Sonocatalyzed synthesis of 2-phenylvaleronitrile under controlled reaction conditions - A kinetic study

Article abstract of DOI:10.1016/j.ultsonch.2011.02.002

In the current study, kinetics of synthesis of 2-phenylvaleronitrile (PVN) was successfully carried out by selective C-alkylation of benzyl cyanide (BC) with n-bromopropane (BP) using aqueous KOH and catalyzed by TBAB under ultrasonic (300 W) assisted org

Full text of DOI:10.1016/j.ultsonch.2011.02.002

Ultrasonics Sonochemistry 18 (2011) 1241–1248
Contents lists available at ScienceDirect
Ultrasonics Sonochemistry
journal homepage: www.elsevier.com/locate/ultsonch
Sonocatalyzed synthesis of 2-phenylvaleronitrile under controlled reaction
conditions – A kinetic study
⇑
P.A. Vivekanand, Maw-Ling Wang
Department of Environmental Engineering, Safety and Health, Hungkuang University, Shalu, Taichung County, Taiwan 43302, Taiwan, ROC
a r t i c l e i n f o
a b s t r a c t
Article history:
In the current study, kinetics of synthesis of 2-phenylvaleronitrile (PVN) was successfully carried out by
selective C-alkylation of benzyl cyanide (BC) with n-bromopropane (BP) using aqueous KOH and cata-
lyzed by TBAB under ultrasonic (300 W) assisted organic solvent-free conditions. Selective monoalkyla-
tion of benzyl cyanide has been achieved by controlling the reaction conditions and has been followed
using gas chromatogram. The effects of various parameters such as agitation speed, catalyst concentra-
tion, KOH concentration, benzyl cyanide concentration, volume of water, ultrasonic frequency and tem-
perature were studied systematically to understand their influence on the rate of the reaction. The
experimental observations are consistent with an interfacial-type process. Further the kinetic results
demonstrate clearly, that ultrasonic assisted phase-transfer catalysis significantly increased the reaction
rate when compared to silent reactions.
Received 16 October 2010
Received in revised form 8 January 2011
Accepted 3 February 2011
Available online 17 February 2011
Keywords:
Sonocatalysis
2
-Phenylvaleronitrile
C-alkylation
Interfacial reaction
Kinetics
Ó 2011 Elsevier B.V. All rights reserved.
1
-Bromopropane
1
. Introduction
Application of traditional techniques [1] in reaction systems
The salient feature of this study is the serious hydration of potas-
sium salt of phthalimide from the reaction of 1-bromobutane
and potassium salt of phthalimide can be avoided compared to li-
quid–liquid two-phase system.
involving immiscible reactants (lipophilic and hydrophilic reac-
tants), for removing the constraints of mutual insolubility of aque-
ous phase with organic phase, are industrially unattractive and
polluting. Mutual insolubility of such reaction systems can be alle-
viated by an environmentally benign technique known as ‘‘phase
transfer catalysis’’ (PTC). This technology has emerged as a broadly
useful tool [2–6] in solving the heterogeneity of the reaction med-
ium. In this key green approach [7,8], involving a substrate (in the
organic layer) and an anionic reagent or a nucleophile (in the
aqueous layer), reacting anions are continuously introduced into
the organic phase by the phase transfer agent. Currently, PTC is
an important choice in organic synthesis and is widely applied in
the manufacturing processes of specialty chemicals, such as phar-
maceuticals, perfumes, dyes, additives, pesticides and monomers
Currently, ingenious new analytical and process experimental
techniques which are environmentally benign techniques viz.,
ultrasound and microwave irradiation have become immensely
popular in promoting various organic reactions [12–16]. Ultra-
sound irradiation is a transmission of a sound wave through a
medium and is regarded as a form of energy for the excitation of
reactants consequently enhancing the rate of diffusion [17–19].
Richards and Loomis [20] reported, on the chemical effects of
high-power ultrasound, two types of chemical reaction: (i) the
acceleration of conventional reactions by ultrasound and (ii) redox
processes in aqueous solutions. In a liquid medium, the effects of
ultrasound are produced due to the phenomenon called cavitation.
When a liquid is irradiated by ultrasound, microbubbles can
appear, grow and oscillate extremely quickly and even collapse
violently if the acoustic pressure is high enough. The occurrence
of these collapses near a solid surface will generate microjets and
shock waves [21]. Moreover, in the liquid phase surrounding the
particles, high micromixing will increase the heat and mass trans-
fer and even the diffusion of species inside the pores of the solid
[22].
[
6]. One of the most important applications of PTC is in the alkyal-
tion of benzyl cyanaide and its derivatives, because many pharma-
ceuticals contain the phenylacetic framework [9–11].
We reported [1] the synthesis of N-butylphthalimide, from the
reaction of 1-bromobutane and potassium salt of phthalimide, un-
der solid–liquid phase-transfer catalytic condition (SL-PTC) instead
of carrying out the reaction in a liquid–liquid two-phase medium
i.e., the reaction was followed under non-aqueous PTC condition.
Application of ultrasonic waves in organic synthesis (homoge-
neous and heterogeneous reactions) has been boosted in recent
years [23–29]. Sonification of multiphase systems accelerates the
reaction by ensuring a better contact between the different phases
[30,31]. Further, they also increase the reaction rate and avoid the
⇑
Corresponding author. Tel.: +886 426 318652; fax: +886 426 529226.
E-mail address: chmmlw@sunrise.hk.edu.tw (M.-L. Wang).
1
350-4177/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.ultsonch.2011.02.002

1
242
P.A. Vivekanand, M.-L. Wang / Ultrasonics Sonochemistry 18 (2011) 1241–1248
use of high reaction temperatures [32]. These days this environ-
mental benign technology is combined with PTC with primary
objective of optimizing reaction conditions [33–35]. Palladium
catalysts along with PTC proved to be excellent catalytic systems
for Heck reactions involving several aryl bromides with styrene
and acrylic compounds under ultrasonic conditions [36]. Yang
and Peng [37] investigated the green synthesis of butyl salicylate
by an efficient process of ultrasound-assisted third-liquid phase
transfer catalysis in a countercurrent two-phase-flow reactor.
Recently, we reported the synthesis of 1-(3-phenylpropyl)-pyrrol-
idine-2,5-dione, which is a biologically and industrially useful
imide derivative, from the reaction of succinimide with 1-bromo-
heteronuclear two-dimensional techniques. 13C NMR spectra were
recorded with complete proton decoupling. Gas chromatography
was carried out using a GC–Shimadzu 17 A model.
3
. Ultrasonic process equipment
Ultrasonic energy is transmitted to the process vessel through
the liquid medium, usually water in the tank. For safety purpose,
the sonochemical reactor consisted of two layers stainless steel
body. The sonochemical reactor configuration used in the present
work is basically an ultrasonic bath (model L-600) equipped with
flat transducer, procured from Ko Hsieh Instruments Co. Ltd.,
Taipei, Taiwan (http://www.kohsieh.com.tw/). The internal dimen-
sion of the ultrasonic cleaner tank is 250 mm ꢀ 250 mm ꢀ 380 mm
with liquid holding capacity of 23 liters. The external tank size is
3
-phenylpropane under ultrasound assisted solid-liquid phase-
transfer catalytic almost water-free conditions [38].
