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mfilip62
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p-benzoquinone HELP!!!
Yes it is me again with this stupid but unavoidable chemical.
I don't know how and why but this stuff helped me to make something that might be explosive peroxide polymer!
Unfortunately it is stable only at sub zero temperatures and has pretty interesting properties.
Since then I am obsessed with this stuff and trying to get/make as much as I can to continue my research.
I will publish my discovery here so please help!
I bough decent amount of iodine and hydroquinone
(both extremely expensive here) but I had no luck producing p-benoz.
I used Erowid document.
First I followed From Hydroquinone using hydrogen peroxide [4] procedure in isopropyl alcohol
(I used same amount of ethanol instead, since isopropyl alcoholis hard to find here)
with iodine and H2O2, and that resulted in lot of smelly acetaldehyde and acetic acid.
That is probably because I let temperature climb at 60°C or so at first, since procedure doesn't mentions ice bath
that is necessary here.
Then i tried to do same in water.
(Quinones from phenols or hydroquinones with H2O2 [8], B method)
This time I mixed water and H2SO4 first and than added hydroquinone and hot ethanol solution of Iodine.
(Procedure does not specify how to add iodine but I assume you cant simply mix it with water,since it is insaluble)
Then 25g of 30% H2O2 was added drop wise instead of 10ml 60% H2O2 (0.22 moles) with stirring while watching on temperature.
Golden-black-green participate appeared soon after but even after 6h of mixing and than heating it at cca. 45°C
I didn't get yellow p-benzo. Reaction smelled, well...it hurted when you smell it!
Most disgusting suffocating smell of acid or burnt plastic.
Small cubic brown-red crystals appeared, I filtrated them but don't know what to do with them.
Then I made third procedure(Spiceboy method) ,this time with K2Cr207.
(Firstly, you can't dissolve 35g of K2Cr207 in 60ml of water unless you heat it well to make supersaturated solution.)
Procedure gone as discribed, green complex appeared but even after 4h of continuous stirring it didn't turn yellow.
Now it is chilling in fridge, but it does not look promising and this noxious smell is there again!
PLEASE HELP!!!
I am desperate!
Can someone give me link on some step-by-step synthesis of p-benzoquinone with H2O2/I2 method!?
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Nicodem
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Quote: Originally posted by mfilip62  | I didn't get yellow p-benzo. Reaction smelled, well...it hurted when you smell it!
Most disgusting suffocating smell of acid or burnt plastic.
Small cubic brown-red crystals appeared, I filtrated them but don't know what to do with them. |
You don't know what to do with a reaction product? Then why were you wasting time with the reaction? Measure the melting point like every normal
chemist would do before opening a thread and calling "HELP!!!". If it is depressed recrystallize or sublimate. If it still does not fit the literature
value then you don't have the desired product. And who told you you will get a "yellow p-benzo"?
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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xwinorb
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The SpiceBoy recipe is easy. It will not become yellow.
Yes, you can't dissolve the potassium dichromate in the ammount of water used. Just mix it and drip the semi-solid stuff with a spoon, it works.
Initially it becomes black, then it thickens, then is loosen up and you will see yellow solids stirring ( p-benzo ).
After 1 h ( don't need four hours ) place in fridge for 1h, when T = 5 C or 10 C, vacuum filter.
The end product is greenish ( not yellow ) due to chromic impurities. Also the crude product yield is easily more than 100 %. Remember, it is not
pure. The real yield is close to 60 %.
It can be purified with DCM ( better than benzene as in Organic Synthesis ). I have posted on it.
For some applications just dry it and use it w/o puryfing it further. Assume 60 % yield and correct for weight to use.
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mfilip62
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Thing that botthers me is that this stuff looks and smells completely different than pure p-benzo and I really dont feel like using impure product
with organic peroxides!
Brown red stuff I got can't be p-benzo.
If anyone knows where to find foto tutorial of I2/H2O2 method that would be great!
Xwinorb,are you saying that I shuld filter this green stuff and disolve it in nonpolar solvent so that ionic crap falls out?
Any details on ammount of solvent and procedure details?
Thing that botthers me most in I2/H2O2 method is that I2 wont dissolve in water and that both I2 and p-benzo are very saluble in same solvents,so how
to purify w/o flash cromatography and other fancy equipment?!
Any tips and details are highly appreciadet!
Thank!
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Nicodem
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| Quote: Originally posted by mfilip62 | Thing that botthers me is that this stuff looks and smells completely different than pure p-benzo and I really dont feel like using impure product
with organic peroxides!
