ARS PESTICIDE PROPERTIES DATABASE last updated Oct 1, 2001 name:2,4-D-ACID CASRN: 94-75-7 SELECTED VALUES FOR MODELING PURPOSES (from Hornsby, et al., 1996) WATER SOLUBILITY (mg/L): 890 FIELD HALF-LIFE (days): 10 SOIL ORGANIC CARBON SORPTION (Koc, mL/g): 20 VAPOR PRESSURE (mm Hg): 8 x 10-6 pKa: 2.8 PUBLISHED AND MANUFACTURER VALUES AND SOURCES molecular formula: C8H6CL2O3 molecular weight : 221.04 physical state : S (L=liquid; G=gas; S=solid) reference: 9ACHB2 _________________________________________________________________________ Key to sources: (M)Manufacturer, (R)eview, (H)andbook, (E)xperiment, (C)alculated, (U)nknown, (P)EPA data, (W)auchope * denotes a selected value where multiple values of a property are listed. _________________________________________________________________________ -value- -medium- -temp- -pH- -source- -reference- Boiling point(deg C): 160 - 0.4mmHg H 9HERBH Melting point(deg C): 140 - 141 H 9HERBH 135 - 138 (tech) M 6DOWCH Decomposition point(deg C): - Heat of vaporization(deg C): Hydrolysis (per day): NEGLIB.* RT 5-9 M 6DOWCH Photolysis (per day): 0.01* SOIL 24.9 M 6DOWCH 0.92-9.2* AIR RT E AECTCV 2:275,1974 0.053* WATER 24.8 7 M 6DOWCH Vapor pressure (mPa): 0.019* 25 M 6DOWCH 1.3E-2 20 H 9ACHB2 1983 ED. Water solubility (ppm): -temp- -source- -reference- 311* (pH1) 25 M 6DOWCH 20031* (pH5) 25 M 6DOWCH 23180* (pH7) 25 M 6DOWCH 34196* (pH9) 25 M 6DOWCH Organic solubility (ppm): 8.5E05* ACETONE H 9HERBH Henrys law (Pa m3/mol): 1.8E-7* 25 M 6DOWCH 1.3E-5 M 6DOWCH 5.8E-6 M 6DOWCH 1.0E-7 M 6DOWCH 1.5E-9 M 6DOWCH 4.4E-10 M 6DOWCH Octanol/water partitioning (log Kow): 2.83* (pH1) M 6DOWCH -0.75* (pH7) M 6DOWCH 2.81 H 7HOCAS Acid dissociation (pKa): 2.73 25 E ESTHAG 3:1186-1188,1969 2.80 C 8CREAM R ADCSAJ 111:55-120,1972 2.87* E PSSCBG 19:101-112,1987 E JAFCAU 26:289-292,1978 Soil sorption: soiltype temp. Kd Koc %om pH source reference 20 E JEVQAA 16:422-428,1987 R 9EINSP PP.23-67 60 R 8AOACA 56 E JPFCD2 22:55-69,1987 57 C 8BULEV 24:190-195,1980 SILT LOAM 0.94 42 3.84 5.9 M 6DOWCH SANDY LOAM 0.08 36 0.38 7.5 M 6DOWCH LOAM 1.1 36 5.30 6.8 M 6DOWCH CLAY 1.0 79 2.17 7.0 M 6DOWCH 48* Field Dissipation halflife(days): value test area pH source reference <7 M 6DOWCH 14* H 9ACHB2 1983 ED. 7 E JEVQAA 16:422-428,1987 E ETOCDK 8:339-357,1989 4-7 P 8EPAHO 6-14 R 8AGMAW 15 E JAFCAU 32:578,1984 Halflife in soil: Soiltype aerobic anaerobic source reference SILTY CLAY LOAM 7 (pH5.8) M 6DOWCH CLAY LOAM 4 (pH6.9) Comments: WATER SOLUBILITY VALUES 311=PH1, 20031=PH5, 23180=PH7 AND 34196=PH9; HENRY LAW VALUES 1.8E-7=PH7, 1.3E-5=PH1; OCTANOL WATER VALUE 2.83=PH1 & -0.75=PH7; SOIL HALFLIFE=5.5(1.5-8.5)