Synthesis of benzotriazole from o-phenylenediamine
BP406P Medicinal Chemistry I Practical
AIM:
To synthesize and submit benzotriazole from o-phenylene diamine and report its percentage yield.
REFERENCE:
- Practical medicinal chemistry by Dr. Devala Rao, page no:35.
- Comprehensive practical organic chemistry by V.K.Ahluwalia and Renu Aggarval, page no:121.
CHEMICAL REQUIREMENTS:
o-phenylenediamine, glacial acetic acid, sodium nitrite
PRINCIPLE:
The sodium nitrite reacts with glacial acetic acid and liberates nitrous acid. The o-phenylene diamine reacts with nitrous acid and produces a diazonium ion. When the structure and stereochemistry of diazonium ion are stable, intramolecular nitrogen coupling occurs and forms benzotriazole directly.
CALCULATIONS
The molecular weight of o-phenylene diamine = Molecular weight of benzotriazole =
—- g of o-phenylene diamine gives —- g of benzotriazole 1g of o-phenylene diamine =
=
—- g of o-phenylene diamine =
Theoretical yield =
Practical yield =
Percentage yield =
PROCEDURE:
Dissolve 1.3g of o-phenylenediamine in a mixture of 1.5ml of glacial acetic acid and 5ml water in a beaker. Stir until the solid dissolves, warm gently if necessary. Cool the solution to 150C. Stir well and add a solution of 2g of sodium nitrite in 2ml water. Reaction mixture become warm within 2-3 minutes and reaches a temperature of about 850C and then begins to cool. Colour changes from deep red to pale brown. Continue stirring for 15 minutes till the temperature fall about 35-400C. Thoroughly chill in ice bath for 30 minutes. Filter the product and wash with cold water.
USE:
Used in bulk drug industry as an important intermediate compound.
It is the basic nucleus present in anthelmintic drugs like mebendazole, thiabendazole etc.
REPORT:
Benzotriazole was prepared and submitted. The percentage yield was found to be ———
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