Chlorine
Dioxide
Product
Chemistry
Chapter
Case
4023
A.
Najm
Shamim,
Ph.
D.
Office
of
Pesticide
Programs
Antimicrobials
Division
U.
S.
Environmental
Protection
Agency
1200
Pennsylvania
Avenue,
NW
Washington,
DC
20460
April
5,
2006
Page
2
of
4
I.
CHLORINE
DIOXIDE:
PHYSICAL/
CHEMICAL
CHARACTERISTICS
Chemical
Name:
Chlorine
dioxide,
Chlorine
(
IV)
oxide
Chemical
Formula:
ClO2
Chemical
Structure:
Cl
O
O
CAS#:
10049­
04­
4
Molecular
Weight:
67.45
g/
mol
Color:
Gas
phase­
Yellow
green
to
orange
Liquid
phase­
reddish
brown
Melting
Point:
­
59
o
C
Boiling
Point:
11
o
C
Odor:
Strongly
pungent,
chlorine­
like
Physical
State:
Gas
at
room
temperature
Density:
1.64
g/
ml
at
0
o
C
(
liquid)
1.614
g/
ml
at
10
o
C
(
liquid)
Vapor
Pressure:
490
mm
Hg
(
0o
C)
>
760
mm
Hg
(
25
o
C)
Stability:
Unstable,
estimated
half
life
in
water
~
25
minutes*
Solubility
(
water):
3.01
g/
L
at
25
o
C
and
34.
5
mm
Hg**

Note:
1)
It
is
explosive
at
>
­
40
o
C,
and
its
explosive
velocity
in
air
is
50
m/
s.
2)
It
is
highly
miscible
in
water
up
to
60
g/
L.
3)
It
is
highly
unstable
in
sunlight.

*
Dilute
aqueous
solutions
remain
quite
stable
for
long
periods
(
i.
e.
years)
if
kept
cool
and
in
the
dark.

**
In
aqueous
solutions
at
pH>
10,
chlorine
dioxide
will
hydrolyze
to
form
chlorate
and
chlorite
ions.
In
neutral
or
near
neutral
solutions
(
4<
pH
<
10)
chlorine
dioxide
is
relatively
stable
and
exists
as
a
free
radical
in
water.
The
rate
of
the
hydrolysis
reaction
between
water
and
chlorine
dioxide
is
about
ten
million
times
slower
than
that
of
chlorine
at
neutral
pH.

Sources:
ATSDR,
2003;
Gates,
1998;
EPA,
2001
Page
3
of
4
II.
SODIUM
CHLORITE:
PHYSICAL/
CHEMICAL
CHARACTERISTICS
Chemical
Name:
Sodium
chlorite
Synonyms(
s):
Chlorous
acid,
sodium
salt
Chemical
Formula:
NaClO2
Chemical
Structure:
Cl
O
ONa

CAS#:
7758­
19­
2
Molecular
Weight:
90.45
g/
mol
Color:
White
Melting
Point:
180­
200
o
C
(
decomposes)
Boiling
Point:
n/
a
Physical
State:
Solid
Density:
2.468
g/
ml
(
as
a
solid)
Vapor
Pressure:
n/
a
Stability:
Stable
at
Room
Temperature
Solubility
(
water):
390
g/
L
at
30
o
C
Compatibility:
Incompatible
with
organic
matter,
sulfur,
powdered
coal,
and
is
a
powerful
oxidizer.

Sources:
ATSDR,
2003;
MRID
41467601
BIBLIOGRAPHY
41467601
Biehn,
W.
(
1989)
Chlorine
Dioxide­­
Product
Identity
and
Composition
Certification
of
Ingredient
Limits,
Nominal
Concentration,
Ana­
lytical
Methods,
Physical
and
Chemical
Properties:
Lab
Project
Number:
IR­
4/
PR/
NO/
4042.
Unpublished
study
prepared
by
IR­
4
Project,
Rutgers
Univ.
44
p
Chlorite
Agency
for
Toxic
Substances
and
Disease
Registry
(
ATSDR),
2003.
Draft:
Toxicological
Profile
for
Chlorine
Dioxide
and
Sodium
Chlorite.
US
Department
of
Health
and
Human
Services,
Public
Health
Service.
Page
4
of
4
Environmental
Protection
Agency,
2001.
Review
of
Threshold
of
Regulation
Request
for
Chlorine
Dioxide
on
Stored
Potatoes,
A
Memo
from
A.
Najm
Shamim,
Chemist
to
Bob
Brennis,
Product
Manager,
Antimicrobials
Division.
July
2001.

Gates,
Don,
1998.
The
Chlorine
Dioxide
HANDBOOK,
AWWA
Publishers.
