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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: alexanderdundua on December 09, 2007, 05:36:57 AM

Title: grignard reaction
Post by: alexanderdundua on December 09, 2007, 05:36:57 AM

hey,
I have a question
is the following reaction possible?
C₆H₅Br+BrMgCCH = C₆H₅CCH+MgBr₂

Title: Re: grignard reaction
Post by: Yarr on December 09, 2007, 06:37:02 AM

Your alkynyl Grignard reagent is expected to react with itself.

Title: Re: grignard reaction
Post by: alexanderdundua on December 09, 2007, 07:06:44 AM

no, it will not react with itself. BrMgCCH is quite stabile reagent. some chemical companies provide it as solutions in some organic solvents.

Title: Re: grignard reaction
Post by: agrobert on December 09, 2007, 02:21:20 PM

Can you propose a reasonable mechanism?

Title: Re: grignard reaction
Post by: OldThrashbarg on December 10, 2007, 12:45:13 PM

Grignard aside, can you have nucleophilic aromatic substitution without any strong electron withdrawing groups?

Title: Re: grignard reaction
Post by: PAY on December 12, 2007, 11:48:37 AM

Quote from: Yarr on December 09, 2007, 06:37:02 AM

Your alkynyl Grignard reagent is expected to react with itself.

This reagent must react with itself anyway! For avoiding this events needs to protect terminal triple bond with Me3Si- or other protective group. Then? this reaction provide coupling product. Especially, if you'll provide this reaction in Kumada conditions(Pd-catalysis).