Brown red stuff I got can't be p-benzo. |
What you say makes no sense. On which basis do you say that it can not be p-benzoquinone? What is the melting point?
| Quote: | | If anyone knows where to find foto tutorial of I2/H2O2 method that would be great! |
A photo tutorial? It is such a simple procedure that I really do not see why would you want any photos of it. It does not use any fancy glassware and
a beaker you surely already know how it looks.
| Quote: | | Thing that botthers me most in I2/H2O2 method is that I2 wont dissolve in water and that both I2 and p-benzo are very saluble in same solvents,so how
to purify w/o flash cromatography and other fancy equipment?! |
See my previous reply and xwinorb's reply. At the moment it looks like you did not read them carefully enough.
Besides, if you don't even know exactly what you are doing then why don't you strictly stick to the procedures as they are written? Trying to act
smart on subjects where you know nothing can result in accidents if this subject happens to be preparative chemistry.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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mfilip62
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Brown-red produt has m.p. of 136'C.
Yes,I need photo tutorial too see how reaction looks like in different stages.
I made p-benzo with V2O5/NaClO3 once and it looks way different.
First it looked like mine "completed" Spiceboy method and than it turned all yellow,so I assumed this similar reaction shuld look same.
Reason I use different solvents is becouse I can't obtain specified ones here.
I am not trying to act smart,but I assumed that I2 won't dissolve in water as reaction medium,resulting in failure,am I wrong?!
If I could obtain secified chemicals,I wouldn't use anythinh else.
I read both posts,of course you can purify it from ionic crap with benzene or DCM,but can you do the same to purify it from Iodine?!
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crazyboy
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I can't see what you 're problem is. I have tried the I2/H2O2 route before with complete success. Perhaps you are omitting a step? Do you have
magnetic stirring? Did you keep the reaction at the proper temperature? Did you use an addition funnel to slowly add the H2O2?
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mfilip62
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That is what botthers me,it is very simple procedure but it doesn't work for me!You do it in the water or in alchohol?!
In what order you mix your reactants?
What ammount and which slovent you use?!
When you do reaction in wather,
do you dissolve Iodine in warm alchohol before adding it?!
I add H2O2 last,one drop per second or slover while
keeping temp. under 40.
One procedure in alchohol needs H2SO4 while other doesn't and it gives allmost the same jield, how can that be possible?!
Can i use same ammonut of 96% ethanol onstead of methanol and isopropyl alchohol?!
If you can,please write how you do it with every step,this thing drives me nuts!!!
I use improvised but realible mechanical stirrer.
(I have magmetic stirrer but no stir bar,I can't bought it here.)
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turd
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I don't get it either. The IPA/H2O2/I2 method gives very pretty yellow benzoquinone. If it stays at the black precipitate stage, add some more H2O2
and apply gentle heat.
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mfilip62
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I aded more H2O2 and heated to 40,but no sucess.
You get any smelly aldehide and acid in this reaction?!
Do you use any H2SO4?!
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Nicodem
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Then perhaps your hydroquinone is not hydroquinone. If, for some reason, your reaction would not go to completion you would obtain a mixture and
mixtures do not have sharp melting points. Instead they have more or less wide melting intervals. The mp would be intermediate of any of the possible
components: quinhydrone (171°C), p-benzoquinone (115°C), hydroquinone (172°C). You could have a mixture of quinhydrone with some minor amount of
p-benzoquinone, but then the mp would not be a sharp 136°C.
What is the melting point of your putative hydroquinone? What is its origin?
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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turd
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No aldehyde smell (which aldehyde!?), yes with sulfuric acid.
IIRC (sorry, no more notes), amounts like here: "H2O2 (60%) (10 ml, 0.22 mol) was added dropwise with stirring to a solution of dihydroxybenzene (0.20
mol), I2 (10 mmol), and concentrated H2SO4 (10 ml) in MeOH (600 ml) at RT"
Source: http://www.erowid.org/archive/rhodium/chemistry/benzoquinone...
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mfilip62
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I used two different sources of hydroquinone,they are fresh opened and brand new from realible company.Forget abbout crap,lets focus on how to make
something useful...
I first smelled acetaldehide and than ecetic acid,I was working with ethanol since I don't have Isopropy alchohol.
I wasnt using this method(A),but with water instead of MeOH(B) and than other one (From Hydroquinone using hydrogen peroxide [4])
I used 25g of 30% H2O2,since I don't have 60% H2O2.
