SYNTHESIS AND CHARACTERIZATION OF 2-MERCAPTOBENZIMIDAZOLE

About author:
Ramesh Dhani
Dept. of Pharmaceutical Chemistry
JNTUA – OTRI, India
E-mail : [email protected]

Abstract:
Recently in benzimidazole chemistry has been revived somewhat by the discovery that the 5,6-dimethyl benzimidazole moiety is a part of the chemical structure of vitamin B12.The benzimidazoles are also known as benziminazolones or benzoglyoxalines.The new benzimidazole derivative i.e, 2-mercapto benzimidazole was synthesized.The melting point was detected by capillary tube method and the purity of the comound was cheked by TLC, here the solvent system was [hexane: ethyl acetate (1:3)] used and further the compound characterized by IR spectral studies.
Key words: Benziminazolones, 2-mercapto benzimidazole, O-Phenylenedimine,  Ethanol, Ethyl Chloro Acetate
INTRODUCTION :
Numerous heterocyclic compounds, cyclic anhydrates, cyclic imides, cyclic acetals of dihydroxy alcohols, the solvents, dioxanes and tetrahydrofuran, in all of these, the chemistry is essentially that of their open-chain analogues.The benzimidazole contains a phenyl ring fused to an imidazole ring, as indicated in the structure of benzimidazole. The important group of substances has found practical application in a number of fields. Recently in benzimidazole chemistry has been revived somewhat by the discovery that the 5,6-dimethyl benzimidazole moiety is a part of the chemical structure of vitamin B12. The benzimidazoles are also known as benziminazolones or benzoglyoxalines. They have been named also as derivatives of o-phenylene diamines. Benzimidazole which contain a hydrogen atom attached to nitrogen in the 1-position readily tautamerise.
Sang yon cho et.al., synthesized a series of benzimidazole derivatives containing oxycyclic pyridine and evaluated for their gastric H+/ K+-ATPase inhibitory activity. Several of the synthesized compounds exhibited potent anti-secretion in pylorus ligated rats when administered intra duodenal and their inhibitory activities were compared with the standard Omeprazole. Keiji Kubo et.al., synthesized many 2-[4-fluro alkoxy-2-pyridyl) methyl] sulfynyl]-1H-benzimidazoles and tested for anti-secretary, anti-ulcer and cytoprotective activities. Most of these compounds were superior to Omeprazole in anti-secretary and anti-ulcer potencies and especially in protecting the gastric mucosa from ethanol induced damage.G.L.Dunn et. al., synthesized a series of  new benzimidazoles, benzoxazoles and benzothiazoles of nitrothiophene and nitro pyrrole and  reported very potent inhibitors.
MATERIALS AND METHODS :
Preparation of 2-mercapto benzimidazole :
A mixture of 10.8gm (0.1mole) of o-phenylenediamine, 5.65 gm (0.1mole) of potassium hydroxide and 7.67 gm (0.1mole, 6.19ml) of carbon disulfide, 100ml of 95% ethanol and 15 ml of water was taken  in  a 500ml round bottom flask heated under reflux for three hours. Then 1-1.5 gm of charcoal was added cautiously and the mixture is further heated at the reflux for 10 minutes, the charcoal is removed by filtration. The filtrate is heated to 60-70^oC, 100ml of warm water is added, and acidified with dilute acetic acid with good stirring. The product separated as glistening white crystals, and the mixture is placed in a refrigerator for three hours to complete the crystallization. The product is collected on a Buckner funnel and dried over night at 40^oc.
RESULTS & DISCUSSIONS :
From the literature survey it reveals that benzimidazoles and 2-mercapto benzimidazoles have been reported for spectral studies. Synthesized benzimidazole derivatives further studied for characterization of IR. The following functional groups are observed NH-benzimidazole at Wave number 3088 cm^-1, Ar-CH at 2982 cm^-1, NH- at 1640 cm^-1. The dried product is recrystallised by ethanol the yield is 8.5gm (73%) melting point is 300-305^oC.
CONCLUSION:
From the above study concludes that all substituted benzimidazle derivatives like 2-mercapto benzimidazoles molecule was conformed form the IR spectral studies. The purity of the compound was cheked by TLC, solvent system was [hexane: ethyl acetate (1:3)]. The melting point( M.P) of 2-mercapto benzimidazoles was detected.