UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
MEMORANDUM
Date:
3/
25/
04
Subject:
Dimethipin.
HED
Product
Chemistry
Chapter
for
Reregistration
Eligibility
Decision.

DP
Barcode:
D299477
Case
No.:
3063
PC
Code:
118901
From:
Danette
Drew,
Chemist
Reregistration
Branch
3/
Health
Effects
Division
(
7509C)

Through:
Catherine
Eiden,
Branch
Chief
Reregistration
Branch
3/
Health
Effects
Division
(
7509C)

To:
Amaris
Johnson,
CRM
Special
Review
and
Reregistration
Division
(
7508C)

Please
find
attached
the
HED
product
chemistry
chapter
for
the
dimethipin
Reregistration
Eligibility
Decision.
Dimethipin
RED:
Product
Chemistry
Chapter
Barcode:
[
D299477]

2
S
S
CH
3
CH
3
O
O
O
O
Executive
Summary
Dimethipin
[
2,3­
dihydro­
5,6­
dimethyl­
1,4­
dithiin
1,1,4,4­
tetraoxide]
is
a
plant
growth
regulator
for
use
as
a
preharvest
cotton
defoliant.

Dimethipin
is
a
List
C
chemical.
The
Dimethipin
Phase
4
Review
dated
9/
26/
91
by
C.
Swartz
required
additional
product
chemistry
data
concerning
solubility
(
830.7840)
and
octanol/
water
partition
coefficient
(
830.7550);
available
data
for
all
of
the
other
physical/
chemical
guideline
requirements
were
determined
to
be
acceptable
for
Phase
5
review,
and
the
registrant
had
committed
to
conduct
the
required
studies
for
all
Group
A
guidelines.

All
data
requirements
are
satisfied
for
the
only
registered
manufacturing­
use
product,
the
Crompton
Manufacturing
Company
98%
T
(
EPA
Reg.
No.
400­
432),
except
that
data
are
required
concerning
the
UV/
visible
absorption
of
the
PAI
(
OPPTS
830.7050).
Provided
that
the
registrant
submits
the
data
required
in
the
attached
data
summary
table
for
the
dimethipin
T/
TGAI,
and
either
certifies
that
the
suppliers
of
beginning
materials
and
the
manufacturing
process
for
the
98%
T
have
not
changed
since
the
last
comprehensive
product
chemistry
review
or
submits
a
complete
updated
product
chemistry
data
package,
the
Agency
has
no
objections
to
the
reregistration
of
the
dimethipin
with
respect
to
product
chemistry
data
requirements.

Product
Chemistry
Deficiencies
Data
are
required
concerning
the
UV/
visible
absorption
of
the
PAI
(
OPPTS
830.7050)
for
the
Crompton
Manufacturing
Company
98%
T
(
EPA
Reg.
No.
400­
432).

Background
Identification
of
Active
Ingredient
Table
1.
Dimethipin
Nomenclature
Chemical
structure
Common
name
Dimethipin
Molecular
Formula
C6H10O4S2
Molecular
Weight
210.26
IUPAC
name
2,3­
dihydro­
5,6­
dimethyl­
1,4­
dithiine
1,1,4,4­
tetraoxide
CAS
name
2,3­
dihydro­
5,6­
dimethyl­
1,4­
dithiin
1,1,4,4­
tetraoxide
CAS
#
55290­
64­
7
PC
Code
118901
Dimethipin
RED:
Product
Chemistry
Chapter
Barcode:
[
D299477]

Table
1.
Dimethipin
Nomenclature
3
Current
Food/
Feed
Site
Registration
Cotton
Table
A2.
Physicochemical
Properties
of
the
Technical
Grade
Dimethipin
Parameter
Value
Reference
Melting
point/
range
162­
167

C
MRID
41655601
pH
4.52
at
30

C
(
1%
w:
v
solution
in
50%
aqueous
dioxane
due
to
insolubility
in
water)
MRID
41655604
Density
1.5935
g/
cm3
at
23