Please confirm if this is right?!
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mfilip62
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Just examined out brown-red product.
It is most probably p-benzoquinone, but very impure containing red stuff I can't get rid of completely.
I assume it is Iodine since it can't be separated with solvent form p-benzo.
One hint, when you evaporate solvent (I used DCM) you got yellow crystals first and
red crap only at the end when there is no more solvent to hold it dissolved.
Hope this helps in finding appropriate separation method.
I also dissolved green stuff that I got from K2Cr2O7 method in some DCM,washed it with water (thanks xwinorb!) evaporate DCM and rechristalize in
ethanol,obtaining highr yellow christals.
Yellow crystals I got form K2Cr2O7 and I2/H2O2 metods looks definitelly like p-benzo but smells very different and seems to be more volatile than end
product of acetaminophen/aqua regia method.
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leu
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If all else fails then follow the directions; J. Org. Chem. 1989,54, 728-731 is attached so everyone knows what's being attempted 
Attachment: hydroquinone2benzoquinone.h2o2-i2.pdf (480kB)
This file has been downloaded 1759 times
Chemistry is our Covalent Bond
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xwinorb
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SpiceBoy method
I can't help you with the other method, IPA + I2 + H2O2. I never tried it. I have seen several posts from guys that had trouble with this method.
Looks like it has a tendency not to run to completion, and in the end there is a mixture of p-benzo and quinhydrone, black with yellow spots.
The dichromate method is easy, never failed me, yields are consistently 60 %. The final product is kind of green-gray color, this impure p-benzo is
soluble in water.
You can just dry it and use the impure p-benzo. To dry it place in an airtight container with drierite. If you have a dessicator it is the best
choice. It takes one week or so to dry.
If you want to purify your p-benzo, dissolve it in DCM till it has a filterable consistency. You get a green-black thick emulsion. Filter it, some
solids at the filter, then the emulsion breaks. Two layers, amber DCM + p-benzo on bottom, black watery layer on top.
Separate, can wash a bit with water, then distill out DCM, First no vacuum, then gradully apply aspirator vacuum. When it starts to solidify, dump the
orange goo on a big shallow container, pyrex a good choice. Stirr a bit, when the DCM evaporates it becomes nice and yellow p-benzo. Maybe a hint of
green, but quite pure.
If you have a fume hood it is better, but not necessary. I have done it more than once. Don't spill the DCM + p-benzo, it smells strong and stains
everything it touches, even stainless steel. It does not stain glass.
I would suggest, run a boiling point test on "other things" you might be using. There is a lot of scams and fakes. I mean some things you don't buy at
a chemistry store, also not found OTC. Sad situation, it started one year ago or so, according to my own experience. If you know how it should smell
it helps also ( I don't mean the p-benzo smell ).
Good luck.
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mfilip62
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I already did so, thanks!
Dissolved green stuff in DCM and washed it with water twice.
Green black crap was left in the water and amber goodie was in the DCM.
Unfortunately I didn't find way to get rid of the red-brown crap from other batch.
Thing that bothers me the most is that p-benzo you got form acetaminophen
has totally different smell than one you get from K2Cr2O7 method.
First one does not botthers me, other makes me gasp for air and puke.
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mnick12
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The way I usually make benzoquinone is from hydroquinone. There are a number of routes out there but the one I find to be the simplest and cheapest is
the chlorate method. Here is the one I use From Hydroquinone Using V2O5/NaClO3 [1]
"In a 1-litre round-bottomed flask, provided with a mechanical stirrer, place 0.5 g of vanadium pentoxide (catalyst), 500 ml of 2 % sulphuric acid, 55
g (0.5 mol) of hydroquinone and 30 g of sodium chlorate. Stir the mixture vigorously for about 4 hours. Greenish-black quinhydrone is first formed and
this is converted into yellow quinone; the temperature of the mixture rises to about 40 °C (do not allow it to exceed this temperature). Cool the
flask in running water, filter the mixture at the pump and wash it with 50 ml of cold water. Spread the material upon filter paper until dry (but no
longer or the quinone will be lost through sublimation) or dry in a dessicator over anhydrous calcium chloride. The yield is 45 g (83 %); M.P.:
111-112 °C. The crude quinone may be purified by steam distillation as in the method above, or by recrystallisation from boiling light petroleum,
B.P.: 100-120°C (12 ml per gram): the resulting pure, bright yellow quinone has a M.P.: 115°C and recovery is about 95%.
