Kinetics and mechanism of oxidation of substituted 4-oxoacids by N-bromosaccharin

Article abstract of DOI:10.1007/s10953-012-9942-0

The kinetics of the oxidation of substituted 4-oxoacids by N-bromosaccharin (NBSac) has been studied in aqueous acetic acid medium at 30 C. The reactions follow first-order kinetics in the 4-oxoacids, NBSA and H⁺. Variation in the ionic strength has no effect on the reaction rate. The order of reactivity among the studied 4-oxoacids is: 4-methoxy > 4-methyl > 4-phenyl > 4-H > 4-Cl > 4-Br > 3-NO₂. The effect of changes in the electronic nature of the substrate revealed that there is a development of positive charge in the transition state. The activation parameters were computed from an Arrhenius plot. Based on the kinetic results, a suitable mechanism has been proposed. The mechanism involves the attack of the oxidizing species hypobromous acidium ion, (H₂O⁺Br).

Full text of DOI:10.1007/s10953-012-9942-0

J Solution Chem (2013) 42:239–250
DOI 10.1007/s10953-012-9942-0
Kinetics and Mechanism of Oxidation of Substituted
4
-Oxoacids by N-Bromosaccharin
N. A. Mohamed Farook
•
S. Manochitra A. Afroos Banu
•
Received: 29 November 2011 / Accepted: 11 March 2012 / Published online: 3 January 2013
Ó Springer Science+Business Media New York 2012
Abstract The kinetics of the oxidation of substituted 4-oxoacids by N-bromosaccharin
(
NBSac) has been studied in aqueous acetic acid medium at 30 °C. The reactions follow
?
first-order kinetics in the 4-oxoacids, NBSA and H . Variation in the ionic strength has no
effect on the reaction rate. The order of reactivity among the studied 4-oxoacids is:
4
-methoxy [ 4-methyl [ 4-phenyl [ 4-H [ 4-Cl [ 4-Br [ 3-NO . The effect of changes
2
in the electronic nature of the substrate revealed that there is a development of positive
charge in the transition state. The activation parameters were computed from an Arrhenius
plot. Based on the kinetic results, a suitable mechanism has been proposed. The mechanism
?
involves the attack of the oxidizing species hypobromous acidium ion, (H O Br).
2
Keywords Kinetics ꢀ Oxidation ꢀ 4-Oxoacids ꢀ NBSac
1
Introduction
4
-Oxoacid is an attractive substrate in terms of its enolization. In strong acid medium the
substrate undergoes enolization. The reactive species of the substrate has been reported in
the literature to be the enol form [1].
N-Bromosaccharin is a source of positive halogen and this reagent has been exploited as
oxidant for a variety of substrates in both acidic and alkaline medium [2]. The nature of
active oxidizing species and mechanism depends on the nature of halogen atom, the groups
attached to the nitrogen and the reaction condition. The species responsible for such
oxidizing character may be different depending on the pH of the medium. The probable
?
?
reactive species [3] of NBSac in acid solution are[ NX, HOX, [ N HX, or H OX and
2
-
the reaction species in alkaline solutions are [ NH, HOX, and OX .
In recent years, studies of the oxidation of various organic compounds by N-halo
compounds, in the presence of perchloric acid, have attracted considerable attention. A
through literature survey reveals that relatively little work on the oxidation of 4-oxoacid
N. A. Mohamed Farook (&) ꢀ S. Manochitra ꢀ A. Afroos Banu
Department of Chemistry, Khadir Mohideen College, Adirampattinam 614 701, India
e-mail: nafarook@hotmail.com
123