The genesis of the current work lies in these lacunae. Our
interest was centered on first time evaluating the influence of
ultrasound in association with phase-transfer catalyst on the
synthesis of 2-phenylvaleronitrile by monoalkylation of benzyl
cyanide (BC, 1) using n-bromoprpoane (BP, 2) as an alkylating
agent. One of the interesting results of the current study is that
we were able to get exclusive mono-alkylated product (2-phenyl-
pentanenitrile, 3) when we utilize BP as a limiting agent (Scheme
4
20 mm ꢀ 520 mm ꢀ 600 mm. The reactor has an operating
frequency of 25 kHz and 50 kHz with a output of 300 W. Both
ultrasounds are separately produced through a flat transducer
mounted at the bottom of the tank. In this ultrasonic instrument
there is a provision for a drain as well as an outlet at the top, which
gives facility of continuous operation of work. Further, in order to
carry out high and low temperature reactions, an additional heater
1). However, when benzyl cyanide was employed as a limiting
(
Thermo Haake) with facility of temperature controller has been
agent, both mono as well as bis-alkylated products (2-phenyl-2-
propylpentanenitrile) were observed. Since, the kinetic study of
mono-alkylation of BC using 1-bromopropane under controlled
PTC reaction conditions will be interesting and challenging, we
followed the kinetic study of monoalkyaltion using tetrbutylam-
monium bromide (TBAB) as a catalyst under ultrasonic condition
provided. The process vessel is immersed in the water present in
the tank.
4
. General procedure for the synthesis of 2-phenylvaleronitrile
under sonocatalyzed condition
(
50 kHz; 300 W). Further, to best of our knowledge, there are no
To the mixture of KOH (6 g, 0.10 mol) in water (10 mL) and TBAB
literature reports regarding monoalkylation of BC with BP under
PTC-ultrasonic condition.
ꢁ4
(
0.17 g, 5.27 ꢀ 10 mol), benzyl cyanide (12.86 g, 0.10 mmol) was
added under overhead stirring to generate the carbanion. Then n-
bromoprpoane (1.35 g, 0.010 mol) was added slowly. The reaction
mixture was heated at 50 C for 2 hours with vigorous stirring. The
2
. Experimental
0
monoalkylation was followed by GC monitoring. The crude product
was isolated by simple extraction with diethyl ether (2 ꢀ 25 mL).
The organic layer was collected and the solvent was evaporated un-
der reduced pressure. The crude product was chromotographed
2
.1. Materials
All reagents, including benzyl cyanide (Fluka), 1-bromopropane
(
Acros), tetrabutylammonium bromide (TBAB, Acros), tetraethy-
lammonium chloride (TEAC, Acros), tetraethylammonium bromide
TEAB, Acros), benzyltriethylammonium bromide (BTEAB, Acros),
(
2
SiO ) employing hexane: ethylacetate (10:1) as eluent to obtain
pure monoderivative. The identity of the product was confirmed
(
1
13
ꢁ1
by IR, H NMR and C NMR spectra of the product. IR (KBr, cm ):
benzyltriethylammonium chloride (BTEAC, Acros), potassium
hydroxide (Acros), toluene (TEDIA), chlorobenzene (TEDIA) and
other reagents for synthesis were guaranteed grade (GR) chemicals
and were used as received without further purification.
1
6
55, 798, 1455, 1581, 2238, 2935; H NMR (CDCl
3
): d 0.92 (t,
), 3.76 (t,
): d 13.25,
0.14, 36.97, 37.71, 120.77,127.089,127.81,128.87 and 135.92.
J = 7.6 Hz, 3H), 1.44–1.56 (m, 2H), 1.78–1.94 (m, 2H,-CH
2
13
6 5 3
J = 8.0 Hz, 1H), 7.73–7.80 (m, 5H, –C H ). C NMR (CDCl
2
2
.2. General
5
. Sonicated kinetics of the bi-phase reaction system
The reactor was a 150 ml three-necked Pyrex flask, serving the
FTIR spectra were recorded on a Perkin–Elmer Spectrum 1000
1
13
on KBr pellets. H NMR and C spectra were recorded on a Bruker
DRX 400 spectrometer. Chemical shifts (d) are given in ppm and
coupling constants (J) in hertz (Hz). Multiplicities of NMR signals
are designed as t (triplet) and m (multiplet). Attribution of
signals are based on the J-modulated spin-echo sequence and/or
purposes of agitating the solution, inserting the thermometer, tak-
ing samples and feeding the feed. A known quantity of KOH (10 g,
0.17 mol) was dissolved in deionized water (20 ml) to prepare a
aqueous alkaline solution. Known quantities of TBAB (0.30 g,
1
3
C
ꢁ4
9
.3 ꢀ 10 mol), benzyl cyanide (25.73 g, 0.21 moles) and toluene
(
internal standard, 0.1 g) were added to reaction vessel, which
was suspended in the middle of ultrasonic bath to get the maxi-
mum ultrasound energy, to form the organic solution. After stirring
at 600 rpm for ten minutes at 50 °C, n-bromopropane (2.7 g, 0.021)
was added. To start the reaction, the aqueous and organic solutions
were mixed in the flask. The organic-phase sample (0.05 ml) was
withdrawn from the reactor at each time interval and was put into
the glass vials containing 2 mL of chlorobenzene. The contents of
the reaction sample (2-phenylvaleronitrile, n-bromopropane and
benzyl cyanide) were measured by GC. The analyzing conditions
are as follows: Shimadzu GC 17A, J&W Scientific Inc., capillary
C H Br
3
7
2
PhCH(C H )CN
3
3
7
KOH / PTC
PhCH CN
2
C H Br
3 7
1
o
5
0 C/Ultrasound
2
3
PhC(C H ) CN
3 7 2
(Excess)
4
Scheme 1. C-alkylation of benzyl cyanide under controlled PTC assisted ultrasonic
condition.

P.A. Vivekanand, M.-L. Wang / Ultrasonics Sonochemistry 18 (2011) 1241–1248
1243
column (db-1 column); 100% poly(dimethylsiloxane) stationary
phase; 15 m ꢀ 0.525 m column dimension; carrier gas, nitrogen
60 ml/min); flame ionization detector; injection temperature,
50 °C. The product formed was analyzed by comparison of their
0.024
Reactant(BP)
Product(PVN)
(
2
0.020
retention times with authentic samples. Yields were determined
from standard curve and using toluene as internal standard.
Ultrasonic frequency and power employed in the current study is
0.016
5
0 kHz and 300 W respectively.
0
0
0
0
.012
.008
.004
.000
6
. Reaction mechanism and kinetic model
For synthesizing 2-phenylvaleronitrile compound, the overall
reaction of benzyl cyanide (BC) and n-bromopropane (RBr) was
catalyzed by TBAB (QBr) in the aqueous alkaline (KOH) bi-phase
medium and is represented in Scheme 1. The reaction is carried
out under PTC assisted ultrasonic condition. Main reason for inves-
tigating the reaction in presence of ultrasonic irradiation is to
enhance rate of the reaction. In the current investigation the kinet-
ics was followed in presence of excess benzyl cyanide by fixing the
n-bromopropane as limiting agent.