"
I use it because I make the chlorate in my electrolysis cell. It is always very high yielding. I will post some pics if you want in the next few weeks
once I gte back from vaccation.
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mfilip62
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No need, I found this method fully documented with pictures, yield is great and pure.
I find out that you can do I2/H2O2 6-7h method in less than 15min.
You add IPA first, put it in the hot bath, than I2 and than hydroquinone.
Then you add H2O2 rapidly and BOIL it for the 2-5 min.(reflux is optimal)
Cool the solution in ice bath and recrystallize from hot alcohol.
Amount of reactants are same as in 6h method, only difference being 3 times less I2.
yield is extremely pure and around 90% of theoretical.
If this sounds too good to be true just try it for yourself,I didn't believed it at first!
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Intergalactic_Captain
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This thread isn't too old, so I'll dig it up... Was searching for confimation on the rhodium methods, as I've been planning on doing this myself....
mflip, are you sure your peroxide is as strong as you think it is? The rhodium docs specify peroxide of 30-35% - In the US (where a lot of the bees
who wrote those notes) reside, the average consumer, be it an individual or a lab, will see H2O2 labeled in percent - There is, however, another
system - "Volume" - Not v/v, or w/v, but "volume", an archaic system used in the hair-styling industry. To convert from volume to percent, simply
divide by 10 - ie, 30 volume is actually 3 percent (anyone feel free to correct me if I'm wrong, but I'm quite sure it's x10).
....I mention this because from the sounds of it, you're getting a mix of incompletely reacted crap - If you followed the directions, you should have
a mix of quinhydrone (your green stuff) and partially oxidized hydroquinone, along with some other crap. This would be the case if your 30-35%
peroxide was actually 30-35 VOLUME peroxide.
....From the sounds of it, you're not in the US - and, from what I understand, the "volume" system for labeling peroxide is much more common across
the pond - From what you've described, I'd be willing to bet that this was your mistake.... If not, please post - I'm actually intrigued.
....Though, from your last post, you seem to have figured it out... Atmospheric oxygen? Error by an order of magnitude? Not sure, but it warrants
further investigation... As a note, for anyone who doesn't know it, high strength peroxide is available in the US as "baquacil," a non-chlorine pool
shock, at 27..5% w/v....about to run a test with it myself...
If you see me running, try to keep up.
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mfilip62
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Thanks on note I_Captain,very interesting to know!
No,my peroxide is 30% by mass,I got it form the pharmacy from the reliable company.
This 5-6-7h long process of monitoring temp., slow addition and stirring is total bulls**t and waste of time and expensive chemicals.
Someone should warn those folks on rhodium...
This reaction cant be more simple!
Measure out reactants,
add iodine, apply some heat and stirring until it dissolves,
add hydroquinone, apply some heat and stirring until it dissolves,
add H2O2, boil it for few minutes.
After it starts boiling it will continue to boil/react for some time even after it is removed form the heat source,
stirring will make reaction too vigorous so stir only a bit now and then, when it stops boiling even with stirring reaction is done.
Total time 5-10min.
Upon cooling all the liquid will be transformed in moist mass of chrystals.
Use excessively big baker(1L at least),reflux or at least Al foil with some Ice (it is inert enough)
I figured out that it works well in EtOH but yields are much better in IPA.
Next time when I find solubility chart of reactants in comparison of IPA/EtOH/acetone
I will try with acetone as reaction media since it is super cheap here
and hydroquinone/p-banzo is insanely soluble in it, that means lower losses on recrystallization and everything.
Make sure not to use water for any washes of p-benzo crystals since it will react and form a green-black.
Product is super pure, has most beautiful canary yellow color and it is irritating like a damn tear-gas!
Dry under vacuum since it is next to imposable to dry this stuff in any other manner without significant
loses trough sublimation and vastly unpleasant exposure.
(black staining on the skin, skin falling of, extreme irritation to the eyes and nose,etc...)
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digitalemu
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Cleanest and pretty much the easiest is the potassium dichromate and hydroquinone method. Also cheaper too. Purification is simple and is done by
sublimation. Invert a 1000ml beaker on top of a small petri dish containing impure product. This is placed onto a hot plate. Put a 600 ml beaker
filled with ice and h2o on top of the 1000ml beaker, this will help the material sublime. Turn hot plate to medium and wait until you see the gree
p-benzoquinone begin to vape off and a slightly melting orangish liquid turn the heat off and wait about 1/2 hour and beautiful yellow crystal spikes
will form.