240
J Solution Chem (2013) 42:239–250
have been reported so far [4–7]. Although the N-bromosaccharin oxidations of organic
compounds have been studied, there seems to be no report on a systematic kinetic study of
the oxidation of 4-oxoacids by N-bromosaccharin.
The main objectives of the present study are to ascertain the reactive species of the
substrate and oxidant, elucidate a plausible mechanism, deduce an appropriate rate law,
identify the oxidation products and evaluate the kinetic parameters.
2
Experimental
2
.1 Materials
All the chemicals used were of AR grade. Acetic acid (BDH) was first refluxed over
chromic acid for 6 h and then distilled. Solutions of sodium perchlorate and perchloric acid
and were prepared in double distilled water. Double distilled water (conductivity \
-
1
1
0 lSꢀcm ) was employed in all kinetic runs. All the chemicals used were 99.8 % pure.
0
0
The 4-oxo-4-(4 -methoxyphenyl)butanoic acid (S2), 4-oxo-4-(4 -methylphenyl)-buta-
0
noic acid (S3), 4-oxo-4-(4 -chlorophenyl)butanoic acid (S5) and N-bromosaccharin
(NBSac) were obtained from Sigma-Aldrich Chemical Co. The remaining 4-oxoacids (S1,
S4, S6, S7) were prepared by Friedel–Crafts acylation of the substituted benzene with
succinic anhydride [5–12].
All the 4-oxo acids used in this study (Table 1) were crystallized twice from water and
their purity was checked by their melting points and UV, IR and NMR spectra. Solutions of
the reagents were prepared either in doubly distilled water or in purified acetic acid and
were standardized by iodometric methods [10] using standard potassium dichromate and
sodium thiosulfate solutions. Fresh solutions were used for each kinetic run.
2
.2 Kinetic Studies
The reaction mixtures, containing 4-oxo acid, acetic acid and mercuric acetate solutions
were thermally equilibrated for an hour at the desired temperature. The reaction was
initiated by the addition of temperature-equilibrated NBSac solution of the requisite
concentration. The rate of the reaction was followed by estimating the amount of unreacted
NBSac iodometrically. All the reactions were carried out under pseudo-first order
Table 1 List of substituted 4-oxoacids
S.no.
4-oxoacids
Code
Melting point °C
5
Observed
Reported
1
2
3
4
5
6
7
4-Oxo-4-phenylbutanoic acid
0
S1
S2
S3
S4
S5
S6
S7
116
146
128
184
132
148
163
116
147
129
185
133
149
164
4-Oxo-4-(4 -methoxyphenyl)butanoic acid
0
4-Oxo-4-(4 -methylphenyl)butanoic acid
4-Oxo-4-biphenylbutanoic acid
0
4-Oxo-4-(4 -chlorophenyl)butanoic acid
0
4-Oxo-4-(4 -bromophenyl)butanoic acid
0
4-Oxo-4-(3 -nitrophenyl)butanoic acid
1
23