C
MRID
41655602
Water
solubility
0.46
g/
100
mL
at
25

C
MRIDs
41967004,
41967005
Solvent
solubility
At
25

C:
acetone
0.097
g/
mL
1­
octanol
79.356
mg/
100
mL
hexane
1.664
mg/
100
mL
methanol
0.05
g/
100
mL
xylene
0.57
g/
100
mL
chloroform
7.92
g/
100
mL
MRIDs
41967004,
41967005
Vapor
pressure
<
3.81
x
10­
7
mm
Hg
at
24

C
MRID
43898701
Dissociation
constant,
pKa
10.88
+/­
0.39
at
25

C
MRID
41655603
Octanol/
water
partition
coefficient,
Log(
KOW)
0.66
at
24

C
MRID
42282702
UV/
visible
absorption
spectrum
(
not
available)
Data
outstanding
Bolded
MRIDs
were
reviewed
under
the
Dimethipin
Phase
4
Review
dated
9/
26/
91.
All
other
MRIDs
were
reviewed
under
D300604,
3/
25/
04,
D.
Drew.

Manufacturing­
use
Products
A
search
of
the
Reference
Files
System
(
REFS)
conducted
3/
13/
03
identified
a
single
manufacturing­
use
product
(
MP)
registered
under
PC
Code
118901:
the
Crompton
Manufacturing
Company,
Inc.
(
formerly
Uniroyal
Chemical
Company)
98%
T
(
EPA
Reg.
No.
400­
432).
Dimethipin
is
a
List
C
reregistration
chemical;
therefore,
only
the
T/
TGAI
is
subject
to
a
reregistration
eligibility
decision.

830.1550­
7950
Product
Chemistry
Data
Requirements
The
current
status
of
the
product
chemistry
data
requirements
for
the
Crompton
98%
T/
TGAI
is
presented
in
the
attached
data
summary
table.
Refer
to
this
table
for
a
listing
of
the
outstanding
product
chemistry
data
requirements.
Dimethipin
RED:
Product
Chemistry
Chapter
Barcode:
[
D299477]

4
Case
No.
3063
Chemical
No.
118901
Case
Name:
Dimethipin
Registrant:
Crompton
Manufacturing
Company,
Inc.
Product(
s):
98%
T
(
EPA
Reg.
No.
400­
432)

PRODUCT
CHEMISTRY
DATA
SUMMARY
Guideline
Number
Requirement
Are
Data
Requirements
Fulfilled?
1
MRID
Number
2
830.1550
Product
identity
and
composition
Y
3
41943801,
CSF
12/
17/
92
830.1600
Description
of
materials
used
to
produce
the
product
Y
41943802
830.1620
Description
of
production
process
Y
41943802,
42282701
830.1670
Discussion
of
formation
of
impurities
Y
41943803
830.1700
Preliminary
analysis
Y
40361401
4,
41457601
5,
41967001
6
830.1750
Certified
limits
Y
41967002,
CSF
12/
17/
92
830.1800
Enforcement
analytical
method
Y
41967003
830.6302
Color
Y
40410302
4
830.6303
Physical
state
Y
40410302
4
830.6304
Odor
Y
40410302
4
830.6313
Stability
to
normal
and
elevated
temperatures,
metals,
and
metal
ions
Y
40410302
4,
41655605,
41655606
830.7000
pH
Y
40410302
4,
41655604
830.7050
UV/
Visible
absorption
N
830.7200
Melting
point/
melting
range
Y
40410302
4,
41655601
830.7220
Boiling
point/
boiling
range
N/
A
7
830.7300
Density/
relative
density/
bulk
density
Y
40410302
4,
41655602
830.7370
Dissociation
constants
in
water
Y
41655603
830.7550
Partition
coefficient
(
n­
octanol/
water),
shake
flask
method
Y
40410302
4,
42282702
830.7840
Water
solubility:
column
elution
method;
shake
flask
method
Y
40410302
4,
41967004,
41967005
830.7950
Vapor
pressure
Y
40410302
4,
43898701
1
Y
=
Yes;
N
=
No;
N/
A
=
Not
Applicable.

