TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: In the method, the hydroxylamine solution is aqueous solution or 50% aqueous solution. The separation is carried out by a method involves dissolving the mixture comprising the compound (IIB) and the compound (IIA) in a solvent to obtain a solution; adjusting the pH of the solution to 2-3 by adding acid to precipitate the compound (IIB) in a solvent to obtain a solution; and separating the precipitated compound (IIB) from the solution to obtain the compound (IIB). The hydrolysis is carried out using a base selected from sodium hydroxide, potassium hydroxide, sodium methoxide, lithium hydroxide and sodium carbonate. Preferred Components: The carbonic ester is selected from dimethyl carbonate and diethyl carbonate. ACTIVITY - Hypotensive. No biological data given.    MECHANISM OF ACTION - Angiotensin II receptor antagonist.    EXAMPLE - A mixture of 100 g of methyl-1-((2'-cyanobiphenyl-4-yl)-methyl)-2-ethoxy-1H-benzimidazole-7-carboxylate (I), 1 l of dimethyl sulfoxide (DMSO) and neutral aqueous solution of hydroxyl amine; which was prepared by addition of 100 g of hydroxylamine hydrochloride in 200 ml of water, and 52 g of sodium hydroxide was heated to 80-90 degrees C for 12-13 hours. 1 l of Water was added after completion of reaction at 25-30 degrees C; solid mass filtered and washed with 100 ml of isopropylalcohol to obtain mixture of methyl 2-ethoxy-1-((2'-(hydroxyamidino)biphenyl-4-yl)methyl)-1H-benzimidazole-7-carboxylate (IIB) and methyl-2-hydroxy-1-((2'-(hydroxyamidino)biphenyl-4-yl)methyl)-1H-benzimidazole-7-carboxylate (IIA). The mixture of 30 g of the compound (IIB), 120 ml of acetone, 9 g of sodium hydroxide and 300 ml of water were heated to 50-55 degrees C for 2 hours. After completion of the reaction, it was cooled to 25-30 degrees C, and pH was adjusted to 3-4 by acetic acid to get 20 g of 2-ethoxy-1-((2'-hydroxyamidino)-biphenyl-4yl-)methyl-1H-benzimidazole-7-carboxylic acid (III). 6 g of the compound (III) was added to 15 ml of N,N-dimethylformamide (DMF) and 8 g of 10% sodium ethoxide solution, it was cooled to 0-5 degrees C. To this solution, 5.8 g of diethyl carbonate was added. The reaction mass was stirred for 2 hours at a temperature of 20-25 degrees C. A solution of 5% acetic acid, 25 ml was added to adjust pH 3-4, it was later filtered to get 2-ethoxy-3-((2'-(5-oxo-2,5-dihydro-1,2,4-oxadiazol-3-yl)biphenyl-4-yl)methyl)-3H-benzo(d)imidazole-7-carboxylic acid (Azilsartan) (IV) (yield: 90%).