Insight into solid-liquid phase transfer catalyzed synthesis of Mecoprop ester using K 2CO 3 as base and development of new kinetic model involving liquid product and two solid co-products

Article abstract of DOI:10.1007/s12039-017-1368-1

Abstract: 2-Methyl-4-chlorophenoxy propionic acid (Mecoprop) is a widely used household herbicide. In the current work, a simple synthetic method is developed for Mecoprop methyl ester using solid-liquid phase transfer catalysis (S-L PTC) with K ₂CO ₃ as mild base and toluene as solvent. Conversion of 95% was achieved with 100% selectivity for Mecoprop ester at 100°C. Simple isolation process was employed to recover the product from the reaction mixture. A reaction mechanism was proposed and new kinetic model developed involving one liquid and two solid co-products. The activation energy for the reaction was calculated. This is the first example of its kind being reported vis-à-vis kinetics and mechanism. Graphical Abstract: Solid-liquid phase transfer catalyzed (S-L PTC) O-alkylation of 4-chloro-2-methyl phenol is done at relatively mild conditions to form methyl 2-(4-chloro-2-methylphenoxy) propionate (Mecoprop methyl ester). New insight on reaction mechanism and kinetics is presented.

Full text of DOI:10.1007/s12039-017-1368-1

J. Chem. Sci.
© Indian Academy of Sciences
DOI 10.1007/s12039-017-1368-1
REGULAR ARTICLE
Special Issue on Recent Trends in the Design and Development of Catalysts and their Applications
Insight into solid-liquid phase transfer catalyzed synthesis of
Mecoprop ester using K2CO3 as base and development of new
kinetic model involving liquid product and two solid co-products
GANAPATI D YADAV∗ and GUNJAN P DESHMUKH
Department of Chemical Engineering, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga,
Mumbai, Maharashtra 400 019, India
E-mail: gdyadav@yahoo.com; gd.yadav@ictmumbai.edu.in
MS received 15 April 2017; revised 2 August 2017; accepted 5 August 2017
Abstract. 2-Methyl-4-chlorophenoxy propionic acid (Mecoprop) is a widely used household herbicide. In the
current work, a simple synthetic method is developed for Mecoprop methyl ester using solid-liquid phase transfer
catalysis (S-L PTC) with K2CO3 as mild base and toluene as solvent. Conversion of 95% was achieved with
100% selectivity for Mecoprop ester at 100 ◦C. Simple isolation process was employed to recover the product
from the reaction mixture. A reaction mechanism was proposed and new kinetic model developed involving one
liquid and two solid co-products. The activation energy for the reaction was calculated. This is the first example
of its kind being reported vis-à-vis kinetics and mechanism.
Keywords. Phase transfer catalysis; O-alkylation; mecoprop ester; kinetic modelling; solid-liquid reaction.
1. Introduction
is a well-known technique for different reactions. Alka-
lis such as NaOH and KOH are widely used as bases in
phase transfer catalyzed reactions. These strong bases
sometimes portray several disadvantages. The reactions
with alkali as base involve multi-step synthesis and iso-
lation of product, which is a tedious process reported
in a couple of patents.11,12 In the case of water sen-
sitive reactants, carbonates can be used as bases to
avoid side reactions and hydrolysis of reactants. Thus,
carbonates can be a good option to explore them as
non-nucleophilic bases. Non-nucleophilic alkali car-
bonates such as K2CO3 and Na2CO3 can provide an
efficient substitution for these alkali bases.13 Carbon-
ates provide mild conditions for reaction, can suppress
the side reactions and provide minimum corrosion of
reactor and auxiliary equipment. A variety of PTC reac-
tions are reported, wherein carbonates are employed
as bases such as reactions of phosphorous and sul-
phur based compounds,14 oxidation,15 N-alkylation,13
O-alkylation16 and synthesis of amino acids,17 etc. A
variety of multiphasic reactions involving PTC have
been modeled by us.18,19
2-Methyl-4-chloro phenoxy propionic acid (Mecoprop)
is one of the widely used herbicides of the phenoxy
acid family.1 Several salts and esters of Mecoprop are
used as active agents in herbicidal formulations. It is
also utilized as an intermediate in the synthesis of
natural products and pesticides. Methyl-2-(4-chloro-2-
methylphenoxy) propionate (Mecoprop ester) is one of
the esters, employed as an intermediate in the synthesis
of Mecoprop. Several methods are reported for synthe-
sis of chloro phenoxy acid derivatives using alkali as
base.2–6 In almost all processes, strong aqueous bases
are used which are neutralized using mineral acids gen-
erating waste and are difficult to handle.
Phase transfer catalysis (PTC) is a widespread tech-
nique with continuous developments and new appli-
cations in the current age of synthetic chemistry. Dif-
ferent types of phase transfer catalytic techniques are
known with several applications. During last few years,
our laboratory has developed different concepts and
applications of PTC such as process intensification in
liquid-liquid-liquid (L-L-L) PTC,7 microwave irradi-
ated L-L-L PTC (MILL-PTC)8,9 ionic liquid as PTC and
pseudo-PFC.10 Among these studies, solid-liquid PTC
In the present work, a novel route for the synthe-
sis of Mecoprop ester was established. Several phase
transfer catalysts such as tetrabutylammonium bro-
mide (TBAB), ethyltriphenyl phosphonium bromide
(ETPPB), tetrabutylphosphonium bromide (TBPB),
*
For correspondence

