N
N
N
N
O
O
R
E
V
I
S
E
D
4­
23­
02
MEMORANDUM
SUBJECT:
Hexazinone.
List
A
Reregistration
Case
0266.
PC
Code
107201.
Product
Chemistry
Chapter
for
the
Tolerance
Reassessment
Eligibility
Decision
[TRED]
Document.
DP
Barcode
D279324.

FROM:
K.
Dockter,
Chemist
Reregistration
Branch
2
Health
Effects
Division
[7509C]

THRU:
Alan
Nielsen,
Branch
Senior
Scientist
Reregistration
Branch
2
Health
Effects
Division
[7509C]

TO:
Carol
Christensen,
Risk
Assessor
Reregistration
Branch
2
Health
Effects
Division
[7509C]

Hexazinone
[3­
cyclohexyl­
6­(
dimethylamino)­
1­
methyl­
1,3,5­
triazine­
2,4(
1H,
3H)­
dione]
is
a
contact
and
residual
herbicide.
"Apply
when
plants
are
actively
growing
for
control
of
many
annual,
biennial
and
perennial
weeds
and
woody
plants
on
noncropland
areas.
Gives
contact
and
residual
control.
Rainfall
is
needed
for
soil
activation.
Controls
woody
plants
in
reforestation
areas
(site
preparation
or
conifer
release);
selective
weed
control
in
conifers,
sugarcane,
pineapple,
rubber
trees,
alfalfa,
blueberries."
Farm
Chemicals
Handbook,
1999
Empirical
formula:
C12H20N4O2
Molecular
weight:
252.3
CAS
Registry
No.:
51235­
04­
2
PC
Code:
107201
2
Chemical
structure
by
J.
Punzi
A
search
of
REFS
conducted
12/
07/
01
identified
a
single
hexazinone
technical
[T]
registered
under
PC
Code
107201,
the
Dupont
98.7
%
T;
EPA
Reg.
No.
352­
399.
It
is
subject
to
a
TRED.

The
pre­
FQPA
Reregistration
Eligibility
Decision
Document
issued
9/
94.

The
Registration
Standard
+
FRSTR
issued
6/
88;
the
Update
issued
5/
10/
91.

The
product
chemistry
data
base
is
essentially
complete.
There
are
no
reported
impurities
of
toxicological
concern
in
hexazinone.
The
Series
830
physical
and
chemical
properties
are
given
in
the
table
below.

GLN
MRID
Data
6302
Color
41203201
white
6303
Physical
state
"
crystalline
solid
6304
Odor
"
mildly
pungent
7200
MP
"
113.5
C
7300
Bulk
density
"
0.61
g/
mL
7840
Water
solubility
"
2.98
g/
100g
@
25
C
7950
vp
"
1.9
x
10
­7
mm
Hg
@
25
C
7550
Pow
"
15
at
pH
7.0
6313
Stability
"
stable
in
slightly
acidic
or
alkaline
media
at
elevated
temperatures,
slowly
degrades
under
artificial
sunlight.
~1%
decomposition
when
stored
2
yrs
under
ambient
conditions.

7370
Dissociation
constants
in
water
"
a
very
weak
base
7000
pH
"
8.0
3
6320
Corrosion
characteristics
"
0.18­
34
mils/
yr
@
50
C
in
various
metals;
no
change
in
packaging
materials.

cc:
Reg.
Std.
file,
RF,
Dockter,
S.
Kinard,
D.
Anderson.
RD\
I
Hexazinone
TRED
Team.
7509C:
RRB2:
Rm712G:
57886:
KD/
kd
Hexazinone.
TRED
[26]
=
D279324.
mem.
