Selenium dioxide catalysed oxidation of acetic acid hydrazide by bromate in aqueous hydrochloric acid medium

Article abstract of DOI:10.1007/s12039-012-0286-5

Selenium dioxide catalysed acetic acid hydrazide oxidation by bromate was studied in hydrochloric acid medium. The order in oxidant concentration, substrate and catalyst were found to be unity. Increasing hydrogen ion concentration increases the rate of the reaction due to protonation equilibria of the oxidant. The mechanism of the reaction involves prior complex formation between the catalyst and substrate, hydrazide, followed by its oxidation by diprotonated bromate in a slow step. Acetic acid was found to be the oxidation product. Other kinetic data like effect of solvent polarity and ionic strength on the reaction support the proposed mechanism. Indian Academy of Sciences.

Full text of DOI:10.1007/s12039-012-0286-5

J. Chem. Sci. Vol. 124, No. 4, July 2012, pp. 821–826. ꢀc Indian Academy of Sciences.
Selenium dioxide catalysed oxidation of acetic acid hydrazide
by bromate in aqueous hydrochloric acid medium
∗
R S YALGUDRE and G S GOKAVI
Kinetics and Catalysis Laboratory, Department of Chemistry, Shivaji University Kolhapur 416 004, India
e-mail: gsgokavi@hotmail.com
MS received 8 June 2011; revised 31 August 2011; accepted 13 September 2011
Abstract. Selenium dioxide catalysed acetic acid hydrazide oxidation by bromate was studied in hydrochloric
acid medium. The order in oxidant concentration, substrate and catalyst were found to be unity. Increasing
hydrogen ion concentration increases the rate of the reaction due to protonation equilibria of the oxidant. The
mechanism of the reaction involves prior complex formation between the catalyst and substrate, hydrazide,
followed by its oxidation by diprotonated bromate in a slow step. Acetic acid was found to be the oxidation
product. Other kinetic data like effect of solvent polarity and ionic strength on the reaction support the proposed
mechanism.
Keywords. Acetic acid hydrazide; oxidation; bromate; kinetics; selenium dioxide; catalysis.
1
. Introduction
offers an excellent opportunity to look into the mecha-
nistic pathway.
Hydrazides of carbonic acids are important starting
materials in organic synthesis as well as they find
applications in medicine and analytical chemistry.
The oxidative transformation of hydrazides, with
most of the oxidants used, give corresponding acids and
1
2
1
in some cases esters or amides. Hydrazides have also
They also form coordination complexes with many
transition metal ions which make them good reagents
for metal extraction, polymer stabilization and ion
exchange problems.3 These hydrazides act as biden-
tate ligands involving carbonyl oxygen and the nitro-
been converted into N–N-diacylhydrazines by various
18,19
oxidants.
Formation of acids and their derivatives
in presence of different nucleophiles is the indication
–7
20
of direct two-electron transfer to the oxidant, while
cyclization products generally involve a single electron
2
21
gen of the amino group of the hydrazine moiety with
transfer with intervention of a free radical. The oxi-
dation of hydrazide by bromate in aqueous solutions
the metal ions. These hydrazides also exhibit carcinos-
2
1
tatic, antibacterial and antifungal properties and com-
does not occur and requires a catalyst. Potassium and
8
plexation with metal ions is reported to enhance their
sodium bromate are stable solids and easily handled as
compared with liquid bromine and hypobromous acid
solutions. The product of bromate oxidation is bromide
ion which can be safely recycled thus making the meth-
ods of their oxidations environmentally benign than the
metal ion oxidations. Bromates have been used for var-
biological activity. Selenium dioxide has been used as
both oxidant and catalyst in various organic transfor-
mations. In organic synthesis it has been utilized as
9
10
oxidant, dienophile agent, oxidative bond cleaving
11
12
agent, as a catalyst for synthesis of urea derivatives,
oxidative demethylating agent, benzylic oxidizing
agent, allylic hydroxylating agent and in Beckmann
rearrangement. Selenium dioxide has also been used
13
22–26
ious organic oxidative transformations.
