"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

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/

"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?

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. ]


On Fri 03 Jun 2005 16:32:03, Ernie wrote:

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).


Thanks for the info. Can I ask about what you have written in
that paragraph.

Does propanol's "three carbons and one hydroxyl" mean that it is
more likely than ethanol (with only two carbons and one hydroxyl)
to actually DISSOLVE some types of plastics which I am might be
trying to clean?

In article , David Peters wrote:

Does propanol's "three carbons and one hydroxyl" mean that it is
more likely than ethanol (with only two carbons and one hydroxyl)
to actually DISSOLVE some types of plastics which I am might be
trying to clean?

Don't know about your side of the pond, but over here (US) propanol is
normally sold in plastic bottles. I've used 2-propanol to clean a lot of
things, and never had it damage any plastic.

IMO your premise is wrong (that a longer-chain moleule is more likely to
dissolve plastic than a shorter one). I've also successfully used paint
thinner (mineral spirits) to clean various plastics without damage. And I've
not observed gasoline to be particularly harmful to plastics either. OTOH,
acetone (2-propanone) and MEK (2-butanone) are terribly destructive to many
common plastics. IOW, it ain't the length of the chain, but what's attached to
it, that does the damage.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

Doug Miller wrote:
In article , David Peters wrote:

Does propanol's "three carbons and one hydroxyl" mean that it is
more likely than ethanol (with only two carbons and one hydroxyl)
to actually DISSOLVE some types of plastics which I am might be
trying to clean?


Don't know about your side of the pond, but over here (US) propanol is
normally sold in plastic bottles. I've used 2-propanol to clean a lot of
things, and never had it damage any plastic.

IMO your premise is wrong (that a longer-chain moleule is more likely to
dissolve plastic than a shorter one). I've also successfully used paint
thinner (mineral spirits) to clean various plastics without damage. And I've
not observed gasoline to be particularly harmful to plastics either. OTOH,
acetone (2-propanone) and MEK (2-butanone) are terribly destructive to many
common plastics. IOW, it ain't the length of the chain, but what's attached to
it, that does the damage.


Actually, what he stated is generally correct, but
ethanol and propanol are very close, so one would
probably never see any significant difference.

Of course, what you said is correct also, what is
on the end is important, but when comparing two
alcohols, the same thing is on the end.

As for plastics, oil has some fairly long chains
and it is sold in plastic bottles and oil/gas
mixtures certainly don't bother the oil bottle
plastics. And then of course, there are plastic
gas containers. It would be a pretty lousy
plastic that would be bothered by methanol,
ethanol, or propanol.

George E. Cawthon wrote:

Doug Miller wrote:

In article , David Peters
wrote:

Does propanol's "three carbons and one hydroxyl" mean that it is more
likely than ethanol (with only two carbons and one hydroxyl) to
actually DISSOLVE some types of plastics which I am might be trying
to clean?



Don't know about your side of the pond, but over here (US) propanol is
normally sold in plastic bottles. I've used 2-propanol to clean a lot
of things, and never had it damage any plastic.

IMO your premise is wrong (that a longer-chain moleule is more likely
to dissolve plastic than a shorter one). I've also successfully used
paint thinner (mineral spirits) to clean various plastics without
damage. And I've not observed gasoline to be particularly harmful to
plastics either. OTOH, acetone (2-propanone) and MEK (2-butanone) are
terribly destructive to many common plastics. IOW, it ain't the length
of the chain, but what's attached to it, that does the damage.


Actually, what he stated is generally correct, but ethanol and propanol
are very close, so one would probably never see any significant difference.

Of course, what you said is correct also, what is on the end is
important, but when comparing two alcohols, the same thing is on the end.

As for plastics, oil has some fairly long chains and it is sold in
plastic bottles and oil/gas mixtures certainly don't bother the oil
bottle plastics. And then of course, there are plastic gas containers.
It would be a pretty lousy plastic that would be bothered by methanol,
ethanol, or propanol.

Surprisingy enough, methanol is quite agrresive. Dunno why.

I had a toy plastic plane once, with an engine that ran on
methonol/nitromethane/oil mix.

I tried to clean it with petrol...and it dissolved the surface!!!

There is no single simple amswer to which solvent dissolves which plastic.

According to The Natural Philosopher :

Surprisingy enough, methanol is quite agrresive. Dunno why.

I had a toy plastic plane once, with an engine that ran on
methonol/nitromethane/oil mix.

I tried to clean it with petrol...and it dissolved the surface!!!

There is no single simple amswer to which solvent dissolves which plastic.

That's for sure. First, there are "polar" and "non-polar" solvents. Alcohols
are an example of the former (OH bond), and gasoline/kerosene etc are
an example of the latter. What they dissolve _tends_ to be fairly
mutually exclusive.

And of course, "curing type" plastics (ie: epoxy resin, polyethylene)
are immune to most solvents of either kind.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

George E. Cawthon wrote:
It would be a pretty lousy
plastic that would be bothered by methanol,
ethanol, or propanol.

Styrofoam cups seem to melt with booze in them.

--
I miss my .signature.

"Chris Lewis" wrote in message
...
According to The Natural Philosopher :

Surprisingy enough, methanol is quite agrresive. Dunno why.

I had a toy plastic plane once, with an engine that ran on
methonol/nitromethane/oil mix.

I tried to clean it with petrol...and it dissolved the surface!!!

There is no single simple amswer to which solvent dissolves which
plastic.

That's for sure. First, there are "polar" and "non-polar" solvents.
Alcohols
are an example of the former (OH bond), and gasoline/kerosene etc are
an example of the latter. What they dissolve _tends_ to be fairly
mutually exclusive.

And of course, "curing type" plastics (ie: epoxy resin, polyethylene)
are immune to most solvents of either kind.

Except that methanol will dissolve many epoxies. It is rather slow
though.....

William...

--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.