Kinetics of oxidation of 4-oxoacids by N-chlorosaccharin in aqueous acetic acid medium

Article abstract of DOI:10.1007/s10953-006-9116-z

The oxidation kinetics of substituted and unsubstituted 4-oxoacids (S) by N-chlorosaccharin (NCSA) have been studied in aqueous acetic acid media. The reaction follows first-order kinetics in each of the 4-oxoacids, NCSA and H ⁺. The effect of changes in the electronic nature of the substrate reveals that positive charge develops in the transition state. Based on the kinetic results and product analysis, a suitable mechanism has been proposed for the reaction of NCSA with 4-oxoacids. Springer Science+Business Media, LLC 2007.

Full text of DOI:10.1007/s10953-006-9116-z

J Solution Chem (2007) 36:345–356
DOI 10.1007/s10953-006-9116-z
ORIGINAL PAPER
Kinetics of Oxidation of 4-Oxoacids by
N-Chlorosaccharin in Aqueous Acetic Acid Medium
N. A. Mohamed Farook
Received: 8 June 2006 / Accepted: 30 August 2006 /
Published online: 6 February 2007
ꢀ Springer Science+Business Media, LLC 2007
C
Abstract The oxidation kinetics of substituted and unsubstituted 4-oxoacids (S) by
N-chlorosaccharin (NCSA) have been studied in aqueous acetic acid media. The reaction
follows first-order kinetics in each of the 4-oxoacids, NCSA and H+. The effect of changes
in the electronic nature of the substrate reveals that positive charge develops in the transition
state. Based on the kinetic results and product analysis, a suitable mechanism has been
proposed for the reaction of NCSA with 4-oxoacids.
Keywords Kinetics · Oxidation · 4-Oxoacids · NCSA · Reaction mechanism
1 Introduction
In 4-oxoacids, two carbon atoms separate the carbonyl and carboxyl groups and thus they
behave both as oxocompounds and as acids without a direct influence from the other group.
Among the various organic compounds employed in these studies, 4-oxoacids are attractive
substrates because of their enolization in strong acid media. That enols are reactive species
of the substrate has been reported in the literature [1].
N-Chlorosaccharin is a source of a positively charged halogen atom and this reagent has
been exploited as an oxidant for a variety of substrates in both acidic and alkaline media [2].
The nature of the active oxidizing species and the mechanism depends on the nature of the
halogen atom, the groups attached to the nitrogen and the reaction conditions. The species
responsible for this oxidizing character may differ depending on the pH of the medium.
The probable reactive species [3] of NCSA in acidic solutions are >NX, HOX, >N+HX, or
H2OX+, and in alkaline solutions are >NH, HOX, and OX−.
In the recent years, studies of the oxidation of various organic compounds by N-halo
compounds in the presence of perchloric acid have attracted considerable attention [4]. A
thorough literature survey revealed that few studies of the oxidation of 4-oxoacids have been
N. A. M. Farook (
)
ꢀ
Department of Chemistry, Khadir Mohideen College, Adirampattinam 614 701, India
e-mail: nafarook@msn.com
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J Solution Chem (2007) 36:345–356
reported so far [5]. Although the N-chlorosaccharin oxidation of a large variety of organic
compounds have been studied, there seems to be no reports on a systematic kinetic study of
the oxidation of 4-oxoacids by N-chlorosaccharin.
We have carried out a systematic study of the reactions of 4-oxoacids (S) by
N-chlorosaccharin (NCSA). In this report, we have examined the kinetic and mechanistic
aspects of the oxidation of substituted and unsubstituted 4-oxoacids by N-chlorosaccharin
in the presence of perchloric acid. The various unsubstituted and substituted 4-oxoacids
(S1–S7) employed in the present study are listed below:
4-Oxoacid (S1)
O
O
6'
3'
5'
4'
1' C CH2 CH2 C OH
4
3
2
1
2'
S1: Unsubstituted; S2: 4ꢁ-Methoxy; S3: 4ꢁ-Methyl; S4: 4ꢁ-Phenyl; S5: 4ꢁ-Chloro; S6: 4ꢁ-
Bromo; S7: 3ꢁ-Nitro.
