The hydroxide-assisted hydrolysis of cyanogen chloride in aqueous solution

Article abstract of DOI:10.1016/S0043-1354(00)00321-3

The hydrolysis of cyanogen chloride (ClCN) was studied as a function of temperature and pH. Results were used to resolve discrepancies among previously reported kinetic constants. The pH dependence was studied over a range of 9.54-10.93 at a temperature of 21.0°C. The effect of temperature was investigated over the range of 10-30°C at a pH of approximately 10. Changes in the concentrations of ClCN and the reaction products cyanic acid and chloride ion were monitored with time. For the conditions corresponding to these experiments, the hydroxide-assisted hydrolysis pathway predominated. Collision frequency factor and activation energies recommended to represent the hydrolysis of ClCN in aqueous solution are A=2.06x10¹¹M^-1s^-1 and E(a)=60,980Jmol^-1 for the hydroxide-ion-assisted reaction, and A=9.97x10⁸s^-1 and E(a)=87,180Jmol^-1 for the water-assisted reaction. Copyright (C) 2001 Elsevier Science Ltd. The hydrolysis of cyanogen chloride (ClCN) was studied as a function of temperature and pH. Results were used to resolve discrepancies among previously reported kinetic constants. The pH dependence was studied over a range of 9.54-10.93 at a temperature of 21.0 °C. The effect of temperature was investigated over the range of 10-30 °C at a pH of approximately 10. Changes in the concentrations of ClCN and the reaction products cyanic acid and chloride ion were monitored with time. For the conditions corresponding to these experiments, the hydroxide-assisted hydrolysis pathway predominated. Collision frequency factor and activation energies recommended to represent the hydrolysis of ClCN in aqueous solution are A = 2.06×10¹¹ M^-1 s^-1 and E_a = 60,980 J mol^-1 for the hydroxide-ion-assisted reaction, and A = 9.97×10⁸ s^-1 and E_a = 87,180 J mol^-1 for the water-assisted reaction.

Full text of DOI:10.1016/S0043-1354(00)00321-3

Wat. Res. Vol. 35, No. 3, pp. 643–648, 2001
# 2001 Elsevier Science Ltd. All rights reserved
Printed in Great Britain
PII: S0043-1354(00)00321-3
0043-1354/01/$ - see front matter
THE HYDROXIDE-ASSISTED HYDROLYSIS OF CYANOGEN
CHLORIDE IN AQUEOUS SOLUTION
ERIK J. PEDERSEN III*y and BENITO J. MARINASM
School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA
(First received 1 January 2000; accepted in revised form 1 May 2000)
Abstract}The hydrolysis of cyanogen chloride (ClCN) was studied as a function of temperature and pH.
Results were used to resolve discrepancies among previously reported kinetic constants. The pH
dependence was studied over a range of 9.54–10.93 at a temperature of 21.08C. The effect of temperature
was investigated over the range of 10–308C at a pH of approximately 10. Changes in the concentrations of
ClCN and the reaction products cyanic acid and chloride ion were monitored with time. For the
conditions corresponding to these experiments, the hydroxide-assisted hydrolysis pathway predominated.
Collision frequency factor and activation energies recommended to represent the hydrolysis of ClCN
in aqueous solution are A¼ 2:06 Â 1011
M
and Ea ¼ 87; 180 J mol
1 s 1 and Ea ¼ 60; 980 J mol 1 for the hydroxide-ion-assisted
1
1
reaction, and A¼ 9:97 Â 108 s
for the water-assisted reaction. # 2001
Elsevier Science Ltd. All rights reserved
Key words}chloride, cyanate, cyanic acid, cyanogen chloride, disinfection by-product, hydrolysis,
reaction rate, kinetics, temperature effect, pH effect
INTRODUCTION
species (including cyanogen compounds) (WHO,
1993).
