the filtrate obtained was heated at 60 u00b0 c for 3 4 hours and cooled to 20 u00b0 c before addition of an aqueous solution of hcl 17 5 3 vol the mixture was stirred for 30 minutes and the solid filtered washed with water 2 u00d7 5 vol and dried under vacuum at 60 65 u00b0 c the suberanilic acid 1 eq obtained in stage 1 was dissolved in dmf 5 vol and cdi 2 eq was added at 25 30 u00b0 c and maintained for 30 minutes under stirring hydroxylamine hydrochloride 4 eq was added and stirring continued for 30 minutes water 25 vol was then added and the mixture stirred for 2 hours the precipitated solid was filtered washed with water 2 u00d7 5 vol and dried under vacuum at 50 u00b0 c aqueous ammonia 2 5 vol was added to the crude vorinostat 1 eq in acetonitrile 15 vol at 25 30 u00b0 c the mixture was then maintained at 55 60 u00b0 c for 1 hour before being cooled to 20 25 u00b0 c and being stirred for a further hour the resulting solid was filtered washed with acetonitrile 2 u00d7 0 5 vol and dried under vacuum at 45 50 u00b0 c for 5 hours a mixture of cdi 0 5 eq and dcc 0.