Chemical Forums

Please login or register.

Login with username, password and session length

Sponsored links

Pages: [1]   Go Down

Author Topic: Synthesis of quinone methide.  (Read 5090 times)

0 Members and 1 Guest are viewing this topic.

ptb969

  • Guest
Synthesis of quinone methide.
« on: May 14, 2007, 05:08:59 AM »

Hallo,
I am supposed to prepare a quinone methide (number 3, attachment below) for my further study.
I am thinking to start from 2,6-diphenyl phenol (1) via the alcohol number 2 and with an oxidation by Ag2O to get the desired product.
I am not quite sure how to prepare the alcohol number 2. I am intending to convert 2,6-diphenyl phenol to 4-chloromethyl-2,6-diphenyl phenol (4) and then to do a Friedel-Craft alkylation with methoxybenzene. If the Friedel-Craft reaction worked, however, one would have to consider to obtain a mixture of two products as the result of the alkylations at the ortho and para positions with respect to the methoxy group.
Any one has ideas, suggestions or comments? I would appreciate very much.
Best regards,
PTB969
Logged

Panoramix

  • Regular Member
  • ***
  • Mole Snacks: +1/-1
  • Offline Offline
  • Posts: 13
Re: Synthesis of quinone methide.
« Reply #1 on: May 14, 2007, 08:11:04 AM »

Why not use 4-methoxybenzoyl chloride (50 ml/30Euro) under Friedel-Crafts conditions to get the benzophenone and reduce the ketone with any of the dozen possibilities?
Perhaps 4-methoxy benzylchloride might even work, too.
4-Methoxy benzylalcohol with BF3*OEt2 could be an alternative.

I don't think you will have problems with the regioselectivity because the positions ortho to the phenyl rings are quite hindered, the phenol is para dirigating and the central ring is the most activated.
Logged

ptb969

  • Guest
Re: Synthesis of quinone methide.
« Reply #2 on: May 14, 2007, 11:46:24 PM »

Hallo everyone,
Hallo Panoramix,
thank you for your suggestions.

I have also thought of the possibility to carry out a direct Friedel-Craft reaction between 2,6-diphenyl phenol and 4-methoxy benzylchloride. In my opinion, that would be the shortest way to get the alcohol number 2. If you also do not think there will be problems with the regioselectivity (because the positions ortho to the phenyl rings are quite hindered, on the other hand, the phenol is para dirigating and the central ring is the most activated), it is worth to do try.

The use of 4-methoxybenzoyl chloride (50 ml/30Euro) under Friedel-Crafts conditions to get the benzophenone and reduce the ketone is also an idea. It is, however, one more step to do.

Best regards,
PTB969
Logged

Panoramix

  • Regular Member
  • ***
  • Mole Snacks: +1/-1
  • Offline Offline
  • Posts: 13
Re: Synthesis of quinone methide.
« Reply #3 on: May 15, 2007, 02:20:34 AM »

Please keep us updated about the results so we can learn something....
Logged

ptb969

  • Guest
Re: Synthesis of quinone methide.
« Reply #4 on: May 15, 2007, 10:13:00 PM »

Unfortunately, I am in hospital because of a knee injury caused by soccer.
Later on, I will try to do some experiments and I can tell the result.
In hospital, I still keep thinking about the work and I will get to the forum when I am allowed to go to Internet Corner.
Hope to get more discussion form you.
Best regards to all.
PTB969
Logged

ptb969

  • Guest
Re: Synthesis of quinone methide.
« Reply #5 on: May 30, 2007, 03:27:23 AM »

Hallo,
Yesterday, I thought of a way to perform the Friedel-Craft alkylation of the diphenyl phenol. I did not want to use any catalyst, so just wanted to take a solvent with high ionizing power to get the 4-methoxy benzylchloride ionized. The carbocation will react with phenyl ring to get the alkylation product.
The point is the solvent and should have sufficient ionizing power and should be of lower nucleophilicity than the diphenyl phenol, this way the carbocation formed would not be trapped by the solvent but the phenol. I have used trifluoro ethanol as a solvent, it still does not work well. Do you have any suggestions?
It would be interesting to perform some experiments of that type.
Best regards,
PTB969
Logged
Pages: [1]   Go Up
 

Mitch Andre Garcia's Chemical Forums 2003-Present.

Page created in 0.056 seconds with 23 queries.