The reagent 'R' in the given sequence of chemical reaction is : [figure]
- CuCN/KCN
- H2O
- CH3CH2OH
- HI
Answer
(3) CH3CH2OH
Solution
2,4,6-Tribromoaniline is diazotised to 2,4,6-tribromobenzenediazonium chloride.
The product, 1,3,5-tribromobenzene, has H in place of -N2+Cl- ⇒ reductive removal of the diazo group.
As per NCERT, mild reducing agents such as ethanol (or hypophosphorous acid) reduce diazonium salts to arenes:
ArN2+Cl- + CH3CH2OH ArH + N2 + CH3CHO + HCl
(CuCN/KCN gives ArCN, H2O gives ArOH, HI/KI gives ArI.)
∴ R = CH3CH2OH
Answer: (3)