p-aminophenol from acetaminophen/paracetamol
Wilco Oelen
As a photographer I was wondering if it is possible to make
p-aminophenol from acetaminophen/paracetamol, by splitting off acetic
acid/acetate, according to the following reaction.
HO-C6H4-NH-C(O)CH3 + H2O ---> HO-C6H4-NH2 + HOC(O)CH3.
I read that the =N-C(O)- group can be cleaved by means of hydrolysis
in strong acids or strong bases. I tried this, but it does not work at
all in acid (20% H2SO4) and only a little bit in strong bases (10%
NaOH). The alkaline solution turns somewhat violet/brown, indicating
that some p-aminophenol is formed, which is quickly oxidized by oxygen
from air.
Does anyone know a means to use paracetamol as starting point for
making p-aminophenol in acceptable yield? The p-aminophenol does not
need to be isolated in the solid state. If a solution of this can be
obtained, e.g. 1% strength, together with some alkali, some acetate
and some left over paracetamol, then this is quite OK for its intended
use (as a photography developer).
Please keep in mind, that the synthesis is not performed in a
laboratory with all kinds of equipment and chemicals. The procedure
and the required chemicals must be such, that the reaction can be done
outside a lab by a person with a fairly well equipped photography
darkroom.
I know that p-aminophenol (or the less oxidation sensitive compound
p-aminophenol HCl) can be purchased, but it is not easy for private
users to find this stuff, and _if_ it can be bought, then it is quite
expensive, so I just wanted to look for the paracetamol-alternative.
Thanks in advance for your reply,
Wilco
Uncle Al
>
> Hello,
>
> As a photographer I was wondering if it is possible to make
> p-aminophenol from acetaminophen/paracetamol, by splitting off acetic
> acid/acetate, according to the following reaction.
>
> HO-C6H4-NH-C(O)CH3 + H2O ---> HO-C6H4-NH2 + HOC(O)CH3.
>
> I read that the =N-C(O)- group can be cleaved by means of hydrolysis
> in strong acids or strong bases. I tried this, but it does not work at
> all in acid (20% H2SO4) and only a little bit in strong bases (10%
> NaOH). The alkaline solution turns somewhat violet/brown, indicating
> that some p-aminophenol is formed, which is quickly oxidized by oxygen
> from air.
It must be done with rigorous exclusion of oxygen. An excess of
concentrated ammonia would do better than stoichiometric hydroxide and
simplify product isolation thereafter. Adding some zinc dust toward
the end to reduce advantitous quinhydrone helps. Sulfite is a close
call; dithonite would also do it.
Tylenol et al. are compounded with excipients. It's going to be
messy.
If Homeland Severity catches you buying large quantities of Tylenol
they will sweat the truth out of you. You had better be equipped with
lots of co-conspirators to name in your long and detailed confession.
Then, be eager to hold a similar conversation with the War on Drugs,
followed by BATF, EPA, and Haz-Mat. You'll wish you never saw a
camera and the rest of us wil be assured our freedom (at least until
Room 101 comes for each of us).
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
Ron Jones
I agree with Al. Oxygen is your bigest ememy, it will go brown so fast in
alkali...
If you are determined to go with the paracetamol route, you will ideally
need to grind the tablets down and extract the active ingredient with a
solvent (methanol or acetone could work). All that will put the cost up.
Try seaching for suppliers of Photographic Chamicals
I found easily..
http://www.raycochemicals.f9.co.uk/B&W%20Developers.htm (says they might be
able to supply - in EU so no customs) and
http://www.alternativephotography.com/dir_chemicals.html (has a Dutch option
in Rotterdam)
probably many others. Or try you local photographic shop (a proper shop not
a mutil national chain!) who could possibly order for you. PAP has been
used for photography for years, so one one should be suprised at your
request.
--
--
Ron Jones
Don't repeat history, see unreported near misses in chemical lab/plant
at http://www.crhf.org.uk
ph...@woelen.nl
a photo developer anyway, so it can be left in solution. Must this also
be added at the end of the reaction, or is it better to add it right
away when starting?
>
> Tylenol et al. are compounded with excipients. It's going to be
> messy.
Yes, I noticed. The tablets I have, have magnesium stearate and a kind
of compressed starch as a binder. I first "dissolve" the tablets of 500
mg in hot water, occasionally shaking, leaving them there for a few
hours. Then I decant the liquid from the white solid stuff, hoping that
most of the paracetamol has dissolved.
>
> If Homeland Severity catches you buying large quantities of Tylenol
> they will sweat the truth out of you. You had better be equipped
with
> lots of co-conspirators to name in your long and detailed confession.
> Then, be eager to hold a similar conversation with the War on Drugs,
> followed by BATF, EPA, and Haz-Mat. You'll wish you never saw a
> camera and the rest of us wil be assured our freedom (at least until
> Room 101 comes for each of us).
Don't worry, I'm working with gram quantities only ;-)
Uncle Al
Exclude oxygen, keep it reducing. I don't know whether sulfite will
be a strong enough reductant.
[snip]
> > If Homeland Severity catches you buying large quantities of Tylenol
> > they will sweat the truth out of you. You had better be equipped
> with
> > lots of co-conspirators to name in your long and detailed confession.
>
> > Then, be eager to hold a similar conversation with the War on Drugs,
> > followed by BATF, EPA, and Haz-Mat. You'll wish you never saw a
> > camera and the rest of us wil be assured our freedom (at least until
> > Room 101 comes for each of us).