The stuff is a powerful lacrymator when pure so prepare for tearing eyes!
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peach
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| Quote: | | Unfortunately it is stable only at sub zero temperatures and has pretty interesting properties. |
Interesting article about hydroquinone, peroxide and explosions in this link.
| Quote: | I bough decent amount of iodine and hydroquinone
(both extremely expensive here) |
The Wacker isn't on the cards then, given the cost of palladium salts at the moment.
| Quote: | | I used Erowid document. |
Here's the original patent that reference comes from. The quoted section on Erowid (from Rhodium?) is a direct quote from the patent. The patent isn't
particularly long but does mention more of the details.
| Quote: | This time I mixed water and H2SO4 first and than added hydroquinone and hot ethanol solution of Iodine.
(Procedure does not specify how to add iodine but I assume you cant simply mix it with water,since it is insaluble) |
The patent mentions that iodide salts are preferable for that there reason.
| Quote: | I didn't get yellow p-benzo. Reaction smelled, well...it hurted when you smell it!
Most disgusting suffocating smell of acid or burnt plastic. |
I've done this with IPA and iodine and it's worked fine. Assuming your hydroquinone is okay, I would hazard a guess it's due to the use of ethanol, as
you noted it working okay when you switched to IPA as well.
| Quote: | | If anyone knows where to find foto tutorial of I2/H2O2 method that would be great! |
<iframe sandbox width="640" height="480" src="http://www.youtube-nocookie.com/embed/0ccKPSVQcFk" frameborder="0" allowfullscreen></iframe>
Flask
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Stir bar
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Stopper
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Thermometer
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Reducing adaptor
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Some means of adding 58g of 35% hydrogen peroxide
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Scrape remaining gram of iodine out of container, because someone still hasn't posted me the replacement! 
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Weigh
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55g of hydroquinone, 1g of iodine, 115g (about 150ml of) iso-propyl alcohol
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Combine the three above
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Tap up, X, three triangles and hold selected down with R1 to turn the stirring on. It may become a little pasty and difficult to stir. If so, add
another 25 to 50ml of IPA
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Don't need a stopper here, or a condenser. Begin adding the H2O2 drop wise. My flask is at about 17C, and the peroxide has come out of the freezer.
After about an hour of addition and half the volume gone, the flask will be warming it's self towards 50C. If you don't want it boiling, simply stop
the addition and pour some cool water around the flask. Ice should not be necessary as the climb is not particularly drastic.
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Continue stirring for hours, add a bit of heat to keep it around 45C if need be...
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Take photo...
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Take photo with flash to show pretty sparkles...
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Keep an eye on temperature, continue stirring, stop after it's had about three hours from the addition end, replace bath water with cool water, allow
to come down to 15C (put it in the fridge once reasonably cool if having trouble); there will be a soft, sparkly solid floating around in there
throughout the reaction, but cooling it will ensure you keep as much of it out of the solvent as possible on filtration.
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Clean glassware with aqua regia, because it's disgustingly mucky
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Begin sucking. Allow all of the dirty solvent to leave; so the funnel is no longer dripping
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See that dirty brown / orange solvent left in there? Wash it through with a few squirts of cold IPA, letting it fully drain between each and then
after the washes
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Canary? Looks more budgie to me, but the RSPCA won't let me borrow any more wildlife to use as a reference standard.
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Budgies, plotting something...
Caaaaaaa! Nary.
If left out in the open, you may get some brown (iodine traces?) or green (quinhydrone?) tinged patches on the surface
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Sucking it 100% dry under vacuum
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TaDa! I used a 500ml flask for the stuff in the photos below, 200ml of IPA and 61g of '35%' hydrogen peroxide from the freezer, to do 55g of
hydroquinone. The addition took about two hours. After one hour and half the volume, it peaked at about 50 to 60C before I cooled it back down to 35C.
There was no noticeable temperature rise as the rest went in. I held it at 45C for three hours after that and filtered at 15C, rinsing with cold IPA
before drying under vacuum. Yield, 79%.
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What you will observe
At the start:
The iodine will go into the alcohol, staining it dark brown (extremely dark yellow) almost immediately. The hydroquinone will not fully dissolve, but
will float around as speckles. It will smell of IPA. It may thicken up but will loosen as the peroxide goes in.
About the middle of the addition:
The temperature has probably risen a bit by now and it'll stir easy. The solid speckles still tend to settle to the bottom if the stirring isn't
relatively quick. It'll still be brown / dark yellow and stink of IPA.
