Sciencemadness Discussion Board

p-benzoquinone HELP!!!

mfilip62 - 28-7-2010 at 14:19

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!?

Nicodem - 28-7-2010 at 14:55

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"?

xwinorb - 28-7-2010 at 19:21

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.

mfilip62 - 29-7-2010 at 05:11

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!

Nicodem - 29-7-2010 at 05:39

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.

mfilip62 - 29-7-2010 at 07:05

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?!


crazyboy - 29-7-2010 at 07:50

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?

mfilip62 - 29-7-2010 at 08:30

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.)

turd - 29-7-2010 at 08:49

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.

mfilip62 - 29-7-2010 at 09:01

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?!

Nicodem - 29-7-2010 at 09:27

Quote: Originally posted by mfilip62  
Brown-red produt has m.p. of 136'C.

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?

turd - 29-7-2010 at 09:32

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...

mfilip62 - 29-7-2010 at 10:17

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?!

mfilip62 - 29-7-2010 at 16:28

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.

leu - 29-7-2010 at 16:33

If all else fails then follow the directions; J. Org. Chem. 1989,54, 728-731 is attached so everyone knows what's being attempted :cool:

Attachment: hydroquinone2benzoquinone.h2o2-i2.pdf (480kB)
This file has been downloaded 1545 times


SpiceBoy method

xwinorb - 30-7-2010 at 14:44

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.

mfilip62 - 30-7-2010 at 14:54

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.

mnick12 - 31-7-2010 at 08:12

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.

mfilip62 - 1-8-2010 at 13:50

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!

Intergalactic_Captain - 18-8-2010 at 18:34

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...

mfilip62 - 19-8-2010 at 11:55

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...)

digitalemu - 26-7-2011 at 18:42

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!

peach - 20-9-2011 at 10:12

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! :P
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Weigh
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55g of hydroquinone, 1g of iodine, 115g (about 150ml of) iso-propyl alcohol
<a href="http://img41.imageshack.us/i/img0203oh.jpg/" target="_blank"><img src="http://img41.imageshack.us/img41/205/img0203oh.jpg" alt="Free Image Hosting at www.ImageShack.us" border="0"/></a><br>

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:

  1. 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.
  2. 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.
  3. 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
  4. 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
  5. 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:

  1. 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
  2. I used slightly more IPA, so I may have lost a bit more during filtration
  3. 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]

mr.crow - 21-9-2011 at 08:00

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

peach - 21-9-2011 at 15:05

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. :D

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]

peach - 21-9-2011 at 15:51

I should add, since some of the viewers may be looking at the photos and wondering about the numbers, that in the first post, the photo of the 'orange / brown filter cake being washed' is actually the second filtration I'm doing (the bulk of it has been through and emptied out), and that's the last of what's in the flask, I haven't washed a load through with the IPA. It is not particularly soluble in cold IPA.

Some of the photos, e.g. the ones near the top of the first post, are not from the same batch (that's a 250ml flask in the first photos).

The hotplate probe is in the flask when I'm holding the temperature; I've removed the mercury thermometer and stuck the digital feedback one in.

And there is a lot more benzoquinone, in terms of volume, than it looks in the photos. I had to take some of them with a sample of what was coming out, not the entire lot. The hydroquinone and benzoquinone are 'fluffy' materials that use up lots of volume for their mass. In that first sublimation photo, there is only about a gram in there. It took multiple goes and about six hours to get 43g through.

Some more ideas

To get as much of the iodine out as possible, you will either want to squirt cold IPA on between additions to the funnel or dump the cake back out into icy cool IPA to rinse the traces off. I used a few tens of mls and it's essentially gone, this suggestion is mainly for people who might have problems if there are any traces of halogens in their results, acting as catalysts in subsequent work; for instance.

Iodine sublimates at a similar temperature to benzoquinone at atmospheric pressure, so gross contamination after the filtration will pass over in the sublimation as well.

Hydroquinone, however, does not sublimate. It boils at 287C at atmospheric pressure, so that'll be gone with atmospheric sublimation.