Cyanogen chloride (ClCN) is a toxic disinfection by-
Progress has been made in determining the possible
product (DBP) which forms in drinking waters
treated with chloramines (Krasner et al., 1989). This
formation appears to be enhanced in systems using
with a variety of organic compounds, including
sequential ozone/chloramines treatment schemes
(Ferguson et al., 1990; Krasner et al., 1991). ClCN
is currently unregulated in the United States. How-
ever, this DBP was included in the information
collection rule (USEPA, 1996) (4), and appeared on
the Drinking Water Priority List as early as 1988
the reaction of monochloramine with formaldehyde
(USEPA, 1988, 1991). The ICR required quarterly
monitoring of ClCN by utilities serving populations
of at least 50,000 or 100,000, for groundwater or
waters containing natural organic matter (Glaze
surface water sources, respectively (USEPA, 1996).
Two goals of the ICR were to establish a database on
the occurrence of ClCN in drinking water, and to
gain understanding of the corresponding role of
rapidly and reversibly with monochloramine to form
water quality parameters (USEPA, 1996). The World
formation pathways for ClCN in drinking water.
ClCN is produced from the reaction of chloramines
amino acids, peptides, proteins, nitriles, and others
(Maeda et al., 1987; Hirose et al., 1988, 1989). Many
of the aforementioned compounds have been identi-
fied as trace constituents in natural waters.
More recently, ClCN has been shown to form from
(Pedersen et al., 1999). Formaldehyde is a common
DBP produced during ozonation or chlorination of
et al., 1989; Weinberg et al., 1993; Meyers, 1998),
and from the reaction of monochloramine with
glycine (Hand et al., 1983). Formaldehyde reacts
N-chloroaminomethanol (Pedersen et al., 1999). This
carbinolamine dehydrates slowly and irreversibly into
N-chloromethanimine, which in turns decomposes
quickly into cyanide. Cyanide then reacts with
Health Organization (WHO) has proposed a drink-
ing water guideline value of 70 mg L 1 for all cyanide
additional monochloramine to form ClCN. Under
*Current address: Carus Chemical Company, 1500 Eighth
Street, LaSalle, IL 61301, USA.
characteristic drinking water conditions, the decay of
N-chloroaminomethanol is the rate-limiting step. Rate
and equilibrium constants for these reactions were
yAuthor to whom all correspondence should be addressed.
Current address: Department of Civil and Environmen-
reported in a previous study (Pedersen et al., 1999).
Predicting the formation of ClCN in drink-
ing water would require not only an accurate
tal Engineering, University of Illinois, Urbana, IL
61801, USA. Tel.: +1-217-333-6961; fax: +1-217-333-
6968; e-mail: marinas@uiuc.edu
643

644
Erik J. Pedersen III and Benito J. Marinas
understanding of the kinetics for all formation approximately 0.05 mM. The temperature depen-
reactions but also for those that result in ClCN dence for kOh H, within the range of 5–458C, was
decomposition. ClCN is known to hydrolyze in basic determined at a pH of 10.1. The corresponding
solution, producing cyanic acid and chloride ion activation energy was determined to be
(Eden and Wheatland, 1950) according to the general 59.1 Æ 0.5 kJ mol 1. Edwards et al. (1986) reported
1
base-catalyzed reaction (Bailey and Bishop, 1973; koh and khOH values of 5.7 Â 10 7 s
and
Edwards et al., 1986):
13 M 1 s 1, respectively, at 258C. Respective activa-
tion energies were found to be 86.4 and
85.0 kJ mol 1. The pH and temperature ranges
studied were 0–10.5 and 18–418C, respectively. These
researchers also reported kBh values for a number of
organic and inorganic nucleophiles. Douglas and
kh
ClCN þ H2O ! HOCN þ Hþ þ Cl
ð1Þ
The cyanic acid formed is a weak acid with pKa ¼
3:48 at 258C (Smith and Martell, 1976). Therefore,
under drinking water conditions, cyanate ion
1
Winkler (1947) reported a koh value of 5.7 Â 10 7 s
1
.