0
20
40
60
Time (min)
80
100
Fig. 1. Distribution of reactant and product during the reaction period (mass
ꢁ
2
balance plot); 21.93 ꢀ 10 mol of benzyl cyanide, 10 g of KOH, 20 mL of H O, 0.1 g
of internal standard (toluene), 21.96 ꢀ 10 mol of n-bromolpropane, 0.3 g of TBAB,
0 °C, 600 rpm; under ultrasound conditions (50 kHz, 300 W).
2
ꢁ
3
5
6.1. Definition
The conversion (X) of n-bromopropane, (BP) is defined as
follows:
on the conversion (X) of the limited reactant RBr and the apparent
rate constant (kapp) are discussed below.
½
BPꢂ
0
X ¼ 1 ꢁ
ð1Þ
½
BPꢂ
7.1. Effect of Stirring Speed
0
;i
where [BP]0,i and [BP]
pane at time (t) t = 0 and t > 0, respectively.
0
represent the concentration of n-bromopro-
To ascertain the influence of agitation speed on the rate of
monoalkyaltion of benzyl cyanide, the speed of agitation was
varied in the range of 100-1000 rpm under otherwise similar
conditions using TBAB as the catalyst. Apparent rate constants
are evaluated from the linear plot of ꢁln(1 ꢁ X) versus time. The
results indicate that the rate of the reaction increases linearly as
the agitation speed increases from 100 to 600 rpm (Fig. 2). How-
ever, on further increasing the agitation speed from 600 to
1000 rpm, there is no significant improvement in the reaction rate
constant. This is because the interfacial area per unit volume of
dispersion increased linearly with increasing the stirring speed till
6.2. Rate expression
The rate expression for this reaction may be expressed as
ꢁr
BP ¼ kapp½BPꢂ0
ð2Þ
where kapp is the apparent reaction rate constant. This reaction is
carried out in a batch reactor, so the diminution rate of BP with time
(t) can be expressed as
6
00 rpm is reached, where there is no significant increase in the
d½BPꢂ
0
ꢁ
¼ ꢁrArCl ¼ kapp½BPꢂ0
ð3Þ
interfacial area per unit volume of dispersion with the correspond-
ing increase in the speed. Thus, increasing the stirring speed
dt
on integrating the Eq. (3) yields:
BPꢂ
½
0
35
ꢁ
ln
¼ ꢁ lnð1 ꢁ XÞ ¼ kapp
0;i
ð4Þ
½
BPꢂ
3
2
2
0
5
0
Using Eq. (4), we can get the kapp value experimentally by plot-
ting ꢁln(1 ꢁ X) against time (t).
7
. Results and discussion
The monoalkylation of benzyl cyanide with n-bromopropane
was performed using potassium hydroxide as a base and tetrabu-
tylammonium bromide as a phase transfer catalyst at 50 °C under
ultrasonic condition (Scheme 1). The kinetic results show a mate-
rial balance between reactant and products, i.e., the consumption
of the amount of reactant (n-bromopropane, BP) equals to the
sum of the generation of the amount of the product (2-phenylvale-
ronitrile) from the reactant n-bromopropane (2) under ultrasonic
conditions, as shown in Fig. 1. Further, no byproducts were
observed during or after reaction. Thus, rate of the decrease of
n-bromopropane is consistent with the rate of production of
15
10
5
0
0
200
400
600
800
1000
1200
Strring Speed (rpm)
Fig. 2. Plot of the apparent rate constants versus various agitation speeds;
2
-phenylvaleronitrile. Pseudo-first order kinetics was indicated
ꢁ2
2
1.93 ꢀ 10 mol of benzyl cyanide, 10 g of KOH, 20 mL of H
2
O, 0.1 g of internal
by the linearity of the plot of ꢁln(1 ꢁ X) versus time. The reaction
ꢁ3
standard (toluene), 21.96 ꢀ 10 mol of n-bromolpropane, 0.3 g of TBAB, 50 °C;
mixture was analyzed by GC. The effects of the reaction conditions
under ultrasound conditions (50 kHz, 300 W).

1
244
P.A. Vivekanand, M.-L. Wang / Ultrasonics Sonochemistry 18 (2011) 1241–1248
changes the particle size of the dispersed phase. Therefore, the agi-
tation speed was set at 600 rpm for studying the reaction phenom-
ena from which the resistance of mass transfer stays at a constant
value. Generally in the two-phase reaction system, the effect of
stirring speed on the rate of the reaction can be explained by (i)
Starks’ extraction mechanism and (ii) Makosza’s interfacial reac-
tion mechanism. Kinetic studies into effects of variation in stirring
speed reveal that the interfacial mechanisms [3,5,39–42] are trans-
fer rate-limited below a given stirring speed (600–800 rpm) and
are intrinsic reaction rate-limited above this stirring speed. Our
lab reported [43] an interfacial mechanism in the synthesis of
dichlorocyclopropane catalyzed by quaternary ammonium salt
from the reaction of 1,7-octadiene and chloroform in an alkaline
solution of a NaOH/organic solvent two-phase medium. Viveka-
nand and Balakrishnan [44] observed a linear dependence of rate
constant on stirring speed up to 500 rpm for C-alkylation of indene
using the new onium salt for which an interfacial mechanism was
proposed. Reactions involving extraction mechanism, proposed by
Starks and Owens [45], display analogous performance but with a
smaller limit of agitation speed between physical and chemical
control (100–300 rpm).
50
40
30
20
10
0
0
.0
0.2
0.4
0.6
0.8
Catalyst (g)
Fig. 4. Effect of the amount of catalyst on the apparent rate constant:
ꢁ
2
21.93 ꢀ 10 mol of benzyl cyanide, 10 g of KOH, 20 mL of H
2
O, 0.1 g of internal
ꢁ
3
standard (toluene), 21.96 ꢀ 10 mol of n-bromolpropane, 600 rpm,50 °C; under
ultrasound conditions (50 kHz, 300 W).
7.2. Effect of the amount of TBAB
Table 1
Effect of amount of BC on the rate of C-alkylation under ultrasonic condition: 10 g of
ꢁ
3
Experiments were conducted by varying the amount of catalyst
KOH, 20 mL of H O, 0.1 g of internal standard (toluene), 21.96 ꢀ 10 mol of n-
2
quantity but keeping other experimental parameters constant un-
der pseudo-first order condition. Influence of amount of TBAB on
the monoalkyaltion of benzyl cyanide has been studied by varying
amount of catalyst from 0.1 g to 0.5 g under ultrasound activation.
Apparent rate constants were evaluated from the plot of –ln(1 ꢁ X)
versus Time (Fig. 3). In general, the reactivity is increased with an
increase in the amount of quaternary ammonium salt. As shown in
Fig. 4, the rate of the reaction increased with the increase in the
amount of tetrabutylammonium bromide. The rate constants are
linearly dependent on the amount of catalyst used (Table 1). The
increase in the kapp value is attributed to the change in the size,
surface area and morphology of phase-transfer catalyst [46].
