The kinetics of the reaction between cyclopentene and aqueous hydrogen peroxide under phase-transfer catalysis

Article abstract of DOI:10.1134/S0965544114030086

The kinetics of the reaction between cyclopentene and an aqueous solution of hydrogen peroxide under phase-transfer catalysis conditions has been studied. The activation energies of the successive stages of cyclopentene epoxidation to 1,2-epoxycyclopentane and the hydration of the resulting epoxide to 1,2-cyclopentanediol have been found, and the orders of the reactions with respect to the reactants have been determined. A mathematical model of the process that adequately describes the available experimental data in the entire range of reactant concentrations has been proposed.

Full text of DOI:10.1134/S0965544114030086

ISSN 0965ꢀ5441, Petroleum Chemistry, 2015, Vol. 55, No. 1, pp. 51–56. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © A.E. Meshechkina, L.V. Mel’nik, G.V. Rybina, S.S. Srednev, Yu.A. Moskvichev, A.S. Shevchuk, 2015, published in Neftekhimiya, 2015, Vol. 55, No. 1, pp. 54–59.
The Kinetics of the Reaction between Cyclopentene and Aqueous
Hydrogen Peroxide under PhaseꢀTransfer Catalysis
A. E. Meshechkina, L. V. Mel’nik, G. V. Rybina, S. S. Srednev, Yu. A. Moskvichev, and A. S. Shevchuk
Yaroslavl State Technical University, Yaroslavl, Russia
eꢀmail: meshechkinaae@ystu.ru
Received October 24, 2013
Abstract—The kinetics of the reaction between cyclopentene and an aqueous solution of hydrogen peroxide
under phaseꢀtransfer catalysis conditions has been studied. The activation energies of the successive stages of
cyclopentene epoxidation to 1,2ꢀepoxycyclopentane and the hydration of the resulting epoxide to 1,2ꢀcycloꢀ
pentanediol have been found, and the orders of the reactions with respect to the reactants have been deterꢀ
mined. A mathematical model of the process that adequately describes the available experimental data in the
entire range of reactant concentrations has been proposed.
Keywords: cyclopentene, hydrogen peroxide, 1,2ꢀepoxycyclopentane, 1,2ꢀcyclopentanediol, phaseꢀtransfer
catalysis, kinetics, reaction rate, mathematical model
DOI: 10.1134/S0965544114030086
At present, the epoxidation of olefins with oxygen,
The catalyst complex used in the process is formed
organic hydroperoxides, and peracids are being impleꢀ in situ in the reaction mixture during mixing of tungsten
mented on an industrial scale, and hydrogen peroxide
is becoming more commonly used as an oxidizing
agent. This is caused by the fact that hydrogen peroxꢀ
ide is an effective and environmentally friendly oxidizꢀ
ing agent and the product of its reduction is water.
A method for oxidizing unsaturated compounds with a
dilute aqueous solution of hydrogen peroxide using
tungsten and phosphorus heteropoly compounds in
combination with phaseꢀtransfer catalysis was first
proposed in the 1980s [1]; since then, the number of
studies in this domain is increasing every year [2–5].
salts, phosphoric acid, a phaseꢀtransfer catalyst (PTC)
in a molar ratio of 1 : 1 : 0.36, and hydrogen peroxide.
Haloalkanes or aromatic hydrocarbons are used as a
solvent for the organic phase; hydrogen peroxide is
taken in slight excess with respect to CP (1.3 : 1) to proꢀ
vide a more complete conversion of the olefin. This
method is characterized by mild synthesis conditions,
instrumentation simplicity, and high yields of the
desired products [8].
The aim of this study is to examine the kinetics of
the reaction between CP and an aqueous solution of
hydrogen peroxide in the presence of a catalyst system
of sodium tungstate and phosphoric acid in combinaꢀ
tion with a PTC and develop a mathematical model of
this reaction.