2 Materials
All of the chemicals used were of p.a. grade. Acetic acid (BDH) was first refluxed over
chromic acid for 6 h and then distilled. Solutions of sodium perchlorate, perchloric acid
and mercuric acetate were prepared in double-distilled water. Double-distilled water was
employed in all kinetic runs.
The parent 4-oxoacid, namely 4-oxo-4-phenylbutanoic acid (S1), and the phenyl sub-
stituted 4-oxoacids (S2–S7) were prepared by Friedel-Crafts acylation of the substituted
benzene with succinic anhydride. Nitration of the oxoacids was performed under mild con-
ditions to prepare nitro compounds.
3 Experimental section
The reaction was followed potentiometrically by setting up a cell containing the reaction
mixture, into which a platinum electrode and a standard calomel electrode were dipped. The
Emf of the cell was measured periodically using an Equip-Tronics potentiometer while the
reaction mixture was continuously stirred. An electrically operated thermostat was used to
maintain the desired temperature with an accuracy of 0.1◦C. A double-walled 100 mL
beaker with inlet-outlet water circulation facility, specially designed for this experiment, was
used as the reaction vessel.
The Emf values of the reaction mixtures were determined at definite time intervals. The
pseudo-first-order rate constants were computed from plots of ln(Et − E ) versus time. The
∞
precision of the values of the rate constant are given in terms of their 95% confidence limits
as determined by the student’s t test [6].
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4 Results and discussion
4.1 Order of reaction
347
The rate of oxidation was found to be first order each in [NCSA] and [S]. Linear plots of
log10k1 versus log10[S] with unit slope (S1: slope = 1.01 0.03, r = 0.999; S2: slope =
0.998 0.01, r = 0.999; S3: slope = 1.02 0.01, r = 0.989; S4: slope = 1.04 0.03,
r = 0.997; S5: slope = 0.999
0.04, r = 0.989; S6: slope = 1.03
0.03, r = 0.999;
S7: slope = 1.01 0.02, r = 0.997) demonstrate the first-order dependence of the rate on
[S]. The k1 values at different [S] are given in Table 1. The k1 values obtained at different
initial concentrations of NCSA reveal that the rates are almost independent of the initial
concentration of NCSA (Table 1). This ensures that the order of the reaction with respect to
NCSA is one.
The dependence of the reaction rate on the hydrogen ion concentration has been investi-
gated at different initial concentrations of perchloric acid while keeping the concentrations
of the other reactants constant. It may be seen that the rate of reaction increases linearly
with an increase in the hydrogen ion concentration. This establishes that the reaction rate is
first order with respect to the hydrogen ion concentration. A plot of k1 versus [H+] is also
linear and passes through the origin (Fig. 1), showing that the reaction proceeds completely
through an acid-catalyzed pathway [7].
It was reported earlier in the case of N-halo oxidants that, in the absence of mineral acids,
HOCl is the reactive oxidant species. Bishnoi et al. [7] have observed, for the oxidation of
some α-hydroxy acids by NCSA, that the linear increase in the oxidation rate with an increase
in [H+] indicates that protonation of HOCl occurs to give a cationic chlorine species, see
Eq. (1), which is a stronger electrophile and oxidant.
HOCl + H3O+ ꢀ H2O+Cl + H2O
(1)
Thus, the most probable oxidizing species is the hypochlorous acidium ion, (H2O+Cl). The
participation of the hypohalous acidium ions in many electrophilic substitution and oxidation
reactions is well documented [8].
4.2 Effect of varying the ionic strength
The ionic strength of the reaction medium was changed by the addition of anhydrous sodium
perchlorate to study the influence of ionic strength on the reaction rate. It was found that the
ionic strength of the reaction medium has no significant effect on the reaction rate.