[Edited on 22-9-2011 by peach]

bryce126 - 15-11-2011 at 14:30

hate to revive an old thread, but better than opening a new one. I've followed this route and the patent and had great success. BUT...peach's pictures look bright yellow, and I'm looking at something bordering between orange and golden yellow, leading me to believe there are iodine impurities remaining. Should I:


• pass dissolved (in cold IPA) benzoquinone through some activated charcoal to catch iodine
• dissolve, recrystallize, , and gravity filter, having the iodine stay in the solvent

lastly, the patent says that H2O2 amount and I2 amount should be based on the amount of hydroquinone initially used. I'm thinking of trying this with less hydroquinone, since I don't have that much, simply to use it up. Can someone help me scale this down to half-scale? I can't seem to find, or write, the equation of this oxidation. (sorry, new OChem student)

peach - 18-11-2011 at 13:36

"hate to revive an old thread, but better than opening a new one."

Yup, it is better. For some reason, on the Ubuntu forums, they'll close / lock old threads that are revived despite them being about the same problem.

Simple question, did you squirt some cold IPA over the cake in the filter? That will clean it up orange / brown tints. It will also dissolve some of the BQ, so it will always drip out a yellow colour at the bottom. Just give it a couple of squirts, not half a bottle's worth of IPA.

If you want it super sparkly yellow, sublimate it. It does take aaaaages, however.

bryce126 - 29-11-2011 at 08:15

Quote: Originally posted by peach  
"hate to revive an old thread, but better than opening a new one."

Yup, it is better. For some reason, on the Ubuntu forums, they'll close / lock old threads that are revived despite them being about the same problem.

Simple question, did you squirt some cold IPA over the cake in the filter? That will clean it up orange / brown tints. It will also dissolve some of the BQ, so it will always drip out a yellow colour at the bottom. Just give it a couple of squirts, not half a bottle's worth of IPA.

If you want it super sparkly yellow, sublimate it. It does take aaaaages, however.


figured this out the hard way. Especially because you can only do such a small amount at a time. I tried scaling this up and ended using WAY too much iodine. even with cold IPA over vacuum filtration, I'm still getting light brown samples until I sublimated it. For anyone that considers scaling this up, by the way, everything on the original patent is fine, except the amount of iodine needed can be much much lower than 1% by weight.

Now that I've got it, though, I'm wondering if activated carbon (since I've read its superb at adsorbing iodine) might get the job done, or if it would just adsorb all the BQ as well.

Peach, your pictures gave me some confidence while running this, and my first time doing it came out with some giant yellow crystals, beautiful. They sting the nose though!

Alastair - 29-11-2011 at 13:28

Quote: Originally posted by peach  

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. :D

[Edited on 22-9-2011 by peach]


Could you please go into more detail? I am sorry to ask unrelated questions, but it seems really interesting. I always imagined some sub-milligram level of iodine at any amount of seaweed :o

homeslice - 28-1-2012 at 22:00

http://parazite.nn.fi/hiveboard/methods/000473279.html

In a 3 litre beaker, 460g 91% isopropyl alcohol, store-bought, was added. One 30ml bottle of generic 2% iodine tincture containing 45% alcohol and 2% iodine was also added. The solution was heated to 30°. Heat was removed and 220g Hydroquinone was added. The mixture was agitated until all hydroquinone dissolved in the solution. Temperature is not to exceed 35 now or during the addition of the h2o2.

240g of 35% hydrogen peroxide was added at about 1-2 drops per second with an addition funnel. After the addition was over, the solution is brought to a boil. As heat is being added, you may notice quinhydrone in the solution. This is fine. It will all dissolve as it approaches its boiling point. The solution is allowed to boil for about 2 minutes.

The solution is cooled in a freezer. Decant off as much IPA as possible. Then 215ml IPA was added and the solution heated until all of the p-benzoquinone crystals dissolved. The solution was cooled once again and placed in a freezer. The crystals were then filtered under vacuum and washed with ice cold isopropyl alcohol. They are then dried in a dessicator.

Yields between 85% and 93%.

