Question

These are grinard experiment questions from organic chemistry lab

1) why is it ao critical to the Grinard formation that the diethyl ether solvent be from a freshly-opened can of anhydrous ether?

2) What is the purpose of mechanically-abrading the surface of the Mg pieces prior to use?

3) Work up the magnesium alkoxide product specifies adding cold 1.0M H2SO4 to the crude reaction mixture. Do you think other acids might be used instead of sulfiric for the operation? Why or why not

Answer 1

R -Br + Mg ------------> R -MgBr

R -MgBr is a Grignard reagent which acts as a good nucleophile and a strong base.

Diethyl ether is a good solvent for Grignard reagents formation because of the following reasons :

Generally Diethyl ethers is non-acidic (aprotic).

It is highly volatile as they forms vapors and prevent   oxygen and isolate from the rea.

Diethyl ether helps in stabilizing the Grignard reagent.

As Grignard reagent is highly nucleophilic, other solvents like Water/ alcohols protonate the reagent .So diethyl ether is preferred.

Grignard reagent contains a the magnesium ion that is been stabilized by the diethyl ether.