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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Bart on January 20, 2015, 04:40:43 PM

Title: Sb(Ph)3 as catalyst (POCl3 + PhOH)
Post by: Bart on January 20, 2015, 04:40:43 PM

Hi guys,

I'm new to this forum, so I would like to say hello!  :)

I have a question regarding mechanism of a reaction that I'm currently working 'cause and I hit the wall.

I'm working on the reaction of POCl3 with PhOH in the presence of Sb(Ph)3 as a catalyst, the product is P(OPh)3. Now I try to figure out the possible mechanism of this reaction and what's the role of the catalyst in this process.
What knocked me out is that I have observed in the product some small amounts of benzene and I have no idea how to connect this with the mechanism.

Do you have any suggestions concerning the possible path of this reaction. There is almost noe literature about this processes.

Thanks in advance!

Title: Re: Sb(Ph)3 as catalyst (POCl3 + PhOH)
Post by: mjc123 on January 21, 2015, 04:49:01 AM

What gets oxidised in this reaction? You've got P(V) going to P(III), what happens to the oxygen?

Title: Re: Sb(Ph)3 as catalyst (POCl3 + PhOH)
Post by: Bart on January 21, 2015, 07:03:24 AM

Oh, I'm sorry, my mistake. The final product is O=P(OPh)₃

Regards

Title: Re: Sb(Ph)3 as catalyst (POCl3 + PhOH)
Post by: mjc123 on January 21, 2015, 08:23:54 AM

That makes more sense.
It would seem to me more likely that the benzene came from the SbPh₃ than the phenol, reacting perhaps with the acidic H of phenol.
What if you do the reaction with 4-methylphenol instead of phenol? Do you still get benzene, or toluene? (Or both - that would be confusing!)