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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: a confused chiral girl on November 30, 2006, 04:43:34 PM

Title: How come the Grignard reagent is actaully consumed?
Post by: a confused chiral girl on November 30, 2006, 04:43:34 PM

when you add one equivalent of methylmagnesium iodide to ethyl acetoacetate, the Grignard reagent is consumed, but the only organice product obtained after H+ workup, the mixture is ethyl acetoacetate. Why is it like this, what happened to the Grignard reagent?
thank you!!

Title: Re: How come the Grignard reagent is actaully consumed?
Post by: Yggdrasil on November 30, 2006, 06:46:15 PM

What solvent are you using?  Do you have pure ethylacetoacetate or is there some ethyacetoacetic acid as well?

Title: Re: How come the Grignard reagent is actaully consumed?
Post by: Custos on November 30, 2006, 07:05:13 PM

The protons between the carbonyl groups of ethyl acetoacetate are relatively acidic. One equivalent of methyl Grignard is likely to abstract one proton (remember Grignards are both nucleophiles and strong bases) - which quenches the Grignard as methane. Aqueous work up gives ethyl acetoacetate back again.