and corresponding activation energy of 88 kJ mol
(OCN
) rather than cyanic acid will be the
The pH and temperature ranges of the experiment
were 4–6 and 0–508C, respectively. Initial ClCN
concentrations ranged from 0.04 to 0.184 M. The
reactions occurred in water saturated with carbon
predominant observed product of equation (1). The
integrated rate expression for equation (1) at
constant pH is
kht
dioxide. Lister (1957) determined an activation
1
energy of 85.8 kJ mol
½ClCNŠ ¼ ½ClCNŠ e
in which [ClCN]0 and [ClCN]t are the initial and time
t concentrations. kh is the overall rate constant
defined as
ð2Þ
t
0
for koh. The experiments
were performed at 40-608C, in apparently unbuffered
solutions.
Discrepancies between koh and khOH values reported
by different groups in the literature were the basis for
undertaking the present study. The first objective of
this investigation was to do a critical analysis of the
relevant literature data. A second goal was to
perform new experiments that would allow the
determination of kho and kOh H values, including their
temperature dependence. This information will be
used in future modeling tasks regarding the forma-
kh ¼ kho þ khOH½OH Š þ khB½BŠ
where koh, khOH, kBh are the water, hydroxide ion, and
generic base-B-assisted rate constants. The tempera-
ture dependence of each of these rate constants can
be represented with the Arrhenius equation
ð3Þ
kih ¼ Ae
ð4Þ
Ea=ðRTÞ
where Ea is the activation energy (J mol 1), R is the tion and decomposition of ClCN, specifically from
ideal gas constant (8.314 Jmol 1 K 1), T is absolute the reaction of formaldehyde with monochloramine
temperature (K), and A is the collision frequency under drinking water conditions.
factor (same units as kih).
The hydrolysis of ClCN has been investigated by
several research groups. Unfortunately, there is little
consistency among the reported kinetic parameters.
MATERIALS AND METHODS
Price et al. (1947) determined kOh H to be approxi-
mately 10 M 1 s 1. The experiments were performed Experimental design
at ambient temperature in tap water naturally
Two sets of experiments were performed to investigate
buffered to pH 7.70–8.15, and also in basic solutions the effect of solution pH and temperature on the kinetics of
hydroxide-assisted ClCN hydrolysis.
The pH dependence was investigated at pH values
at a pH of approximately 10. Initial ClCN concen-
trations ranged from 0.2 to 1.3 mM. Eden and
ranging from 9.54 to 10.93, and
a temperature of
Wheatland (1950) determined kOh H to be
21.0 Æ 0.28C. Initial ClCN concentrations and the corre-
sponding pH values are presented in Table 1. The solutions
were buffered with the carbonate–bicarbonate system at a
total target concentration of 0.005 M. Higher buffer
concentrations were found to cause interferences with the
determination of the reaction product chloride ion. Lower
buffer concentrations would have resulted in unwanted pH
1
8.83 M 1 s
determined to be 51.9 kJ mol
at 258C. The activation energy was
1
by performing
experiments at pH 11, and temperatures ranging
from 0 to 308C. Carbonate and borate were added to
buffer the solution; the resulting ionic strength was
approximately 0.15 M. Initial ClCN concentrations changes, especially at pH 9.54.
A second set of four tests was performed to investigate
were approximately 0.41 mM. Bailey and Bishop
(1973) found koh, khOH, and kBh for borate ion
the effect of temperature on ClCN hydrolysis. The
temperatures studied ranged from 10.0 to 30.08C
( Æ 0.28C). Each target temperature was achieved by
immersing the reaction vessel in a thermostatted water bath
(Brinkmann Model RM-6, Brinkmann Instruments, Inc.,
Westbury, New York). The pH was maintained at a target
value of 10 by means of the same carbonate–bicarbonate
buffer system (target total buffer concentration of 0.005 M).
Initial ClCN concentration, pH, and temperature values for
1
1
to be 2.58 Â 10 6 s
,
4.53 M 1 s
,
and
6.02 Â 10 3 M 1 s 1, respectively, at 26.58C. The
pH range studied was 7.5–11.2. A total borate
concentration of 0.018 M was used to buffer the
solution; additions of either strong perchloric acid or
sodium hydroxide were used to obtain the desired
solution pH. The initial ClCN concentration was each experiment are presented in Table 1.

