Synthesis of benzotriazole from o-phenylenediamine
BP406P Medicinal Chemistry I Practical
To synthesize and submit benzotriazole from o-phenylene diamine and report its percentage yield.
- Practical medicinal chemistry by Dr. Devala Rao, page no:35.
- Comprehensive practical organic chemistry by V.K.Ahluwalia and Renu Aggarval, page no:121.
o-phenylenediamine, glacial acetic acid, sodium nitrite
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.
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 =
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.
Used in bulk drug industry as an important intermediate compound.
It is the basic nucleus present in anthelmintic drugs like mebendazole, thiabendazole etc.
Benzotriazole was prepared and submitted. The percentage yield was found to be ———
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