Further, the opportunity of collision between intermediates is
increased by increasing catalyst concentration. Therefore, the
opportunity of forming a complex between them is largely
increased. Hence, the apparent rate constant values increased with
the increase in the amount of catalyst.
bromolpropane, 0.3 g of TBAB, 600 rpm, 50 °C; under ultrasound conditions (50 kHz,
3
00 W).
Entry. no.
Amount of BC (g)
kapp (ꢀ10ꢁ3, minꢁ1
)
1
2
3
4
5
12.8
19.3
25.7
32.1
38.5
28.8
25.4
23.6
18.5
12.9
7.3. Effect of volume of BC
To investigate the influence of benzyl cyanide (BC) on the kinet-
ics of synthesis of 2-phenylvaleronitrile under sonocatalyzed
reaction condition, the amount of BC was varied from 0.109 mol
to 0.328 mol. Apparent rate constants are calculated from the plot
–ln(1 ꢁ X) versus time. The results are shown in Fig. 4. The reaction
rate is decreased with an increase in the amount of BC. The reason
is that the concentration of the reactants is diluted using a larger
volume of BC. Hence, the kapp value decreases with increasing the
amount of BC. Similar decrease in the rate of the reaction is
reported [46] on increasing the amount of ethanol in the ethoxyla-
tion of p-chloronitrobenzene using benzyltriethylammonium chlo-
ride as a phase-transfer catalyst under ultrasound irradiation
conditions. In the dicholorcarbene addition to styrene under PTC
condition [47], the rate was found decrease with increase in con-
centrateion of styrene.
3
2
1
1
0
0
.0
.4
.8
.2
.6
.0
0.1 g
0.2 g
0.3 g
0.4 g
0.5 g
7
.4. Effect of variation of temperature
The effect of temperature on the reaction between BC and
n-bromopropane was studied under otherwise similar conditions.
The temperature was varied from 40 to 60 °C. The kinetic profile
of the reaction is obtained by plotting -ln(1 ꢁ X) versus time. The
rate constant increased with the increase in temperature. The
energy of activation was also calculated from the Arrhenius plot;
0
20
40
60
80
Time (Min)
a
E = 16.20 (Fig. 5). The result is consistent with results obtained
Fig. 3. Plot of ꢁln(1 ꢁ X) versus time with various amounts of phase-transfer
ꢁ
2
previously in studies of different reaction systems [48,49]. It is evi-
dent that the rate of C-alkylation increases with an increase in the
temperature along with ultrasonic effect [46]. We attribute this
catalysts; 21.93 ꢀ 10 mol of benzyl cyanide, 10 g of KOH, 20 mL of H
2
O, 0.1 g of
ꢁ
3
internal standard (toluene), 21.96 ꢀ 10 mol of n-bromolpropane, 600 rpm, 50 °C;
under ultrasound conditions (50 kHz, 300 W).

P.A. Vivekanand, M.-L. Wang / Ultrasonics Sonochemistry 18 (2011) 1241–1248
1245
4
4
4
3
3
2
.8
.4
.0
.6
.2
.8
80
60
40
20
0
3.00
3.05
3.10
3.15
3.20
0
10
20
30
40
1
/T X 103 (1/K)
Water (mL)
ꢁ
2
Fig. 5. Arrhenius plot for ꢁln(kapp) versus 1/T; 21.93 ꢀ 10 mol of benzyl cyanide,
Fig. 6. Plot of the apparent rate constants versus various different volumes of
ꢁ
3
ꢁ2
1
0 g of KOH, 20 mL of H O, 0.1 g of internal standard (toluene), 21.96 ꢀ 10 mol of
n-bromolpropane, 0.3 g of TBAB, 600 rpm; under ultrasound conditions (50 kHz,
00 W).
2
water; 21.93 ꢀ 10 mol of benzyl cyanide, 10 g of KOH, 0.1 g of internal standard
ꢁ
3
(toluene), 21.96 ꢀ 10 mol of n-bromolpropane, 0.3 g of TBAB, 600 rpm,50 °C;
3
under ultrasound conditions (50 kHz, 300 W).
phenomenon to the increase in collision of the reactants molecules
at higher temperature. Hence, the reaction rate is increased at
higher temperature. The activation energy of intraparticle diffusion
of anion exchange resins in aqueous solutions is of the order of 5-
is decreases. This situation would dramatically reveal the hydra-
tion effect of the active catalyst as the volume of water changed
from 15 to 30 mL. Thus, concentration of the alkali compound in
aqueous solution would also affect the distribution of the active
catalysts between two phases. Thus, less active catalyst exists in
the organic phase. In the kinetic study [57] of the phase-transfer
catalyzed etherification of 4,4-bis(chloromethyl)-1,1-biphenyl
with phenol in an alkaline solution of KOH/organic solvent two-
phase medium, similar decrease in rate of the reaction on corre-
sponding increase in volume of water was reported.
ꢁ1
1
8
0 kcal mol [50]. The energy of activation was reported to be
kcal mol in the dehydrobromination of (2-bromoethyl)benzene
ꢁ1
catalyzed by tetraoctylammonium bromide. For this process, an
extraction mechanism was proposed [51]. In general, a higher acti-
vation energy suggest that a contribution of intrinsic reactivity
limitations is more than that of intraparticle diffusion limitations
[
47,52]. The activation energy for the heterogeneous ethylation
ꢁ
1
of phenylacetonitrile was reported to be 20 kcal mol and for this
an interfacial mechanism was proposed [53]. In the alkylation of
pyrrolidine-2-one under solid/liquid PTC in presence of potassium
7.6. Effect of Ultrasonic Power
Ultrasonic irradiation is defined as acoustic waves with fre-
quencies in the 20 kHz -100 MHz range [26,58]. Their energy cre-
ate cavities generating locally high temperatures and pressures
carbonate, Sasson and Bilman reported [54] a higher E
a
value
ꢁ1
(
12.4 kcal mol ) and for this reaction they proposed an interfacial
mechanism was proposed. They concluded that the deprotonation
of the substrate takes place at the interphase and consequently the
organic anion is extracted and reacts in the bulk of the organic
phase. The rate-determining step in the process is the anion ex-
[
59–62] or strong electric fields [60,62–64]. Ultrasound is known
to accelerate diverse types of organic reactions and it is established
as an important technique in organic synthesis [58,60,62]. Hetero-
geneous reactions, which are otherwise slow due to poor mass
transfer are accelerated by sonication due to cavitation [61]. It
has been reported that a combination of PTC and ultrasound is of-
ten better than either of the two techniques alone [62]. In such
cases, the phase-transfer catalyst initiates the reaction by the
transfer of species across the interface and ultrasound merely facil-
itates this transfer, possibly by increasing the interfacial area
across which this transfer occurs.
change at the interphase. In our study, the observed higher E
a
va-
ꢁ1
lue, i.e. 16.20 kcal mol
, indicates that the contribution of
intrinsic reactivity limitations is more than that of intraparticle dif-
fusion limitations and hence we propose an interfacial mechanism
[
6,44,47,55,56].
7.5. Influence of amount of water
To ascertain the influence of various ultrasonic frequencies on
the rate of monoalkyaltion of benzyl cyanide with same output
power of 300 W, the ultrasonic frequency was varied in the range
of 40-120 kHz under otherwise similar conditions using TBAB as
the catalyst. Also we followed the reaction under silent condition.