Ganapati D Yadav and Gunjan P Deshmukh
Scheme 1. Synthesis of Mecoprop ester from 4-chloro-2-methyl phenol under S-L PTC.
tetrabutyl ammonium hydrogen sulfate (TBAHS) and The products were confirmed by GCMS (Perkin Elmer, Clar-
ius Model 500 on Elite 1 capillary column of length 30m and
inner diameter 0.25mm).
triethylammonium bromide (TEAB) were screened for
the reaction. Among these K2CO3–TBAB: base-catalyst
pair in solid-liquid PTC was found the best. In rela-
tively milder conditions, >95% conversion and 100%
selectivity for the product was achieved. Kinetics for
the reaction was established and the activation energy
was also calculated. The product was recovered by sim-
ple isolation process.
2.4 Reaction scheme
2.4a Overall reaction: See Scheme 1.
2.4b Reaction mechanism: See Scheme 2.
2.5 Isolation of the product
2. Experimental
At the end of the experiment, the reaction mass was filtered
to remove solid KHCO3, unreacted K2CO3 and KBr. The
solid was washed with 5mL toluene to collect the adsorbed
product on the surface of solid particles. The collected filtrate
was washed with 2% NaOH. Further, toluene was distilled
out to obtain the pure product.
2.1 Chemicals and catalysts
4-Chloro-2-methyl phenol (CMP) and ethyl-2-chloro propi-
onate (ECP) were obtained from Sigma Aldrich. All PTC
reagents were obtained from Dishman Pharmaceuticals and
ChemicalsLtd., Ahmedabad, Indiaasgiftsamples. NaOHand
toluene were obtained from M/s S.D. Fine Chemicals, Mum-
bai, India. All the chemicals were used as received without
purification.
3. Results and Discussion
3.1 Mechanism and kinetic model
2.2 Experimental procedure
In the usual mechanism of S-L PTC, an ion-pair is
formed between the quaternary phase transfer cation
and the reactive anion (ion-exchange reaction) as dis-
cussed in our previous work.18,19 However, in this case,
a different model is developed due to the specific nature
of reaction forming two solid products. The complete
reaction sequence can be illustrated as given below.
In this overall reaction, the first reaction step is an
abstraction of a proton from the phenolic compound
(R1 PhO− H+) by K2CO3 in organic phase. All inor-
ganic salts are sparingly soluble in organic medium and
thusthereisasaturationsolubilitydenotedbyanasterisk
withanequilibrium. Thevariousequilibriaandreactions
are also depicted as given below:
All the reactions were studied in a glass reactor. The details of
the reactor are mentioned in previous work done in our lab.18
The impeller of the reactor was kept 2cm above the bottom to
ensure complete mixing of solid–liquid suspension to achieve
maximum mass transfer rates. The reactor was placed in an
isothermal oil bath at the temperature required to perform
the reaction. The quantities of chemicals and reagents were
weighed, added to the reactor and then the temperature raised.
The catalyst quantity was added in reactor once it reached
the desired temperature. Typical experimental runs were con-
ducted by preparing reaction mixture of CMP (0.0028mol),
ECP (0.003mol), K2CO3 (0.0032mol), toluene (20 cm3) and
TBAB (3 × 10−4 mol) at 100 ◦C.
2.3 Analysis
K
1
K2CO3(s)←→ K2CO3∗(org)
(1)
(2)
Samples were withdrawn periodically. Agitation was stopped
and the solid suspension allowed to settle. The sample was
centrifuged after withdrawal and further analyzed by GC
(Chemito model 1000) using capillary column (BPX- 50).
K
2
R1 PhO− H(+org) + K2CO3∗(org)←→ R1 PhO− K(+org)
+K HCO3∗(org)