Magic Muzzlet - 29-1-2012 at 08:00

Potassium/sodium iodide doesnot work better, I have tried it. If you have these salts, make iodine from them. The peroxide decomposes and you get runaway or foam, don't use these salts. Same thing with tinctures

Also, thanks for the pictures and account of the reaction Peach.
However it really does not need to take so long,

If you use the general procedure given in the "rhodium" method it can be made much simpler. If you do it on 55g scale use .3g I2. If you scale more use more I2 but you can already see it is much less.
Now, add all the reactants to the flask, H2O2 last. If you use I2 there is no exotherm at all, you do not need to wait for Hydroquinone dissolution in the isopropanol.
Then heat with flame/heat gun to internal temp of about 70C, and you will see the temp suddenly begin to rise. With stirring place ice bath under flask to keep it under a little control, then remove quite rapidly so it refluxes on its own for a bit. You may want to stop stirring depending on how vigorous it gets, use a slightly oversized flask and good condenser. Put a moist cotton ball on top of condenser.
After the reaction comes to 40-50C cool in ice, to get massive benzoquinone needles. Filter, much less iodine so color comes out easier with washes.
Yield 80-90% in about 40 minutes. Don't scale up too much (no more than 4-5x) or exotherm can get problematic, better just run it several times.

I feel like many people don't know about this, heating it actually works better. The solution will never get very out of control, and this is very fast and you use less iodine.
But again, do not use iodide salts it does not work. Reason this is beneficial is how quick it is...benzoquinone is not the nicest thing, so being able to do this quickly but still yield a pure product is great. And who wants to spend time making this if it is for use in further reactions? It's frankly not an interesting thing to do.


I think a user here named something along the lines of mfilip reported success with similar method (heating)
It DOES work and it is much better than taking hours to add the peroxide. I never had success with slow addition...
Hopefully someone can make use of this information.

Edit: turns out mfilip made this damn thread and even stated to heat to boiling. Does anyone else actually do this or is it just me and him??


[Edited on 30-1-2012 by Magic Muzzlet]

DJF90 - 30-1-2012 at 16:51

When using the Iodine catalysed H2O2 oxidation, heating to 70*C before addition of peroxide and maintenance of this temperature is important to prevent accumulation of peroxide in solution, which could then possibly undergo a runaway reaction.

Magic Muzzlet - 30-1-2012 at 17:44

I don't really agree because what I posted above basically is a run away, you add everything before heating. It never gets out of control, and in 40 minutes you have a crop of benzoquinone.
I have found it is beneficial to have a "runaway" because it actually makes it work, I've tried nearly every method of benzoquinone production and can never get replicable results with same quality of product.
Mfilip is the only other person I have read about that heats it, only to find the reaction is MUCH faster. This is not something that needs to be complicated, it literally is add everything, heat, cool, filter, wash and dry.
I simply post this because I would like to see less people having problems making this material.


homeslice - 31-1-2012 at 18:40

Drop your h2o2 in over twenty minutes or so and there will be no temperature change. Then apply heat.

Swih can vouch for up to 6x scale up of the original. But id imagine you can go scale this up much much more without worrying about a runaway.

Art&Dreams - 27-2-2012 at 11:12

Question, This is my first post and I know that this is a older topic.

Peaches pic synth. has worked for me.
The P-benzoquinone comes out yellow BUT it has some slightly darker (Iodine??) traces?
It looks pretty close.. I also do not know how to post pictures here or I could show you.

Any help with filtering that stuff out? Already squirted it with cold IPA...
another thing... does the IPA have to be dry?

The experiment pretty much goes according to the process.

I have vacuum filtration also btw.


(add the 3 substances)
Start stirring
Slowly drip 35% H202 over 3 hrs from add. funnel
Keep stirring 3hrs after addition w my magnetic stirrer.
Stop stirring, Throw in a ice bath.
Get the temp down to 15C.
as soon as it reaches 15c internally, V. Filter it.
Squirt some IPA.


so yeah now it looks pretty close BUT again, In the vac buchner there is always a layer of blackish on the bottom that will not filter out. so just go around it.


Magic Muzzlet - 27-2-2012 at 11:19

It is either iodine or quinhydrone.
If you do it as I said above you can use much less I2 and this in turn results in a cleaner product.
I have also had that issue when using the slower method, dirty crystals and black spots all through it, the crystals are also granular in nature and not needles.

Art&Dreams - 27-2-2012 at 12:06

Quote: Originally posted by Magic Muzzlet  
It is either iodine or quinhydrone.
If you do it as I said above you can use much less I2 and this in turn results in a cleaner product.
I have also had that issue when using the slower method, dirty crystals and black spots all through it, the crystals are also granular in nature and not needles.


Thank you VERY much :). will try less iodine next time.. Any Idea how much less I should use? maybe use 3/4 of :)1g?

Pics!