The kinetic profile of the reaction is obtained by plotting
ꢁln(1 ꢁ X) versus time. In our experiments the ultrasonic bath,
model L-400 was used. It is consisted of two layers stainless steel
body. The internal dimensions of the ultrasonic cleaner tank are
250 mm ꢀ 250 mm ꢀ 380 mm with liquid holding capacity of
23 l. The external tank size is 420 mm ꢀ 520 mm ꢀ 600 mm. We
used water as a liquid in the ultrasonic cleaner. Further details
are presented in experimental section. At 80 minutes, without
C-alkylation of benzyl cyanide with n-bromopropane as a limit-
ing agent under sonocatalysis conditions was examined by varying
the amount of water from 10 to 30 mL under standard reaction
conditions. Apparent rate constants were obtained from the plot
of –ln(1 ꢁ X) versus time. Generally, the volume of water directly
affects both the concentration of KOH in the aqueous phase and
also generation of anions. Therefore, the conversion (or the reac-
tion rate) will be affected by the volume of water. Fig. 6 shows
the effect of the amount of water on the rate of the reaction. In
principle, the conversion of RBr (n-bromopropane) is decreased
with greater volume of water. The decreased rate constant is
ꢁ
+
attributed to the decrease in the active catalyst, Ph [CH Q ] CN,
at higher volume of water. Further on increasing the volume of
water, the concentration of alkali compound in aqueous solution
ꢁ3
ꢁ1
ultrasonic irradiation the rate constant is only 8.5 x 10 min
,
but in the presence of ultrasonic the rate constants are

1
246
P.A. Vivekanand, M.-L. Wang / Ultrasonics Sonochemistry 18 (2011) 1241–1248
Table 2
Influence of ultrasonic frequencies on the on the rate of C-alkylation of benzyl
Table 4
Effect of various PTC’s on the rate of C-alkylation of benzyl cyanide under ultrasonic
ꢁ
2
ꢁ2
cyanide: 21.93 ꢀ 10 mol of benzyl cyanide,10 g of KOH, 20 mL of H
2
O, 0.1 g of
condition: 21.93 ꢀ 10 mol of benzyl cyanide, 10 g of KOH, 20 mL of H
2
O, 0.1 g of
ꢁ
3
ꢁ3
ꢁ4
internal standard (toluene), 21.96 ꢀ 10 mol of n-bromolpropane,0.3 g of TBAB,
internal standard (toluene), 21.96 ꢀ 10 mol of n-bromolpropane, 9.30 ꢀ 10 mol
of PTC, 600 rpm, 50 °C; under ultrasound conditions (50 kHz, 300 W).
6
00 rpm, 50 °C; under ultrasound conditions (300 W).
Ultrasonic frequency (kHz)
0
28
40
50
120
33.4
Entry. no.
PTC
k
app (ꢀ10ꢁ3, minꢁ1
)
3
ꢁ1
k
app (ꢀ10 , min
)
8.5
17.7
20.8
23.6
1
2
3
4
5
TEAC
TEAB
BTEAC
BTEAB
TBAB
36.1
33.5
30.4
28.2
23.6
ꢁ
ꢁ
3
3
ꢁ1
ꢁ3
ꢁ1
ꢁ3
ꢁ1
1
3
7.7 ꢀ 10
3.4 ꢀ 10
min , 20.8 ꢀ 10
min , 23.6 ꢀ 10
min
and
ꢁ1
min
for 28 kHz, 40 kHz, 50 kHz, and 120 kHz,
respectively (Table 2). From these observed results, it can be in-
ferred that ultrasonic assisted phase-transfer catalysis significantly
increased the rate of the reaction. Similar trend was observed by
Entezari and coworkers [65,66]. Hence, the application of ultra-
sounds in organic synthesis is one of the popular areas in
sonochemistry.
Table 5
Influence of alkalinity on
k
app in the C-alkylation of benzyl cyanide with n-
ꢁ2
bromopropane catalyzed by TBAB under ultrasonic condition; 21.93 ꢀ 10 mol of
ꢁ
3
benzyl cyanide, 20 mL of H O, 0.1 g of internal standard (toluene), 21.96 ꢀ 10 mol
2
of n-bromolpropane, 0.3 g of TBAB, 600 rpm, 50 °C; under ultrasound conditions
(
50 kHz, 300 W).
Entry. no.
Amount of KOH (g)
k
app (ꢀ10ꢁ3, minꢁ1
)
7.7. Effect of organic solvents
1
2
3
4
5
5.0
7.5
10
15
20
10.30
15.30
23.60
32.10
41.20
In this work, the influence of various organic solvents on the
rate of monoalkylation of BC was followed under otherwise stan-
dard reaction conditions. Five organic solvents employed in this
study are cyclohexanone, anisole, cyclohexene, chlorobenzene,
and benzene. From the plot of ꢁln(1 ꢁ X) versus time, the rate
constants are obtained. The order of the reactivity for these five
reaction mechanism. For an interfacial reaction mechanism, the
reaction rate is highly dependent on the concentration of the cata-
lyst at the interface. By comparing the catalytic activity of the qua-
ternary ammonium cations with that of the same halide ion, the
order of the reactivities of these PTCs is TEA cation > BTEA cat-
ion > TBA cation. We attribute the higher reactivity obtained for
TEA cation to lower total carbon number. In general, the activity
of the catalyst is dependent on the structural characteristics of a
quaternary ammonium cation [5]. For this, the yield of the product
is correlated with the accessibility of the quaternary ammonium
salt, q, which is a function of carbon in each chain. It is thus con-
cluded that the order of the reactivity is TEA cation > BTEA cat-
ion > TBA cation, which is consistent with the results indicated
by Starks et al. In an interfacial mechanicsm driven dichlorocar-
bene addition to 1,7-octadiene under PTC conditions a similar
trend was observed [43].
organic solvents is: cyclohexanone(C
Cl) > anisole(C ) > benzene (C
The effect of the organic solvents on the apparent rate constant
app) is shown in Table 3. The increased rate constant is attributed
to the increase in the dielectric constant of the organic solvent. As
the dielectric constant values of solvents increases, the activity of
the nucleophilic reagent and also the distance between the bro-
mide atom and the propyl group is increased. Hence the rate of
the reaction increases [67].
6
H
12
O
1
) > chlorobenzene(C
6
-
H
5
H
7 16
O
1
6
H
6
) > cyclohexene (C
6
H10).
(k
7.8. Effect of different catalysts
Comprehensive comparative kinetic studies for the propanation
of benzyl cyanide by n-bromopropane (alkylating agent) were car-
ried out using various onium salts viz., benzyltriethylammounium
chloride (BTEAC), benzyltriethylammounium bromide (BTEAB),
tetrabutylammounium bromide (TBAB), tetraethylammonium bro-
mide(TEAB) and tetraethylammonium chloride(TEAC).The reaction
was carried out under ultrasonic condition at standard reaction
conditions. The pseudo-first order rate constants were evaluated
for all the catalysts from the plot of the plot of –ln(1 ꢁ X) versus
time and are presented in Table 4 (entries 1–5). According to
Stark’s extraction mechanism, the order of the distribution of ha-
7.9. Effect of varying potassium hydroxide concentrations
In the PTC/OH catalyzed reaction, the reaction rate is known to
be greatly affected by the concentration of the alkaline compound.
