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Preparation of B-Naphthol

This document provides the procedure for preparing phenyl azo β-naphthol. The procedure involves diazotizing aniline to form a diazonium salt solution, then coupling this diazonium salt with a β-naphthol solution in the presence of sodium hydroxide to form crystals of phenyl azo β-naphthol. The product is a direct dye that can be used for drying cotton cloth. Yield calculations and reactions are presented but not described in detail.

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3K views4 pages

Preparation of B-Naphthol

This document provides the procedure for preparing phenyl azo β-naphthol. The procedure involves diazotizing aniline to form a diazonium salt solution, then coupling this diazonium salt with a β-naphthol solution in the presence of sodium hydroxide to form crystals of phenyl azo β-naphthol. The product is a direct dye that can be used for drying cotton cloth. Yield calculations and reactions are presented but not described in detail.

Uploaded by

nithansa
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Chemical Engineering Department

EXPERIMENT NO. :

“PREPARATION OF PHENYL AZO β-NAPHTHOL”

1 Preparation of phenyl azo β-Naphthol


Chemical Engineering Department

EXPERIMENT NO. :

“PREPARATION OF PHENYL AZO β-NAPHTHOL”

Aim : To prepare phenyl Azo β-Naphthol.

Apparatus : Beaker, Ice- bath, stirrer, measuring cylinder, funnel, filter paper,
oven, etc.

Chemical : Aniline 5 gm, Conc. 16 ml HCL, 16 ml H 2O, NaOH 10 %, ice,


Glacial acetic acid, Alcohol, Methylated spirit etc.

Procedure : Dissolve 5 gm of aniline in 16 ml of conc. HCl & 16 ml water


contained in a small beaker or conical flask, Put the aniline solution
with a thermometer in a crushed ice bath & cool until the
temperature of the stirred solution falls below 5 0C.

Dissolve 4 gm of NaNO2 in 20 ml water by immerging in ice bath.


Add NaNO2 solution in small volume(1-2 ml at a time) to the cold
aniline solution & keep the aniline well stirred. The temperature
should be < 10 0C (Add ice to the mix if required). Add last portion
of NaNO2 more slowly, stir for 3-4 minute & test it with RI starch
paper for completion of diazotization.

Test the drop of solution with 3-4 drops of water with KI paper if
no intermediate blue colour observe at point of content with paper,
further add 1 ml of NaNO2. Prepare a solution of 7-8 gm β-
naphthol in 45 ml of 10 % NaOH solution in 250 ml beaker. Cool
the solution 5 0C by immersing in ice bath. (10% NaOH=4 gm
NaOH +40 gm H2O)

Stirr the naphthol solution vigorously and add the cold diazonium
salt solution very crystals of phenyl azo β-naphthol solution,
separate when all the diazonium salt solution has been added.
Allow the mix to stand in an ice bath for 30 minute with constant
stirring. Filter the solution through a Buckner funnel with gental
solution wash with water and drain water by pressing the crystals.

2 Preparation of phenyl azo β-Naphthol


Chemical Engineering Department

Application : Use in the drying of cotton cloth, this dye is direct dye.

Result :
(1) Theoretical yield = ________
(2) Practical yield obtained = ________
(3) % yield = ___________

3 Preparation of phenyl azo β-Naphthol


Chemical Engineering Department

Reactions :

Calculation :

gm Naphthol gm Dye
148 248
?

4 Preparation of phenyl azo β-Naphthol

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