Why is propanol better cleaner than ethanol?

[David Peters]

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/Uksi_19872009_en_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. ]

 

[Dr_Dickie]

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/Uksi_19872009_en_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. ]

Because you cannot safely drink 2-propanol.

 

[Grunff]

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.

 

[Aaron (archive)]

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?

Hmm dunno if it is, is it? It may depend on the relative concentrations of each when compared to each other.

For example 0.02M propan-2-ol (isopropyl alcohol) will be stronger than
0.002M ethanol. Assuming the same concentrations (water to pure chemical ratio), then the only two reasons I can see are that:

1. Propan-2-ol has a longer hydrocarbon chain than ethanol (dunno how much difference this can make apart from making the chemical more viscous)...

H H H H H
| | | | |
H-C-C-C-H H-C-C-H
| | | | |
H O H O H
| |
H H
(propan-2-ol) (ethanol)

2. The functional alcohol (O-H) group is on the second chain in propan-2-ol and therefore is joined to a carbon with only one hydrogen atom connected to it... Therefore propan-2-ol is a secondary alcohol. As to why this would make too much of a difference I am not sure, look up the chemistry of primary and secondary alcohols. Since I don't think you are fully oxidising them I can't see how this would make too much difference.

Another thing apart from concentrations, is that you mention meths... It is only valid really comparison if the two chemicals are in their pure form.. Not apart of a cleaning agent such as meths of window cleaner etc.

Good luck, maybe you could feed us some more background information.

P.S. Clever people this is only what I remember from my A level chemistry.. Please correct me if I've made a mistake .

 

[Custos Custodum]

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.

 

[Andy Dingley]

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 ?

 

[Ernie]

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/Uksi_19872009_en_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

 

[Doug Miller]

I know that in the US denatured alcohol is not necessarily made of ethyl alcohol.

That is not correct. In the US, "denatured alcohol" is specifically ethanol with small amounts of poisonous additives (usually, but not always, methanol) to render it unfit for beverage use.

 

[Chris Lewis]

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.

[/QUOTE]

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.

 

[Uncle Al]

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/Uksi_19872009_en_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. ]

The denaturants for ethanol to render it non-drinkable (short of Kitty Dukakis) are crud. Ethanol is rather volatile.

 

[Grunff]

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).

 

[Ron Jones]

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...)

 

[The Natural Philosopher]

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.

 

[Mike (archive)]

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.

 

[Gary Dyrkacz]

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/Uksi_19872009_en_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]

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/Uksi_19872009_en_5.htm#mdiv14

 

[Andy Dingley]

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.

 

[Custos Custodum]

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.

 

[Custos Custodum]

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/Uksi_19872009_en_5.htm#mdiv14

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

 

[Derek *]

The additives in household meths seem to affect its value as a cleaner,

I have an application involving the removal of self adhesive glue residues from transparent conveyor belts. Meths seems to soften it but not remove it, rubbing with a meths soaked wad just seems to move it about, and after about 2-3 minutes of rubbing it starts to get dirty ending up worse than it started.

D- Limonene AKA Orange cleaner, or Label remover works a treat especially applied with a commercial isopropanol impregnated wad.

which, as it is sold as a fuel, is not unreasonable. If you want to use meths as a cleaner, you need to get hold of industrial meths.

DG