J Solution Chem (2013) 42:239–250
241
conditions by keeping an excess (910 or greater) of [4-oxo acid] over [NBSac]. The
pseudo-first order rate constants were computed from linear plots of log10 [NBSac] against
t
time up to 90 % completion of the reaction, the rate constants (k) were reproducible within
5
%.
The precision of the rate constant values is given in terms of 95 % confidence limit of
the student’s t test [13]. Freshly prepared solutions of 4-oxo acids in purified acetic acid
were used. The stoichiometry of the reaction was determined by equilibrating reaction
mixture of various [NBSac]/[4-oxo acid] ratios at 30 °C for 12 h, keeping all other reagent
concentrations constant. Estimation of unconsumed NBSac revealed that one mole of
4
-oxo acid consumed one mole of NBSac.
C6H5COCH2CH2COOH þ C6H4SO2CONBr þ 5H2O
!
C6H5COOH þ C6H4SO2CONH þ 3CO2 þ 6H2 þ HBr
ð1Þ
The products were extracted with ether, dried and analyzed. Benzoic acid was identified by
its melting point (121 °C). Then it was estimated quantitatively using UV–Vis spectro-
photometry with a standard curve at kmax = 235 nm and also tested with its characteristic
spot test. Identification of benzoic acid was also made by comparing the R values of
f
authentic samples.
3
Results and Discussion
3
.1 Order of Reaction
The rate of oxidation was found tobefirst ordereachin[NBSac] and [S]. Linearplots oflog k
10 1
versus log10 [S] with unit slope (S1: slope = 1.03 ± 0.02, r = 0.994; S2: slope = 1.01 ±
0
.03, r = 0.996; S3: slope = 1.04 ± 0.01, r = 0.989; S4: slope = 1.04 ± 0.03, r = 0.999;
S5: slope = 0.995 ± 0.02, r = 0.991; S6: slope = 0.993 ± 0.07, r = 0.994; S7: slope =
.10 ± 0.08, r = 0.992) show first order dependences of the rate on [S]. The k values at
1
1
different [S] are given in Table 2. The k values obtained at different initial concentrations of
1
NBSac reveal that the rates are almost independent of the initial concentration of NBSac (Table 2).
The dependence of the reaction rate on the hydrogen ion concentration has been
investigated at different initial concentrations of perchloric acid, keeping the concentra-
tions of the other reactants constant. The observed k values are presented in the Table 2. It
1
may be seen that the rate of the reaction increases linearly with increase in concentration of
hydrogen ion. This establishes that the reaction is first order with respect to hydrogen ion
?
concentration. A plot of k versus [H ] is linear, passing through the origin (Fig. 1),
1
showing that the reaction proceeds completely through the acid-catalyzed pathway [14].
It was reported earlier in the case of N-halo oxidants that in the absence of mineral
acids, HOBr is the reactive oxidant species. Farook et al. [14] have observed for the
oxidation of some a-hydroxy acids by NBSac that the linear increase in the oxidation rate
?
with an increase in [H ] indicates the protonation of HOBr to give a cationic bromine
species (Eq.2), which is a stronger electrophile and oxidant:
þ
þ
HOBr þ H3O ꢀ H2O Br þ H2O
Thus the most probable oxidizing species is the hypobromous acidium ion, (H O Br). The
ð2Þ
?
2
participation of hypohalous acidium ions in many electrophilic substitution and oxidation
reactions is well documented [15].
123

242
J Solution Chem (2013) 42:239–250
1
23

J Solution Chem (2013) 42:239–250
243
?
versus [H ]
Fig. 1 Plots of k
for the reaction between S and
1
16
NBSac
S2
1
1
1
4
2
0
8
6
4
2
0
S3
S4
S1
S5
S6
S7
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
+
-3
[
H ], mol dm
3
.2 Effect of Varying Ionic Strength
The ionic strength of the reaction medium was changed by the addition of anhydrous
sodium perchlorate and the influence of ionic strength on the reaction rate was studied. It is
found that the ionic strength of the reaction medium had no significant effect on the
reaction rate.
3
.3 Effect of Products
The addition of saccharin decreased the rate of the oxidation reaction. Thus the retardation
of reaction rate on the addition of saccharin suggests a pre-equilibrium step involving a
process in which saccharin is one of the products:
þ
þ
NBSac þ H3O ꢀ H2O Br þ saccharin
ð3Þ
If this equilibrium is involved in the oxidation process, 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 (r = 0.982) plot against [saccharin]. Similar
conclusions have been arrived at in the N-chloronicotinamide [16] oxidation of amino
acids.
3
.4 Effect of Free Radical Inhibitor
The oxidation reactions of S1 with NBSac catalyzed by perchloric acid at different initial
concentrations of acrylonitrile have been investigated. The reaction neither induces
polymerization nor retards the reaction. Under the experimental conditions, there is no
reaction between NBSac and acrylonitrile. Consequently it may be inferred that free
radicals are not involved in the rate controlling step of the present reaction.
123