2
Bolded
references
were
reviewed
under
D300406,
3/
25/
04,
D.
Drew;
and
all
other
references
were
reviewed
as
noted.

3
The
name
of
one
impurity
listed
on
the
CSF
is
incorrect.

4
RD
Memorandum,
12/
1/
89,
C.
Welch.

5
RD
Memorandum,
10/
24/
90,
C.
Welch.

6
RD
Memorandum,
11/
25/
92,
A.
Skapars.

7
Data
are
not
required
because
the
TGAI
is
a
solid
at
room
temperature.
Dimethipin
RED:
Product
Chemistry
Chapter
Barcode:
[
D299477]

5
AGENCY
MEMORANDA
CITED
IN
THIS
DOCUMENT
DP
Barcode(
s):
RD
Memorandum;
None
Subject:
Product
Chemistry
Review;
Uniroyal
Chemical
Co.;
EPA
Registration
No.
400­
UGE;
Dimethipin.
From:
C.
Welch
To:
R.
Taylor
Dated:
12/
1/
89
MRID(
s):
40361401
and
40410302
DP
Barcode(
s):
RD
Memorandum;
None
Subject:
Product
Chemistry
Review
on
Harvarde
Technical.
From:
C.
Welch
To:
R.
Taylor
Dated:
10/
24/
90
MRID(
s):
41457601
DP
Barcode(
s):
RD
Memorandum;
None
Subject:
Product
Chemistry
Review;
EPA
File
Symbol
400­
UGE;
Product
Name:
Harvarde
Technical;
Company
Name:
Uniroyal
Chemical
Co.,
Inc.
From:
A.
Skapars
To:
Product
Manager
No.
22
(
Giles­
Parker)
Dated:
11/
25/
92
MRID(
s):
41967001
DP
Barcode(
s):
D300406
Subject:
Product
Chemistry
Data
for
the
Uniroyal
Chemical
Company
98%
T
(
EPA
Reg.
No.
400­
432).
From:
D.
Drew
To:
S.
Plummer
Dated:
3/
25/
04
MRID(
s):
41655601­
41655606,
41943801­
41943803,
41967002­
41967005,
and
42282701­
42282702
Dimethipin
RED:
Product
Chemistry
Chapter
Barcode:
[
D299477]

6
PRODUCT
CHEMISTRY
CITATIONS
Bibliographic
citations
include
only
MRIDs
containing
data
which
fulfill
data
requirements.

References
(
cited):

40361401
Tsai,
A.;
Mertz,
J.;
Hageman,
F.
(
1987)
Preliminary
Analysis
of
Product
Samples
to
Support
Registration
of
Harvarde
(
Dimethipin)
Technical.
Unpublished
study
prepared
by
Uniroyal
Chemical
Co.
26
p.

40410302
Spare,
W.;
Steeves,
S.;
Harned,
W.
(
1987)
Chemical
and
Physical
Properties
of
Harvarde
(
Dimethipin)
Technical.
Unpublished
study
prepared
by
Uniroyal
Chemical
Co.,
Inc.
117
p.

41457601
Uniroyal
Chemical
Co.,
Inc.
(
1990)
Submittal
of
Samples
of
TGAI
and
Sample
of
PAI
Analytical
Standard
with
Analytical
Method
for
Active
Ingredient
To
Support
Registration
Application
for
Harvade
Tech.
(...):
Lab
Method
No.
AC­
1086C.
Unpublished
study.
33
p.

41655601
Riggs,
A.
(
1990)
The
Melting
Point
Range
of
Technical
Harvarde:
Lab
Project
Number:
89120:
GRL­
10066.
Unpublished
study
prepared
by
Uniroyal
Chemical
Ltd.
14
p.

41655602
Thomson,
P.
(
1989)
Determination
of
the
Density
of
Harvarde
Using
a
Helium
Pycnometer:
Lab
Project
Number:
89121:
GRL­
10031.
Unpublished
study
prepared
by
Uniroyal
Chemical
Ltd.
15
p.