4.3 Effect of the products
The effect from adding saccharin was studied, which caused a decrease in the oxidation
rate. Thus, retardation of the reaction rate upon addition of saccharin suggests that there is a
pre-equilibrium step involving a process in which saccharin is a product:
NCSA + H3O+ ꢀ H2O+Cl + saccharin
(2)
If this equilibrium is involved in the oxidation process, then the rate should be an inverse
function of the saccharin concentration, which is borne out by the observation that the inverse
of the rate constant gives a linear curve (r = 0.999) when plotted against [saccharin]. Similar
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Fig. 1 Plots of k1 versus [H+]
for the reaction between S and
NCSA
conclusions were reached in the N-chloronicotinamide [9] oxidation of amino acids and in
the N-bromoacetamide oxidation of some α-hydroxy acids.
4.4 Effect of a free radical inhibitor
The oxidation reactions of S1 with NCSA, catalyzed by perchloric acid, have been inves-
tigated at different initial concentrations of acrylonitrile [10]. This reagent neither induces
polymerization nor retards the reaction. Under the experimental conditions there is no reac-
tion between NCSA and acrylonitrile. Consequently, it may be inferred that free radicals are
not involved in the rate-controlling step of the present reaction.
4.5 Effect of solvent composition
The effect from changing solvent composition on the reaction rate was studied by varying
the concentration of acetic acid from 50% to 80%. The pseudo-first-order rate constants
were estimated for the oxidation reactions of all of the oxoacids, S1–S7, with NCSA in the
presence of perchloric acid at a constant ionic strength. The reaction rate increases markedly
with the increase in the proportion of acetic acid in the medium (see Table 2). When the
acetic acid content increases in the medium, the acidity of the medium is increased whereas
the dielectric constant of the medium is decreased. These two effects cause the rate of
the oxidation to increase markedly. The observed effect is similar to those reported for the
oxidation of other organic compounds by NCSA [10]. When the acetic acid content of the
medium is increased from 50% to 80%, the pH of the medium changes thus leading to an
increase in [H+] and, hence, catalysis by the acetate ion is untenable.
The enhancement of the reaction rate with an increase in the amount of acetic acid
generally may be attributed to two factors, viz, (i) the increase in acidity occurring at
constant [perchloric acid], and (ii) the decrease in the dielectric constant with an increase
in the HOAc content. The plots of log10k1 against the inverse of the dielectric constant are
linear with positive slopes, indicating that an interaction occurs between a positive ion and a
dipolar molecule [11]. This supports the postulation of H2O+Cl as being the reactive species.
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Table 2 Effect of the solvent polarity on the rate of reaction where [S] = 2.0 ×
10−2 mol·dm−3, [NCSA] = 1.0 × 10−3 mol·dm−3, [H+] = 0.5 mol·dm−3, and the
temperature is 303 K
104 × k1, a s−1 (CH3 COOH + H2O (v/v), %)
S
50–50
60–40
70–30
80–20
Slopeb
r b
S1 1.72 0.10
S2 5.84 0.60
S3 4.14 0.58
S4 1.84 0.11
S5 1.07 0.17
S6 0.99 0.04
S7 0.26 0.03
2.54 0.24 3.35 0.14 5.83 0.29 23.8
7.23 0.36 8.31 0.48 9.96 0.60 10.1
5.30 0.25 6.73 0.54 7.94 0.54 12.7
2.36 0.07 3.30 0.14 4.55 0.18 17.6
1.47 0.06 2.20 0.11 3.44 0.01 19.0
1.19 0.05 1.85 0.15 2.87 0.15 14.7
0.52 0.03 0.86 0.07 1.26 0.08 37.9
0.998
0.983
0.985
0.998
0.998
0.994
0.998
aEstimated from the pseudo-first-order reaction plots.
bThese values were calculated from the plots drawn between log10 k1 and 1/D.
