Butanal → 4-[(4-Aminophenyl)sulfanyl]-3-(butylamino)-5-sulfamoylbenzoic acid

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Reaction Steps

To the solution of 1.52 g of 4-(4-acetamidophenylmercapto)-3-amino-5-sulfamoylbenzoic acid in 600 ml of dimethylformamide, 40 g of butyraldehyde and 1.60 g of molecular sieves [Na12 (AlSiO4)12. 27 H2O], 36 g of sodium cyanoborohydride are added while stirring under nitrogen and keeping the temperature between about 20° and 30° for 1 hour. After stirring the mixture for 68 hours at room temperature, 6 lt of water are added, followed by 110 ml of concentrated hydrochloric acid and stirring is continued for 1 hour. The precipitate formed is filtered off, washed with water, dissolved in 1.2 lt of 2N aqueous sodium hydroxide and the solution refluxed for 2 hours under nitrogen. After cooling to room temperature it is filtered and the filtrate combined with 250 ml of glacial acetic acid. The precipitate formed is collected, 333 g thereof are dissolved in 2.8 lt of hot, 80% aqueous acetonitrile, the solution filtered, the filter washed with 500 ml more of said acetonitrile and the filtrate diluted with 3.3 lt of hot water. The precipitate formed at 14° is filtered off, taken up in 2.15 lt of hot, 90% aqueous ethanol and the solution diluted with 2.5 lt of hot water. The solids separated after cooling are collected and washed with water, to yield the 4-(4-aminophenylmercapto)-3-n-butylamino-5-sulfamoylbenzoic acid melting at 232°-234°, it is identical with that obtained according to Example 3.

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