Friday, March 02, 2012

Cancelling a Stink with another Stink?

I'm not expert on stinky chemicals, but two major classes that send people reeling are thiols and amines. I personally find the thiols to be less offensive to work with. Not that they smell better, but because of odor fatigue - it just seems that you get use to them as your nose saturates, such as what happens with the thiol that is added to natural gas. Unfortunately, I do not have odor fatigue with amines. They smell just as bad at the end of the day as the beginning.

I bring this up because of a new thiol compound that I ran across. I run a lot of thiol-ene reactions, so I'm always on the lookout for new thiols. A biochemistry research group from Wisconsin reported the synthesis ($) last month of a novel dithiol. Their interest in the molecule and the focus of the report was in solvating proteins, which they claim the new molecule does better than existing alternatives. But most importantly for me they claim that it is nearly odorless. And how did they accomplish that neat trick? Ironically by incorporating an amine to the molecule.

Understanding how the nose senses odors has always been a challenge, as sometimes even the tiniest change to a molecule can have a tremendous impact on its aroma. The classic examples is that of carvone, a compound with two stereoisomers, one which smells like caraway while the other smells like spearmint. But this new molecule is almost a case of two wrongs making a right. Or tongue-in-cheek, proof that thiols and amines are on opposite ends of the stink scale, and that amines are twice as stinky as thiols.

The only downside for me is that the material is not commercially available and it is a 6-step synthesis to make it from aspartic acid. 6-steps is a lot, but I have to stay at least three times that number of steps away from my wife after a day in the thiol lab, so I may just make try to crank some out someday.


Chemjobber said...

Bleach doesn't help?

John said...

Can't use bleach until I get the cloths off and in the washer. And not all fabrics handle bleach very well. I've had to rework my wardrobe - I were certain shirts/pants when I know I'm working with thiols.