4.6 Rate of enolization by the bromination method
It has earlier been reported that oxidation of keto compounds proceeds via enolization of the
keto compounds [12]. The rate of enolization of a keto compound is found to be faster than
the rate of oxidation. The reactive species of the substrate may be determined by enolization,
which is both an acid and base catalyzed reaction that proceeds by a concerted or push-pull
mechanism. The rate of enolization was determined by the bromination method for the
system under investigation.
4.7 Effect of substituents
The oxidation of 4-oxo-4-phenylbuanoic acid (S1) and substituted 4-oxoacids (S2–S7) was
carried out in the temperature range of 303 to 323 K. The observed rate constants increase
with temperature for all the studied compounds. The activation parameters for the oxidation
of the 4-oxoacid by NCSA have been evaluated from the slopes of the Arrhenius plots.
A close look at the activation parameters presented in Table 3 shows that the activation
energies for the oxoacids with electron-releasing substituents are relatively lower than for
those with electron-withdrawing substituents. The entropy of activation is negative for all
the 4-oxoacids, ranging from −126 to −232 J·K−1·mol−1. The large negative entropy of
activation, in conjunction with other experimental data, supports the mechanism outlined in
the Scheme 1.
It is interesting to note that the reactivity decreases in the order 4-methoxy > 4-methyl >
4-phenyl > 4-H > 4-Cl > 4-Br > 3-NO2 for the substituents.
A Hammett’s plot for the oxidation of S by NCSA at various temperatures was found to
be linear. This Hammett’s plot is shown in Fig. 2. The values of the reaction constants (ρ)
are reported in Table 4.
The observed ρ values indicate that the reaction is sensitive to the effects of electronic
perturbations. It also provides information about the nature of the transition state occurring
during the reaction. A reaction involving the development of a positive charge in the transition
state is aided by electron-releasing substituents and the resulting ρ values are negative
[13–16].
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Fig. 2 Hammett plot (at 303 K)
for the oxidation of S by NCSA
0.80
0.40
slope = -1.34
r = 0.998
S2
S3
S4
0.00
S5
S1
S6
-0.40
-0.80
-1.20
S7
-0.4
0.0
0.4
0.8
Substituent constant,
p
In the present investigation, both the acceleration of the reaction rates from the presence
of electron-releasing substituents and the negative value of the reaction constant, ρ, indicate
explicitly that the mechanism of oxidation involves the development of positive charge in
the transition state.
It is generally recognized that oxidation lead to electron deficient species that are radical
cations, radicals or carbocations. These reactions normally have a negative ρ value and the
magnitude of the ρ value depends on the extent of electron deficiency. Oxidation reactions
involving free radical formation during the rate-controlling step usually have a small negative
ρ value and oxidation involving the formation of a carbocation have large a negative ρ value.
Based on these arguments we expect to observe a large absolute value for ρ, but the measured
values are in the range ρ = −1.34 to −0.93. The low ρ value may be attributed to the nature
of observed rate constant. The observed rate constant is a composite of several terms as
shown in Eq. (12).
The terms shown in Eq. (12) deserve comment. The rate constant k3 depends on the
concentration of the protonated substrate (S+). The electron donating substituents tend to
delocalize the positive charge on S+ and, hence, favor the formation of this positive species.
In the rate-limiting step, Eq. (6) of Scheme 1, the formation of the carbocation is facilitated
by electron-releasing substituents.
Table 4 Reaction constant values at different temperatures
Temperature K Reaction constanta
ρ
Correlation coefficient s∗
303
308
313
323
−1.34 0.09
−1.23 0.17
−1.11 0.20
−0.93 0.19
0.998
0.998
0.998
0.998
0.027
0.050
0.057
0.056
Note. The σ values were taken from a reported study [13].
aThe values were obtained by correlating log10 (k2/k2◦) with σ for the
p
oxidation reactions of S1–S7 with NCSA (s∗ is the standard deviation).