The rate of monoalkylation of benzyl cyanide strongly depends on
the strength of the potassium hydroxide. Kinetic experiments were
carried out, employing 5-20 g under similar reaction conditions.
The kinetic profile of the reaction is obtained by plotting –ln(1 ꢁ X)
versus time. The rate constants tremendously increased with in-
crease in basicity of hydroxide ion i.e., the rate constants were
found to increase with an increase in potassium hydroxide concen-
tration (Table 5). This suggests that the hydroxide ions are less sol-
vated by water molecules and thereby the activity of the hydroxide
ꢁ
ꢁ
ꢁ
lide ions in the organic phase is I > Br > Cl . Conversely, in the
current study, the order of the reactivities in choosing the TEA cat-
ion group in this work is TEAC > TEAB. Thus, highier reaction rate is
obtained by choosing a small size of the anionic ion in the halide
groups of PTC’s. Hence, this phenomenon is more consistent with
the interfacial reaction mechanism rather than the extraction
Table 3
ꢁ
2
Influence of organic solvents on the rate of C-alkylation of benzyl cyanide under ultrasonic condition: 21.93 ꢀ 10 mol of benzyl cyanide, 10 g of KOH, 20 mL of H
2
O, 0.1 g of
ꢁ
3
internal standard (toluene), 20 mL of solvent, 21.96 ꢀ 10 mol of n-bromolpropane, 0.3 g of TBAB, 600 rpm, 50 °C; under ultrasound conditions (50 kHz, 300 W).
Solvents
Cyclohexane
Benzene
Anisole
Chlorobenzene
Cyclohexanone
a
e
2.02
2.2
2.28
2.9
4.3
5.7
5.6
7.0
8.2
9.8
k
app (ꢀ10ꢁ3, minꢁ1
)
a
Dielectric constant.

P.A. Vivekanand, M.-L. Wang / Ultrasonics Sonochemistry 18 (2011) 1241–1248
1247
PhCH-Q+
Q+Br-
(mono-product) from benzyl cyanide and n-bromopropane under
ultrasonic-PTC controlled condition. The apparent reaction rates
were observed to obey the pseudo-first order kinetics. Performing
the reaction in sonicatalysis condition resulted in shorter reaction
time, high yield, etc. The reaction mechanism and the apparent
rate constants were obtained from the experimental results. The
apparent rate constants are found to be directly dependent on each
kinetic variable viz., [catalyst], [KOH], ultrasonic frequency, stirring
speed and temperature. However it decreases with increase in vol-
ume of water and benzyl cyanide. Five different ammonium salts
were compared under ultrasonic conditions and TEAC was found
to be more efficient under given experimental conditions. Energy
of activation was calculated from the Arrhenius plot. Based on
the experimental evidence, an interfacial mechanism has been
proposed. Combination of ultrasound and PTC resulted in better
efficacy as compared to the individual operations.
PhCHR
CN
RBr +
+
Organic Phase
CN
PhCH-Q+
CN
-
PhCH K+
Q+Br-
KBr
+
+
CN
Interphase
Aqueous
-
PhCH K+
PhCH2
KOH
H O
2
+
+
CN
CN
KOH
H O
2
+
-
Where, RBr = C H Br ; Q Br = PTC
3
7
Acknowledgment
Scheme 2. Interfacial mechanism of monoalkylation of benzyl cyanide under PTC
condition.
The authors thank the National Science Council, Taiwan, for
financial support under Grant NSC-98-2221-E-241-013-MY3.
ion increases. Landini et al. [68] observed that, on increasing the
alkalinity concentration of, the quantity of hydroxide extracted de-
creases. The overall activity of the hydroxide actually increases due
to the dependence of hydroxide basicity on hydration. In the ki-
netic study [44] of C-alkylation of indene with 1,4-dibromobutane
under PTC condition, the observed rate constants tremendously in-
creased with increase in basicity of hydroxide ion. In the case of
phenoxide allylation [49], the extraction of phenol using is more
effective if the base concentration is higher.
References
[1] M.L. Wang, W.H. Chen, F.S. Wang, Kinetic study of synthesizing N-
butylphthalimide under solid-liquid phase-transfer catalysis conditions, J.
Mol. Catal. A: Chem. 236 (2005) 65–71.
[
[
[
[
[
2] Y. Sasson, R. Neumann, Handbook of Phase Transfer Catalysis, Blackie
Academic and Professional (Chapman & Hall), London, 1997.
3] E.V. Dehmlow, S.S. Dehmlow, Phase Transfer Catalysis, third ed., VCH, New
York, 1993.
4] T. Kano, T. Kumano, K. Maruoka, Rate enhancement of phase transfer catalyzed
conjugate additions by CsCl, Org. Lett. 11 (9) (2009) 2023–2025.
5] C.M. Starks, C.L. Liotta, M. Halpern, Phase Transfer Catalysis, Chapman & Hall
Publications, New York, 1994.
8
. Mechanism
6] P.A. Vivekanand, T. Balakrishnan, Kinetics of dichlorocyclopropanation of
vinylcyclohexane catalyzed by
Catalysis Commun. 10 (2009) 687–692.
a new multi-site phase transfer catalyst,
Generally, mechanism [3,5,44,43,69] for hydroxide ion initiated
PTC reactions are classified into two types viz, (i) Starks extraction
mechanism and (ii) Maksosza Interfacial mechanism. The extrac-
tion-like mechanism is more likely to be part of reactions when
they depend agitation speed only upto certain level (300 rpm)
and there after the rate will be constant factor. Also the energy
of activation calculated from the Arrhenius plot will be below
[7] M. Makosza, Phase-transfer catalysis. A general green methodology in organic
synthesis, Pure Appl. Chem. 72 (2000) 1399–1403.
[
8] G.D. Yadav, Insight into green phase transfer catalysis, Top. Catal. 29 (2004)
45–161.
1
[9] J.P. Rieu, A. Boucherle, H. Cousse, G. Mouzin, Methods for the synthesis of
antiinflammatory 2-aryl propionic acids, Tetrahedron 42 (1986) 4095–4131.
10] J.C.R. Jarrouse, The influence of quaternary chemicals on the reaction of labile
hydrogen compounds and chlorine-substituted derivatives, Hebd. Seances
Acad. Sci., Ser. C 232 (1951) 1424–1426.
11] M. Makozsa, A. Jonczyk, Phase transfer alkylation of nitriles: 2-
Phenylbutyronitrile, Org. Synth. 55 (1976) 91.
12] C.J. Li, Aqueous barbier-grignard type reaction: scope, mechanism and
synthetic applications, Tetrahedron 52 (1996) 5643–5668.
[
ꢁ1
1
0 kcal mol . On the other hand, if the reaction is interfacial dri-
[
[
[
ven reaction the rate of the reaction keep on increasing even after
ꢁ1
3
00 rpm and energy of activation will be above 10 kcal mol
.