Oxygenated cyclopentene (CP) derivatives, such as
epoxide, alcohols, and carbonyl compounds, are used
in the synthesis of macromolecular compounds, fraꢀ
grances, pharmaceuticals, and bactericides [6, 7]. We
have developed a method for oxidizing CP with aqueꢀ
ous hydrogen peroxide [8], which makes it possible to
obtain either 1,2ꢀepoxycyclopentane or 1,2ꢀcyclopenꢀ
tanediol with a high yield (over 95%) using a single
setup. Methods for changing the ratios between the
reaction rates of oxidation of CP (I) and hydration of
the resulting epoxide (II) and thus controlling the
direction of the process have been found:
EXPERIMENTAL
Materials
Cyclopentene (NII Yarsintez) was purified by fracꢀ
tional distillation (to 98%). Petroleum xylene (GOST
(State Standard) 9410ꢀ78) used as a solvent was puriꢀ
fied with sulfuric acid and dried by fractional distillaꢀ
tion. Hydrogen peroxide (35% aqueous solution,
reagent grade, GOST 177ꢀ88), sodium tungstate dihyꢀ
drate (analytical grade, GOST 18289ꢀ78), 80% phosꢀ
phoric acid (reagent grade, GOST 6552ꢀ80), and an
+ H2O2
+ H O
2
O
,
(I)
OH
.
+ H2O2
O
(II) Adogen 464 PTC (98%, Aldrich) were used without
additional treatment.
OH
51

52
MESHECHKINA et al.
Experimental Procedure
A 50ꢀcm3 temperatureꢀcontrolled glass reactor
oxygen to the double bond of the olefin takes place in
the organic phase; however, it occurs from the cataꢀ
lytic peroxo complex formed in the aqueous phase at
the initial instant rather than directly from the hydroꢀ
gen peroxide. The peroxo complex is formed accordꢀ
ing to the reaction
equipped with a mechanical stirrer, a reflux condenser,
a thermometer, and a sampler was charged with a sepꢀ
arately prepared aqueous phase (sodium tungstate,
phosphoric acid, hydrogen peroxide, water) having a
specified pH value and an organic phase (PTC, xylene,
CP). The pH value of the aqueous phase was adjusted
by adding a 30% H2SO4 or NaOH solution. The reacꢀ
tion time was counted from the beginning of stirring.
The reaction progression was monitored from the
conversion of hydrogen peroxide (iodometric method)
and the accumulation of the epoxide (reaction with perꢀ
chloric acid) in the reaction mixture [9]. The CP conꢀ
tent was determined by the bromine–bromide method
(Kaufman method) [9]; the content of 1,2ꢀcyclopenꢀ
tanediol was found by GLC (a CHROMꢀ5 chromatoꢀ
4Na2WO4 + H3PO4 + 8H2O2
(III)
Na3[PO4{W(O)(O2)2}4] + 5NaOH + 7H2O.
This equation does not describe the true state of forꢀ
mation of peroxo heteropoly compounds in the system
to the full extent; however, the reduced PW4 complex
is dominant [5].
The catalyst complex is transferred into the organic
phase, where the epoxidation of CP occurs, by a lipoꢀ
philic PTC:
graph with a flameꢀionization detector; a 1.5 m 3 mm
×
Na3[PO4{W(O)(O2)2}4] + 3QCl
(IV)
glass column packed with 15% PEGꢀ20 Mꢀcoated
Chromaton NꢀAWꢀDMCS with temperature programꢀ
ming in isothermal portions at 65 (2 min), 100 (4 min),
and 195°C (8 min); the rate of temperature rise,
20°C/min; the carrier gas (nitrogen) flow rate of
30 cm3/min, and the chart speed of 240 mm/h; the
internal standard, hexanolꢀ1). Samples were collected
from the common reaction mixture under vigorous stirꢀ
ring. It has been shown that the sampling mode (from
the common reaction mixture or from each phase sepꢀ
arately) has no effect on the results.
Q3[PO4{W(O)(O2)2}4] + 3NaCl.
The catalyst complex, which underwent activeꢀ
oxygen depletion during the oxidation of CP, restores
its activity in contacting with hydrogen peroxide.
Analyses have shown that the content of active oxygen
of the peroxo complex in the organic phase is constant
during the reaction; it is 0.5–0.6% in terms of hydroꢀ
gen peroxide, which corresponds to the represented
composition of the catalyst.
The effect of the stirring rate on the rate of reacꢀ
tion (I) was studied to find that the reaction rate
remains constant at an intensity of stirring of more
than 250 rpm. Hence, the epoxidation of CP occurs
in the kinetic region in the organic phase. Further
studies were carried out at a stirring rate of 400 rpm.
It was shown that the products of reactions (I) and
(II)—1,2ꢀepoxycyclopentane and 1,2ꢀcyclopenꢀ
tanediol—have no effect on the rate of the oxidation
reaction, which is described by a firstꢀorder equation
until the complete conversion of the reactants. In
addition, a side reaction of decomposition of hydroꢀ
gen peroxide can occur in the system.
