Volatilization | The Henry's Law constant for N-methylaniline estimated from its vapor pressure, 0.453 mm Hg(1), and water solubility, 5624 mg/L(2), is 1.14X10-5 atm-cu-m/mol(SRC). Using this value for the Henry's Law constant, one can estimate a volatilization half-life of 3.5 days for N-methylaniline in a model river 1 m deep flowing at 1 m/s with a wind speed of 3 m/s(3). Similarly, the volatilization half-life for N-methylaniline from a model lake 1 m deep, with a 0.05 m/s current and a 0.5 m/s wind is estimated to be 28 days(3). Literature: (1) Riddick JA et al; Organic Solvents 4th ed; NY, NY: Wiley (1986) (2) Yalkowsky SH, Dannenfelser RM; Aquasol Data Base of Water Solubility Ver 5, Tuscon,. AZ: Univ Arizona, College of Pharmacy (1992) (3) Lyman WJ et al; Handbook of Chemical Property Estimation Methods, NY: McGraw-Hill Chapt 15 (1982) |
Soil Adsorption | Since the pKa of N-methylaniline is 4.848(2), N-methylaniline will be partially ionized at acidic environmental pHs and its adsorption to soil would be expected to be pH-dependent(SRC). The Koc for N-methylaniline predicted from molecular structure is 65(3). According to a suggested classification scheme(5), this estimated Koc suggests that N- methylaniline will be highly mobile in soil(SRC). Batch equilibrium studies used to determine the adsorption isotherms for N-methylaniline to a Podzol (4.85% OC pH 2.8), an Alfisol (1.25% OC, pH 6.7) and a sediment (1.58% OC, pH 7.1) yielded the results (soil, Freundlich adsorption constants (Kf), Freundlich exponent (1/n), Koc): Podzol, 22.29, 0.89, 460; Alfisol, 0.59, 0.78, 47; Sediment, 1.12, 0.77, 71(1). N-Methylaniline will be almost completely ionized at the pH of the Podzol and therefore ionic interactions may be dominant(1,SRC). N-Methylaniline reacts slowly with humates possibly by adding to quinoidal structures in the humic substances(4). Covalent bond formation is inferred by the lack of extractability of the aniline from the humic material as well as reactions with model compounds(4). Literature: (1) Von Oepen B et al; Chemosphere 22: 285-304 (1991) (2) Riddick JA et al; Organic Solvents 4th ed; NY, NY: Wiley (1986) (3) Meylan WM et al; Environ Sci Technol 26:1560-7 (1992) (4) Parris GE; Environ Sci Technol 14: 1099-105 (1980) (5) Swann RL et al; Res Rev 85:17-28 (1983) |