On Fri, 3 Jun 2005 11:32:03 -0400, "Ernie"
wrote:


"David Peters" wrote in message
...
Why is isopropyl alcohol (propanol) reckoned by many people to be a
better general cleaner around the house than the ethyl alcohol
(ethanol) which is found in methylated spirits?

Thanks for any info.

David

------



FOOTNOTE:

I can add that here in the UK the main type of denatured alcohol we
can buy for home use is "methylated spirits" and in the UK this is
made up almost entirely of ethyl alcohol.
http://www.hmso.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

I know that in the US denatured alcohol is not necessarily made of
ethyl alcohol. This can lead to confusion about what someone is
referring to, so for clarity I can repeat that I am referring to UK
meths/ethanol. ]

I strongly suspect that the cleaning power of ethanol vs. propanol depends
on the nature of the dirt being removed.
While it is an oversimplification, think of dirt as being either water
soluble or oil soluble. Ethanol (two carbons and one hydroxyl group) will
be more effective in removing water soluble dirt, while propanol (three
carbons and one hydroxyl) will be more effective at removing grease (oil
like substances). Lighter fuel is very effective at removing grease, but is
even is more fire hazard than the alcohols.

Ernie


Ernie is essentially correct. There are other nuances of chemistry
that enter into consideration such as the relative acidity of ethyl
alcohol versus iso-propanol and the molecular shape, but the "grease"
solubilizing idea is a simple way of representing the why you might
use 2-propanol over ethanol.
Gary Dyrkacz

Radio Control Aircraft/Paintball Physics/Paintball for 40+
http://home.comcast.net/~dyrgcmn/