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 ?

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

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 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.

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.

On Sat, 04 Jun 2005 04:05:59 +0100, David Peters
wrote:

On Fri 03 Jun 2005 23:16:22, The Natural Philosopher wrote:

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.


I don't believe there is any methanol in UK "methylated spirits".
See the link in my footnote to my original posting which says:

"in the case of mineralised methylated spirits, with every 90
parts by volume of spirits there shall be mixed 9.5 parts by
volume of wood naphtha and 0.5 parts by volume of crude pyridine,
and to the resulting mixture there shall be added mineral naphtha
(petroleum oil) in the proportion 7.5 litres to every 2,000 litres
of the mixture".

http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

These are simply the additives for the different classes of methylated
spirits. What constitutes the basic 'spirits' is presumably defined
elsewhere.

David Peters wrote:

On Fri 03 Jun 2005 23:16:22, The Natural Philosopher wrote:


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.



I don't believe there is any methanol in UK "methylated spirits".
See the link in my footnote to my original posting which says:

"in the case of mineralised methylated spirits, with every 90
parts by volume of spirits there shall be mixed 9.5 parts by
volume of wood naphtha

I think that IS methanol^^^^

and 0.5 parts by volume of crude pyridine,
and to the resulting mixture there shall be added mineral naphtha
(petroleum oil) in the proportion 7.5 litres to every 2,000 litres
of the mixture".

http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

David Peters wrote:
On Fri 03 Jun 2005 23:16:22, The Natural Philosopher wrote:

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.


I don't believe there is any methanol in UK "methylated spirits".
See the link in my footnote to my original posting which says:

"in the case of mineralised methylated spirits, with every 90
parts by volume of spirits there shall be mixed 9.5 parts by
volume of wood naphtha and 0.5 parts by volume of crude pyridine,
and to the resulting mixture there shall be added mineral naphtha
(petroleum oil) in the proportion 7.5 litres to every 2,000 litres
of the mixture".

http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

IIRC wood naphtha = wood alcohol = methanol

--
--
Ron Jones

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

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


On Sat 04 Jun 2005 11:26:47, Andy Dingley wrote:

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.


That uncoloured meths you refer to should not have pyridine. As I
understand it this link defines what can be sold in the UK as
"methylated spirits".
http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

If it helps, the contents page is at at:
http://www.opsi.gov.uk/si/si1987/Uks..._en_1.htm#tcon

It says that UK "Industrial Methylated Spirits" has no colouring
and also no pyridine. And it has 5% wood naptha.

If it has colouring then my reading says it would be UK
"Mineralised Methylated Spirits" which has colouring and also
pyridine. This has twice the wood naptha at 10%.

I wouldn't think that the last class "Denatured Ethanol" is
something which is commonly sold to the public.

On Sun, 05 Jun 2005 15:33:25 +0100, David Peters
wrote:

That uncoloured meths you refer to should not have pyridine. As I
understand it this link defines what can be sold in the UK as
"methylated spirits".
http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

This is "Mineralised Methylated Spirits" made by Barrettine. Exactly the
same label as for their purple product and the same smell of pyridine,
but no colour.

It says that UK "Industrial Methylated Spirits" has no colouring
and also no pyridine. And it has 5% wood naptha.

There's a spec for it, but I haven't found a supplier in less than 40
gallon drums.

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


On Sat 04 Jun 2005 11:26:47, Andy Dingley wrote:

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.


That uncoloured meths you refer to should not have pyridine. As I
understand it this link defines what can be sold in the UK as
"methylated spirits".
http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

If it helps, the contents page is at at:
http://www.opsi.gov.uk/si/si1987/Uks..._en_1.htm#tcon

It says that UK "Industrial Methylated Spirits" has no colouring
and also no pyridine. And it has 5% wood naptha.

If it has colouring then my reading says it would be UK
"Mineralised Methylated Spirits" which has colouring and also
pyridine. This has twice the wood naptha at 10%.

I wouldn't think that the last class "Denatured Ethanol" is
something which is commonly sold to the public.

Quite right. If fact there there tends to be 2 main grades of IMS:
74op = colourless dry ethanol/methanol, now usually called 99% IMS
66op = same but damp with water (made from ethanol/water azeotrope IIRC) now
usually called 95% IMS

[op means "over proof", that means 74op = 174 UK proof. 100 proof =
ethanol:water mix which when wetted with gunpowder will flash when lit
(about 56.5% IIRC)]

There are also a few other grades of denatured ethanol, for use when the
methanaol would give rise to unwanted impurities - cyclohexane, toluene,
pyridine are all known. I would guess all grades of ethanol are unavailable
to the general public - except the purple one and "duty paid". (unless you
brew it yourself... hic..)

--
--
Ron Jones

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

According to Ron Jones :
David Peters wrote:
On Fri 03 Jun 2005 23:16:22, The Natural Philosopher 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.

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

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

I don't believe there is any methanol in UK "methylated spirits".
See the link in my footnote to my original posting which says:

"in the case of mineralised methylated spirits, with every 90
parts by volume of spirits there shall be mixed 9.5 parts by
volume of wood naphtha and 0.5 parts by volume of crude pyridine,
and to the resulting mixture there shall be added mineral naphtha
(petroleum oil) in the proportion 7.5 litres to every 2,000 litres
of the mixture".

http://www.opsi.gov.uk/si/si1987/Uks...n_5.htm#mdiv14

IIRC wood naphtha = wood alcohol = methanol

Yeah. Methanol is one of the main ingredients of the gas given off when
you heat wood to high temperatures. Principle component that
causes the "flame" in burning wood. It used to be called wood alcohol,
because the primary source was charcoaling ovens - capture the gasses,
let it condense, and voila, wood alcohol.

[Naptha is an old fashioned name. Used because it approximates the
same thing as petrochemical naptha - which is pretty much a "heavy
gasoline". Wood alcohol produced by classic means isn't very pure.]

Books describe it as "destructive distillation of wood".

Nowadays, most of it is a petrochemical industry product, and much
purer.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

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.

On Mon, 06 Jun 2005 17:44:57 GMT, PaPaPeng wrote:

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).

Its not just the molecular weight that changes and effects the
evaporatoin, especially in small chain alcohols. There are both
molecular shape factors and hydrogen bonding changes that also
influence the evaporation/heat capacity.

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.

Gary Dyrkacz

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

"Gary Dyrkacz" wrote in message
...
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).

Its not just the molecular weight that changes and effects the
evaporatoin, especially in small chain alcohols. There are both
molecular shape factors and hydrogen bonding changes that also
influence the evaporation/heat capacity.

I believe that in most short chain hydrates in the liquid form (water,
methane, alcohols, etc) it is the weak hydrogen bonds between molecules that
affect the evaporation most. Water would be wholly gaseous at room
temperature/standard pressure without this.