Aryl Halides and Phenols - Result Question 14

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

(2014 Adv.)

(a) dichloromethane solution of $\beta$-naphthol

(b) acidic solution of $\beta$-naphthol

(c) neutral solution of $\beta$-naphthol

(d) alkaline solution of $\beta$-naphthol

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Answer:

Correct Answer: 17. (d)

Solution:

PLAN: This problem can be solved by using the concept of synthesis of dye using electrophilic aromatic substitution reaction.

In basic (alkaline) solution naphthol exists as naphthoxide ion which is a strong $o, p$-directing group.

<img src=“https://temp-public-img-folder.s3.amazonaws.com/sathee.prutor.images/sathee_image/snip_images_aktWLNRmGTp6zCZyCE4nWyqndSBA7pZHehCjz3zoLeE_original_fullsize_png.jpg"width="400"/>

Thus, formation of dye can be shown as

<img src=“https://temp-public-img-folder.s3.amazonaws.com/sathee.prutor.images/sathee_image/snip_images_QcLFenwWA7eu1vSsy5aFuQQrEF3NJfLLAEmuadNMfTM_original_fullsize_png.jpg"width="400"/>

Thus, (d) is the correct choice.