Art&Dreams - 27-2-2012 at 12:59

This is how it turned out.. I know there is no way for you guys to actually tell over a picture but I think it looks correct. going to try the new process today after a bit more research.

php7dLjCePM.jpg - 18kB



*EDIT! adding new pics and update on the synth possibly later
today! It really helps if you end up with severe
iodine/quin contamination.

[Edited on 28-2-2012 by Art&Dreams]

homeslice - 5-3-2012 at 09:27

Thats correct and its absolutely usable "as is". Dont sit on it long though as it will break down. You will notice brown/black specs forming as it reacts with the air. Keep it stored under dessication until use.

Also, if you are an absolute stickler for purity you can recrystallize with store bought 91% IPA. Use about 1ml IPA to .8g para-benzoquinone. Most, if not all, will dissolve as the IPA hits its boiling point. If your looking for longer crystals, for whatever scientific purpose, allow the solution to cool slowly rather than plunging into an ice bath. Benzo grows nice long crystal lattices.

Ephesian - 21-11-2012 at 08:27

I used Fisher IPA, sigma Aldrich iodine chips, 30% Fisher ACS H2O2 and photograde hydroquinone. Followed the procedure that Peach gave and came out with a black coal like product with a yellow/gold sheen. I cannot wash the black out for the life of me. I tried subliming a sample of the crude wet product and a orange/yellow vapor filled the flask (which is a great sign that there is quinone present). Has anyone had this issue during washing? I've spent nearly 1 L of cold IPA, and even though its dirt cheap I'd hate to continue if there is no hope. If anyone has some tricks let me know please

DJF90 - 21-11-2012 at 09:20

I don't think you continued the reaction far enough. Perhaps your H2O2 has degraded over time or something.

Magic Muzzlet - 21-11-2012 at 09:21

Quote: Originally posted by Ephesian  
Has anyone had this issue during washing? I've spent nearly 1 L of cold IPA, and even though its dirt cheap I'd hate to continue if there is no hope. If anyone has some tricks let me know please


I have already told of the method I use and it always works. Please try it. There is also more information outlined at The Vespiary by pyramid.

Slow addition of H2O2 is a hit or miss, usually a miss. Please try how I have explained and report back. Cool the post reaction mixture to RT over 15-20 mins before cooling in a cool bath, sometimes if you cool on ice too long the product will be contaminated with iodine so look out.
What you have obtained is quinhydrone...

DJF90 - 21-11-2012 at 09:39

I did the slow addition method and it worked fine for me. I followed a similar method to Christian on Versuchschemie (http://www.versuchschemie.de/topic,11289,-1%2C4-Benzochinon....) but I heated to 70*C before commencing dropwise addition of the hydrogen peroxide. I also used the patent (I'm sure it was mentioned upthread) as a reference, and on one occasion I tried water as a solvent (using I2 catalysis). I found this much less simple and quite alot of iodine was noticed as vapour and sublimate in the flask. So definately use IPA. The reaction becomes homogenous at the end. (yellowy browny solution with no green-black solids).

[Edited on 21-11-2012 by DJF90]

Ephesian - 6-12-2012 at 17:43

I've struck gold, just not benzoquinone


reporting back...with terrible results

@magicbullet

I followed your instruction, added the hydroquinone (55g batch size), .3 g iodine chips, and 60 g 30% H2O2, and ~150 mL IPA. Took the heat up to ~70 C with a heat gun where an exotherm took place and went up to ~80 C. I quickly got it in an ice bath and brought it back down to 70 C and kept it going for about 15 minutes and then slowly brought it down to 50-60 C. At this point the reaction flask was not homogenous but contained a solid mass which coated the round bottom flask. Cooled the reaction mass down more with ice and filtered, washed with cold IPA. The crude product again resembled the same product I obtained from using Peach's method. From the looks of it, I got quinhydrone yet again. Tell me what you think...

IMG_1290.jpg - 102kB

DJF90 - 7-12-2012 at 00:19

It seems like you're not letting the reaction go to completion. I've already mentioned that at the end of the reaction, it is yellow-brown in colour and homogenous (in IPA). If there are still solids, maintain heating at say 60*C until there are not. I believe it took me a couple hours after the slow addition of peroxide.

I've attached some pictures from a recent attempt using water as a solvent, as per the patent. I found it was not half as pleasant as using IPA.