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Thus, we obtain a slightly lower negative ρ value of (−1.34 at 303 K) because kobs is a
composite of the enolization reaction as well as the oxidation of the 4-oxoacids. Hence, in
the present investigation the measured ρ value and other findings fit in with the formulation
of the mechanism as outlined in Scheme 1.
The dependence of the reaction rate on the structure of the reacting molecule is related
to the activation parameters. The decisive term concerning the dependence of the reaction
rate on the structure is neither the Gibbs energy nor enthalpy, but the potential energy that is
experimentally not accessible. Many authors support the opinion that the activation energy
at a certain temperature is a better approximation for the unknown potential energy [17].
The validity of the isokinetic relation can be tested graphically with Exner plots. The
isokinetic temperature evaluated from the Exner plots was found to be 378 K. As the
experiments have been carried out at temperatures far away from the isokinetic temperature,
the application of Hammett’s equation to the observed kinetic data is valid. The validity of
the isokinetic relationship in the present study implies that all of the 4-oxoacids undergo
oxidation by the same mechanism [18].
4.8 Mechanism
A probable mechanism for the oxidation of 4-oxoacids by NCSA has been proposed, based
on the experimental results and in analogy with the oxidation mechanisms of oxo compounds
with other oxidants.
k1
NCSA
H3O
H2O Cl
Saccharin
+
+
(3)
k
-1
O
O
k
2
H O
C
CH2 CH2
(S)
C OH
+
3
k
-2
OH
O
H2O
C
CH2 CH2
C
OH
+
(4)
(S )
O
OH
k
k
3
H3O
C
CH CH2
(E)
C
OH
+
(S )
H2O
+
-3
(5)
O
C
OH
k
4
C
CH CH2
OH
slow
O
C
OH
C
H2O Cl
CH CH2
OH
H2O Cl
(6)
(7)
(F)
O
fast
C
OH
(F)
Other products
+
Scheme 1
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5 Derivation of the rate law
Based on kinetic observations and the mechanism proposed, the following rate expressions
can be derived by applying the steady-state approximation.
The rate of the reaction is given by
−d[NCSA]
= k4 [E][H2O+Cl]
(8)
dt
Applying the steady-state approximation for [E] yields
−d[NCSA]
dt
k2k3k4[H3O+][S][H2O+Cl]
−2k−3[H3O+] + k4(k−2 + k3)[H2O+Cl]
(9)
k
At high concentration of [H3O+] = 0.5 mol·dm−3
,
k
−2k−3[H3O+] ꢂ k4(k−2 + k3)[H2O+Cl]
and thus Eq. (9) simplifies to the form:
−d[NCSA]
k2k3k4[H3O+][S][H2O+Cl]
=
=
dt
k
−2k−3[H3O+]
k2k3k4[S][H2O+Cl]
−2k
(10)
k
−3
The value of [H2O+Cl] can be obtained from Eq. (3) as given in Scheme 1.
k
k1
[NCSA][H3O+]
−1
Ka =
=
[H2O+Cl][saccharin]
Therefore,
[NCSA][H3O+]
[H2O+Cl] =
Ka[Saccharin]
Using the value of [H2O+Cl] in Eq. (10),
−d[NCSA]
dt
k2k3k4[S][H3O+][H2O+Cl]
=
(11)
k
−2k−3 Ka[saccharin]
Hence, at higher concentrations of mineral acid, the reaction is first order with respect to the
oxoacid (S), [NCSA] and [H3O+].
The observed rate constant at high [H3O+] is
k2k3k4
−2k−3 Ka
kobs
=
(12)
k
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5.2 Product analysis and stoichiometry
In a typical experiment, 4-oxoacid (0.1 mol·L−1), perchloric acid (0.5 mol·L−1) and NCSA
(0.5 mol·L−1) were mixed in a 50% acetic acid + 50% water (v/v) mixture inside a closed
vessel with an outlet, and then allowed to react. The ensuing gas was identified as carbon
dioxide. After 24 h the solution was extracted with ether. The ether extract was dried over
anhydrous sodium sulfate and the solvent evaporated. The colorless solid obtained was
identified as benzoic acid by measuring the mixed melting point and using a chemical
method and TLC techniques.