The hydroxide-assisted hydrolysis of cyanogen chloride in aqueous solution
645
some of the tests were also analyzed for cyanate and
chloride to check the stoichiometry of equation (1).
Table 1. Summary of experimental conditions and results for ClCN
hydrolysis experimentsa
1
pH
9.54
9.71
10.24
10.66
10.93
10.32
10.32
9.98
Temperature (oC)
[ClCN]0 (M)b
kh (s
)
Analytical methods
5
4
4
4
3
5
4
4
3
21.0
21.0
21.0
21.0
21.0
10.0
15.0
25.0
30.0
0.00933
0.0176
0.0194
0.0241
0.0210
0.00691
0.0104
0.0257
0.0294
7.85 Â 10
1.13 Â 10
3.45 Â 10
9.15 Â 10
1.32 Â 10
7.72 Â 10
1.50 Â 10
5.83 Â 10
1.13 Â 10
ClCN concentrations in standard and test samples were
determined by extraction and subsequent analysis by gas
chromatography. The two products formed in the hydro-
lysis reaction, cyanate and chloride ions, were determined
by ion chromatography.
The analytical procedure followed for ClCN determina-
tion was a modification of that recommended by West
(1991). A 15 mL volume was obtained from the reaction
vessel and transferred to a 17 mL glass vial with a screw cap
and a PTFE-coated septa. The sample was acidified with
reagent-grade sulfuric acid (95–98% purity, Fisher Chemi-
cal Co., Pittsburgh, Pennsylvania) to essentially stop
(greatly reduce the rate of ) the reaction at which instant
the reaction time was recorded. The acidified sample was
then extracted by magnetic stirring (PTFE coated stir bar)
after the following steps: the sample was first transferred to
a 40 mL glass vial with a screw cap and PTFE-coated septa,
a 2 mL volume of n-pentane (99% purity, Phillips Petroleum
Co., Bartlesville, OK) was added, and then a 3.5 g mass of
reagent grade, anhydrous, powdered sodium sulfate (100%
purity, J.T. Baker, Inc., Phillipsburgh, NJ) was added. The
sodium sulfate, added to enhance the extraction efficiency,
had previously been dried at 1038C for at least 2.5 h. The
sample was extracted for exactly 1 min, starting from the
time it was placed on the magnetic stirrer.
9.98
a All experiments were performed using a total carbonate buffer
concentration of 0.005 M.
b These numbers correspond to the [ClCN]0 values determined by
linear regression, not the dosages.
ClCN stock solution preparation
1
A stock solution containing approximately 1 g L
of
ClCN was used to prepare all standard and test solutions.
The stock solution was prepared gravimetrically by
discharging a small amount of ClCN gas into the head-
space above a tared glass bottle containing 25 mL of
0.021 M reagent-grade H2SO4. ClCN gas, denser than air,
remained on top of the liquid surface and absorbed into
solution. A 5–10 min waiting period was usually required to
reach a stable balance reading. The source of the gas was a
pressurized cylinder containing approximately 300 g of
ClCN (>99% purity, Solkatronic Chemicals, Inc., Fair-
field, NJ). ClCN gas is extremely toxic. For this reason, all
work involving concentrated amounts of the compound was
done inside a fume hood.
A 1-min extraction time was used because it was found to
yield a greater amount of ClCN compared to a 10 min
extraction time due to the decomposition of ClCN in n-
pentane (Pedersen, 1992). Approximately 1 mL of pentane
phase was withdrawn and then injected into the GC exactly
1 min after the extraction was stopped. Not every pentane
sample contained exactly 1 mL, so the actual volume was
recorded before injection.