2012-08-23 14.20.05.jpg - 163kB 2012-08-23 14.37.55.jpg - 171kB 2012-08-23 15.26.10.jpg - 137kB

Unfortunately I do not have any pictures from the last attempt using IPA.

[Edited on 7-12-2012 by DJF90]

Ephesian - 7-12-2012 at 04:32

@DJF90

Do you suggest heating the hydroquinone, iodine and IPA up to ~60-70 prior to slow addition of H2O2? during addition, I assume there will be an exotherm, so I will have to remove external heat from the mantle. Is there a specific temperature where it will definitely produce byproduct (i.e what is the max I should let the internal temperature get to)? Also I see that everyone is using 35% H2O2, I've used the same stoichiometry with 30%, I take it since you are using water as a solvent, the extra water from the 30% H2O2 is not affecting anything at all.

DJF90 - 7-12-2012 at 06:23

@Ephesian: I roughly followed the method outlined by Christian at VC: http://www.versuchschemie.de/topic,11289,-1%2C4-Benzochinon....

The exotherm was in my opinion not very significant, especially using IPA as solvent as the boiling point kinda helps moderate the reaction if it gets a little excitable (use a reflux condenser). I also used 30% H2O2, as its all I had on hand. I think I left the reaction at 50*C for about 2 hours after the addition of H2O2. Better yields can be had by leaving it longer, but I recall something like 80-90% so I wouldnt worry too much about it. I think the patent mentions 4hrs giving quantitative yield.

Magic Muzzlet - 7-12-2012 at 07:04

The problem is you instantly cooled it in an ice bath, you cooled it way too much. This is a point a few have been confused on and I have had to explain at length via pm. I only mentioned use of the bath for a few seconds to keep it from going out the condenser, later I found it never does go that far, so I do not use an ice bath. It needs to not be cooled to actually lower temperature on the thermometer, it's a precaution to save a huge mess (but I found in even a 500ml flask it doesn't foam that much it's fine)

After the exotherm, just leave it for half an hour. After that, scratch from the inside with the stirbar and it should begin crystallizing, or hold a piece of ice on the side of the flask (just at a single point).

Try using 10-15% more H2O2 than you are now to compensate for both possible degradation in your peroxide and also at the said reaction temperatures in the reaction.

homeslice - 13-12-2012 at 07:23

Recently.

800g 91% IPA, 385g hydroquinone, and 6.2g I2 were added to a 6 liter 2 neck flat bottom flask fitted with two 400mm allihn condensers. Solution was stirred and heated until hydroquinone dissolved completely, to about 35 degrees. Stirring was discontinued.

420g 35% H2O2 was added all at once to the solution and the hotplate was placed on HI. Stirring was kept to a minimum. Solution is brought right to the boiling point. If the reaction becomes too violent, slow down the stirring and remove the heat. Boil 2-3 minutes.

Gas very well might escape the condensers when the B.P. is initially reached so be prepared. Gloves, glasses, respirator.

Solution was cooled at room temperature, then transferred to a freezer. Solution was vacuum filtered and at first the crystals appeared dark, almost black, but washing them once with IPA showed nice bright yellow crystals with few, less than 5%, dark specs. Recrystallize with 300g IPA. Cool and vacuum filter.

Yield: 341.6g

Alternatively, you can bring the solution to a rolling boil without any H2O2 and then add it dropwise into the rolling boil for a much more contained, safer, and calmer reaction and you will get decent results, but not as good as if you just add it wholesale and then bring it to a boil. Your yield will suffer if you go this route, however, if you have plenty of reagents, just scale it up and take the hit to yield.



Id like to add that ive tried the low heat addition over time and then letting it stir for hours. It never one time worked. All that was left was quinhydrone. Ive tried slower H2O2 additions prior to just boiling it, and it seems like ill get less of a yield with more black sludge. Ive tried adding the H2O2 drop by drop under reflux, not boiling, and you get nothing, just 100% black sludge. It has to boil.

And as far as the I2 is concerned. Ive seen as little a .5g I2 for every 50g Hydroquinone used. But, it seems to be more consistent using around the actual 1.0 gram. This reaction was done with .8 gram and it worked fine.

And one more note. It seems you can be left with 3 possible ending products. The para-benzoquinone, quinhydrone, and these black specs/black sludge. Quinhydrone is a mix of hydroquinone and parabenzoquinone that is formed by the reaction going halfway but not all the way to parabenzoquinone.

