For the identification of $\beta$-naphthol using dye test, it is necessary to use

(D) alkaline solution of $\beta$-naphthol.

(A) dichloromethane solution of $\beta$-naphthol.

(B) acidic solution of $\beta$-naphthol.

(C) neutral solution of $\beta$-naphthol.

JEE Advanced · 2014 · 25 May 2014 · Paper 2 · Compounds Containing Nitrogen

For the identification of

β

-naphthol using dye test, it is necessary to use

(A)dichloromethane solution of $β$ -naphthol.
(B)acidic solution of $β$ -naphthol.
(C)neutral solution of $β$ -naphthol.
(D)alkaline solution of $β$ -naphthol.✓ Correct

Answer: (D)

Solution

The dye test for

β

-naphthol involves coupling with a diazonium salt to form an azo dye. This coupling reaction occurs best in alkaline (basic) conditions. In alkaline solution,

β

-naphthol exists as the phenoxide ion (

β

-naphtholate), which is more nucleophilic and readily undergoes electrophilic substitution with the diazonium cation to form the colored azo dye. Therefore, an alkaline solution is necessary.

JEE Advanced · 2014 · 25 May 2014 · Paper 2 · Single correct option

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JEE Advanced · 2014 · 25 May 2014 · Paper 2 · Compounds Containing Nitrogen

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