2012: Advent Chemistry: Acetone

by on December 5, 2012

A line drawing of an acetone molecule

This is acetone, one of my favourite solvents. Its systematic name is propanone and it’s the simplest possible ketone. A ketone is any compound with a carbon backbone and a CO group that isn’t on the end. Since when there are only one or two carbons all of them are ends, three is the minimum you can have for a ketone.

Acetone is a wonderful thing, because the majority of organic compounds dissolve in it, and it mixes with water making it easy to dispose of. It’s used around labs for cleaning glassware. Acetone is especially good for doing a final rinse of cleaned glassware, because it will remove the water and the glass will dry off almost instantly. That trick works because acetone has a very low boiling point. It will visibly evaporate away from a surface, including skin – that’s why it feels cold to the touch, because it steals heat from you in order to evaporate.

Acetone has a strong, distinctive smell. If you’ve ever smelt nail polish remover, that was probably acetone. I quite like the smell, but it smells chemical and solventy, so I would.

Acetone is a polar, aprotic solvent. The carbon-oxygen group is the polar part, and as usual the oxygen is negative and the carbon positive. It’s “aprotic” because while there’s plenty of hydrogen in there, it’s all bonded to carbon and will take serious persuading to fall off. It won’t just drift away and interact with other things the way hydrogen bonded to oxygen often will.

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