1,2-Propanediol Dinitrate

The Henry's Law constant for 1,2-propanediol dinitrate is estimated as 9.4X10-7 atm-cu m/mole(SRC) calculated using a fragment constant estimation method(1). This Henry's Law constant indicates that 1,2-propanediol dinitrate is not expected to volatilize from moist soil or water surfaces(2). Laboratory experiments using 10 ml of Otto fuel II (76% 1,2-propanediol dinitrate, 22.5% dibutyl sebacate, and 1.5% 2-nitrodiphenylamine) added to an unspecified amount of water showed that 1,2-propanediol dinitrate in solution does not obey ideal solution behavior and there is a positive deviation in Raoult's Law due to the formation of an azeotrope with water(3). This resulted in the unexpected volatilization of 1,2-propanediol dinitrate from water under aerated laboratory conditions(3). The Henry's law constant for the azeotrope was estimated to be about 1X10-2 atm-cu m/mole(3). Based on the Henry's Law constant for the azeotrope, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as 2 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 5 days(SRC). 1,2-Propanediol dinitrate is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 0.38 mm Hg(SRC), determined from a fragment constant method(4).