Preparation of benzimidazole

Here, you find out the
Requirements for preparation of benzimidazole
Synthetic reaction of benzimidazole
Theory regarding benzimidazole
Procedure for preparation of benzimidazole
Observation and calculations
Result or report

1. D epartment of Pharmaceutical Sciences , MDU ROHTAK Medicinal Chemistry Practical Assignment Benzimidazole Presented by Dheeraj B.Pharm.4 th sem Roll no: 1431

2. A im : Prepare and submit benzimidazole from o-phenylenediazone. M ateria l requirements : O -phenylenediamine, formic acid(90 %) , sodium hydroxide, round bottle flask, beakers, buchner funnel, measuring cylinder, filter paper. Chemical reaction :

3. Condensation reaction is a reaction in which two molecules combines to form a single molecules.. A small molecule often water is usually removed during a condensation reaction. Amino acids are Important biological molecule that have a amine functional group on the end of molecules and a carboxylic acid functional group on the other end. When two amino and combine in a Condensation reaction , a covalent bond forms between the amino nitrogen of one amine acid and the carboxyl carbon of the second amine and a molecule of water is then removed as a side product. Different types of condensation reactions are : Aldol condensation Knoevenagel condensation Claisen condensation dieckman condensation Theory:

4. The two carbon –n-bond is benzimidazole when disconnected give o- phenylenediamine and formic acid. Therefore , synthesis of benziemidazole is affected by simply heating at o- phenylenediamine and formic acid together. P rinciple : Mechansim of reaction :

5. Place 27g if o- phenylenediamine in a round bottom flask of 250ml. Add 17.5g of 90%foromic acid. Heat the mix on water bench at 100degree celsius for other cool and add 10% sodium hydroxide solution. Slowly with constantly mix, rotation of flask , until the mixture in Just alkaline to litmus. Filter off the synthesized crude benzimidazole by Using the pump, wash with cold water, drain well and wash again with 25ml of cold water. Procedure:

6. Dissolve the synthesized product in 400ml of boiling water. Add 2gra of decolouring carbon and digest for 15mintues. Filter rapidly through a preheated bucheer funnel and a flask at the pump. Cool the filtrate at about 10 degree Celsius . Filter off the benzimidazole and wash with 25ml of cold water and dry at 100 degree Celsius. The yield of pure benzimidazole of melting point 171-172 degree celcious is 25 g. R ecrystallization

7. Molecular formula of o- phenylenediamine =C6H6N2 Molecular weight of o- phenylenediamine =108g/mol Molecular formula of benzimidazole =C7H7N2 Molecular wight of benzimidazole =118g/mol 108 g/mol o- phenylenediamine gives=118g/mol benzimidazole 27g/mol o- phenylenediamine gives=118*27/108=29.5 Theortical yield=29.5 Pracitcal yield= % yield=…./29.5*100=….. C alculations and observations

8. Benzimidazole was synthesised successfully and the percentage yield to be R esult References: Brian S., Anatony F., Pter W.,Vogel’s textbook of practical organic chemistry,5 th editon , page number:1162 Ravel H., Sunil L., Practica in organic chemistry, Nirali Prakashan , page number: 309