Therefore,
14
15
it is of significance to investigate the mechanism of oxi-
dation of a hydrazide by bromate in the presence of
selenium dioxide as a catalyst.
16
16
as catalyst for oxidation of aldehydes in the pres-
ence of a secondary oxidant. Colloidal selenium has
good photoelectrical properties which can be prepared
by reducing selenium dioxide by hydrazine. Hydrazides
are the derivatives of hydrazine17 therefore, interaction
of these hydrazides with selenium dioxide in acidic
solutions in the presence of an oxidant like bromate
2. Experimental
The double distilled water was used throughout the
work. All the chemicals used for experiments were of
reagent grade. The stock solution of KBrO was pre-
3
pared by dissolving KBrO (BDH) in water and stan-
dardized iodometrically. The solution of acetic acid
3
∗
For correspondence
821

822
R S Yalgudre and G S Gokavi
hydrazide [acetohydrazide] (Spectrochem) was pre- moles of hydrazide require two moles of bromate as
pared by dissolving requisite amount of it in water.
The solution of catalyst selenium(IV) was obtained
by dissolving selenium dioxide (SD fine) in distilled
water. The ionic strength was maintained using sodium
perchlorate and to vary hydrogen ion concentration HCl
shown in equation 1.
−
2
BrO + 3CH CONHNH
3
3
2
−
→
2Br + 3CH COOH + 3H O + 3N . (1)
3
2
2
(BDH) was used. Acetic acid and acrylonitrile were
used directly as received to study the effect of sol-
vent polarity on the reaction medium and free radical
formation, respectively.
3
. Results
3.1 Effect of oxidant and hydrazide concentration
The uncatalysed reaction did not occur under the exper-
imental conditions. The catalysed reaction was car-
ried out under pseudo-first-order conditions keeping
the concentration of hydrazide in large excess over the
oxidant concentration at a constant concentrations of
2
.1 Kinetic measurements
The reaction was studied under pseudo-first-order con-
ditions keeping hydrazide concentration in large excess
over that of oxidant, KBrO , at constant temperature
3
−5
−3
HCl and catalyst at (0.1–1.0) × 10 mol dm , respec-
tively at a constant ionic strength of 0.5 mol dm
table 1). The pseudo-first-order plots were found to be
linear on varying the concentration of oxidant between
◦
of 27.0 + 0.1 C. The reaction was initiated by mix-
−3
ing the previously thermostated solutions of the oxi-
dant, catalyst and substrate, which also contained the
required amount of hydrochloric acid, sodium perchlo-
rate and distilled water. The reaction was followed by
(
−
3
−2
−3
2
.0 × 10 to 2.0 × 10 mol dm keeping the con-
centration of catalyst and hydrazide constant at 1.0 ×
3
titrating 5 cm of the reaction mixture for unreacted oxi-
−5
−2
−3
10
and 5.0 × 10 mol dm , respectively (table 1)
dant iodometrically and the rate constants were deter-
mined from the pseudo-first-order plots of log[oxidant]
against time. The pseudo-first-order plots were linear
for more than 90% of the reaction and rate constants
were reproducible within +6%.
+
Table 1. Effect of [bromate], [hydrazide] and [H ] on
the selenium dioxide catalysed oxidation of acetic acid
5
hydrazide by bromate at T = 300 K. 10 [Se(IV)] =
−
3
−3
.