Standard and test solutions
A
Varian gas chromatograph (GC) Model 3300,
Standard ClCN solutions with concentrations in the equipped with a 63Ni pulsed electron capture detector
range of approximately 0.015–1.5mg L 1 were prepared by (ECD) (Varian, Sunnyvale, California), was used to
diluting the stock solution with deionized water. The pH of
the standards was always less than 3.8. Samples were wide bore, fused silica capillary column with a length of
withdrawn from the standard bottles and analyzed for 30 m and an i.d. of 0.53 mm (Supelco Inc., Bellefonte,
ClCN as described subsequently in the analytical methods Pennsylvania) was used. The temperatures of the injection
determine the ClCN concentration. A Supelco VOCOL
section.
Cyanate and chloride standards were prepared by
port and ECD were set at 120 and 2758C, respectively. A
temperature ramp was used for the column oven: from
dilution of
1.0 g L
a
of each ion. The buffers used were identical to
concentrate stock solution containing room temperature (usually 25–308C) to 458C at a rate of
1
78C min 1. The initial and final oven temperatures were
held constant for 30 s. Nitrogen was used as the carrier gas,
with a flow rate of 30 mL min 1. The ClCN peak had an
average retention time of approximately 2.5 min. The
those in the reaction solutions. Reagent grade sodium
cyanate (96% purity, Aldrich Chemical Company, Inc.,
Milwaukee, WI) and sodium chloride (greater than 99.99%
purity, Mallinckrodt Specialty Chemicals Co., Paris, KY)
were used for this purpose. The sodium chloride was dried
at 1038C for 2.5 h and cooled in a desiccator (at least 30 min)
method detection limit was found to be approximately
1
0.05 mg L
.
Cyanate and chloride ions were determined simulta-
prior to weighing. Cyanate and chloride ions in standard neously. First, a 15 mL volume of sample was transferred
and test samples were analyzed as described in the analytical from the reaction vessel to a 17 mL glass vial with a screw
methods section.
cap and PTFE-coated septa. The sample was quickly
acidified with a volume of 0.052 M H2SO4 (reagent grade)
solution, predetermined by trial-and-error (usually
0.5 Æ 0.2 mL), to pH 5 Æ 0.2. The mixture was then shaken,
and the time was recorded. It is noted that equation (1)
Test solutions were prepared by diluting 1 mL of ClCN
stock solution to 1 L of carbonate–bicarbonate buffer
solution at target pH. Before adding ClCN, the buffer
solution temperature in the reaction vessel was allowed to
equilibrate in the water bath. Prior to starting the reaction, proceeds extremely slowly at pH 5.
the temperature was always verified with a hand-held
mercury thermometer. The pH was checked near the start
of the reaction, and usually once or twice more during the
course of the reaction. The highest pH change observed over
the course of a reaction was 0.05 pH units (this was at pH
9.54, and 21.08C). The average pH value was used when a
deviation was observed. Samples were withdrawn from the
reaction vessel at various times, stabilized by dropping the
pH below 3.8 with sulfuric acid, then analyzed for ClCN as
described in the analytical methods section. Samples for
Within 10 min following acidification, the samples were
injected into a Dionex Model 2000i/SP ion chromatograph
(Dionex Corporation, Sunnyvale, California). Standard
Method 4110 (APHA et al., 1989) was followed. The
elution times for the chloride and cyanate peaks were
approximately 2.2 and 3.1 min, respectively. The method
for both ions.
1
detection limit was approximately 10 mg L
A Fisher Accumet pH/ion meter (Model 925, Fisher
Scientific, Pittsburgh, Pennsylvania) equipped with a Corn-
ing general purpose combination electrode (Corning Glass

646
Erik J. Pedersen III and Benito J. Marinas
Works, Corning, New York) was used to measure pH.
Before each pH reading, a three point standardization was
performed using standard buffer solutions. The pH meter
was designed to compensate for temperature changes, so
standardizations were done at room temperature.
RESULTS AND DISCUSSION
pH dependence experiments
Results obtained for the experiments designed to
assess the pH dependence of kOh H are shown in Fig. 1.
