Sciencemadness Discussion Board

Metol chemistry

TheMrbunGee - 8-2-2019 at 14:54

Hey, SM!

I am moving, so sorting my chems I stumbled on few hundred grams of metol, not being in to photography, I was wondering if any interesting/useful chemistry can be done with it? After doing some simple tests, the molecule seems to be pretty inert and boring. Do you have any ideas what to do with it, or should I just dispose of it?

Thanks!

Lex - 8-2-2019 at 15:14

It looks like it could be used to create para-benzoquinone or hydroquinone. The former can be used as a gentle oxidant and the latter a gentle reductant. Benzoquinone can be used as a dienophile if you want to play with some diels-alder reactions, and hydroquinone is used to prevent peroxide formation in etherial solvents. Could be pretty rewarding to make yourself!

[Edited on 8-2-2019 by Lex]

[Edited on 8-2-2019 by Lex]

DavidJR - 8-2-2019 at 15:47

If you don't want it, I'm sure you could find someone willing to buy it from you.

TheMrbunGee - 9-2-2019 at 03:16

Quote: Originally posted by Lex  
It looks like it could be used to create para-benzoquinone or hydroquinone. The former can be used as a gentle oxidant and the latter a gentle reductant. Benzoquinone can be used as a dienophile if you want to play with some diels-alder reactions, and hydroquinone is used to prevent peroxide formation in etherial solvents. Could be pretty rewarding to make yourself!


Yes, hydroquinone did got my attention, but I could not find a way to convert motol to hydroquinone.


Quote:

If you don't want it, I'm sure you could find someone willing to buy it from you.


The thing is - it is a very old sample, I am guessing - 60 years old. It is discolored, now being more beige. not even close to a good quality stuff. What I am saying - it is not worth selling, especially because I must send it abroad, chemistry is not that common in my country. Not worth the trouble.

j_sum1 - 9-2-2019 at 03:39

I also have a large jar and some hydroquinnone as well. Maybe even the same age. I decided to hang on to mine since it isn't a bother to store and there is the possibility of perhaps doing something with it at some stage. It has an interesting enough structure and I figured that I would have a play some time as I built up my OC skills. Nice to have something to practice on that I don't mind losing.

DavidJR - 9-2-2019 at 04:08

If it's impure/oxidized, why not try recrystallizing it?

TheMrbunGee - 9-2-2019 at 06:28

Quote: Originally posted by j_sum1  
I also have a large jar and some hydroquinnone as well. Maybe even the same age. I decided to hang on to mine since it isn't a bother to store and there is the possibility of perhaps doing something with it at some stage. It has an interesting enough structure and I figured that I would have a play some time as I built up my OC skills. Nice to have something to practice on that I don't mind losing.


That is why I have it until this point. :D
Quote:

If it's impure/oxidized, why not try recrystallizing it?


Because of its very low solubility it would be a lot of work, and it is pointless, if I have no idea what to do with it.

Lex - 9-2-2019 at 13:36

Quote:

Yes, hydroquinone did got my attention, but I could not find a way to convert motol to hydroquinone.


Yeah, I think you would have to go via the benzoquinone, and then reduce that to the hydroquinone.

There are a few patents around converting para-aminophenol directly to the hydroquinone by a hydrolysis, and there is a chance that the same process could be applied to metol, but you might need an autoclave! I've attached an example.

Conversion of para-aminophenol to benzoquinone is something I've been trying to do myself, and reaction with MnO2 in dilute sulfuric acid seems viable. I think H2O2 would work too, and I've been meaning to try it. I would guess that aminophenol, and your N-methyl derivative, would oxidise in the same way - but would be very interesting to experiment with. This thread is quite useful:
http://www.sciencemadness.org/talk/viewthread.php?tid=8250&page=5#pid599837

Reduction of benzoquinone can be effected by iodide in acidic conditions (according to wikipedia), but sulfur dioxide might be a goer too!

As for recrystallisation, I would try it from hot water, with a tiny drop of sulfuric acid added. These para-phenolic compounds have annoying propensities to polymerise or discolour, especially in alkaline coniditions.

Do you know if yours is the bisulfate salt (1:1 N-methyl-para-aminophenol : sulfuric acid), or the sulfate salt (2:1 N-methyl-para-aminophenol : sulfuric acid)? The internet seems to give both options as "metol" after a search.

Attachment: US3862247.pdf (344kB)
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TheMrbunGee - 10-2-2019 at 11:57

Quote: Originally posted by Lex  
Quote:

Yes, hydroquinone did got my attention, but I could not find a way to convert motol to hydroquinone.


Yeah, I think you would have to go via the benzoquinone, and then reduce that to the hydroquinone.

There are a few patents around converting para-aminophenol directly to the hydroquinone by a hydrolysis, and there is a chance that the same process could be applied to metol, but you might need an autoclave! I've attached an example.

Conversion of para-aminophenol to benzoquinone is something I've been trying to do myself, and reaction with MnO2 in dilute sulfuric acid seems viable. I think H2O2 would work too, and I've been meaning to try it. I would guess that aminophenol, and your N-methyl derivative, would oxidise in the same way - but would be very interesting to experiment with. This thread is quite useful:
http://www.sciencemadness.org/talk/viewthread.php?tid=8250&page=5#pid599837

Reduction of benzoquinone can be effected by iodide in acidic conditions (according to wikipedia), but sulfur dioxide might be a goer too!

As for recrystallisation, I would try it from hot water, with a tiny drop of sulfuric acid added. These para-phenolic compounds have annoying propensities to polymerise or discolour, especially in alkaline coniditions.

Do you know if yours is the bisulfate salt (1:1 N-methyl-para-aminophenol : sulfuric acid), or the sulfate salt (2:1 N-methyl-para-aminophenol : sulfuric acid)? The internet seems to give both options as "metol" after a search.



Thanks I might go into this, and maybe save the stuff! :)

Packaging says it's 1:1, but I don't trust that 100%, because ammonium nitrate from those days had formula NO4NO3. :D

woelen - 11-2-2019 at 02:20

I would not dump it. If you have no use for it, you could at least try to sell it. Quite a few people may love to have some. It is hard to get these days and for people, who are in old-school photographic processes it may be very interesting, even if it is not a pristine white powder anymore.