1
.0 mol dm and I = 0.5 mol dm
2.2 Stoichiometry and product analysis
3
−
2
+
3
1
0 [BrO ]
10 [hydrazide]
10[H ]
10 kobs
3
−
3
−3
−3
−1
(mol dm
)
(mol dm
)
(mol dm
)
(s
)
The stoichiometry of bromate oxidations predicts either
Br or HOBr as the product of reaction but the 2.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
1.0
2.0
3.0
5.0
8.0
10
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.5
0.6
0.8
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0.62
0.61
0.61
0.61
0.62
0.61
0.62
0.62
0.62
0.62
0.62
0.61
0.62
0.62
0.15
0.25
0.32
0.62
1.4
2
3.0
hydrazides can be very easily oxidized by both of them
in acidic solutions due to the oxidation potentials of
HOBr and Br of 1.34 and 1.07 V, respectively. The
test for formation of bromide ion was carried out in
27
4.0
5
6
8
.0
.0
.0
2
sulphuric acid solution instead of hydrochloric acid by 10
adding silver nitrate to the reaction mixture after com- 20
5
5
5
5
5
.0
pletion of the reaction. The precipitation of silver bro-
mide confirmed the formation of bromide ion as one of
the product of the reaction. Therefore, the product of
the reaction under the present experimental conditions
.0
.0
.0
.0
is bromide ion. It is also noticed during the kinetic stud- 5.0
5
5
5
5
5
.0
.0
.0
.0
.0
ies and the stoichiometric analysis that no bromine was
evolved, confirming the bromide ion as the only prod-
uct. The other product of the reaction is nitrogen gas
and the effervescence of its evolution were observed
during the kinetic runs as well as while determining 5.0
the stoichiometry. The stoichiometry of the reaction 5.0
2.5
4.0
5.4
6.8
5
.0
5.0
.0
was assessed by determining excess of bromate ido-
−5
−3
metrically in presence of 1.0 × 10 mol dm SeO2
5
9.4
after completion of the reaction. It was found that three

Selenium dioxide catalysed oxidation of acetohydrazide by bromate
indicating the order in oxidant concentration is unity.
823
The pseudo-first-order rate constants, k , were fairly
obs
constant as the concentration of hydrazide was varied
−2
−2
−3
between 1.0 × 10 and 10.0 × 10 mol dm keeping
all other concentrations constant (table 1). Therefore,
the order in hydrazide concentration is also unity.
3.2 Effect of catalyst concentration
The effect of catalyst concentration was studied in
−
6
the concentration range of 2.0 × 10
to 5.0 ×
−5
−3
10
mol dm and the plot of k against [catalyst]
obs
(
figure 1) was found to be linear indicating the first
order dependence of reaction on catalyst.
.3 Effect of hydrogen ion concentration
Figure 2. Plot of log kobs against (1/D) at T = 300 K.
3
−
−3
2
1
5
1
0 [BrO ]
=
5.0 mol dm
,
10 [Hydrazide]
=
3
−
3
−3
5
.0 mol dm , [HCl] = 0.1 mol dm
10 [Se(IV)] =
3
−3
−3
.
.0 mol dm and I = 0.5 mol dm
The effect of hydrogen ion concentration was studied
in order to understand the nature of reactant species
+
3.5 Test for free radical intervention
present in the solution. The [H ] was varied between
−
2
−3
+
+
5
.0 × 10 and 0.4 mol dm (table 1). Increasing [H ]
In order to understand the intervention of free radicals
in the reaction, the reaction was studied in the presence
of added acrylonitrile. There was no induced polymer-
ization of the acrylonitrile as there was no formation of
the precipitate and also it did not affect the rate of the
reaction.
accelerates the rate of the reaction and the order in [H ]
is found to be 1.9 as determined from the plot of log k
obs
+
against log [H ].
3.4 Effect of ionic strength
The effect of ionic strength was studied keeping
3
.6 Effect of solvent polarity
[
5
1
hydrazide], [KBrO ], [catalyst] and [HCl] constant at
3
−3
−2
−3
−3
.0 × 10 mol dm , 5.0 × 10 mol dm , 1.0 ×
The effect of solvent polarity on the reaction was
studied by varying percentage of acetic acid from
2
−5
−3
−3
0
mol dm and 0.1 mol dm , respectively. Sodium
perchlorate was used to vary the ionic strength. There
was no effect of ionic strength on the reaction.
to 40% v/v keeping hydrazide and bromate con-
−2
−3
centration constant at 5.0 × 10 mol dm , 5.0 ×
−3
−3
5
10
mol dm , respectively and catalyst concentration
−
−3
at 1.0 × 10 mol dm . The dielectric constants of the
reaction mixture were calculated by using the D values
for pure solvents. It was found that the decrease in the
dielectric constant of the medium increases the rate of
the reaction. The plot of log kobs against (1/D), where D
is the dielectric constant, were found to be linear with
negative slope as shown in figure 2.