Consistent with equation (2), the rate of ClCN
hydrolysis was found to be pseudo first order at
each constant pH investigated. Pseudo-first-order
rate constants, obtained by fitting each data set to
equation (2) (see Table 1), are plotted against the
corresponding hydroxide ion concentrations in Fig.
2. Hydroxide ion concentrations were calculated
based on water ionization constants reported by
Harned and Owen (1958). In spite of some data
variability, the dependence of the rate constant on
hydroxide ion concentration was generally consistent
with the second term on the right-hand side of
equation (3), or kh ffi kOh H½OH Š. Notice that due to
data variability and the relatively high pH range
investigated, the value koh5khOH½OH Š could not be
determined accurately from the intercept with the
vertical axis in Fig. 2. The experimental variability
might have been the result of unaccounted for
carbonate catalysis, small errors in pH measurement,
or a certain combination of these two factors. In
order to obtain a more representative linear regres-
Fig. 2. Dependence of pseudo-first-order rate constant kh
on hydroxide ion concentration at 21.08C and pH 9.54–
10.93.
Edwards et al. (1986). As depicted in the figure, there
was better agreement between the line corresponding
to the former study and the data obtained in this
investigation. The higher kOh H value reported by
Edwards et al. (1986) might have been an artifact
resulting from these authors not taking into con-
sideration the effect of catalysis by buffer species.
Edwards et al. (1986) stated that borate buffer did
not result in catalysis in contradiction with the
finding by Bailey and Bishop (1973).
A representative example of experimental results
used to check the stoichiometry of equation (1) is
presented in Fig. 3, using data from the experiment
performed at pH 9.54. The curves in the figure
correspond to plots of equation (2) for ClCN, and
the expressions
sion (continuous line in Fig. 2), the data were fitted to
1
equation (3) with koh ¼ 3:29Â10 7 s
, a value
calculated from the temperature dependence of kho
(see Fig. 6) recommended in a later section of this
article.
Also presented in Fig. 2 are lines corresponding to
results reported by Bailey and Bishop (1973) and
kht
½Cl Š ¼ ½OCN Š ¼ ½ClCNŠ0ð1
e
Þ
ð5Þ
t
t
for cyanate and chloride ions; the kh value from
Table 1 was used. As depicted in Fig. 3, stoichio-
metry consistent with equation (1) was observed.
Temperature dependence experiments
Results obtained for the temperature dependence
experiments, performed at high pH (see Table 1), are
presented in Fig. 4. Once again, the validity of
Equation 2 was confirmed. The kOh H values were
obtained by dividing the slope of each curve by the
corresponding hydroxide ion concentration (see
Table 1). The results of these efforts are plotted in
Fig. 5 according to equation (4). As depicted in the
figure, the effect of temperature on kOh H was
consistent with the Arrhenius expression.
Also presented in Fig. 5 are the temperature
dependency of kOh H reported in other studies. The
data of Bailey and Bishop (1973) were consistent with
the results from the present study. In contrast, khOH
Fig. 1. Effect of pH on the rate of ClCN hydrolysis at
21.08C and pH 9.54–10.93.

The hydroxide-assisted hydrolysis of cyanogen chloride in aqueous solution
647
values reported by Eden and Wheatland (1950) and
Edwards et al. (1986) were generally higher. As
discussed previously, the apparently higher rates
might have been an artifact resulting from unac-
counted for catalysis by borate used to buffer the
solutions by both Eden and Wheatland (1950) and
Edwards et al. (1986).
Because of the good agreement between the data of
Bailey and Bishop (1973) and the results obtained in
this study, it was decided to fit the two data sets
together with equation (4). The resulting fitting
1
parameters were A¼ 2:06 Â 1011
M
1 s
and
Ea ¼ 60; 980 J mol 1. It is noted that these values
should not have been affected greatly by ionic
strength; the solutions used in this study were
relatively dilute, and only one of the reactants,
hydroxide ion, was a charged species (Espenson,
1981).