> Don't worry, I'm working with gram quantities only ;-)
Confiscation of all drug related possesons (anything of value), 20
years mandatory to life. Major crystal meth producers generally get
off with a warning, but you are dangerous. Better that 1000
innnocents be executed than one guilty party not be given pro bono
social advocacy. "8^>)
Ron Jones
"Uncle Al" <Uncl...@hate.spam.net> wrote in message
news:414A0B55...@hate.spam.net...
Standard phot developers always use sodium sulphite to keep them nice. But
they still have a tendency to colour on exposure to air - which is one
reason why (many years ago when b/w was all the rage!) most amateurs used to
make up strong stock solutions and then use them in a diluted form *once*
only - I still remember 1:1 D76:water, 9.5 mins, 20C for Ilford FP4.
ph...@woelen.nl
Ron Jones wrote:
> Standard phot developers always use sodium sulphite to keep them
nice. But
> they still have a tendency to colour on exposure to air - which is
one
> reason why (many years ago when b/w was all the rage!) most amateurs
used to
> make up strong stock solutions and then use them in a diluted form
*once*
> only - I still remember 1:1 D76:water, 9.5 mins, 20C for Ilford FP4.
>
I prepared a solution of p-aminophenol from paracetamol, with exclusion
of air. This solution contains some sodium sulfite, as suggested by
'Uncle Al' and it is not totally oxidized. I tried reducing some silver
compounds with it and that works OK, so indeed p-aminophenol has
formed. The liquid is light purple/brown, so it is just oxidized
slightly (otherwise I expect it to be dark brown, almost black).
The solution, I prepared is based on 500 mg paracetamol in 50 ml of
water, so it is quite dilute. If I keep this solution well stoppered,
then I think I can keep this for a long time without oxidation, even
when I dilute much further. Can't this solution be used multiple times?
I did not yet use it as a photo developer, because I need to experiment
quite a lot on how a good developer can be made from this solution.
I use other photo developer working solutions multiple times, so I
expect this p-aminophenol solution to be suitable multiple times as
well. If you think otherwise, then I would be pleased to know about
that and why you think so.
Wilco
Ron Jones
> Ron Jones wrote:
<snip>>
> almost black).
>
> The solution, I prepared is based on 500 mg paracetamol in 50 ml of
> water, so it is quite dilute. If I keep this solution well stoppered,
> then I think I can keep this for a long time without oxidation, even
> when I dilute much further. Can't this solution be used multiple
> times? I did not yet use it as a photo developer, because I need to
> experiment quite a lot on how a good developer can be made from this
> solution.
>
> I use other photo developer working solutions multiple times, so I
> expect this p-aminophenol solution to be suitable multiple times as
> well. If you think otherwise, then I would be pleased to know about
> that and why you think so.
>
You can use any photo developer multiple times if you wish. But each time
you use it, you will use up the active ingredients, so you must adjust the
development times accordingly. Eventually it will all be spent. How much
you adjust the development times will depend on how much film is processed
and how much active ingredient is there to start with. That's why I always
used to go for the one shot approach - a bit dearer, but the development
time never alters.
Steve Turner
wrote:
>You can use any photo developer multiple times if you wish. But each time
>you use it, you will use up the active ingredients, so you must adjust the
>development times accordingly. Eventually it will all be spent. How much
>you adjust the development times will depend on how much film is processed
>and how much active ingredient is there to start with. That's why I always
>used to go for the one shot approach - a bit dearer, but the development
>time never alters.
I've been watching this thread with some interest. What Ron says is
correct ... but it seems that, in practice, developer has a fair bit
of capacity. I commonly process a dozen 36-exposure rolls with one
liter of D-76, without replenishment and without any noticeable
decrease in activity or negative density.
I used to use D-76 single-shot, in diluted form, as Ron also
described. I stopped doing this after reading the fine print on the
processing information, which indicates that full-strength D-76 gives
finer grain than the 1:1 dilution.
That's my experience ... YMMV.
Steve Turner
ph...@woelen.nl
somewhat soft, but there is no fogging and development is very fast at
20 C. Just the sulfite, hydroxide and paracetamol and allowing this
whole brew to 'ripen' for a day or two, while keeping the bottle
stoppered all the time. More experimentation is needed to increase the
contrast, but the first rsults are promising. The essential step in
using this developer is the 'ripening'. During this time, the
paracetamol is allowed to be cleaved into p-aminophenol and acetate.
When used immediately after mixing, the developer does not work at all.
I used the developer several times for developing a small print on
Ilford Multigrade RC paper and the characteristics hardly changed
during the session. So this developer can also be used multiple times
and has a reasonable capacity. Using paracetamol tablets, however,
makes single-session development affordable. The price of one such a
tablet is just a few cents and one tablet can be used for making
multiple prints. The total cost of a developer for a single session
will be at most $0.20.
Wilco
Ron Jones
Ah, well. I never read the small print beacuse I never had any! Years ago,
I used to work for May & Baker (now what's left is Aventis), where they
would sell us their photo chemicals in the factory shop - so I always made
mine up from raw ingredients.
sreenath
Would it not be easier to take plain phenol and add the amino group to
get p-aminophenol? Any suggestions for such conversion?
-Sreenath
Chris Cooksey
<sreen...@rocketmail.com> writes
Mononitrate phenol, which gives a mixture of o- and p-nitrophenol. Steam
distill out the o-nitrophenol and reduce the remaining p-nitrophenol to
p-aminophenol, which then needs separating and purifying.
So, it is easier to hydrolyse the readily available p-acetamidophenol.
--
Chris Cooksey