Polynuclear hydrocarbons Module3

Module 3
Preparation of Naphthalene derivatives - Naphthols - 1-Naphthols and 2-Naphthols - Preparation - Reactions of naphthols

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Preparation of Naphthalene derivatives
1. Naphthols
a) Preparation of Naphthols:
There are 2 isomeric naphthols

i) Fusion of naphthalene-1-sulphonic acid with NaOH gives 1-naphthol or -naphthol

ii) Similarly fusion of naphthalene-2-sulphonic acid with NaOH gives 2-naphthol or
-naphthol.

iii) Pure 1-naphthol is prepared by heating 1-naphthyl amine with dil.H
2
SO
4
at 300
o
C
under pressure.

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Reactions of naphthols
i) Electrophilic substitution reactions:
They undergo halogenation, nitration, sulphonation, etc.

ii) They reduce ammonical silver nitrate (Tollen’s reagent)
iii) Reduction : They are reduced by sodium and isoamyl alcohol to yield
tetrahydronaphthols.

iv) Reaction with nitrous acid: They react with nitrous acid to form monoximes like
resorcinol or phloroglucinol.

Similarly -naphthol forms -Naphthaquinone-1-oxime

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v) Oxidation: They are oxidised by alkaline permanganate to phthalonic acid.

-Naphthol is oxidised to -naphthaquinone by chromic acid.

Prepared by
Dr. A. Syed Mohamed
HoD and Senior Assistant Professor, Research Dept. of Chemistry
Sadakathullah Appa College (Autonomous)
Tirunelveli, Tamilnadu, India. [email protected]
The author ackowledges Prof. H. Kassali Rahmathullah, Dr. T. Syed Ismail, Dr. M.
Kamalutheen, Former Professor, Dept. of Chemistry, Sadakathullah Appa College for their
valuable contribution.