Fig. 3. Stoichiometry of ClCN decomposition and cyanate
and chloride ion formation at 21.08C and pH 9.54.
Water-assisted hydrolysis
Rate constants reported in the literature for the
hydrolysis of ClCN at low pH are presented in Fig. 6.
As depicted in the figure, there is very good
agreement among all studies with the exception of
the rate constant reported by Bailey and Bishop
(1973). The apparently erratic higher value given by
these investigators probably resulted from the fact
that they determined the water-assisted rate constant
based on results obtained from experiments per-
formed at relatively high pH values (7.5–11.2). The
hydroxide ion and borate-assisted components of the
overall hydrolysis rate (equation (3)) were predomi-
nant and likely impaired the determination of the
water-assisted term.
With the exception of the rate constant by Bailey
and Bishop (1973), all data sets presented in Fig. 6
were fitted simultaneously with equation (4). The
Fig. 4. Effect of temperature on the rate of ClCN hydrolysis
at 10–308C and pH 9.98–10.32.
Fig. 6. Arrhenius plot of water-assisted rate constants for
the hydrolysis of ClCN.
Fig. 5. Arrhenius plot of hydroxide ion-assisted rate
constants for the hydrolysis of ClCN.

648
Erik J. Pedersen III and Benito J. Marinas
1
resulting fitting parameters were A¼ 9:97 Â 108 s
Hand V. C., Snyder M. P. and Margerum D. W. (1983)
Concerted fragmentation of N-chloro-a-amino acid an-
ions. J. Am. Chem. Soc. 105, 4022–4025.
1
.
and Ea ¼ 87; 180 J mol
Harned H. S. and Owen B. B. (1958) The Physical Chemistry
of Electrolyte Solutions, 3rd ed. Reinhold Publishing
Corp., New York, NY.
CONCLUSIONS
Hirose Y., Maeda N., Ohya T., Nojima K. and Kanno S.
(1988) Formation of cyanogen chloride by the reaction of
amino acids with hypochlorous acid in the presence of
ammonium ion. Chemosphere 17, 865–873.
The hydrolysis of ClCN in dilute aqueous solution
was found to proceed according to equation (1),
as reported in earlier studies. ClCN reacted with
hydroxide ions at a one-to-one molar stoichiometric
ratio, and produced equimolar concentrations of
cyanate and chloride ions. Arrhenius law provided a
good representation of the temperature dependence
of both the water and hydroxide ion-assisted rate
constants.
Arrhenius equation parameters are recommended
for calculating both the water and hydroxide ion-
assisted rate constants for the hydrolysis of ClCN in
aqueous solution. These parameters could be used to
represent the overall hydrolysis of ClCN in the
absence of interfering levels of other nucleophiles.
Hirose Y., Maeda N., Ohya T., Nojima K. and Kanno S.
(1989) Formation of cyanogen chloride by the reaction of
peptides and proteins with hypochlorous acid in the
presence of ammonium ion. Chemosphere 18, 2101–2108.
Krasner S. W., Hwang C. J., Liew T. K. and West M. J.
(1991) Development of a bench-scale method to investi-
gate the factors that impact cyanogen chloride production
in chloraminated waters. Proceedings 1991 American
Water Works Association Water Quality Technology
Conference, American Water Works Association, Denver,
CO, pp. 2101–2108.
Krasner S. W., McGuire M. J., Jacangelo J. G., Patania N.
L., Reagan K. M. and Aieta E. M. (1989) The occurrence
of disinfection by-products in US drinking water J. Am.
Water Works Assoc. 80, 41–53.
Lister M. W. (1957) Some observations on the hydrolysis of
cyanogen chloride. Can. J. Chem. 35, 736–739.
Jafvert of Purdue University for his advice, and Stuart Maeda N., Ohya T., Nojima K. and Kanno S. (1987)
Acknowledgements}The authors are indebted to Dr. Chad
Krasner and Michael West of The Metropolitan Water
District of Southern California for providing valuable
analytical and safety information. Financial support pro-
vided by the Physical Plant of Purdue University is greatly
appreciated.
