Grignard P2P Synthesis: Catalysts

[PrimoPyro]

This is some info for the search engine that I did not see upon review of

https://www.thevespiary.org/rhodium/Rhodium/chemistry/phenylacetone.html#grignard

so I will add it.

"Ketones can be prepared by addition of Grignard reagents to nitriles and subsequent hydrolysis. Many ketones have been made in this manner, though when both R groups are alkyl, yields are not high. Yields can be improved by the use of Cu(I) salts or by using benzene containing one equivalent of ether as solvent, rather than ether alone. The ketimine salt does not in general react with Grignard Reagents: Hence, tertiary alkyl amines are not often side products...."

So perhaps the low yield reported for the P2P synth from benzyl grignard and acetonitrile is due to the aliphatic nature of the reactants. Cu(I) salts and/or benzene may really help raise the yields of this reaction, and should seriously be considered by anyone wanting to attempt this reaction.

Alchemy_bee, I hope you are seeing this,as I know you wished for more information on the subject. I found this, and figured everyone might like to hear it.

I wonder if toluene can sub for benzene here?

Source:
March's Advanced Organic Chemistry, 5th Ed. pg.1217

Additional references cited in this excerpt for the cited data:
Kharasch, M.S.; Reinmuth, O. Ref. 366, p. 767
Weiberth, F.J.; Hall, S.S. J. Org. Chem., 1987, 52, 3901.
Canonne, P.; Foscolos, G.B.; Lemay, G. Tetrahedron Lett., 1980, 155.

Keywords to help Users of TFSE find this post: Grignard, Nitrile, Ketone, P2P, Catalyst, Cu, Copper.

                                                  PrimoPyro
Vivent Longtemps La Ruche!

[hest]

I wonder if toluene can sub for benzene here

Yes it's posible, As lomg as you has 1 (2-4)mole of ether (THF) to one mole of Mg. I'm sure the best way to doo it is to make the Grignard reagens in pure ether, and then dilute the gn. reagense with dry toluene. after all, my dimethozybromobenzene might come handy.