[Moz29386]

We are synthesisng 5,5-diphenylhydantoin from urea and benzil.

I need to know the mechanism for that synthesis if possible please.

I've searched the forum and this is what I found 

http://en.wikipedia.org/wiki/Benzilic_acid_rearrangement

But it doesnt help as the reaction is not complete.

Thanks.

Also; Describe a convienient method (with equations) for the synthesis of benzil. (do not include full experimental details),

[OC pro]

It´s a simple condensation. 2 Moles of water will be formed. Thats all for the mechanism.

[Doc Oc]

It's not just a simple condensation, at least one of those ketones from the benzil has to be preserved in the final product.

Take a look at this paper:  J. Chem. Educ.  1986, 63, 650.

[orgopete]

I would try writing the mechanism as an aza-benzylic acid rearrangement. First form a C=NCONH₂ from one of the C=O groups. Do the rearrangement to give the urea-acid. Loss of water should give the hydantoin.