ABSTRACT

CASRN: 504-29-0; DOT: 2671; DOT label: Poison; molecular formula: C5H6N2; FW: 94.12; RTECS: US1575000; Merck Index: 12, 494 Physical state, color, and odor: Colorless to yellow crystals, leaflets, flakes, or powder with a characteristic odor. May darken after prolonged storage. Melting point (°C): 57-58 (Weast, 1986) Boiling point (°C): 210.6 (Windholz et al., 1983) Density (g/cm3): 1.065 at 20 °C (Standen, 1963) Diffusivity in water (x 10-5 cm2/sec): 0.84 at 20 °C using method of Hayduk and Laudie (1974) Dissociation constant, pKa: 6.86 at 25 °C (Dean, 1973) Flash point (°C): 92 (Acros Organics, 2002) Ionization potential (eV): 8.85 (Lias et al., 1998) Soil organic carbon/water partition coefficient, log Koc: Unavailable because experimental methods for estimation of this parameter for pyridines are lacking in the documented literature. However, its high solubility in water and low Kow suggest its adsorption to soil will be nominal (Lyman et al., 1982). Octanol/water partition coefficient, log Kow: -0.544 (shake flask-UV spectrophotometry, Li et al., 1999) -0.48 (shake flask-UV spectrophotometry, Yamagami et al., 1990) Solubility in organics: Soluble in acetone, alcohol, benzene, ether (Weast, 1986), acetonitrile, ethyl acetate, pyridinem, and trihalomethanes. Solubility in water: Miscible (NIOSH, 1994)

25 at 25 °C (NIOSH, 1994) Environmental fate: Soil. When radio-labeled 4-aminopyridine was incubated in moist soils (50%) under aerobic conditions at 30 °C, the amount of 14CO2 released from an acidic loam (pH 4.1) and an alkaline, loamy sand (pH 7.8) was 0.4 and 50%, respectively (Starr and Cunningham, 1975). Chemical/Physical. Releases toxic nitrogen oxides when heated to decomposition (Sax and Lewis, 1987). Exposure limits: NIOSH REL: TWA 0.5 ppm (2 mg/m3), IDLH 5 ppm; OSHA PEL: 0.5 ppm; ACGIH TLV: TWA 0.5 ppm. Toxicity: LC50 (48-h) for red killifish 63 mg/L (Yoshioka et al., 1986). Uses: Manufacture of pharmaceuticals, especially antihistamines.