Since this topic isn't dead enough, I'll make a quick write up on my recent synth

p-benzoquinone was produced in the usual manner with Hydroquinone, H2O2 and I2(cat)

22.5g of hydroquinone was dissolved in 175ml of methanol to form a clear solution, followed by 22.5ml of sulfuric acid.  The sulfuric acid should be added very very slowly because it reacts violently with methanol.  After this, 2.25g of benzoquinone was added (the last of it).  This was set up for reflux for 4 hours.  After the four hours were up, the set-up was converted to distillation and 100ml of methanol stripped off. While doing this, a saturated solution of NaCl was prepared with 140g of NaCl and 400ml of water.  After 100ml of methanol was removed, the solution cooled.  200ml of this concentrated salt solution was added and immediately a brown oil floated to the top.

The mixture was extracted 3 times with 50ml of xylene.  All extracts were pooled together, and washed twice with the remaining NaCl solution.  This was added to a flask and set up for simple distillation.  150ml of xylene was stripped off and vacuum was pulled on the apparatus.  Violent bumping occurred as volatile organics boiled off suddenly.  The water was removed from the condenser and methoxy phenol began distilling over.  ~20ml was collected, but it began solidifying in the condenser.  I would recommend some way to heat up the other side of the glass to prevent this from happening for anyone who tries this.  Methanol was added to solvate and I'm now evaporating the methanol off.  Yields to be posted later.

It has not completely evaporated.  It was off white crystals coming over at roughly 140C (never looked hard at the thermometer) at full vacuum.  There was a tinge of red/brown in the receiving flask, due to the flask boil from the vacuum forcing a little extra into the condenser.  I'll finish evaporating and do a recrystallization tomorrow.

What are you recrystallizing it from? I know the suggestion is pet ether/ethyl acetate but what is the ratio?

Jesus he ain't kiddin when he says methanol and sulfuric acid react violently!

I had made quinhydrone not to long ago, and so i am attempting to make 4-methoxyphenol from it, with excess methanol and H2SO4 along with the addition of iron filings to produce the hydroquinone.
I originally reduced some of the quinhydrone to hydroquinone but upon evaporation it pretty much went back to quinhydrone since I left it at room temp for a few weeks

Either way, I hope the Fe reduction & methoxylation work in the same flask at the same time! It would make p-methoxyphenol significantly easier for me, so I guess I'll just have to see.

It was originally a dark black but with green bubbles but now it is black without the green bubbles - just a tiny of maybe brown? I think this suggests that the quinhydrone has turned into p-methoxyphenol and benzoquinone, why else would it lose its green color?

Careful if you had the acid to the methanol or the methanol to the acid. It was a bitch.

Douchermann, do you think you your p-methoxyphenol is free of hydroquinone and its buddies? Do you feel it is important to reflux 4 hours? I have been refluxing mine a for about four hours now, but I think I'll keep it going for another hour or so just for good measure I guess.

Awesome! Thanks for that info, I'll look into this and see if I can really purify the methoxyphenol from the junk I may have in it. I'd assume methoxyphenol would be more soluble in say.. toluene or something then hydroquinone.

I left my H2SO4/MeOH/Quinone crap in the flask overnight since I ran out of time to purify it, and I also used an excess of both MeOH and H2SO4 so along with the 6.5 hours of reflux it received, another ~15 hours of sitting should do it some good I guess.

Oh by the way, does your 4-methoxyphenol smell like pigs? I've read that p-cresol, aka 4-methoxyphenol, is the main chemical pigs let off to make their piggy smell.

I see. I thought mine started to smell like burning rubber, but then I realized the water tube to the condenser was touching the element.
I'll be pretty pissed if I don't get 4-methoxyphenol. I took it all the way from acetominophen haha

Considering I made my KNO3 to make my KNO2 to make the hydroquinone, no its a few more lol
This is straight up OTC.

p-cresol is para-methylphenol, yes.  You need to evaporate half the methanol before you add the brine.  You don't want to evap all of it, because the sulfuric acid will become too concentrated and mess with the product.  Then, it'll work quite well.

Dry methanol is unnecessary.  HEET is plenty water free (being around 1% H2O).  However, I could see how it could improve yeilds, so if you have it around, go for it.

So I was wondering if you could just leave out the condenser when distilling the oil? This would make a shorter path and maybe it wouldn't condense in the tube. I guess you would have to cool the receiving flask just to ensure that it doesn't escape. Is this possible?