4
. Discussion
The reaction was found to be accelerated by hydro-
gen ion concentration and the order in its concentra-
tion was found to be 1.9. Such acceleration due to the
hydrogen ion concentration is either due to its direct
involvement in any one of the steps of the mechanism or
due to the existence of prior protonation equilibria. The
Figure 1. Effect of catalyst concentration on the sele-
nium dioxide catalysed oxidation of acetic acid hydrazide
3
−
−3
,
by bromate at T = 300 K. 10 [BrO ] = 5.0 mol dm
3
2
−3
−3
28
1
0 [Hydrazide] = 5.0 mol dm and I = 0.5 mol dm
.
oxidations by bromate in acidic medium are known to

824
R S Yalgudre and G S Gokavi
involve hydrogen ion dependent induction period due acetic acid hydrazide as the active species of the cat-
to initial slow oxidation of bromate by the reductant, alyst, oxidant and substrate, respectively is shown in
as shown in equation (2), generating unreactive bro- scheme 1. The mechanism of scheme 1 involves for-
mous acid, HBrO . The bromous acid further undergoes mation of a complex between catalyst, H SeO , and
2
2
3
disproportionation to generate reactive HOBr and
protonated hydrazide in a fast prior equilibrium. The
complex thus formed is then oxidized by active dipro-
−
+
+
Red + BrO + 3H → Ox + HBrO + H O (2)
3
2
2
tonated oxidant, H BrO , in a rate determining step
2
3
−
+
2
HBrO → BrO + HOBr + H (3) generating catalyst along with HBrO and acyl diimide
2
3
2
as the intermediates of the oxidant and the substrate,
respectively.
bromate. Such induction periods were observed for the
reductants with redox potential more than 1.1 V. But in
the present investigation there was no such induction
Hydrazides are good reductants with reduction
34
potential of benzoic acid hydrazide is reported to
2
9
period which was also not observed by Thompson.
be 0.19 V. Preliminary experiments in the absence of
bromate have indicated that red colloidal selenium
was precipitated which on standing turns grey. But
in the presence of oxidant no such precipitation was
observed and the pseudo-first-order plots were lin-
ear for all the kinetic runs. If the catalyst is reduced
completely to selenium metal, which is oxidized by
bromate rapidly in acidic medium, then the reaction
would have been independent of bromate concentra-
tion resulting in zero-order kinetics. Further, bromate
Therefore, the hydrogen ion dependence of the reaction
is not due to the equilibrium (2) but due to one or more
prior protonation equilibria. Selenium dioxide in aque-
ous solution exists as selenous acid, H SeO and step-
2
3
2
7
wise dissociations constants (Eq. 4 and 5) of this acid
−
2−
generating HSeO and SeO
3
3
−
3
2−
H SeO3 ꢀ HSeO + H +
(4)
(5)
2
−
+
HSeO3 ꢀ SeO3 + H
35
has been used as an analytical volumetric reagent
for the titration of small amount of colloidal sele-
nium. In such titration the colloidal selenium is oxi-
dized to selenous acid and further oxidation to selenic
acid by bromate does not takes place. Therefore, con-
sidering the kinetic data obtained and the reported
results, the mechanism of the reaction involves fast
complex formation between the catalyst and hydrazide
in a prior equilibria followed by its oxidation by
the diprotonated bromate as shown in scheme 1.
According to the mechanism summarized in scheme 1,
the corresponding rate law can be represented as in
equation (7) corresponding expression for the kobs as in
equation (8).
