David Peters wrote:
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?

It isn't.

Ethanol has a lower toxicity. However, denatured ethanol (meths) has
pyridine added to it. Apart from being one of the most vile smelling
compounds, pyridine is relativly toxic.

So, given the choice between ethanol and isopropanol, I'd choose
ethanol. But given the choice between meths and isopropanol, I'd choose
the latter any day.


--
Grunff

On Fri, 03 Jun 2005 13:59:36 +0100, Grunff wrote:

David Peters wrote:
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?

It isn't.

Ethanol has a lower toxicity. However, denatured ethanol (meths) has
pyridine added to it. Apart from being one of the most vile smelling
compounds, pyridine is relativly toxic.

It also rots rubber, which is why you should never use meths for
cleaning tape recorder pinch rollers.

So, given the choice between ethanol and isopropanol, I'd choose
ethanol. But given the choice between meths and isopropanol, I'd choose
the latter any day.

On Fri, 03 Jun 2005 15:17:55 +0100, Custos Custodum
wrote:

It also rots rubber, which is why you should never use meths for
cleaning tape recorder pinch rollers.

Why does it do that? is it the methanol or the pyridine ?

On Fri, 03 Jun 2005 16:04:06 +0100, Andy Dingley
wrote:

On Fri, 03 Jun 2005 15:17:55 +0100, Custos Custodum
wrote:

It also rots rubber, which is why you should never use meths for
cleaning tape recorder pinch rollers.

Why does it do that? is it the methanol or the pyridine ?

Not sure about the methanol, but pyridine is certainly used in
industry as a solvent for rubber.

According to Custos Custodum :
On Fri, 03 Jun 2005 13:59:36 +0100, Grunff wrote:

David Peters wrote:
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?

It isn't.

Ethanol has a lower toxicity. However, denatured ethanol (meths) has
pyridine added to it. Apart from being one of the most vile smelling
compounds, pyridine is relativly toxic.

It also rots rubber, which is why you should never use meths for
cleaning tape recorder pinch rollers.

Um, I think someone's confused. Methanol (which does eat rubber)
is _not_ denatured ethanol - it's methyl alcohol, aka methyl hydrate
aka CH3OH, aka "wood alcohol". Ethanol is C2H5OH (aka ethyl alcohol).

Isopropyl alcohol is the next alcohol in the series: C3H7OH

The methanol/ethanol/propanol/butanol etc naming conventions
follow the same prefixes as methane/ethane/propane/butane etc.
(1, 2, 3 and 4 carbons).

Methanol is considerably more toxic than ethanol.

I don't know what the Grunff is referring to when he says "meths".
if he means methanol, he's wrong.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Chris Lewis wrote:

I don't know what the Grunff is referring to when he says "meths".
if he means methanol, he's wrong.


In the UK, you can purchase something called 'methylated spirit' or
'meths' for short. This is typically 97% ethanol, 3% methanol, and a
touch of pyridine + purple dye (to stop people drinking it).


--
Grunff

Grunff wrote:
Chris Lewis wrote:

I don't know what the Grunff is referring to when he says "meths".
if he means methanol, he's wrong.


In the UK, you can purchase something called 'methylated spirit' or
'meths' for short. This is typically 97% ethanol, 3% methanol, and a
touch of pyridine + purple dye (to stop people drinking it).

I doubt if the purple dye (IIRC methyl violet) would stop anybody ;-) It's
the pyridine that really gives it a nose!
I wouldn't use meths for cleaning alone, as there's always the likelyhood of
leaving some dye residue. Properly denatured ethanol would be better, but I
think the Exercise men would take a dim view of retail sales - although one
can buy "duty-paid" pure ethanol (at about 75GBP per Winchester), and the
C&E probably won't bother so much (but you will be very, very much
poorer...)

--
--
Ron Jones

Don't repeat history, see unreported near misses in chemical lab/plant
at http://www.crhf.org.uk

On Fri, 3 Jun 2005 19:29:12 +0100, "Ron Jones"
wrote:

I wouldn't use meths for cleaning alone, as there's always the likelyhood of
leaving some dye residue.

It's not too hard to find uncoloured meths. Try a real hardware shop, or
a painters' supplier.

OTOH I still haven't found a source for it without the pyridine.

Chris Lewis wrote:

According to Custos Custodum :

On Fri, 03 Jun 2005 13:59:36 +0100, Grunff wrote:



David Peters wrote:

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?


It isn't.


Ethanol has a lower toxicity. However, denatured ethanol (meths) has
pyridine added to it. Apart from being one of the most vile smelling
compounds, pyridine is relativly toxic.


It also rots rubber, which is why you should never use meths for
cleaning tape recorder pinch rollers.


Um, I think someone's confused. Methanol (which does eat rubber)
is _not_ denatured ethanol - it's methyl alcohol, aka methyl hydrate
aka CH3OH, aka "wood alcohol". Ethanol is C2H5OH (aka ethyl alcohol).

Isopropyl alcohol is the next alcohol in the series: C3H7OH

The methanol/ethanol/propanol/butanol etc naming conventions
follow the same prefixes as methane/ethane/propane/butane etc.
(1, 2, 3 and 4 carbons).

Methanol is considerably more toxic than ethanol.

I don't know what the Grunff is referring to when he says "meths".
if he means methanol, he's wrong.

Methylated spirits is etahnol with enough mathoanol to make it
undrinkable exceptr by bums.

And Pyridine to make it obvious it's not bacardi.

David Peters wrote:

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?

Probably because it's a little less volatile and so doesn't evaporate before
you've wiped it off.

For the same reason it is used in industry because less of the vapour
escapes the containment or extraction system.

On Fri, 3 Jun 2005 23:39:26 +0100, "Mike" wrote:

Probably because it's a little less volatile and so doesn't evaporate before
you've wiped it off.

For the same reason it is used in industry because less of the vapour
escapes the containment or extraction system.



That would be my guesstimate although I can't give a good explanation
why this should be so. I'm no chemist. It is only one carbon atom
higher and that shouldn't affect the evaporation that much. Home use
solvent alcohols are mainly ethyl alcohol because they are cheap to
manufacture from fermentation or from raw stock (CO, H2).

The adulteration by methyl alcohol is from historical times when wood
alcohol was used to make grain alcohol undrinkable. Grain alcohol was
too useful a solvent to use for just drinks alone. But drinks alcohol
was one of the few staples the lord could depend on for taxes (salt
and grain harvests being some of the others.) By adding wood alcohol
(from charcoal manufacturing distillates?) even the dumbest village
yokel knew that adulterated alcohol would make him blind, make him
lose his bodily functions or more likely kill him.

Wood alcohol in the test tube oxidizes into formaldehyde, then to
formic acid and finally CO2 and water. In the body oxidation stops
at formaldehyde the stuff used in biology class to preserve
specimens. Nerves being the most sensitive get "preserved" first,
thus blindness and ataxia. By the time there is enough to kill you
the result will be a well pre-preserved corpse. Ethyl alcohol on the
other hand oxidizes to acetaldehyde, acetic acid then to CO2 and
water.