Im not sure what the black sludge/specs are but i have noticed that this forms most predominately when the solution is not brought to an absolute rolling boil. For instance, you will get this black sludge if you add all of your H2O2 dropwise under gentle reflux where you add no heat of your own and just let the reaction of the H2O2 heat your solution. The black sludge dissolves very readily into IPA, even ice cold IPA, whereas parabenzoquinone will not. This is why recrystallization with IPA works best.

Also, if you end up with more black specs/sludge for whatever reason, you can always recrystallize two or three times to get down to the remaining benzo.

Hope this helps.

[Edited on 13-12-2012 by homeslice]

VitaminX - 17-12-2012 at 08:26

Have you tried Oxidation of Hydrochinone with HNO3 in an organic solvent like Chloroform/DCM?

E. Baroni and W. Kleinau described quantitative oxidation to benzoquinone 1936 ("Die Nitrierung yon Phenolen in Chloroform):

"Setzt man zu einer Lösung yon Hydrochinon in Chloroform
einige Tropfen Salpetersäure, so entsteht sofort eine starke Gelbfärbung,
die auch bei weiterem Zusatz yon Salpetersäure sich
nicht ändert. Es bildet sich in quantitativer Ausbeute Chinon.
Eine vorübergehende Bildung yon Chinhydron war nicht zu beobachten."

They say you basically just have to add concentrated HNO3 dropwise to your solution, it will turn yellow and you got 100% Benzoquinone. Unfortunately no molar ratios or anything like this is given but with a little bit of experimenting you can figure it out.

Edit: Maybe DCM would be better suited as a solvent for this particular reaction since its bp is much lower than CHCl3 and you can probabaly distill it off losing less product.

[Edited on 17-12-2012 by VitaminX]

lolcat - 17-1-2013 at 09:59

A few weeks ago I tried the synthesis of p-benzoquinone by route of the patent earlier noted. The experiment went alright until the vacuum filtration, at which that point I could only ever see a few of the yellow crystals. My first concern was that the vacuum was not strong enough and that not enough liquid was being pulled through, and although the pump that I use to run water through my aspirator is just a small aquarium pump, I don't think that was the issue. The labeled 35% hydrogen peroxide that I used, had originally when I bought it not been in the freezer, I had just left it out at room temperature for probably a month(I was scared that the label was lying, and that if I put it in the freezer, it would freeze and bust the bottle. Shortly after reading this form though, I then started to store it in the freezer, although I think it might be too late.

I have two questions; is the degradation of hydrogen peroxide an issue in my case? Would it have degraded that much after a month, such that I did not have an enough oxidizer in my experiment and that could be why I could only see such a small amount of yellow para-benzoquinone crystals?
My second question, (and forgive me if my chemistry is horrible, I am only a first year student at university) but could not more of a less concentrated hydrogen peroxide be used? Could one not use stoichiometry to see how many moles of H2O2 are in X amount of 35% H2O2 and then see how much say 3% H2O2 would need to be used? Admittedly, a great deal more 3% H2O2 would have to be used, but 3% is very cheap and can be bought at the drug store compared to 35%. I would appreciate if someone would care to explain the chemistry of whether or not that works. I am rather new here, and just learning chemistry, so please don't be too harsh.

DJF90 - 17-1-2013 at 11:02

You allowed the product to crystallise for long enough?

Hydrogen peroxide should not decompose that quickly. I store mine at room temperature, which reaches the mid twenties on the rare hot summer day. Its also quite old (several years), and it worked fine for the reaction. Don't use a more dilute solution of peroxide; 30 and 35% are both available and cheap (at least here in the uk).

mad.chemist - 26-1-2013 at 14:38

I am interested in trying this reaction but I have one concern. About 2 months ago I purchased food grade, i think 30%, hydrogen peroxide but I stupidly ignored the label and didn't put it in the freezer. Then about a month ago I read the wikipedia article on hydrogen peroxide and read that it decomposes at higher concentrations, so then I put it in the freezer. So my question is, will a significant amount of it have decomposed during that month period? I have tried looking online, but I haven't found any articles that discuss the rate of decomposition of hydrogen peroxide. Any advice or resources would be appreciated.

