EXPERIMENT 11: GRIGNARD

Grignard

alkynes get de-protonated by _________ reagents. -reacts with carbonyl to add on alkyl group, reacts twice with esters and can act as strong base

GRIGNARD

rignard reagents are very reactive and must be synthesized in an environment free of water or any other source of potential proton donor. Once made, the Grignard reagent will do a nucleophilic attack on the carbonyl carbon of the ketone, benzophenone. The result is an alkoxide that is then protonated to give the alcohol, triphenylmethanol. The purity of the final product will then be characterized by melting point determination and IR spectroscopy.

If water were present in the first step of bromobenzene with magnesium, what products would you form?

If water were present in the first step of bromobenzene with magnesium the product that would form is benzene due MgBr reacting with H2O acidic proton.

Grignard Reagent Formation

R-Br + Mg -> R-MgBr

After you isolated your product, you were told to add hexanes. What was the purpose off adding hexanes?

The product is triphenyl methanol which has very little solubility with hexanes allowing it to crystallize while the remaining material is in solution.

Grignard Reaction

A carbonyl addition reaction between a Grignard reagent (R-MgX) with an aldehyde or ketone to produce an alcohol.

Grignard reagent

An alkyl magnesium halide that is used to make carbon-carbon bonds.