Different sets of reaction mixtures containing different quantities of NCSA and oxoacid,
at constant concentrations of perchloric acid and sodium perchlorate, were allowed to react
for 24 h at 303 K and then analyzed. The remaining NCSA was assayed iodometrically
and the results are in good agreement with 1:1 stoichiometry, and the reaction may thus be
represented by:
H+
C6H5COCH2CH2COOH + C6H4SO2CONCl + 5H2O −→
C6H5COOH + C6H4SO2CONH + 3CO2+6H2+HCl
(13)
References
1. Basheer Ahamed, K.-A., Sikkandar, G., Kannan, S.: Kinetics of oxidation of 4-oxoacids by permanganate
in buffer media. Indian J. Chem. 38A, 183–186 (1999)
2. (a) Sundaram, G.-S., Venkatasubramanian, N.: Oxidation of diphenylmethanol by bromamine T–A ki-
netic and mechanistic study. J. Chem. Soc. Perkin Trans. 2, 949–954 (1983); (b) Sharma, J.-P., Singh,
R.-N.-P., Singh, A.-K., Singh, B.: Kinetics and mechanism of Ru(III) catalysed oxidation of some
polyhydric alcohols by N-bromosuccinimide in acidic media. Tetrahedron 42, 2739–2747 (1986); (c)
Ramachandrappa, R., Puttaswamy, M., Mayanna, S.-M., Made Gowda, N.-M.: Kinetics and mechanism
of oxidation of aspirin by bromamine-T, N-bbromosuccinimide, and N-bromophthalimide. Int. J. Chem.
Kinet. 30, 407–414 (1998); (d) Harihar, A.-L., Kembhavi, M.-R., Nandibewoor, S.-T.: Kinetics and mech-
anism of N-bromosuccinimide oxidation of L-arginine in aqueous acidic medium. J. Indian Chem. Soc.
76, 128–130 (1999); (e) Singh, A.-K., Rahmani, S., Singh, K.-V., Gupta, V., Kesarwani, D., Singh, B.:
Iridium(III) catalysis of N-bromosuccinimide oxidation of reducing sugars in aqueous acid. Indian J.
Chem. 40, 519–523 (2001)
3. Negi, S.-C., Banerji, K.-K.: Kinetics and mechanism of the oxidation of secondary alcohols by N-
bromoacetamide in acid medium. Indian J. Chem. 21B, 846–848 (1982)
4. (a) Thimme Gowda, B., Ishwara Bhat, J.: Kinetics and mechanism of oxidation of thiosemicarbazidde
by N-chloro- and N-bromo-seccinimides in aqueous and partially aqueous media. Indian J. Chem. 28A,
211–216 (1989); (b) Sukla, A., Upadhyay, S.-K.: Kinetics and mechanism of iridium(III) catalysed
oxidation of aliphatic amines by N-bromosuccinimide. J. Indian Chem Soc. 11, 745–750 (1992); (c)
Gopalakrishnan, G., John, L.-H.: Kinetic and mechanistic studies of the N-bromosuccinimide-promoted
oxidative decarboxylation of glycine, DL-alanine, and DL-valine. J. Org. Chem. 50, 1206–1212 (1985);
(d) Bharat, S., Lalji, P., Sharma, J., Pandey, S.: Mechanism of oxidation of some aliphatic ketones by
N-bromosuccinimide in acidic media. Tetrahedron 38, 169–172 (1982)
5. (a) Freeda Gnana Rani, D., Maria Pushparaj, F.-J., Alphones, I., Rangappa. K.-S.: Kinetics and mechanism
of oxidation of 4-oxoacids by hexacyanoferrate(III) catalysed by Os(VIII). Indian J. Chem. 41B, 2153–
2159 (2002); (b) Sikkandar, G.: Kinetics of oxidatative decarboxylation of β-benzoylpropionic acid by
