Trans-3-Methyl-2-hexenoic acid
Chemical compound
From Wikipedia, the free encyclopedia
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]
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| Names | |
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| Preferred IUPAC name
(2E)-3-Methylhex-2-enoic acid | |
| Other names | |
| Identifiers | |
3D model (JSmol) |
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.225.656 |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| C7H12O2 | |
| Molar mass | 128.171 g·molâ1 |
| Density | 0.97 g/cm3 |
| Melting point | â3.4 °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).
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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]
TMHA & Schizophrenia
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 RodrÃguez.[8]