RESULTS AND DISCUSSION
The reaction between CP and an aqueous hydrogen
peroxide occurs in the twoꢀphase liquid–liquid system;
the ratio between the oxidation and hydration rates is
controlled by changing the acidity of the aqueous phase.
At pH 2.5 of the aqueous phase, the yield of 1,2ꢀepoxyꢀ
cyclopentane is more than 94% because the rate of its
hydration reaction (II) is extremely low, whereas a
decrease in the pH value to 1.5 leads to a significant
acceleration of the hydration of the epoxide and to an
increase in the yield of 1,2ꢀcyclopentanediol to 95%.
The CP conversion is more than 98% in either case [8].
There are different points of view on the place of
occurrence of epoxidation reaction (I): at the interface
Typical kinetic curves for cases where the pH of the
aqueous phase is 2.5 or 1.5 are shown in Figs. 1a and 1b.
The reaction between CP and an aqueous solution
or in the entire volume of the organic phase. Based on of hydrogen peroxide under phaseꢀtransfer catalysis
the data of [2], it has been assumed that the transfer of can be represented by the following scheme:
K
1
[Cat]aq.ph. + 3[QCl]org.ph.
[CP]org.ph. + [QCat]org.ph.
[QCat]org.ph. + 3[Cl–]
aq.ph.
k
·
2
*
[ECP]org.ph + [QCat]org.ph.
[QCat]org.ph. + [H2O]aq.ph.
[ECP]org.ph.
k
3
*
[QCat]org.ph. + [H2O2]aq.ph.
K
4
[ECP]org.ph.
k
5
[H2O2]aq.ph.
[H2O]aq.ph. + 1/2[O2]
k
6
[ECP]aq.ph. + [H2O]aq.ph.
[diol]aq.ph.
,
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THE KINETICS OF THE REACTION
53
2.5
2.0
1.5
1.0
0.5
(а)
3
1
2
4
0
20
40
60
80
100
120
Time, min
(b)
2.5
2.0
1.5
1.0
0.5
4
1
2
3
0
20
40
60
80
100
120
Time, min
Fig. 1. Typical reactant consumption and product buildup rate curves for the reaction between cyclopentene and aqueous hydrogen
3
peroxide. Solvent, xylene; aqueous phase : organic phase volume ratio, 1.6 : 1; initial concentrations in the total volume, mol/dm :
CP, 1.91; hydrogen peroxide, 2.45; sodium tungstate, 0.037; Na WO : H PO : Adogen 464 molar ratio, 1 : 1 : 0.36: (a) 50°C, pH of
2
4
3
4
the aqueous phase of 2.5 and (b) 60°C, pH of the aqueous phase of 1.5; (
1) hydrogen peroxide, (2) cyclopentene, (3) 1,2ꢀepoxycyꢀ
clopentane, and ( ) 1,2ꢀcyclopentanediol. The symbols and the curve refer to the experimental and calculated data, respectively.
4
where
stants; k2
respective stages, dm3 mol–1 min–1, dm3 mol–1 min–1,
min–1, and dm3 mol–1 min–1, respectively; [QCl]org.ph.
[Cat]aq.ph., [QCat]org.ph., and [QCat]org.ph* are the conꢀ
centrations of the PTC and the catalyst complex in
the aqueous and organic phases, respectively (the
K
1 and
K
4 are the equilibrium (extraction) conꢀ
,
The following assumptions have been made: (i) the
,
k3,
k5 and k6 are the rate constants of the rate constant of reactivation of the peroxo complex k3
is so high that it has no effect on the rate of other reacꢀ
tions; therefore, this reaction has been ignored;
(ii) hydration reaction (II) occurs in the aqueous
phase; according to solubility, 1,2ꢀepoxycyclopentane
is transferred to this phase in large excess water; thereꢀ
,
asterisk (*) denotes the activeꢀoxygen depleted comꢀ fore, the water concentration has been assumed conꢀ
stant and included into rate constant 6, i.e., k6 eff
plex), mol/dm3; [CP]org.ph., [H2O2]aq.ph., [ECP]org.ph.
