ARS PESTICIDE PROPERTIES last update May 1995


name:DIMETHOATE                                CASRN: 60-51-5

molecular formula: C5H12NO3PS2
molecular weight : 229.3
physical state   : S
(L=liquid; G=gas; S=solid)
reference: 9MERCK

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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):
       -

Melting point(deg C):
52     -   52.5                                  H     9MERCK

Decomposition point(deg C):
       -

Heat of vaporization(deg C):

--RATE CONSTANTS--

Hydrolysis (per day):
0.0044                           25     5        M     9AMCY1
0.0010*                          25     7        M     9AMCY1
0.154                            25     9        M     9AMCY1

Photolysis (per day):
0.058                SOIL                        H     9PME10

Vapor pressure (mPa):
1.1                              20              H     9ACHB2 1983 ED.
0.37                             20              E     PSSCBG 4:137-147,1973
0.24*                            25              M     9AMCY1
1.55                             35              M     9AMCY1


Water solubility (ppm):       -temp-         -source- -reference-
23800 (pH7)                      25              H     9PME10
25000                            21              H     9ACHB2 1983 ED.
3.98E+4*                         25              M     9AMCY1

Organic solubility (ppm):
>3E05 *   ALCS,BENZENE           20              H     9PMED8
>3E05 *   CHLOROFORM             20              H     9PMED8
>3E05 *   DICHLOROMETHANE        20              H     9PMED8
>5E04 *   CCL4,SATD,HC'S         20              H     9PMED8
>5E04 *   OCTAN-1-OL             20              H     9PMED8

Henrys law (Pa m3/mol):
1.38E-6 *                        25              M     9AMCY1

Octanol/water partitioning (log Kow):
5.06 *                                           M     9AMCY1

Acid dissociation (pKa):

Soil sorption:
soiltype      temp.   Kd    Koc    %om   pH   source   reference
                            9                    C     8GLEAM
                            17                   R     EESADV
SAND                  0.06  12     0.9           M     9AMCY1
SANDY LOAM            0.30  34     1.5           M     9AMCY1
SILT LOAM             0.57  28     3.5           M     9AMCY1
LOAM                  0.74  17     7.4           M     9AMCY1
                            20*

Field Dissipation halflife(days):
value             test area      pH   %OM     source   reference
7*                                               C     8GLEAM

Halflife in soil:
Soiltype           aerobic      anaerobic     source   reference
                    2-4                          H     9PME10
                    3*
Comments:
SOIL SORPTION KOC VALUE 15(9-20)