244
J Solution Chem (2013) 42:239–250
-2
-3
Table 3 Effect of solvent polarity on the rate of reaction, where [S] = 2.0 9 10
molꢀdm
,
-3
-3
?
-3
[
NBSac] = 2.0 9 10 molꢀdm , [H ] = 0.5 molꢀdm , and T = 303 K
4
a
-1
a
r
S
10 k
CH COOH–H
0–50
1
/ s
3
2
O (v/v) %
60–40
5
70–30
80–20
S1
S2
S3
S4
S5
S6
S7
a
1.44 ± 0.12
5.25 ± 0.42
3.82 ± 0.41
1.56 ± 0.11
0.98 ± 0.14
0.91 ± 0.02
0.18 ± 0.03
2.24 ± 0.24
6.83 ± 0.34
4.91 ± 0.22
2.11 ± 0.07
1.32 ± 0.06
1.07 ± 0.05
0.31 ± 0.03
3.12 ± 0.14
7.85 ± 0.48
6.31 ± 0.24
2.92 ± 0.14
2.92 ± 0.11
1.68 ± 0.12
0.61 ± 0.07
5.28 ± 0.29
9.35 ± 0.60
7.52 ± 0.34
4.23 ± 0.18
3.01 ± 0.01
2.36 ± 0.15
0.92 ± 0.08
0.998
0.983
0.985
0.998
0.998
0.994
0.998
Estimated from pseudo first-order plots
3
.5 Effect of Solvent Composition
The effect of 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
for the oxidation reactions of all oxoacids, S1–S7 with NBSac, were estimated in the
presence of perchloric acid at constant ionic strength. The rate of the reaction increases
remarkably with increase in the proportion of acetic acid in the medium (Table 3).
When the acetic acid content increases in the medium, the acidity of the medium is
increased while the dielectric constant of the medium is decreased. These two effects
cause the rate of oxidation to increase remarkably. The observed effect is similar to
those reported in the oxidation of other organic compounds by N-chlorosaccharin [17].
When the acetic acid content of the medium is increased from 50 to 80 %, the pH of the
?
medium changes, leading to the increase in [H ] and hence catalysis by acetate ion is
untenable.
The enhancement of the reaction rate with an increase in the amount of acetic acid may
generally be attributed to two factors: (i) increase in acidity at constant [perchloric acid]
and (ii) decrease in dielectric constant with increase in HOAc content. The plots of log10 k1
against the inverse of dielectric constant are linear with positive slopes, indicating an
interaction between a positive ion and a dipole molecule [18, 19]. This supports the
?
postulation of H O Br as the reactive species.
2
3
.6 Rate of Enolization by the Bromination Method
It has been reported, in the case of oxidation of keto compounds, that the oxidation
proceeds via enolization of the keto compounds [20]. The rate of enolization of keto
compound was found to be faster than the rate of oxidation. The reactive species of the
substrate may be determined by enolization, which is an acid as well as base catalyzed
reaction and proceeds by a concerted or push–pull mechanism. The rate of enolization was
determined by the bromination method for the system under investigation.
1
23