−3
−3
species are 2.4 × 10 mol dm
and 4.76 ×
−9
−3
10
mol dm , respectively. The values of dissociation
constants indicate that both the deprotonations occur
in negligible extent in aqueous acidic solutions of the
present study due to very low values of the disoocia-
tion constants. Therefore, under the present conditions
of the reaction, selenium dioxide exists as selenous acid
which is the active species of the catalyst. Another pos-
sible protonation in the present system would be that
of the hydrazides. Hydrazides are known to undergo
30
protonation and the pK of the acetic acid hydrazide
31
is reported to be 3.24. Using the reported pK of
acetic acid hydrazide the concentration of the proto-
nated hydrazide was calculated. It was found that as
under the hydrogen ion concentration of the present
study, hydrazide is completely converted into its pro-
tonated (Eq. 6) form indicating protonated hydrazide
as the
ꢀ
ꢁ
2
+
Rate = k K K K H
1
1
2
3
×
[H SeO ] [CH CONHNH ]
2
3
3
2
ꢂ
ꢃ
ꢀ
+ꢁ
ꢀ
ꢁ
2
+
×
[BrO ] / 1 + K H K K H
(7)
3
1
1
2
+
+
CH CONHNH ꢀ CH CONHNH + H
(6)
3
3
3
2
ꢀ
ꢁ
2
+
kobs = k K K K H
1
1
2
3
active species of the reductant. Potassium bromate is
a strong electrolyte and in aqueous solution it exists
ꢂ
ꢃ
ꢀ
+ꢁ
ꢀ
ꢁ
2
+
× [H
SeO
] / 1 + K
H
+ K
K
H
.
2
3
1
1
2
−
−
as BrO . In a recent study, protonation of BrO has
3
3
(8)
32,33
been considered
erating diprotonated H BrO with a reported protona-
tion constant of 0.21 dm mol . The order of about solutions have been reported to be in the range
in presence of strong acids gen-
+
2
3
The pK of protonation of bromate in aqueous acidic
32
6
−2
33
1
.9 in hydrogen ion concentration can be explained by of −0.5 to 2.3 on the basis of kinetic results. The
+
considering the diprotonated bromate, H BrO as the equilibrium constant of equation (9) of scheme 1 is
active species of the oxidant. The mechanism of the 3.16 dm mol and the cumulative equilibrium con-
reaction considering H SeO , H BrO and protonated stants K and K is reported to be 0.21 dm mol .
2
3
3
−1
+
32
6
−2
2
3
2
3
1
2

Selenium dioxide catalysed oxidation of acetohydrazide by bromate
825
K
1
+
-
3
H + BrO
HBrO3
(9)
K
2
+
BrO +
(10)
H + HBrO
3
H
2
3
OH
H
N
+
Se
3
H C
HO
Se
HO
3
N
H
K
H
N
(11)
H3
C
+
+
O
O
OH
NH
3
-H O
2
O
Complex
H
3
C
N
k
1
N
H
+
Complex + H
2
BrO
3
+ 2H+
+
HBrO
2
+ H
2
SeO
3
(12)
(13)
O
fast
H
3
C
N
OH + HNNH
H3
C
+
H2
O
N H
O
O
fast
fast
HN=NH + HBrO2
(14)
(15)
N + H O + HOBr
2
2
+
-
2
N
2
+ 2H
2
O + 2H +2Br
2
HOBr + 2HN=NH
Scheme 1. Detailed mechanism of selenium dioxide catalysed oxidation of acetic acid hydrazide by bromate.