Lambda-Eyde - 26-1-2013 at 14:52

In a month..? Not much. I have some 35% hydrogen peroxide that's probably ten years old, it's still good and fizzy. I don't know *how* fizzy, I'll titrate it when I get the opportunity.

declined - 3-4-2013 at 08:16

Are we able to scale this up with, say, a 22L flask? Or do you think there can potentially be hazardous runaway rxns, or uncontrollable exothermic heating?

VitaminX - 14-4-2013 at 12:07

Quote: Originally posted by declined  
Are we able to scale this up with, say, a 22L flask? Or do you think there can potentially be hazardous runaway rxns, or uncontrollable exothermic heating?


I did it a while ago with about 180 grams Hydroquinone in a 1L flask. Total volume was about 750 ml and when it heated up it nearly poured out of my condenser. I would say that your total rxn volume should NOT exceed 40% of the volume capacity of your flask, then you should be fine because there is plenty of breathing room. Reaction works really nice though

angry tapir - 14-11-2013 at 18:17

I just love to read all the fascinating highlights of amateur chemistry that can be found here but usually I´m not really the person that actively participates. Suddenly erverything changed: I found myself in need of some benzoquinone and today is the day I finally give something back :)

My desperate need made me check some of the techniques discussed. I have some lab experience, so I was not really sure why I fucked up the last 3 times. Today I finally found out how it can be accomplished. But let's not get ahead of ourselves.

My first try was the synthesis found on Rhodium. I tried the method with the IPA and hydrogen peroxide. (mine had a concentration of about 30% so that *might* have something to do with it) The reaction mixture took on a dark colour, and in the end I heated everything to about 50 degree for three hours. The next day the solution was nearly colorless, leaving me behind clueless.

The next try: I added some 20ml of 50% H2SO4 and heated to 40 degree before slowly dripping in the peroxide. I heated to 55 degree and stirred for 3 hours. I ended up with qiunhydron. I said to myself "well, that's better than nothing" and filtered it. yield sucked, filtration as well.

I thought that it might be necessary to add some acid so I tried the whole thing with 50% hydrogen peroxide (made by destilling of water of peroxide with a rotary evaporator at 30 mbar) and added about 5 grams of p-Toluenesulfonic acid and did the reaction (0.5 mole scale) in 200ml IPA. After dripping in the peroxide I ramped up the temperature to about 74 degree. It started to boil and I had a hard time keeping it from becoming to vigorous. I ended up with black goo and no benzoquinone.

Then I did the following:

I concentrated peroxide with a rotovap to ~50% (I washed the flask with EDTA beforehand and added about 82ml of ~30% peroxide solution to a 250ml flask, and concentrated it until ~30-40 ml water had been collected. I used a graduated cylinder on a scale to determine the concentration and ended up with 48ml solution that weighed 56,2g, so this is a good way to concentrate peroxide solution without losing much of it) In a 500ml RBF I added 0.63g Iodine, 66,4g Benzoquinone and 200ml IPA. I heated to exactly 62 degree and started to add the peroxide at a rate of 1 drop every 2 seconds. Quinhydrone started to precipitate and stirring became nearly impossible. (if you have them use the stir bars that look like weights, for me they did a good job) After a bit less than half of the peroxide had been added I heated to 65 degree and decided to add the peroxide solution a bit faster. Two minutes later it looked like the soultion started to boil at the spot where the peroxide drippped in. I lowered to temperature to 60 degree and dripped in the peroxide more slowly. After having added all the peroxide heated to 64 degree again and 30 minurtes after that the precipitated quinhydrone had gone leaving behind a dark yellow/orange solution. I put that in the fridge and nice yellow crystals started to seperate. I put the flask in the freezer over night filtered the product and washed with ice cold IPA. The yield was 61,6g.



DJF90 - 15-11-2013 at 13:27

You do not need to pre-concentrate your peroxide. I've done this prep several times before on various scales, each time using 30% peroxide, and each time it worked as described.

I suspect the failures people are having is due to the execution of the reaction, and not the reaction itself.

angry tapir - 16-11-2013 at 09:15

I tried it again with 30% peroxide and did in the exact same way as before and it worked. So you´re right, it doesn´t depend on the concentration of the peroxide. So my mistakes were 1. adding acid (not necessary) and the wrong teperature management.
Again the yield was over 90% :)


[Edited on 16-11-2013 by angry tapir]