manganese(III) acetate. Asian J. Chem. 12, 1037–1040 (2000)
6. Srinivasan, C., Rajagopal, S., Chellamani, A.: Mechanism of picolinic-acid-catalysed chromium(VI)
oxidation of alkyl, aryl and diphenyl sulphides. J. Chem. Soc., Perkin Trans. 2, 1839–1844 (1990)
7. Bishnoi, M.-L., Negi, S.-C., Banerji, K.-K.: Kinetics and mechanism of oxidation of some α-hydroxy
acids by N-bromoacetamide in perchloric acid solution. Indian J. Chem. 25A, 660–662 (1986)
8. (a) Khan, S., Khan, M.-U., Singh, S.-K., Gupta, H.-D., Singh, P.-K.: Kinetic and mechanistic investigation
of N-chlorosaccharin oxidation of 2-alkanones. Asian J. Chem. 15, 595–600 (2003); (b) Mohamed Farook,
Springer

356
J Solution Chem (2007) 36:345–356
N.-A., Prabhkaran, R., Rahini, S., Senthil Kumar, R., Raja Mahendran, G., Gopala Krishnan, G.: Kinetics
of oxidation of some amino acids by N-chlorosaccharin in aqueous acetic acid medium. E-J. Chem. 2,
127–131 (2004)
9. Vivekanandan, K., Nambi, K.: Kinetics and mechanistic study of amino acids by N-chloronicotinimide
in acid medium. J. Indian Chem. Soc. 76, 198–202 (1999)
10. (a) Mohamed Farook, N.-A., Alhaji, N.-M.-I.: Kinetics of oxidation of substituted γ -ketoacid by N-
chlorosaccharin in aqueous acetic acid medium. Int. J. Chem. Sci. 2, 76–80 (2004); (b) Mohamed Farook,
N.-A., Seyed Dameem,G. -A., Murugesan, A., Kanagaraj, M.: Kinetics of oxidation of some essential
amino acids by N-chlorosaccharin in aqueous acetic acid medium. E-J. Chem. 2, 132–136 (2004); (c)
Kavitha, S., Pandurangan, A., Alphones, I.: Kinetics and mechanism of oxidation of betabenzoylpropionic
acids by pyridinium fluorochromate in aqueous acetic acid medium. Indian J. Chem. 44A, 715–718 (2005)
11. Kothari, S., Agarwal, A., Banerji, K.-K.: Kinetics and mechanism of oxidation of primary alcohols by
N-bromo-3-5-dinitrobenzamide. Indian J. Chem. 25A, 722 (1986)
12. Nath, M.-P., Banerji, K.-K.: Kinetics and mechanisms of the oxidation of methyl aryl ketones by acid
permanganate. Aust. J. Chem. 29, 1939–1945 (1976)
13. (a) Wiberg, K.-B.: Physical Organic Chemistry. John Wiley, New York pp. 416–420, (1964); (b) Gould E.-
S.: Mechanism and Structure in Organic Chemistry. Holt Reinhart and Winston, New York, pp. 181–185
(1964)
14. (a) Richard Johnes, A.-Y.: Physical and Mechanistic Organic Chemistry. Cambridge Univ. Press, New
York p. 42 (1984) (b) Ruff, F., Kucsman, A.: Mechanism of the oxidation of sulphides with sodium
periodate. J. Chem. Soc. Perkin Trans. 2, 683–688 (1985)
15. Cotton, F.-A., Wilkinson, G.: Advanced Inorganic Chemistry. New York, 5th edn. John Wiley, p. 707
(1988)
16. Greenwood, N.-N., Earnshaw, A.: Chemistry of the Elements. Pergamon Press, Oxford p. 1222 (1984)
17. Neil Issacs, S.: Physical Organic Chemistry. Longman Scientific & Technical, New York (1987)
18. Leffler, J. -F., Grunwald, E.: Rates and Equilibrium of Organic Reactions. Wiley, New York (1963)
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