The experimental results from the present kinetic studies indi-
cate the dependencies of the kinetic data on the entire stirring
speed, concentration of the catalyst, aqueous potassium hydroxide,
13] A. Loupy, A. Petit, J. Hamelin, F.T. Boullet, P. Jacquault, D. Mathe, New solvent-
free organic synthesis using focused microwaves, Synthesis (1998) 1213–
1234.
temperature and higher E
a
value are indicative of an interfacial
[14] S. Lemoine, C. Thomazeau, D. Joannard, S. Trombotto, G. Descotes, A. Bouchu, Y.
Queneau, Sucrose tricarboxylate by sonocatalysed TEMPO-mediated
oxidation, Carbohydr. Res. 326 (2000) 176–184.
15] F.A. Luzzio, W.J. Moore, Ultrasound in oxochromium(VI)-mediated
transformations. 2. Ultrasound-mediated preparation and applications of
chromyl chloride, J. Org. Chem. 58 (1993) 512–515.
16] J.L. Luche, A few questions on the sonochemistry of solutions, Ultrason.
Sonochem. 4 (1997) 211–215.
17] T.J. Mason, J.P. Lorimer, Sonochemistry, Theory, Applications and Uses of
Ultrasound in Chemistry, Ellis Horwood Ltd./JohnWiley and Son, 1988.
18] A. Tuulmets, Ultrasound and polar homogeneous reactions, Ultrason.
Sonochem. 4 (1997) 189–193.
19] B.A. Omera, D. Barrowb, T. Wirth, Effect of segmented fluid flow, sonication
and phase transfer catalysis on biphasic reactions in capillary microreactors,
Chem. Eng. J. 135S (2008) S280–S283.
20] W.T. Richards, A.L. Loomis, The chemical effects of high frequency sound
waves I. A preliminary survey, J. Am. Chem. Soc. 49 (1927) 3086–3100.
21] K.S. Suslick, D.J. Cassadonte, Heterogeneous sonocatalysis with nickel powder,
J. Am. Chem. Soc. 109 (1987) 3459–3461.
mechanism. Hence we propose interfacial mechanism for the cur-
rent study (Scheme 2). Initially, the hydroxide ion deprotonates the
[
+
ꢁ
organic substrate R–H at the interface, forming an ion pair [K R ].
This ion pair at the phase boundary cannot migrate into either
phase (aqueous or organic) because it is insoluble in both phases.
[
[
[
[
+
ꢁ
Upon addition of the catalyst, Q X , ion exchange takes place at
+
ꢁ
the interface and the newly formed ion pair Q R easily migrates
into the organic phase. This ion pair reacts with the alkylating
agent in the organic phase resulting in the formation of the
required mono-alkylated product (2-phenylvaleronitrile). The
function of onium salt in this reaction is to enhance the carbanion
formation at the interface and transfer it to organic phase.
[
[
9
. Conclusions
[22] F. Contamine, F. Faid, A.M. Wilhelm, J. Berlan, H. Delmas, Chemical reactions
under ultrasound: discrimination of chemical and physical effects, Chem Eng
Sci. 49 (1994) 5865–5873.
In the present study, the reaction was controlled to study the
[
23] T.J. Mason, Ultrasound in synthetic organic chemistry, Chem. Soc. Rev. 26
(1997) 443–451.
kinetic aspects of the formation of the 2-phenylvaleronitrile

1
248
P.A. Vivekanand, M.-L. Wang / Ultrasonics Sonochemistry 18 (2011) 1241–1248
[
[
24] J.T. Li, G.F. Chen, W.Z. Xu, T.S. Li, The Michael reaction catalyzed by KF/basic
alumina under ultrasound irradiation, Ultrason. Sonochem. 10 (2003) 115–118.
25] F. Alonso, I.P. Beletskaya, M. Yus, Non-conventional methodologies for
transition-metal catalysed carbon-carbon coupling: a critical overview. Part
[46] M.L. Wang, V. Rajendran, Ethoxylation of p-chloronitrobenzene using phase-
transfer catalysts by ultrasound irradiation -A kinetic study, Ultrason.
Sonochem. 14 (2007) 368–374.
[47] T. Balakrishnan, J.P. Jeyachandran, New multi-site phase transfer catalysts for
the addition of dichlorocarbene to styrene, J. Chem. Soc., Perkin Trans. 2 (1995)
2081–2085.
1
: The Heck reaction, Tetrahedron 61 (2005) 11771–11835.
[
26] G. Cravotto, G. Palmisano, S. Tollari, G.M. Nano, A. Penoni, The Suzuki
homocoupling reaction under high-intensity ultrasound, Ultrason.
Sonochem. 12 (2005) 91–94.
[48] H.S. Wu, J.J. Lai, Phenoxide Allylation in a Phase-Transfer Catalytic Extraction
System, Ind. Eng. Chem. Res. 34 (1995) 1536–1538.
[
[
27] V. Polackova, M. Hutka, S. Toma, Ultrasound effect on Suzuki reactions. 1.
Synthesis of unsymmetrical biaryls, Ultrason. Sonochem. 12 (2005) 99–102.
28] R. Cella, H.A. Stefani, Ultrasound-assisted synthesis of Z and E stilbenes by
Suzuki cross-coupling reactions of organotellurides with potassium
organotrifluoroborate salts, Tetrahedron 62 (2006) 5656–5662.
29] C. Stavarache, A.M. Pocsan, M. Vinatoru, T.J. Mason, A comparison between the
sonochemical and thermal reaction of 5H, 5Cl-Dibenz[a,d]cycloheptatriene
with nitrobenzene, Ultrason. Sonochem. 10 (2003) 49–53.
[49] M. Tomoi, W.T. Ford, Mechanisms of Polymer-Supported Catalysis. 2. Reaction
of Benzyl Bromide with Aqueous Sodium Cyanide Catalyzed by Polystyrene-
Bound Onium Ions, J. Am. Chem. Soc. 103 (1981) 3828–3832.
[50] F. Helfferich, Ion Exchange, McGraw Hill, New York, 1962.
[51] M. Halpern, Y. Sasson, M. Rabinovitz, Hydroxide-ion initiated reactions under
phase-transfer catalysis conditions. 6. Dehydrobromination of (2-
bromoethyl)benzene via slow hydroxide-ion extraction, J. Org. Chem. 49
(1984) 2011–2012.
[52] V. Rajendran, M.L. Wang, Dichlorocarbene addition to allyl phenyl ether under
phasetransfer catalysis conditions – A kinetic study, J. Mol. Catal. A: Chem. 288
(2008) 23–27.
[53] E. Chiellini, R. Solaro, S.D. Antone, Heterogeneous ethylation of
phenylacetonitrile, J. Org. Chem. 45 (1980) 4179–4183.
[54] Y. Sasson, N. Bilman, Mechanism of solid/liquid phase transfer catalysis in the
presence of potassium carbonate: Alkylation of 2-pyrrolidinone, J. Chem. Soc.,
Perkin Trans. 2 (1989) 2029–2033.
[55] P.A. Vivekanand, T. Balakrishnan, Superior catalytic efficiency of a new multi-
site phase transfer catalyst in the C-alkylation of dimedone – A kinetic study,
Catal. Commun. 10 (2009) 1371–1375.
