Question

When phenyl magnesium bromide is reacted with t-Butyl alcohol it gives

• A. $\mathrm{Ph}-\mathrm{H}$
• B. $\mathrm{Ph}-\mathrm{OH}$
• C. $\mathrm{Ph}-\mathrm{O}-\mathrm{C}-{\mathrm{CH}}_2-{\mathrm{CH}}_3$
• D. $\mathrm{Ph}-\mathrm{O}-\mathrm{C}-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_3$

Answer 1

The correct option is A

$\mathrm{Ph}-\mathrm{H}$

Explanation for correct option:

(a) $\mathrm{Ph}-\mathrm{H}$$\left({\mathrm{C}}_6{\mathrm{H}}_6\right)$

• $$\begin{gathered} \mathrm{Ph}-\mathrm{Mg}-\mathrm{Br}+\mathrm{tBu}-\mathrm{OH}\to {\mathrm{C}}_6{\mathrm{H}}_6+\mathrm{tBu}-\mathrm{OMgBr} \\ \left(\mathrm{Benzene}\right) \end{gathered}$$
• The resulting product is benzene.
• When a Grignard reagent, such as phenyl $\mathrm{MgBr}$ combines with alcohol, we obtain alkane, which corresponds to the alkyl portion of the Grignard reagent.
• Because the $\mathrm{C}$ atom is more electronegative than the Mg atom, the alkyl portion serves as a nucleophile, absorbing an active H to produce the equivalent alkane.
• Hence it is the correct option.

Explanation for incorrect options :

(a) $\mathrm{Ph}-\mathrm{OH}$

• The resulting product is benzene
• $\mathrm{Ph}-\mathrm{OH}$ is not the product.
• Hence this option is not correct

(b) $\mathrm{Ph}-\mathrm{O}-\mathrm{C}-{\mathrm{CH}}_2-{\mathrm{CH}}_3$

• The resulting product is benzene
• $\mathrm{Ph}-\mathrm{O}-\mathrm{C}-{\mathrm{CH}}_2-{\mathrm{CH}}_3$ is not the product.
• Hence this option is not correct

(d) $\mathrm{Ph}-\mathrm{O}-\mathrm{C}-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_3$

• The resulting product is benzene
• $\mathrm{Ph}-\mathrm{O}-\mathrm{C}-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_3$ is not the product.
• Hence this option is not correct

Therefore the correct option is (a) $\mathrm{Ph}-\mathrm{H}$.