TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The condensation and hydrolysis in step (a) and (b) are carried out in-situ in presence of solvent comprising dimethylformamide, dimethylsulfoxide, sulfolane, N-methylpyrrolidinone or methanol at a temperature of 30-100 degrees C. The condensation and hydrolysis in step (a) and (b) is carried out in-situ in presence of a base comprising sodium carbonate, potassium carbonate or sodium hydroxide or potassium hydroxide. The condensation in step (a) is carried out in absence of a phase transfer catalyst. The reduction in step (c) is carried out in presence of an alcoholic solvent comprising methanol and a base sodium hydroxide. The cyclization in step (d) is carried out in a solvent comprising dimethylformamide, methanol, ethanol and/or acetonitrile and a base like sodium hydroxide. The methylation of (I) to obtain triclabendazole comprises: methylating (I) using a methylating agent to obtain triclabendazole methanesulfonate salt; converting triclabendazole methanesulfonate salt to a hydrochloride salt of triclabendazole; and hydrolyzing triclabendazole hydrochloride to obtain triclabendazole. (I) is methylated using a methylating agent which is dimethylsulfate in presence of an alcoholic solvent comprising methanol and the base comprising sodium carbonate, potassium carbonate at a temperature of 40-90 degrees C to obtain triclabendazole directly. The obtained triclabendazole is crystallized using toluene and isopropanol. EXAMPLE - 2,3-Dichlorophenol (1 kg) in dimethylformamide (1.5 l), 2-nitro 4,5-dichloroacetanilide (1.52 kg), and potassium carbonate were heated into flask for 12 hours at 90 degrees C under vacuum and then cooled. Methanol (2 l), 48% of caustic lye (0.3 kg) in water (300 ml) were added to it and heated to 50 degrees C for 4 hours. Further water (4 l) was added, stirred, filtered and washed with water and with methanol to obtain 4-chloro-5(2,3-dichlorophenoxy)-2-nitroaniline. Raney nickel (10.8 g) was added into a reaction mixture (containing 4-chloro-5(2,3-dichlorophenoxy)-2-nitroaniline (900 g), methanol (3.4 l) and caustic lye (2.72 g)). Nitrogen was flushed and charged with hydrogen. The reaction mixture was heated slowly to 100 degrees C for 12 hours, cooled and filtered to obtain 4-chloro-5(2,3-dichlorophenoxy)-1,2-phenylenediamine. Methanol (800 g), caustic lye (245 ml) and carbon disulfide (259 g) were added slowly to 4-chloro-5(2,3-dichlorophenoxy)-1,2-phenylenediamine (819 g) and reaction mass was refluxed for 6 hours. After completion of reaction water (2.5 l) and acetic acid were added for 2hours at 60 degrees C. Water was added (2.5 l) again and heated to 90 degrees C for 2 hours, filtered and washed with hot water to obtain 6-chloro-5(2,3-dichlorophenoxy)-1H-benzimidazole-2-thiol. 6-Chloro-5(2,3-dichlorophenoxy)-1H-benzimidazole-2-thiol (400 kg) was added to methanol (700 l) and heated to 40 degrees C. Dimethyl sulfate was added slowly at 40 degrees C to the reaction mass. The reaction mass was heated to 60-65 degrees C for 6 hours. Then, reaction mass was cooled to 15 degrees C, centrifuged and washed with methanol (75 l) to obtain wet cake of triclabendazole methanesulfonate. Triclabendazole methanesulfonate (200 g) and methanol (1.2 l) were refluxed, cooled and charcoal was added and refluxed again for 1 hour. The reaction mass was filtered and concentrated hydrochloric acid was added to obtain precipitate. The precipitate was cooled, stirred for 1 hour, filtered and triclabendazole hydrochloride was isolated. The water was added to the triclabendazole hydrochloride and ammonia was charged and stirred for 2-3 hours. The reaction mass was filtered, washed with water and dried to obtain triclabendazole (156 g).