POLY-PHOSPHORIC ACID IN HNO₃-H₃PO₄-P₂O₅-MIXED ACID AND ITS INFLUENCE ON DEGREE OF NITRATION OF CELLULOSE NITRATE

Behaviour of poly-phosphoric acids in the nitrating mixture containing HNO3-H3PO4-P2O5 and their influence on the degree of nitration of cellulose nitrates were investigated.(1) It is not proper to estimate H2O% in the P2O5-H2O-HNO3 mixtures simply based on P2O5+3H2O=2H3PO42) Composition of the mixed acids varies slowly owing to the production of poly-phosphoric acids and it requirs about 4 days to reach the equilibrium.(3) Comparing the Dolmetsch's, Staudinger's and Mitchell's nitrating mixed acids for DP determination, Mitchell's is most preferable.