Preparation Characterization and Acid Number Measurement by the Potentiometric Titration Method for the Keggin Type Organo-phosphorus-heteropolytungstic Acids

The organo phosphorus heteropolytungstic acids with 2 amminoethylphosphonic acids and its N substituded derivatives as the coordinate center were synthesized and characterized by IR, weight analysis ,scanning electron microscope and enegy dispersive X ray analysis,elemental analysis, for the first time. The results show that the five of organo phosphorus heteropolytungstic acids possess Keggin type structure. Their general formula is R 2R 1N +CH 2CH 2PO 3H -·W 12 O 36 · n H 2O( R R 1 H;R CH 3 , R 1 H; RH, R 1 n C 4H 9;RH, R 1 i C 3H 7;R R 1 CH 3 ). Their acid number in the aqueous solution was measured by the potentiometric titration method. Especially,the effect of the N substituents on the acid number of the organo phosphorus heteropolytungstic acids in the water was also studied and discussed.