Question

In the following reaction, the product X is:
\[{{C}_{6}}{{H}_{5}}C{{H}_{2}}Br\xrightarrow[2.{{H}_{3}}{{O}^{+}}]{1.Mg/Ether}X\]
(a) ${{C}_{6}}{{H}_{5}}C{{H}_{2}}OC{{H}_{2}}{{C}_{6}}{{H}_{5}}$
(b) ${{C}_{6}}{{H}_{5}}C{{H}_{2}}OH$
(c) ${{C}_{6}}{{H}_{5}}C{{H}_{3}}$
(d) ${{C}_{6}}{{H}_{5}}C{{H}_{2}}C{{H}_{2}}{{C}_{6}}{{H}_{5}}$

Answer 1

Hint: Grignard reagents on reaction with the alkyl halides undergoes the substitution reaction i.e. the replacement of the halide group by another group i.e. R group of the Grignard reagent . Now write the chemical reaction and then ,you can easily identify the product.

Complete step by step solution:
- The above reaction is of the alkyl halide with the Grignard reagent. Now first discuss what are alkyl halides and the Grignard reagents. Alkyl halides consist of the alkyl group and the halogens and are formed due the reactions between the alkanes with the halogen, halogen acids and thus, results in the formation of the alkyl halides.
- On the other hand, Grignard reagents are the alkyl or aryl derivatives of magnesium halides and has the general chemical formula as $RMgX$
- Here, $R$ is the alkyl or aryl group and $X$ is the halogen and $Mg$ is the magnesium.
- The $C-Mg$ bond in the Grignard reagent is very highly polar because of the highly electronegative nature of the carbon atom. Due to this polar nature, the Grignard reagents are very versatile reagents.
- The reaction of the alkyl halide with the Grignard reagents involves the simultaneous attack of the nucleophile alkyl carbanion of the Grignard reagent on the carbon atom and the halide ion from the alkyl halide group attaches to the Mg. The reaction of the Grignard reagent occurs always in the dry conditions i.e. these reactions occur always in the presence of the dry ether.
The reaction occurs as;
\[{{C}_{6}}{{H}_{5}}C{{H}_{2}}Br\xrightarrow[2.{{H}_{3}}{{O}^{+}}]{1.Mg/Ether}{{C}_{6}}{{H}_{5}}C{{H}_{3}}MgBr\to {{C}_{6}}{{H}_{5}}C{{H}_{3}}+Mg(Br)(OH)\]

Thus, option (c) is correct.

Note: Grignard reagents are very strong alkalis and are very strong nucleophiles too ( i.e. they can easily donate electrons to the other atoms)’ it is very important and useful organic compound and helps in the formation of many new compounds such as alcohols, alkanes , alkynes etc.