Formation of cyanide ion or cyanogen chloride through
the cleavage of aromatic rings by nitrous acid or chlorine.
IX. Reactions of chlorinated, nitrated, carboxylated or
methylated benzene derivatives with hypochlorous acid
in the presence of ammonium ion. Chemosphere 16,
2249–2258.
Meyers R. (1998) Encyclopedia of Environmental Analysis
and Remediation, p. 1398. Wiley, New York, NY.
Pedersen III E.J. (1992) Hydrolysis of cyanogen chloride in
dilute solutions. M.S. Thesis, Purdue University, West
Lafayette, IN.
Pedersen III E. J., Urbansky E. T., Marinas B. J. and
Margerum D. W. (1999) Formation of cyanogen chloride
from the reaction of monochloramine with formaldehyde.
Environ. Sci. Technol. 33, 4239–4249.
Price C. C., Larson T. E., Beck K. M., Harrington F. C.,
Smith L. C. and Stephanoff I. (1947) Hydrolysis and
chlorinolysis of cyanogen chloride. J. Am. Chem. Soc. 69,
1640–1644.
REFERENCES
American Public Health Association (APHA), American
Water Works Association (AWWA) and Water Pollution
Control Federation (WPCF) (1989) Standard Methods for
the Examination of Water and Wastewater, 17th ed.
American Public Health Association, Washington, DC.
Bailey P. L. and Bishop E. (1973) Hydrolysis of cyanogen
chloride. J. Chem. Soc. Dalton Trans. 9, 912–916.
Douglas D. E. and Winkler C. A. (1947) The preparation,
purification, physical properties and hydrolysis of cyano-
gen chloride. Can. J. Res. 25, 381–386.
Eden G. E. and Wheatland A. B. (1950) Effect of
temperature and presence of hypochlorite on the rate of
hydrolysis of cyanogen chloride in alkaline solution.
J. Soc. Chem. Ind. 69, 166–169.
Edwards J. O., Erstfeld T. E., Ibne-Rasa K. M., Levey G.
and Moyer M. (1986) Reaction rates for nucleophiles
with cyanogen chloride: comparison with two other
digonal carbon compounds. Int. J. Chem. Kinetics 18,
165–180.
Espenson J. H. (1981) Chemical Kinetics and Reaction
Mechanisms, pp. 172–176. McGraw-Hill, New York, NY.
Ferguson D. W., McGuire M. J., Koch B., Wolfe R. L. and
Aieta E. M. (1990) Comparing PEROXONE and ozone
for controlling taste and odor compounds, disinfection
by-products, and microorganisms J. Am. Water Works
Assoc. 82, 181–191.
Glaze W. H., Koga M. and Cancilla D. (1989) Ozonation
byproducts. 2. Improvement of an aqueous phase West M. (1991) Personal Communication.
derivatization method for the detection of formaldehyde World Health Organization (WHO) (1993). Guidelines for
Smith R. M. and Martell A. E. (1976) Critical Stability
Constants. Vol. 4: Inorganic Complexes. Plenum Press,
New York, NY.
US Environmental Protection Agency (USEPA) (1988)
Priority list of substances which may require regulation
under the safe drinking water act; Notice. Fed. Regist. 53,
1892–1902.
US Environmental Protection Agency (USEPA) (1991)
Priority List of substances which may require regulation
under the safe drinking water act; Notice. Fed. Regist. 56,
1470–1474.
US Environmental Protection Agency (USEPA) (1996)
National primary drinking water regulations: monitoring
requirements for public drinking water supplies; Final
Rule. Fed. Regist. 61, 24353–24388.
Weinberg H. S., Glaze W. H., Krasner S. W. and Sclimenti
M. J. (1993) J. Am. Water Works Assoc. 85, 72–85.
and other carbonyl compounds formed by the ozonation
of drinking water. Environ. Sci. Technol. 23, 838–847.
Drinking Water Quality. Vol. I, 2nd edn. World Health
Organization, Geneva.