41655603
Thomson,
P.
(
1990)
Determination
of
the
Dissociation
Constant
of
Harvarde
Using
a
Spectrophotometric
Method:
Lab
Project
Number:
89124:
GRL­
10034.
Unpublished
study
prepared
by
Uniroyal
Chemical
Ltd.
19
p.

41655604
Thomson,
P.
(
1990)
Determination
of
the
pH
of
Harvarde:
Lab
Project
Number:
89125:
GRL­
10035.
Unpublished
study
prepared
by
Uniroyal
Chemical
Ltd.
13
p.

41655605
Riggs,
A.
(
1990)
Accelerated
Storage
Test
for
Technical
Harvarde:
Lab
Project
Number:
89126A:
GRL­
10063.
Unpublished
study
prepared
by
Uniroyal
Chemical
Ltd.
25
p.

41655606
Riggs,
A.
(
1990)
The
Stability
of
Technical
Harvarde
in
the
Presence
of
Metals
and
Metal
Ions:
Lab
Project
Number:
89126B:
GRL­
1006.
Unpublished
study
prepared
by
Uniroyal
Chemical
Ltd.
31
p.

41943801
Pierce,
J.
(
1991)
Dimethipin
(
Harvarde):
Chemical
Identity:
Lab
Project
Number:
9181.
Unpublished
study
prepared
by
Uniroyal
Chemical
Co.,
Inc.
8
p.

41943802
Pierce,
J.
(
1991)
Dimethipin:
Beginning
Materials
and
Manufacturing
Process:
Lab
Project
Number:
9102.
Unpublished
study
prepared
by
Uniroyal
Chemical
Co.,
Inc.
70
p.
Dimethipin
RED:
Product
Chemistry
Chapter
Barcode:
[
D299477]

7
41943803
Pierce,
J.
(
1991)
Theoretical
Discussion
of
Possible
Impurities
in
Dimethipin:
Lab
Project
Number:
9178.
Unpublished
study
prepared
by
Uniroyal
Chemical
Co.,
Inc.
10
p.

41967001
Mitchell,
D.
(
1991)
Compositional
Analysis
of
Technical
Harvarde:
Lab
Project
Number:
GRL­
10134:
9061.
Unpublished
study
prepared
by
Uniroyal
Chemical
Ltd.
61
p.

41967002
Pierce,
J.
(
1991)
Dimethipin:
Guaranteed
Limits
and
Confidential
Statement
of
Formula:
Lab
Project
Number:
91106.
Unpublished
prepared
by
Uniroyal
Chemical
Co.
12
p.

41967003
Mitchell,
D.
(
1991)
Development
of
Analytical
methods
for
the
Compositional
Analysis
of
Technical
Harvarde:
Lab
Project
Number:
GRL
10201:
9112.
Unpublished
study
prepared
by
Uniroyal
Chemical
Ltd.
86
p.

41967004
Spare,
W.
(
1987)
Solubility
of
Harvarde:
Lab
Project
Number:
1904:
88709.
Unpublished
study
prepared
by
Agrisearch,
Inc.
43
p.

41967005
Young,
K.
(
1991)
Solubility
of
Harvarde
in
Organic
Solvents
and
Aqueous
Buffers:
Lab
Project
Number:
GRL­
10133:
9060.
Unpublished
study
prepared
by
Uniroyal
Chem.
Ltd.
56
p.

42282701
Pierce,
J.
(
1992)
Supplemental
Information
for:
Dimethipin:
Beginning
Materials
and
Manufacturing
Process:
Lab
Project
Number:
9102.
Unpublished
study
prepared
by
Uniroyal
Chemical
Co.
5
p.

42282702
Steeves,
E.
(
1986)
Octanol/
Water
Partition
Coefficient
of
Dimethipin:
Lab
Project
Number:
8670.
Unpublished
study
prepared
by
Uniroyal
Chemical
Co.,
Inc.
10
p.