[
[
[
[
[
30] K. Bougrin, M. Lamiri, M. Soufiaoui, Synthèse ‘‘one pot’’ dé derivés
Isoxazoliniques par Activation Sonochimique, Tetrahedron Lett. 39 (1998)
4
455–4458.
31] M. Atobe, Y. Kado, R. Asami, T. Fuchigami, T. Nonaka, Ultrasonic effects on
electroorganic processes. Part 25. Stereoselectivity control in cathodic
debromination of stilbenedibromides, Ultrason. Sonochem. 12 (2005) 1–5.
32] P.W. Cains, P.D. Martin, C.J. Price, The use of ultrasound in industrial chemical
synthesis and crystallization. 1. Applications to synthetic chemistry, Org. Proc.
Res. Dev. 2 (1998) 34–48.
33] M.N. Masuno, D.M. Young, A.C. Hoepker, C.K. Skepper, T.F. Molinski, Addition
of Cl
2
C: to (–)–O–menthyl acrylate under sonicationꢁphase-transfer catalysis.
Efficient synthesis of (+)- and (ꢁ)-(2-chlorocyclopropyl)methanol, J. Org.
[56] P.A. Vivekanand, T. Balakrishnan, Catalytic potential of a new polymer-
Chem. 70 (2005) 4162–4165.
anchored multisite phase tansfer catalyst in the dichlorocarbene addition to
indene, Cat. Lett. 13 (2009) 587–596.
[57] M.L. Wang, Z.F. Lee, Reaction of 4,4-bis(chloromethyl)-1,10-biphenyl and
phenol in two-phase medium via phase-transfer catalysis, J. Mol. Catal. A:
Chem. 264 (2006) 119–127.
[
[
[
[
[
34] M.L. Wang, V. Rajendran, A kinetic study of thioether synthesis under influence
of ultrasound assisted phase-transfer catalysis conditions, J. Mol. Catal. A:
Chem. 244 (2006) 237–243.
35] M.L. Wang, V. Rajendran, Ultrasound assisted phase-transfer catalytic
epoxidation of 1,7-octadiene
2007) 46–54.
–
A
kinetic study, Ultrason. Sonochem 14
[58] B.S. Bhatkhande, M.V. Adhikari, S.D. Samant, Sonochemical chloro-oxidation of
(
phenols using HCl–H
[59] M.A. Margulis, Sonochemistry as
2
O
2
, Ultrason. Sonochem. 9 (2002) 31–35.
new promising area of high energy
36] K. Saïd, Y. Moussaoui, M. Kammoun, R.B. Salem, Ultrasonic activation of Heck
type reactions in the presence of Aliquat-336, Ultrason. Sonochem. 18 (2011)
a
chemistry, High Energ. Chem. 38 (2004) 135–142.
[60] T.J. Mason, J.P. Lorimer, Applied Sonochemistry: The Uses of Power Ultrasound
in Chemistry and Processing, Wiley-VCH, 2002.
[61] G.V. Ambulgekar, B.M. Bhanage, S.D. Samant, Low temperature recyclable
catalyst for Heck reactions using ultrasound, Tetrahedron Lett. 46 (2005)
2483–2485.
2
3–27.
37] H.M. Yang, G.Y. Peng, Ultrasound-assisted third-liquid phase-transfer
catalyzed esterification of sodium salicylate in a continuous two-phase-flow
reactor, Ultrason. Sonochem. 17 (2010) 239–245.
38] M.L.
Wang,
C.J.
Chen,
Kinetic
Study
of
Synthesizing
1-(3-
Phenylpropyl)pyrrolidine-2,5-dione under Solid-Liquid Phase-Transfer
Catalytic Conditions Assisted by Ultrasonic Irradiation, Org. Process Res. Dev.
[62] R.S. Davidson, A. Safdar, J.D. Spencer, B. Robinson, Applications of ultrasound
to organic chemistry, Ultrasonics 25 (1987) 35–39.
1
4 (2010) 737–745.
[63] T. Lepoint, F. Mullie, What exactly is cavitation chemistry?, Ultrason
Sonochem. 1 (1994) S13–S22.
[64] T.J. Mason, Industrial sonochemistry: Potential and practicality, Ultrasonics 30
(1992) 192–196.
[65] P. Kruus, R.C. Burk, M.H. Entezari, R. Otson, Sonication of aqueous solutions of
chlorobenzene, Ultrason. Sonochem. 4 (1997) 229–233.
[
[
39] W.P. Reeves, R.G. Hilbrich, Phase transfer catalysis: Amine catalyzed
alkylation, Tetrahedron 32 (1976) 2235–2237.
40] T. Balakrishnan, W.T. Ford, The effect of polymer swelling on alkylation of
phenylacetonitrile by polymer-supported phase transfer catalysis,
Tetrahedron Lett. (1981) 4377–4380.
[
41] M. Rabonivitz, Y. Sasson, M. Halpern, Hydroxide ion initiated reactions under
phase-transfer-catalysis conditions. 5. Isomerization of allylbenzene via
hydroxide ion extraction, J. Org. Chem. 48 (1983) 1022–1025.
[66] M.H. Entezari, A. Heshmati, A.S. Yazdi, A combination of ultrasound and
inorganic catalyst: removal of 2-chlorophenol from aqueous solution,
Ultrason. Sonochem. 12 (2005) 137–141.
[
[
42] M.L. Wang, Z.F. Lee, Kinetic study of synthesizing bisphenol a dially ether in a
phase transfer catalytic reaction, Bull. Chem. Soc. Jpn. 79 (2006) 80–87.
43] M.L. Wang, Y.M. Hsieh, R.Y. Chang, Kinetic study of dichlorocyclopropanation
of 1,7-octadiene under phase-transfer catalysis conditions at high alkaline
concentration, Ind. Eng. Chem. Res. 42 (2003) 4702–4707.
44] P.A. Vivekanand, T. Balakrishnan, Synthesis and characterization of a novel
multi-site phase transfer catalyst and a kinetic study of the intramolecular
cyclopentanation of indene, Appl.Catal.A: Gen 364 (2009) 27–34.
[67] M.L.
Wang,
W.H.
Chen,
Kinetic
study
of
synthesizing
dimethoxydiphenylmethane under phase-transfer catalysis and ultrasonic
irradiation, Ind. Eng. Chem. Res. 48 (2009) 1376–1383.
[68] D. Landini, A. Maia, A. Rampoldi, Extractability and reactivity of hydroxide
ion in low-polarity media under phase-transfer catalysis conditions:
dramatic effect of the aqueous base concentration, J. Org. Chem. 51
(1986) 5475–5476.
[69] M. Makosza, E. Bialecka, Reactions of organic anionx. LXXIII. Alkylation of
phenylacetonitrile at the interface with aqueous sodium hydroxide,
Tetrahedron Lett. 18 (1977) 183–186.
[
[
45] C.M. Starks, R.M. Owens, Phase-transfer catalysis. II. Kinetic details of cyanide
displacement on 1-halooctanes, J. Am. Chem. Soc. 95 (1973) 3613–3617.