ChemSemBlog

This week’s presenter was Jeffery Turk from Alma College.  His presentation revolved around sandalwood.  First, Turk gave a basic introduction to olfaction, the sense of smell.  Odor molecules bind to receptor cells, located on the cilia inside the nose.  Odor molecules need to be volatile, that is, have a vapor pressure, and they need to be relatively hydrophobic.  Odor molecules are small, usually weighing less than 300 grams per mole.  Approximately 400 genes code for olfactory receptors.  The study of olfaction is complicated by the fact that an odorant can bind to multiple receptors, and receptors can accept more than one type of odorant.  The binding of odorants to receptors is based on functional groups.

After this introduction, Turk went on to talk about sandalwood itself.  Sandalwood is a hunted tree, and odors are specific to each species of the tree.  Therefore, sandalwood oils will have different aromas depending on the region they are harvested from.  Sandalwood trees are so precious that companies place barbed wire and guards armed with machine guns around the trees.  I wouldn’t have believed it if I hadn’t seen a picture.  The sandalwood molecules themselves are made of carbon chains terminated by alcohols.  A bulky hydrophobic group is placed somewhere on the molecule.  A sandalwood molecule can cause temporary loss of smell.  Aldol chemistry is used to make sandalwood oils from campholenic aldehydes.  Fragrance chemistry involves stereoselective and catalytic techniques.  However, large scale reactions are not supported due to the expensive nature of fragrance chemistry.

This presentation was very interesting, and not just because of the chemistry.  Turk passed around several sample fragrances, most of them being very strong smelling.  Javenol, in particular, had an incredibly strong smell.  Also, the audience got to smell ambergris, which was made from whale crap.  This was one of the most interesting things I learned.  It was also eye-opening to learn that fragrance companies heavily guarded their sandalwood trees with guards armed with machine guns.  I would like to know if anyone has ever been shot trying to climb a sandalwood tree.  Finally, Turk told us that if we wanted to clear our nasal passages, we could smell our elbows.  It sounds weird, but it just might work.  To sum up, this presentation was about the fragrance chemistry of sandalwood, and other aspects of fragrance chemistry.

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