Cooling:
You may be able to see the solid floating around in there better by now. Guess what colour it'll be and how it'll smell at this point. If you guessed,
dark browny yellow and IPA, you win!
Filtering:
You now get to see your pretty yellow solid. The IPA smell will begin disappearing.
Dry and packing:
It now smells like bleach and photography shops that still process wet film, I really like the smell actually. Knock it into the air and, like lots of
fine powders, it'll make you sneeze. If it's gotten onto your skin throughout this process, there may be a brown patch there. Which is novel, because
my eBay listings for hydroquinone were taken down for precisely the opposite reason; diluted creams are used by some black guys to lighten their skin
(think Michael Jackson). Being cracker white, the product of the reaction turns my brown.
Suggestions:
A 250ml flask is only just big enough for 55g of hydroquinone (half mole scale), it will be close to full once everything is in
there. If that starts to boil, it will likely make it's way out of the flask, so go with a 500ml.
If you will be running this as per example 1 in the patent, nothing will boil in the flask, so you do not need a condenser or jointed glassware.
A beaker with a sep. funnel over it would work fine.
Stirring it is a good idea, and it may become thick and tricky to stir with the 115g of IPA mentioned in the example, so be prepared to add a
bit of extra solvent (hence the 500ml container). A beaker with a big, flat stir bar in it works significantly better than the oval stir bars in
RBF's. With a bit of extra solvent in there and some firm stirring, it's not a problem
If your hydrogen peroxide has been sat around on the shelf for months, and is not stabilised, the concentration of it may have fallen. Either
check that or add a bit extra to ensure there's enough oxidiser thar
You could try leaving it in the fridge or freezer for a few hours to get it really cool prior to filtering
Possible reasons for why my yield, quoted above, is 10% below the patent:
I left it for three hours, the patent suggests 'several', so starting it in the morning and letting it sit to the night, or leaving
it overnight, may be an idea
I used slightly more IPA, so I may have lost a bit more during filtration
Despite the bottle of peroxide being relatively new and having always lived in the freezer, and me adding a few extra grams, there may have been
a slight lack of oxidiser
My question:
I wonder why the patent is suggesting that temperature range then. If it's just to avoid using condensers, it'll need a water jacket on a big vat of
it anyway. So maybe it's to avoid explosive peroxides or over oxidised organic muck? Patents tend to be optimised for commercial production and they
are aware that it'll work up to 80C (which would increase the rate), meaning there is likely a reason for them recommending it's instead held at 45C.
[Edited on 21-9-2011 by peach]
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mr.crow
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Another excellent post Peach! Maybe move to prepublications?
Did you have any problem with sublimation while drying?
You can also make benzoquinone from acetaminophen/paracetamol and HCl + potassium nitrate. This has been posted elsewhere
Double, double toil and trouble; Fire burn, and caldron bubble
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peach
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Thanks Mr Crow! A lot of birdy terminology going on in this nest.
No problems with it sublimating when drying nope. I am in England and it's September, so it's only about 15C out there.
I just spotted the other thread when I was googling my way back to this one. There are no problems with buying iodine and strong peroxide in the UK
and they're not expensive, so this method works nicely. I'm sure even in the US, a gram of iodine... that is not a lot. KI and NaI work even better,
and you can get them back if it's really an issue. I think I got more than that much out the seaweed I extracted for fun. 
I pushed onwards to Goldfinch yellow this evening by sublimating it in this gigantic 3l beaker that helpfully turned up in the post. There's not a lot
to say about the process, the vast majority of it sublimated leaving very little residue when the plate reached around 130C. I didn't even bother with
water or ice on top since no significant amount of it appeared it be leaving, due to the size of the beaker and temperature outside, and it'd only add
the possibility of getting water in my result.
But there are lots of pretty pictures to look at, and there is no shame in looking at pretty things!
Of note is that my nitrile gloves (the green ones) are a size too small and difficult to put on since they don't stretch, but seem fine with
benzoquinone. The latex (white) ones don't like it. In fact, it seems to have partially gone through the latex, as I'm now the proud owner of a
temporary pimp hand.
It takes a long time to do even a few tens of grams in a gigantic beaker like this, and I'd suggest no one bothers making it in the first place until
they are ready to use it, and then sublimates it immediately before use, since it'll only go nasty over time when stored.
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[Edited on 22-9-2011 by peach]
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