Molecule of the Day

Aqueous bio-compatible reducing agents are legion, but people end up using the same ones over and over. Probably the least used is TCEP (which doesn’t stink at all), next is dithiothreitol (and the related but slightly less effective dithioerythritol), which stinks, but not too badly. Perversely, biologists usually seem to end up using beta-mercaptoethanol, which is the stinkiest of the lot.


BME stinks, but not too badly – the burnt rubber smell has a pleasant organic alcohol note in the background, making it not such a miserable smell. Uninitiated coworkers might disagree.

Certain synthetic DNA bases require a mixture of concentrated ammonia + beta-mercaptoethanol to deprotect and cleave them from the support. Oh, and you heat them. Don’t spill, and work in the hood. I speak from bitter experience.


  1. #1 Erik
    April 25, 2007

    You should do p-anisaldehyde for a MOTD.

  2. #2 Oskar
    April 26, 2007

    I know this is off topic but there is a subject that has had me puzzling for quite some time and if there is somebody out there that can explain.
    When you put solvents on dry silica gel it heats up, it is especially pronounced when using EtOAc but not as much with chlorinated solvents.
    the only thing that I can think of is if the entropy rises.
    Again I apologize if a topic like this is not allowed.

  3. #3 MoTD
    April 26, 2007

    As far as I understand, the answer is as simple as this: just like with any substrate in regular-phase chromatography, the polar Si-OH surfaces interact quite strongly with more polar solvents – resulting in in the release of heat. Silica is actually a fair drying agent because it interacts with water so strongly.

  4. #4 Chris Jeans
    April 28, 2007

    I like the smell of BME. But DTT really gets stuck in my nose and makes me feel ill. I’ve never found a co-worker who feels the same…

  5. #5 Darksyde
    April 30, 2007

    Chris! I totally agree. BME smells vaguely like roasted glazed rice crackers — an afternoon treat if my mom went to the oriental market. DTT just smells plain bad!

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