Question

The reagent ‘R’ in the given sequence of chemical reaction is

• A. CuCN/KCN
• B. H₂O
• C. CH₃CH₂OH
• D. HI

Answer 1

The Correct Option is C

To solve this question, we need to identify the reagent 'R' in the given chemical reaction sequence.

The sequence involves the following steps:

1. The starting material is an aniline derivative, which is converted into a diazonium salt using NaNO_2 and HCl at 0 - 5°C. This is a standard procedure to form diazonium salts from aromatic amines.
2. The diazonium salt can undergo various reactions depending on the reagent used next. Here, we need to identify 'R'. The product shows that a replacement of N_2^+Cl^- with hydrogen occurs, typically done using an alcohol.

Given the options, we evaluate their suitability for this task:

• CuCN/KCN: Typically used for introducing cyano groups, not suitable here.
• H₂O: Would result in phenol formation, which is not the observed product.
• CH₃CH₂OH (Ethanol): Commonly used in the reduction of diazonium salts to aryl hydrocarbons (replacing N_2^+Cl^- with hydrogen), which fits the product.
• HI: Used for converting diazonium groups into iodides, which does not match the product.

Thus, the correct choice is CH₃CH₂OH, as it successfully reduces the diazonium salt to the corresponding hydrocarbon.