From these values, the equilibrium constant of equa- shown is fast (scheme 1). The test for free radicals was
tion (10) of scheme 1 can be calculated as 6.6 × found to be negative therefore, the reaction proceeds
−2
3
−1
10
dm mol . It was also found that the denominator without any intervention of free radicals. This obser-
of equation (8) does not vary to a considerable extent vation was also supported by the product analysis in
within the range of the hydrogen ion concentration which corresponding acetic acid was the only product
studied when the values of K and K are substituted. obtained. The N–N –diacylhydrazine would have been
1
2
Therefore, if we neglect the contribution from the obtained along with acetic acid as a result of free radical
denominator in comparison with 1 the expression (8) intervention in the reaction. Colloidal selenium was not
simplifies to equation (16). The plot of k against formed in any of the kinetic runs although it has been
obs
+
2
2
[
H ] is found to be linear (R = 0.9967) thus verifying obtained in the absence of oxidant. Therefore, it was
the proposed mechanism and the rate law.
assumed that the complex formed between catalyst and
hydrazide is oxidized by bromate in a rate determining
(16) step.
Further, the nucleophilic attack of water molecule
ꢀ
ꢁ
2
+
kobs = k K K K H [H SeO ] .
1
1
2
3
2
3
The derived expression (16) for the pseudo-first- on the carbonyl carbon of acyl diimide intermediate
order rate constant based on the mechanism of scheme 1 give acetic acid and another intermediate NH=NH as
+
explains the order of two in [H ] and an order of shown in scheme 1. The fast oxidation of NH=NH
unity in the [catalyst]. The reaction is also not affected by the HOBr will complete the observed stoichiome-
by the change in the ionic strength indicating one of try of the reaction. The final product of bromate reduc-
the species involved in the prior equilibria (Eq. 11, tion in the present study is considered to be bromide
scheme 1) of the reaction would be H SeO . The forma- ion rather than bromine which can be justified by its
2
3
tion diimide intermediates have been proposed during thermodynamic feasibility predicted from the known
oxidative conversion of hydrazine moiety by various redox potentials in the following manner. In scheme 1,
oxidizing reagents.1 Since the reaction did not follow HOBr is proposed as the bromate intermediate gener-
,18
the Michealis–Menten type of catalysis the formation ated as a result of its reduction. The redox potentials
−
of the complex between the catalyst and hydrazide as of the couples 2HOBr/Br and HOBr/Br are 1.6 V and
2

8
26
R S Yalgudre and G S Gokavi
5. Lunn G, Philips L R and Pacula-Cox C 1998 J.
1
.34 V, respectively. The conversion of HOBr into Br
2
−
Chromatogr. B 708 217
is thermodynamically more favourable than into Br .
But the generation of bromine requires two moles of
HOBr whose concentration is very small in the reac-
tion mixture. Further, the rate constant of direct oxi-
dation of bromide in acidic solutions by bromate is
3
requires excess of [Br ]. Therefore, in the proposed
mechanism (scheme 1) Br is considered as the prod-
uct rather than Br . The decrease in relative permittiv-
6
. Gad A M, El-Dissouky A, Mansour E M and
El-Maghraby A 2000 Polym. Degrad. Stab. 68 153
. Gursoy A, Terzioglu N and Otuk G 1997 Eur. J. Med.
Chem. 32 753
7
3
6
8. Singh B, Shrivastava R and Narang K K 2000 Synth.
React. Inorg. Met. Org. Chem. 30 1175
9. Priewisch B and Ruck-Brown K 2005 J. Org. Chem. 70
2350
−3
3
−1 −1
−
.94 × 10 dm mol
s
indicating its slowness and
−
1
0. Nguyen T M, Guzei I A and Lee D 2002 J. Org. Chem.
2
67 6553
ity of the reaction medium with increase in acetic acid
content increases the rate of reaction and the plot of log
kobs against (1/D), where D is the dielectric constant of
the medium, is linear (figure 2) with a negative slope.
The charge separation in the transition state formed and
its larger size increases its stability37 in the medium of
1
1. Kariyone K and Yazawa H 1970 Tetrahedron Lett. 11
2885
12. Chen J, Ling G and Lu S 2003 Tetrahedron 59 8251
13. Goswami S P and Maity A C 2007 Chem. Lett. 36 1118
14. Goswami S P and Adak A K 2003 Synth. Commun. 33
475
15. Madec D and Ferezou J P 1996 Synlett. 867
higher relative permittivity thus, increasing the rate of 16. Sosnovsky G and Krogh J A 1978 Synthesis 703
reaction with increase in acetic acid content.
