Question

which one of the following compounds converts methyl magnesium iodide to methane in one step?
A.${{C}_{2}}{{H}_{5}}O{{C}_{2}}{{H}_{5}}$
B.${{C}_{2}}{{H}_{5}}Cl$
C.${{C}_{2}}{{H}_{4}}$
D.${{C}_{2}}{{H}_{5}}OH$

Answer 1

Hint: Methyl magnesium iodide is an organ metallic compound called Grignard reagent. The Grignard reagent is capable of generating a nucleophile that takes part in the reaction. This nucleophile is generated from the carbon of the Grignard reagent due to the presence of a lone pair of electrons on it.

Complete answer:
Methyl magnesium iodide is a Grignard reagent. Grignard reagents are highly basic in nature, so they can react with any species that donates a proton. Grignard reagents are capable of generating a nucleophile, which can react with electrophiles in addition to reactions.
Among the given options, only ethyl alcohol ${{C}_{2}}{{H}_{5}}OH$is capable of providing a proton to the Grignard reagent. Other molecules, like ethers (ethoxy ethane), haloalkane (chloroethane), and ethene, do not have much acidic character so that they liberate a proton.
So, the reaction of Grignard reagent with an alcohol will yield an alkane, which will be a methane molecule with ethyl alcohol, ${{C}_{2}}{{H}_{5}}OH$ in a single step, as the nucleophile from the Grignard will attach with the polar bond, then a cleavage will happen, which will form an alkane. The reaction is as follows,
${{C}_{2}}{{H}_{5}}OH+C{{H}_{3}}MgI\to C{{H}_{4}}+IMgOC{{H}_{2}}C{{H}_{3}}$
Hence, ethyl alcohol, ${{C}_{2}}{{H}_{5}}OH$will convert methyl magnesium iodide into methane in a single step.

Note:
The acidity of alcohols is used in this reaction which breaks the O – H bond in alcohols, due to the basicity of Grignard reagents. Grignard reagents are said to readily react with compounds containing carbonyl groups. They react with aldehydes and ketones to yield alcohols, also they react with carbon dioxide and epoxides.