Chimica Acta. 30 (3): 721–725. doi:10.1016/0009-8981(70)90266-4. ISSN   0009-8981. PMID   5493894.
4. Brewer, Warrick J.; Wood, Stephen J.; Pantelis, Christos; Berger, Gregor E.; Copolov, David L.; McGorry, Patrick D. (January 2007). "Olfactory sensitivity through the course of psychosis: Relationships to olfactory identification, symptomatology and the schizophrenia odour". Psychiatry Research. 149 (1–3): 97–104. doi:10.1016/j.psychres.2006.03.005. ISSN   0165-1781. PMID   17156856. S2CID   37511465.
5. Smith, K.; Thompson, G. F.; Koster, H. D. (1969-10-17). "Sweat in schizophrenic patients: identification of the odorous substance". Science. 166 (3903): 398–399. Bibcode:1969Sci...166..398S. doi:10.1126/science.166.3903.398. ISSN   0036-8075. PMID   5818039. S2CID   21377002.
6. Gordon, S. G.; Smith, K.; Rabinowitz, J. L.; Vagelos, P. R. (July 1973). "Studies of trans-3-methyl-2-hexenoic acid in normal and schizophrenic humans". Journal of Lipid Research. 14 (4): 495–503. doi: 10.1016/S0022-2275(20)36883-8 . ISSN   0022-2275. PMID   4715330.
7. Foster., Wallace David (1996). Infinite jest: a novel (1 ed.). Boston: Little, Brown and Co. pp. 748–749. ISBN   978-0-316-07385-1. OCLC   669069481.
8. Camp, Deniz  ( w ), Rodríguez, Javier  ( a ), Otsmane-Elhaou, Hassan  ( let ). Absolute Martian Manhunter,vol. 1,no. 2,p. 15(April 23, 2025).Burbank, California:DC Comics."His madness is a man-shaped wildfire, and in the smoke of it I smell strains of trans-3-Methyl-2-hexenoic acid and a family history of schizophrenia."