In the given reaction
`RCN underset((ii)H_2O //H^+)overset((i)RMgX)rarr(X)`, (X) will be

Options

A. Aldehyde
B. Ketone
C. Tertiary alcohol
D. Secondary alcohol

Answer

To solve the given reaction:

**Step 1: Identify the Reactants**
The reactants in the reaction are RCN (where R is an organic group and CN is a cyano group) and RMgX (where RMgX is a Grignard reagent).

**Step 2: Understand the Role of Grignard Reagent**
The Grignard reagent (RMgX) acts as a nucleophile. The carbon atom in the cyano group (C≡N) has a partial positive charge due to the electronegativity difference between carbon and nitrogen. Therefore, the Grignard reagent will attack this carbon atom.

**Step 3: Nucleophilic Attack**
When RMgX attacks the carbon of the cyano group, it forms an intermediate where the cyano group becomes a carbon-nitrogen double bond (R-C=N-R') and the nitrogen atom now has a lone pair and a positive charge.

**Step 4: Protonation of the Nitrogen**
The nitrogen atom in the intermediate can then be protonated by water (H2O) or H+. This leads to the formation of a positively charged nitrogen species (R-C=N^+-R').

**Step 5: Water Attack**
Next, the water molecule (H2O) can attack the carbon atom that is now bonded to nitrogen. This results in the formation of a new intermediate where the carbon has a hydroxyl group (OH) and the nitrogen still has a positive charge (R-C(OH)-N^+-R').

**Step 6: Rearrangement and Deprotonation**
The positively charged nitrogen can lose a proton (H+) to stabilize the molecule. This results in the formation of a ketone (R-C(=O)-R').

**Step 7: Final Product**
Thus, the final product (X) of the reaction is a ketone, which is represented as R-C(=O)-R'.

**Conclusion**
The product (X) formed in the reaction is a ketone.