As I noted below on the last ‘What Am I?’ post, I was following a paper in J Chem Ed with the chemical composition of Maple Syrup. This paper was a summary of other analytical chemistry papers. When I was sketching out the components (generally I look up the Smiles or InChI strings and generate the structures in Symyx draw from them rather than trying to draw them all myself), I noticed that one was 2-ethyl hexanol. The paper was by Ball, http://pubs.acs.org/doi/abs/10.1021/ed084p1647.
Now, as this is the 23rd ‘What Am I?’, I’m starting to have a better appreciation for what looks right in terms of certain substances. 2-ethyl hexanol didn’t look right for Maple Syrup, particularly not in the context of table 4 in the paper:
Screenshot of partial table 4 from http://pubs.acs.org/doi/abs/10.1021/ed084p1647 taken without permission.
Now, as you can see there are lots of compounds that sound similar, such as the collection of pyrazine derivatives and the compounds based around benzene rings. 2-ethyl-1-hexanol, when I came to draw it, looked very different.
I usually scan the Wikipedia entry for the molecule, particularly for such complex substances, looking for the compounds that will give the greatest hint towards the identity. Some of the compounds that I did put in the post below clearly stated in the Wikipedia entry that they were obtained from natural sources such as maple trees. But this one doesn’t. http://en.wikipedia.org/wiki/2-Ethylhexanol In fact, it says:
“It is produced on a massive scale as a precursor to plasticizers, some of which are controversial as potential endocrine disruptors.”
This is one of the common plasticisers, Bis(2-ethylhexyl)phthalate, used in PVC and other things. Apparently it is metabolised to mono-ethylhexylphthalate, which would seem to imply that 2-ethyl-1-hexanol might be produced through simple ester cleavage.
I don’t have access to the original analytical chem papers from which the data in table 4 came, but I’m wondering if the presence of this compound was from degraded plasticiser in either labware or a storage bottle (or some plastic during the production process) rather than a naturally occurring substance. On the other hand, it is apparently found in some fruit (source: http://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+1118) .
As a footnote, I did also stumble across this paper: L.G. Valerio Jr. et al. Toxicology and Applied Pharmacology 222 (2007) 1–16 as found at http://elec.polytech.unice.fr/~rgautier/SiteWebEPUTOX/Articale2.pdf . It states (table 1, page 5) that 2-ethyl-1-hexanol is a metabolite of safrole (found in black pepper, basil, sassafras).
Structure of safrole, source: http://en.wikipedia.org/wiki/Safrole
Now, I’m a little confused as to how safrole gets metabolised to 2-ethyl-1-hexanol: anyone got any ideas? It seems…well..a little improbable (but I’m no biological chemist, so know little about metabolism).
As a second footnote, there are a few links here talking about toxicity. At no point am I stating that this compound, present in extremely tiny amounts in the sample of maple syrup that was analysed, is risky to health. The data cited in these papers are relatively old and probably don’t reflect current methods of production (if the compound comes from production), or storage (if the compound comes from storage).