Question

Ethyl formate on treating with excess of methyl magnesium bromide followed by hydrolysis gives:
(A) Ethanol
(B) Propanone
(C) 2-propanol
(D) 1-propanol

Answer 1

This is the Grignard reaction where methyl magnesium bromide being a nucleophile attacks the electrophilic part of carbonyl compound i.e., ethyl formate to give us ethanol (commonly known as acetaldehyde). Once again Grignard reagent will attack as nucleophile until all the electrophilicity of the substrate is replaced by carbon-carbon bonds. Then finally we will hydrolyze it to get our desired product.

Complete step-by-step answer:
As we know that the Grignard reaction is an organometallic chemical reaction in which alkyl, allyl, vinyl, or aryl-magnesium halides is added to carbonyl compounds. Grignard reactions are of huge importance due to their ability to form carbon-carbon bonds.
The reaction takes place as follows:-
-The methyl part of Grignard reagent will act as a nucleophile and will attack the electron deficient part of carbonyl compound i.e., carbon. The negative charge on oxygen atom will show backbond and ethoxy ($-O{{C}_{2}}{{H}_{5}}$ ) group will leave simultaneously. This will lead to the formation of acetaldehyde.

-Since it is given that Grignard reagent is present in excess, therefore it will again attack the carbonyl part and electron cloud will shift on oxygen atom.

-As we can see that all the electrophilicity of the substrate has been replaced by carbon-carbon bonds hence we can finally hydrolyze it to give alcohol. The alcohol formed is 2-propanol.

Hence, the correct option is (C) 2-propanol.

Note: -While solving such types of questions, always see whether excess treatment with reagent is given or not and do it accordingly because if we miss this point, then we may not obtain the desired product.
-Practically we should take safety precautions while preparing Grignard reagent as it is a highly exothermic reaction and can be hazardous.