,
k
;
(iii) hydration reaction (II) is an acidꢀcatalyzed reacꢀ
tion; its rate depends on the concentration of hydroꢀ
gen ions; however, since we considered two cases
where this concentration was constant (the pH of the
[ECP]aq.ph., [H2O]aq.ph., and [diol]aq.ph. are the concenꢀ
trations of CP, hydrogen peroxide, 1,2ꢀepoxycycloꢀ
pentane, water, and 1,2ꢀcyclopentanediol in the
respective phases, mol/dm3.
PETROLEUM CHEMISTRY Vol. 55
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54
MESHECHKINA et al.
describe the consumption of the reactants and the
accumulation of the reaction products in terms of the
total volume of the reaction mixture:
(a)
y
= 1.0594x – 3.9645
R2 = 0.9865
–1.0
–2.0
–3.0
–4.0
d[CP]
,
(1)
(2)
(3)
(4)
= −k2[CP][QCat]
dt
d[H2O2]
dt
d[CP]
,
− k5[H2O2]
= −
dt
d[ECP]
,
= k2[CP][QCat] − k6 eff [ECP]
dt
0
0.5
1.0
ln[CP]0
1.5
2.0
2.5
d[diol]
.
= k6[ECP][H 2O] = k6 eff [ECP]
dt
The rateꢀlimiting step of the formation of
1,2ꢀepoxycyclopentane is the epoxidation of CP by an
active peroxo complex. The concentration of the perꢀ
oxo complex [QCat] in the organic phase in the
steadyꢀstate condition is constant; it is determined by
(b)
y
= 1.0591x – 0.6333
R2 = 0.9825
–0.5
–1.5
–2.5
extraction constant К1
.
In [2, 10], it has been shown that, in the case of
using an Adogen 464 PTC, the catalyst complex is
almost completely transferred to the organic phase
after its formation and remains there during and after
the reaction.
The expression for constant К1 is written as follows:
[QCat]org.ph. [Cl−]3aq.ph.
[Cat]aq.ph. [QCl]3org.ph.
–3.5
–2.0
–3.0
–2.5
ln[Na2WO4]0
–2.0
⎯1.5
(5)
K1 =
.
The current concentration of the PTC in the
organic phase is determined by the difference between
its initial concentration and the amount consumed for
the formation of the complex according to reaction
(IV): [QCl]org.ph. = [QCl]org.ph. – 3[QCat]org.ph.
(c)
y
= 0.0543x – 2.6441
R2 = 0.9716
The current concentration of Cl– ions in the aqueꢀ
ous phase is proportional to the concentration of the
catalyst complex in the organic phase with allowance
for the volume ratio of the organic and aqueous
–2.3
–2.6
–2.9
⎛Vorg.ph.
⎞
⎟
⎠
−
phases:
⎡
⎣
⎤
⎦
Cl
= 3 QCat
.
[
]
⎜
org.ph.
org.ph.
Vaq.ph.
⎝
The concentration of the catalyst complex in the
aqueous phase depends on the initial concentration
of sodium tungstate, which is taken in deficiency
with respect to the other components constituting
the complex with allowance for the stoichiometry of
0
0.5
1.0
ln[H2O2]0
1.5
2.0
Fig. 2. Dependence of the initial rate of cyclopentene
epoxidation with aqueous hydrogen peroxide on the initial
concentrations of the reactants. Temperature, 50°C; solꢀ
vent, xylene; pH of the aqueous phase, 2.5. Variation in the
initial concentrations of (a) cyclopentene, (b) catalyst, and
(c) hydrogen peroxide.
1
4
reaction (III):
Cat
[
=
W
0
aq.ph.
]
[
]
aq.ph.
After transformations of equation (5), constant К1
can be expressed in terms of the initial concentrations
of sodium tungstate and the PTC as well as the current
concentration of the catalyst complex as follows:
aqueous phase was 2.5 and 1.5 for synthesizing the
epoxide and diol, respectively), the concentration of
hydrogen ions was also included in rate constant k6 eff
According to the above conversion scheme, a sysꢀ
tem of differential equations (1–4) was derived to
3
⎛Vorg.ph.
⎞
⎟
⎠
108
[QCat]4org.ph.
.
⎜
Vaq.ph.
⎝
(6)
K1 =
.
([QCl0]org.ph. −3[QCat]org.ph.)3 [W0]aq.ph.