J Solution Chem (2013) 42:239–250
245
3
.7 Effect of Substituents
The oxidation of 4-oxo-4-phenylbutanoic acid (S1) and substituted 4-oxoacids (S2–S7)
were carried out in the temperature range of 303–323 K. The observed rate constants
increase with temperature for all of the compounds. The activation parameters for the
oxidation of 4-oxoacid by NBSac have been evaluated from the slope values of the
Arrhenius plots.
A close look at activation parameters presented in Table 4 shows that the activation
energies for the oxoacids with electron-releasing substituents are relatively lower than
those with electron-withdrawing substituents. The entropy of activation is negative for all
-
1
-1
the 4-oxoacids ranging from -126 to -232 J ꢀ K ꢀ mol . The large negative entropy of
activation in conjunction with other experimental data supports the mechanism outlined in
Scheme-1. The formation of an activated complex from reactant molecules is accompanied
by the conversion of translation-like and rotational-like degrees of freedom of the reactants
to vibrational degrees of freedom of the transition state species. The more widely spaced
energy level for the latter type of molecular motion implies a small entropy and thus a
#
negative value of DS [21].
It is interesting to note that the reactivity decreases for substituents in the order:
4
-methoxy [ 4-methyl [ 4-phenyl [ 4-Cl [ 4-Br [ 3-NO2
ð4Þ
The Hammett’s plot for the oxidation of S by NBSac at various temperatures was found
to be linear. The Hammett’s plot is shown in Fig. 2. The values of reaction constants (q)
are shown in Table 5.
The points are referenced as (1) S2, (2) S3, (3) S4, (4) S1, (5) S5, (6) S6, (7) S7.
The q value indicates the sensitivity of a reaction to the effects of electronic pertur-
bation. It also provides information about the nature of the transition state involved in the
reaction. A reaction involving a development of positive charge in the transition state is
aided by electron-releasing substituents and the q coefficient is negative [21–26].
In the present investigation, the acceleration of reaction rate with the electron-releasing
substituents and the negative value of the reaction constant, q, indicates explicitly that the
mechanism of oxidation involves the development of positive charge in the transition state.
It is generally recognized that oxidations lead to electron deficient species which are
radical cations, radicals or carbocations. These reactions normally have a negative q value
and the magnitude of q depends on the extent of electron deficiency. Oxidation reactions
involving free radical formation in the rate controlling step usually have a small negative q
value and the oxidations involving the formation of a carbocation have large negative q
values. Based on these arguments we expect a large q value but the measured q value is in
the range -1. 41 to -0.98. The low q values may be attributed to the nature of observed
rate constant. The observed rate constant is a composite of several terms and is shown in
Eq. 12.
The terms shown in Eq. 12 deserve comment. The rate constant k depends on the
3
?
concentration of the protonated substrate (S ) and 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 the Scheme-1, the formation of the carbocation
is facilitated by electron releasing substituents.
Thus we get a slightly low negative q value of -1.41 (at 303 K) because kobs is
composite of the enolization as well as the oxidation of the 4-oxoacids. Hence in the
present investigation the measured q value and other findings fit in with the formulation of
mechanism outlined in the Scheme-1.
123

246
J Solution Chem (2013) 42:239–250
1
23

J Solution Chem (2013) 42:239–250
247
k1
NBSac
H O
H O Br
+ Saccharin
+
3
2
(3)
k
-
1
O
C
O
k2
CH2 CH2
S)
C
OH
H O
3
+
k -2
(
OH
O
C
CH2 CH2
C
OH
H O
2
+
(4)
(S )
OH
O
k
3
C
CH CH2
C
OH
H O
+
3
(S )
H O
+
2
k
-
3
(5)
(E)
OH
O
k4
C
CH CH2 C OH
slow
H O Br
OH
C
O
2
CH CH2
C
OH
H O Br
2
(6)
(
F)
O
C
fast
OH
(
F)
Other products
(7)
+
Scheme 1 Reaction mechanism
The dependence of the reaction rate on the structure of the reacting molecule is related
to activation parameters. The decisive term concerning the dependence on the structure is
neither Gibbs energy nor enthalpy but potential energy, which is experimentally not
accessible. Many authors support the opinion that the activation energy at a certain tem-
perature is a better approximation towards the unknown potential energy [27].
The validity of the isokinetic relation can be tested graphically by plotting with Exner
plots. The isokinetic temperature evaluated from the Exner plots is found to be 378 K. As
the experiment has been carried out at a temperature far away from the isokinetic tem-
perature, application of the Hammett equation to the observed kinetic data is valid. The
validity of isokinetic relationship in the present study implies that all the 4-oxoacids
undergo oxidation by the same mechanism [28].
123

