Question

The product formed in the given reaction is Phenylmagnesium bromide (C$_6$H$_5$-MgBr) reacting with D$_2$O, leading to product ?.

• A. C$_6$H$_5$-OD (Phenol with D on O)
• B. C$_6$H$_5$-OH (Phenol)
• C. C$_6$H$_6$ (Benzene)
• D. C$_6$H$_5$-D (Deuterated Benzene)

Hint:

Grignard reagents (R-MgX) act as strong bases (R$^-$ is a strong base).
They react readily with any compound that has acidic hydrogen (protons), such as water, alcohols, amines, terminal alkynes.
In this case, D$_2$O provides acidic deuterium atoms.
The R$^-$ part of the Grignard reagent abstracts D from D$_2$O to form R-D.
C$_6$H$_5$-MgBr + D$_2$O $\rightarrow$ C$_6$H$_5$-D + Mg(OD)Br.

Answer 1

The Correct Option is D

To solve the given reaction, we first need to understand the nature and behavior of phenylmagnesium bromide (C₆H₅-MgBr). It is a Grignard reagent, which is highly reactive and typically acts as a nucleophile.

When phenylmagnesium bromide reacts with deuterium oxide (D₂O), the Grignard reagent acts by abstracting a deuterium ion (D⁺) from D₂O. This is because Grignard reagents are strong organometallic bases that readily react with protic solvents like water to form hydrocarbons. Hence, the specific role of D₂O here is to provide a source of the deuterium isotope (D).

The reaction can be expressed as follows:

C₆H₅-MgBr + D₂O → C₆H₅-D + Mg(OD)Br

In this reaction, C₆H₅-D represents deuterated benzene, where a hydrogen atom on the benzene ring is replaced by deuterium.

Therefore, the product of the reaction is deuterated benzene, C₆H₅-D.

Options	Correct Answer
C6H5-OD	C6H5-D
C6H5-OH
C6H6
C6H5-D