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THE KINETICS OF THE REACTION
55
Kinetic parameters of the reaction between cyclopentene and aqueous hydrogen peroxide
Parameter
Temperature of 50°C; pH of aqueous phase 2.5 Temperature of 60°C; pH of aqueous phase 1.5
K1
(63.7 1.5) ×
103
k
k
k
2, dm3 mol–1 min–1
5, min–1
2.41 0.01
(0.50 0.03)
(0.09 0.01)
9.97 0.03
×
×
10–3
10–3
(1.20 0.04)
×
10–3
10–3
6eff, min–1
(78.0 2.5) ×
E
E
a(I), kJ/mol
a(II), kJ/mol
65.9 4.0
64.0 2.7
S
S
a(I), J/(mol K)
a(II), J/(mol K)
–107
8
–110 10
The constants in the above equations (1–4) were tane concentrations of 2.62–6.94 mol/dm3 in the
selected using two arrays of experimental data on the organic phase is equal to unity. It was shown that
reaction between CP and an aqueous solution of 1,2ꢀepoxycyclopentane hydration reaction (II) occurs
hydrogen peroxide: one for a temperature of 50°C in the aqueous phase and the distribution of the
and a pH of the aqueous phase of 2.5 and the other epoxide between the phases is determined by its total
for a temperature of 60°C and a pH of the aqueous content in the reaction mass and solubility in water.
phase of 1.5.
The order of the reaction with respect to the epoxide
equal to unity suggests that the transfer of the epoxide
into the aqueous phase occurs much more rapidly than
its reaction with water and has no effect on the hydraꢀ
tion reaction rate; therefore, the constant of extraction
of 1,2ꢀepoxycyclopentane from the aqueous phase into
The concentration of the catalyst (sodium tungꢀ
state) in the aqueous phase was varied in a range of
0.028–0.177 mol/dm3, while maintaining the
Na2WO4 : H3PO4 : PTC ratio of 1 : 1 : 0.36. The initial
concentration of hydrogen peroxide was varied in a
range of 1.52–6.18 mol/dm3 in the aqueous phase,
while the concentration of CP in the organic phase
was varied from 1.78 to 10.24 mol/dm3 (solventless
reaction) at constant concentrations of the other
substances. The individual orders of reactions (I) and
(II) were determined from the change in the initial
rates as a function of the initial concentrations of the
analytes, all other parameters and concentrations
being constant.
These data indicate that the individual orders with
respect to CP and the catalyst are equal to unity
(Figs. 2a, 2b), while the order with respect to hydroꢀ
gen peroxide is close to zero (Fig. 2c). The lastꢀmenꢀ
tioned fact indicates that the true oxidizing agent is the
active catalytic intermediate transferred from the
aqueous phase to the organic phase using a PTC rather
than hydrogen peroxide. The studies on the effect of
the pH of the aqueous phase on the thermocatalytic
decomposition of hydrogen peroxide have shown that,
at the presence of the Q3[PO4{W(O)(O2)2}4] catalyst
complex at 50°C and a pH below 3, the rate constant
of decomposition of hydrogen peroxide does not
exceed 0.001 min–1.
the organic phase
K4 was ignored in the calculations.
The extraction constant
K1 was calculated from the
determined concentration of peroxo groups (i.e., the
Q3[PO4{W(O)(O2)2}4] complex) in the organic phase;
it has a value of 63 700 and hardly depends on temperꢀ
ature in the examined range of 30–70°C. Further calꢀ
culations and selection of the rate constants of the
stages were conducted using this value.
The constants in Eqs. (1)–(4) were calculated and
selected in a broad range of variation of the unknown
quantities with minimization of the squared deviation
of the experimental and calculated values. The rate
constants found by graphical analytical methods were
taken as an initial approximation.
In the temperature range of 30–70°C, the activaꢀ
tion energies of reactions (I) and (II) were found to be
65.9 and 64.0 kJ/mol, respectively. The activation
entropies calculated according to the Eyring equation
were also close in value: –107 and –110 J/(mol K) for
the epoxidation and hydration reactions, respectively.
The derived constants are listed in the table; the
agreement between the experimental kinetic curves of
reactant consumption and product accumulation for
It was found that, at a pH of the aqueous phase of the synthesis of 1,2ꢀepoxycyclopentane and 1,2ꢀcycloꢀ
1.5 and a temperature of 60°C, the order of reaction pentanediol and the curves calculated according to the
(II) with respect to the epoxide at 1,2ꢀepoxycyclopenꢀ developed model is shown in Fig. 1.
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MESHECHKINA et al.
The adequacy of the model was tested using the
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Translated by M. Timoshinina
PETROLEUM CHEMISTRY Vol. 55
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2015