mixing 10 ml of concentrated hydrochloric acid with 10 ml of deionised water at 18 u00b0 to 25 u00b0 c followed by stirring for 10 minutes at the same temperature the ph of the reaction mixture was adjusted to 8 0 to 8 5 with aqueous sodium hydroxide solution 28 ml prepared by dissolving 2 1 g of sodium hydroxide in 27 ml of deionised water at 18 u00b0 to 25 u00b0 c the reaction mixture was concentrated under vacuum at about 55 u00b0 c till the residual volume was about 375 ml deionised water 300 ml was added to the concentrated reaction mixture at 25 u00b0 to 30 u00b0 c and stirred for 10 minutes the reaction mixture was washed with toluene 2 u00d7 150 ml at 25 u00b0 to 30 u00b0 c and the toluene layer was extracted with deionised water 150 ml at 25 u00b0 to 30 u00b0 c the aqueous layers were combined and salicylic acid 57 g was added at 25 u00b0 to 30 u00b0 c deionised water 150 ml was added to the reaction mixture and heated to 78 u00b0 to 82 u00b0 c to get a clear solution the reaction mixture was cooled to 25 u00b0 to 30 u00b0 c over a period of 2 h and stirred at the same temperature for 4 h the reaction mixture was further cooled to 10 u00b0 to 15 u00b0 c and stirred for 2 h at 10 u00b0 to 15 u00b0 c the solid was.