248
J Solution Chem (2013) 42:239–250
Fig. 2 Hammett plot (at 303 K)
for the oxidation of S by NBSac
0.80
ρ
= -1.4473
r = 0.9826
1
0
0
.40
.00
2
3
4
6
5
-
-
-
0.40
0.80
1.20
7
-
0.4
-0.2
0.0
0.2
0.4
0.6
0.8
Substituent constant,σ
p
Table 5 Reaction constant values at different temperatures
a
Temperature K
Reaction constant q
Correlation coefficient
SD*
303
308
313
323
-1.41 ± 0.09
-1.32 ± 0.17
-1.20 ± 0.20
-0.98 ± 0.19
0.983
0.992
0.988
0.996
0.025
0.051
0.052
0.054
r values were taken from reported work [21, 22]
*
Standard deviation
a
0
2 2 p
The values were obtained by correlating log10 (k /k ) with r for the reactions of oxidations S1–S7 with
NBSac
3
.8 Mechanism
A probable mechanism for the oxidation of 4-oxoacids by NBSac is proposed based on the
experimental results and in analogy with the oxidation of oxo compounds with other oxidants.
3
.9 Derivation of the Rate Law
Based on kinetic observations and the mechanism proposed, the following rate expression
can be derived applying the steady-state approximation.
The rate of the reaction is given by:
d½NBSacꢂ
þ
ꢁ
¼ k4½Eꢂ½H2O Brꢂ
ð5Þ
dt
Applying the steady state approximation for [E]:
þ
þ
d½NBSacꢂ
k2k3k4½H3O ꢂ½Sꢂ½H2O Brꢂ
kꢁ2kꢁ3½H3Oꢂ þ kꢁ4ðkꢁ2 þ k3Þ½H2O Brꢂ
ꢁ
¼
ð6Þ
þ
dt
1
23

J Solution Chem (2013) 42:239–250
249
?
-3
At high concentration of [H O ] = 0.5 molꢀdm
,
3
þ
þ
kꢁ2kꢁ3½H3O ꢂ [ [ k4ðkꢁ2 þ k3Þ½H2O Brꢂ
ð7Þ
So Eq. 9 simplifies to the form:
þ
þ
d½NBSacꢂ k2k3k4½H3O ꢂ½Sꢂ½H2O Brꢂ
ꢁ
¼
dt
kꢁ2kꢁ3½H3Oꢂ
ð8Þ
þ
k2k3k4½Sꢂ½H2O Brꢂ
kꢁ2kꢁ3
¼
?
The value of [H O Br] can be obtained from Eq. 3 given in Scheme-1:
2
þ
kꢁ1
k1
½NBSacꢂ½H3O ꢂ
Ka ¼
¼
ð9Þ
ð10Þ
ð11Þ
þ
½H O Brꢂ½saccharinꢂ
2
Therefore,
þ
½
NBSacꢂ½H3O ꢂ
þ
½
H2O Brꢂ ¼
Ka½saccharineꢂ
?
Using the value of [H O Br] in Eq. 10:
2
d½NBSacꢂ
k2k3k4½Sꢂ½NBSacꢂ
ꢁ
¼
dt
kꢁ2kꢁ3Ka½saccharineꢂ
Hence, at higher concentrations of mineral acid, the reaction is first order each with respect
?
to the oxoacid (S), [NBSac] and [H O ].
3
?
The observed rate constant at high [H O ] is:
3
k2k3k4
kobs ¼
ð12Þ
kꢁ2kꢁ3Ka
4
Conclusion
?
The above study shows that oxidizing species is the hypobromous acidium ion, (H O Br),
2
which reacts with the enol form of 4-oxo acid in the rate determining step, giving the
product. This experimental protocol suggests that this reaction could find utility as a
regioselective route for the synthesis of benzoic acids. The order of reactivity among the
studied 4-oxoacids is: 4-methoxy [ 4-methyl [ 4-phenyl [ 4-H [ 4-Cl [ 4-Br [ 3-NO2.
References
1. Reddy, C.S., Manjari, P.S.: Kinetics and mechanism of acid bromate oxidation of substituted 4-oxo-
acids. Indian J. Chem. 49A, 418–424 (2010)
2
. Gupta, M.-K., Rekha, L., Sharma, P.-K., Sharma, K., Sharma, V.-K.: Oxidation of glycolic acid by
N-bromosaccharin–A kinetic and mechanistic study in presence and absence of cationic surfactant.
Asian J. Chem. 18, 1340–1346 (2006)
3. Mohamed Farook, N.A.: Kinetics of oxidation of 4-oxo acids by N-bromosuccinimide in aqueous acetic
acid medium. J. Iranian Chem. Soc. 3, 378–386 (2006)
4. Mohamed Farook, N.-A.: Kinetics of oxidation of 4-oxo acids by N-chlorosaccharin in aqueous acetic
acid. J. Solution Chem. 36, 345–356 (2007)
123