17. Gates B, Yin Y and Xia Y 2000 J. Am. Chem. Soc. 122
2582
1
1
8. Kulkarni P P, Kadam A J, Desai U V, Mane R B and
Wadgaonkar P P 2000 J. Chem. Res. (S) 184
9. Jadhav V K, Wadgaonkar P P and Salunkhe M M 1998
J. Chin. Chem. Soc. 45 831
5
. Conclusions
1
The reaction between KBrO and acetic acid hydrazide
in the presence of selenium(IV) as a catalyst occurs
3
20. Kadam S D, Supale A R and Gokavi G S 2008 Z. Phys.
Chem. 222 635
through formation of a complex between catalyst and 21. Shewale S A, Phadkule A N and Gokavi G S 2008 Int.
J. Chem. Kinetics 40 151
2. Farkas L, Perlmutter B and Schachter O 1949 J. Am.
Chem. Soc. 71 2833
hydrazide which will be oxidized by the oxidant in a
2
rate determining step. The mechanism proposed on the
basis of kinetic data does not involve any free radi-
cal intervention and corresponding acetic acid as the
2
3. Farkas L and Schachter O 1949 J. Am. Chem. Soc. 71
2827
product. The active species in the present study are the 24. Mirjalili B F, Zolfigol M A, Bamoniri A, Zaghaghi Z and
Hazar A 2003 Acta Chim. Slov. 50 563
5. Tomioka H, Oshima K and Nozaki H 1982 Tetrahedron
protonated forms of the hydrazide and H SeO of cat-
alyst. The dependence of rate of reaction on hydro-
2
3
2
2
2
2
Lett. 23 539
gen ion concentration of the order of two is due to the
6. Yamamoto Y, Suzuki H and Moro-oka Y 1985 Tetrahe-
dron Lett. 26 2107
7. Lurie Ju 1971 Handbook of analytical chemistry
+
successive protonation of bromate to H BrO species.
2
3
(Moscow: MIR Publishers)
Acknowledgement
8. Mohammad A 2003 Transition Met. Chem. 28 345
One of the authors RSY acknowledges the University 29. Thomson R C 1971 Inorg. Chem. 10 1892
3
3
3
3
0. Manoussakis G, Haristos D and Youri C 1973 Can. J.
Grants Commission (UGC), New Delhi for the award
of Teacher Fellowship under FIP- UGC-XI plan.
Chem. 51 811
1. Lindegren R and Niemann C 1949 J. Am. Chem. Soc. 71
1
504
2. Reddy C S and Manjari P S 2010 Indian J. Chem. 49A
18
References
4
3. Cortes C E S and Faria R B 2001 J. Braz. Chem. Soc. 12
1
. Kocevar M, Mihorko P and Polanc S 1995 J. Org. Chem.
0 1466
. Gudasi K B, Patil M S, Vadavi R S, Shenoy R V, Patil
775
6
34. Amos R I J, Gourlay B S, Schiesser C H, Smith J A and
2
Yates B F 2008 Chem. Commun. 1695
S A, and Nethaji M 2007 Spectrochim Acta. Part A 67 35. Coleman W C and McCrosky C R 1937 Ind. Eng. Chem,
72 Anal. Ed 9 1458
. Zubareva G I, Adeev S U, Radushev A V, Gomzikov A I 36. Domínguez A and Iglesias E 1998 Langmuir 14 2677
1
3
4
and Zubarev M P 1998 Z. Prikladnoi Khimii 71(2) 271
. Shen X and Giese R W 1997 J. Chromatogr. A 777 261
37. Amis E S 1966 Solvent effects on the reaction and
mechanism (New York: Academic Press)