Author Topic: chlorocresol to toluhydroquinone ?  (Read 560 times)

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  • Guest
chlorocresol to toluhydroquinone ?
« on: October 26, 2003, 10:33:00 PM »
4-chlor-3-methylphenol 1Kg ~$100

How would you turn this sucker into something useful without using a pressure vessel like in

Patent US2041593

? Any Ideas ?



  • Guest
« Reply #1 on: October 26, 2003, 11:24:00 PM »
It's too bad aromatic chlorines cannot me methoxylated with the various NaOMe-procedures. 4-methoxy-3-methylphenol would be the DOM precursor to use in a Reimer-Tiemann reaction or other phenol ortho formylations.


  • Guest
« Reply #2 on: October 28, 2003, 03:35:00 PM »
The patent says "from 100 degrees". A pressure cooker at 15 psi should do 120. Ning has a strong suspicion that this would bee enough. Remember that most patents are for industrial processes, so they need it to bee fast and efficient. But for a bee willing to wait a little, maybe milder conditions can bee applied with good results.
Why not put a beaker in a pressure cooker with some water in the botton and steam it for a while?

Yay, research!


  • Guest
You do have a point there with the 120°C ...
« Reply #3 on: October 29, 2003, 08:39:00 PM »
You do have a point there with the 120°C beeing enough if you are willing to wait, but you certainly don't want to do it using a pressure cooker - at least not in your kitchen -think of a 120°C hot cloud of NaOH/chlorocresol from the pressure release valve of the pot. Better put your chlorochresol/NaOH into an airtight heat/chemical resistant container. Now, I don't know what that container would be. Speaking of autoclavable plastic bags: surely not polyester. Polypropylene seems to have quite good resistance to alkaline solutions but max. temp for PP is 200°F (~93°C). Polyurethane seems to be better but I didn't find any good info on it (lack of time). Putting the rxn mixtr. into a bag, sealing it with an impulse sealer and heating it in a pressure cooker sounds good.



  • Guest
« Reply #4 on: October 29, 2003, 09:14:00 PM »
Not sure, but it seems to me that NaOH wouldn't evaporate in steam. That's how distillation works, right? And like I said, if you put it in a beaker, and filled the bottom of the cooker with water to absorb the heat, NaOH problems...Now, you said p-chlorocresol, right? Says on

this page

( that the boiling point is like 267 degrees, so you probably don't have to worry about that travelling around too much either. Might smell a bit....
Also, if you get a pressure cooker with a guage, you could probably just set it to boil a little bit low, so no steam came through the blow-off valve. Might even be able to do it without a guage--just run it till it blows off, then back up the heat a little bit.
Ning thinks a reflux at 100 degrees without pressure cooker, with condenser run to under water to catch any stink/gas is worth a try.


  • Guest
w/o water ?
« Reply #5 on: October 30, 2003, 08:34:00 PM »
What about running the reaction in a high boiling inert solvent, (petroleum?) at reflux ? The water doesn't seem to be essential, or am I off track here ?

ning: try distilling an aqu. alkaline solution and check pH of the contents of the receiving flask. I'm uncertain but suspect it to be still quite basic.

The possibility of chlorocresol being steam-distilled remains. If you put a beaker in a pressure cooker, it *has* to be an airtight one that will resist the pressure/temp/chems.



  • Guest
Sodium hydroxide in water vapour
« Reply #6 on: October 30, 2003, 09:18:00 PM »
Concerning the NaOH, have you ever noticed that when making a concentrated NaOH solution in an erlenmeyer (beakers are even worse) it is nice to put something like tissue paper over the neck, so that breathing in doesn't sting ones throat. It has to be because of NaOH carried over with vater vapour from the still warm solution. Somewhere in the depths of the Hive is a thread where this phenomenon is discussed but I can't find it.

One way to determine the amount of ammonium ions is to pour the solution to be analysed to sodium hydroxide solution in the flask of a distillation apparatus. The distillation head is then quickly replaced and the heat is turned on. The formed ammonium vapor is then lead to a beaker with a known amount of boric acid dissolved in water and the distillation is continued for a while to the point where the water coming over is no more basic. The formed borate ions are then titrated revealing the amount of ammonium ions in the solution. This quantitative analysis can be fucked up by distilling the basic solution to the point where sodium hydroxide starts coming over with the water vapour, giving wrong results in the titration.

What do you think could happen with the pressure cooker?


  • Guest
Low yields, but it might work...
« Reply #7 on: October 31, 2003, 02:02:00 PM »
1. In Tetrahedron, 1989, 45(17), 5565-5578 the reaction of chlorobenzene to methoxybenzene is reported, yield did not exceed 20%.

Post 477850

(Rhodium: "ArBr --NaOMe/Cu(I)--> ArOMe", Chemistry Discourse)

2. There is the possibility of performing an aromatic Finkelstein swap to 4-iodo-3-methylphenol. See J. Am. Chem. Soc. 2002, 124, 14844-14845,

Post 447454

(Rhodium: "Aromatic Finkelstein Reaction", Chemistry Discourse)
, reference 8:

Aryl chlorides react more slowly than aryl bromides. A 35% conversion (GC) of 4-chlorotoluene into 4-iodotoluene was observed after 24 h at 130°C

After the Finkelstein swap iodine can easily bee substituted with OMe to yield the desired compound.