250
J Solution Chem (2013) 42:239–250
5
6
. Mohamed Farook, N.-A., Seyed Dameem, G.-A.: Kinetics of oxidation of 3-benzoylpropionic acid by
N-chlorobenzamide in aqueous acetic acid medium. J. Chem. 8, 561–564 (2011)
. 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)
7
8
9
. Sikkandar, G.: Kinetics of oxidatative decarboxylation of b-benzoylpropionic acid by manganese(III)
acetate. Asian J. Chem. 12, 1037–1040 (2000)
. De Barry, E.B., Sanders, F.G.: The synthesis of some homologous naphthalenes. J. Chem. Soc. 434–437
(
1933)
. Fieser, L.F., Seligman, A.M.: 1 -Methyl- and 1 ,10-dimethyl-1,2-benzanthracene. J. Am. Chem. Soc. 60,
70–176 (1938)
0
0
1
1
1
0. Vogel, A.I.: A Text Book of Practical Organic Chemistry. Longmans Green, London (1962)
1. Russell, R.R., Van der Werf, C.A.: The malonic ester synthesis with styrene oxide and with butadiene
oxide. J. Am. Chem. Soc. 69, 11–13 (1947). doi:10.1021/ja01193a003
12. Hey, D.H., Wilkinson, R.: The preparation of 2-phenylnapthalene from diphenyl. J. Chem. Soc. 1030
(1940)
1
1
3. Chapman, N.B., Shorter, J.: Advances in linear free energy relationships. Plenum Press (1972)
4. Mohamed Farook, N.-A., Dameem, S.: Kinetics of oxidation of 3-benzoylpropionic acid by N-bro-
moacetamide in aqueous acetic acid medium. J. Chem. 8, 479–482 (2011)
1
5. Mohamed Farook, 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. J. Chem. 2, 127–131 (2004)
1
1
1
6. 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)
7. Mohamed Farook, N.-A., Alhaji, N.-M.-I.: Kinetics of oxidation of substituted c-ketoacid by N-chlo-
rosaccharin in aqueous acetic acid medium. Int. J. Chem. Sci. 2, 76–80 (2004)
8. 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. J. Chem. 2,
132–136 (2004)
1
2
2
9. 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, 722–724 (1986)
0. 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)
1. Vanangamudi, G., Srinivasan, S.: Kinetic studies on the oxidation of some para and meta-substituted
cinnamic acids by pyridinium bromochromate in the presence of oxalic acid (a co-oxidation study).
J. Chem. 6, 920–927 (2009)
2
2
2
2. Gould, E.-S.: Mechanism and Structure in Organic Chemistry, pp. 181–185. Holt Riehart and Winston,
New York (1964)
3. Richard Johnes, A.-Y.: Physical and Mechanistic Organic Chemistry. Cambridge University Press, New
York (1984)
4. Ruff, F., Kucsman, A.: Mechanism of the oxidation of sulphides with sodium periodate. J. Chem. Soc.
Perkin Trans. II, 683–688 (1985)
th
5. Cotton, F.-A., Wilkinson, G.: Advanced Inorganic Chemistry. John Wiley, 5 edn. (1988)
2
2
2
2
6. Greenwood, N-.N., Earnshaw, A.: Chemistry of the Elements, p. 1222. Pergamon Press, Oxford (1984)
7. Issacs, S.N.: Physical Organic Chemistry. Longman Scientific & Technical, New York (1987)
8. Leffler, J.-F., Grunwald, E.: Rates and Equilibrium of Organic Reactions. Wiley, New York (1963)
1
23