Insight into solid-liquid phase transfer catalyzed synthesis of Mecoprop ester
Scheme 2. The reaction mechanism for the synthesis of Mecoprop ester under S-L PTC.
[R1 PhO− K+](org)[K HCO3∗](org)
[R1 PhO− H+](org)[K2CO3∗](org)
[R1 PhO− Q+](org)[K X∗](org)
[R1 PhO− K+](org)[Q+ X−](org)
[K HCO3](s)
K
3
R1 PhO− K(+org) + [Q+ X−](org)←→ [ R1 PhO− Q+](org)
K2 =
K3 =
K4 =
K5 =
(9)
(10)
(11)
(12)
+K X(∗org)
(3)
(4)
(5)
K
4
K HCO3∗(org)←→ K HCO3(s)
K
5
K X(∗org)←→ K X(s)
[K HCO3∗](org)
The actual reaction is given by the following:
[K X](s)
k
2
RX(org) + [R1 PhO− Q+](org)−→ RR1PhO(org)
[K X∗](org)
+ -
+ [Q X ](org)
(6)
By using the above equilibria, the following is derived:
K1 K2 K3 K4 K5[R1 PhO− H+] [K2CO3](s)[Q+ X−](org)
[K HCO3]((so)r[gK) X](s)
[R1 PhO− Q+](org)
=
(13)
The rate of reaction of RX is given by:
d[RX](org)
= k2[RX](org)[R1 PhO− Q+](org)
(7)
K1 K2 K3 K4 K5 = Ke
(14)
−
dt
In Equation (7), it is necessary to substitute for [R1
PhO− Q+](org) in terms of known variables.
The following equilibria hold:
The phenolic R1PhOH is taken in stoichiometric
excess over the substrate RX and also the conversion of
R1PhOH is complete in the R1PhOK form since K2CO3
is taken in excess over R1PhOH. Thus, the following
could be written:
[K2CO3∗](org)
K1 =
(8)
[K2CO3](s)

Ganapati D Yadav and Gunjan P Deshmukh
K1 K2 K3 K4 K5[R1 PhO− H+] [K2CO3](s)[Q+ X−](org)
[K HCO3]((so)r[gK) X](s)
[R1 PhO− Q+](org)
=
(15)
(16)
= Ke[Q+ X−](org)
Now, in the organic phase the total catalyst Q0 exists
in the form of two ion-pairs in S-L PTC, unlike the L-L
PTC where it is in four different ion-pairs. The material
balance on total catalyst added to the system gives the
following:
it remains distributed across the aqueous and organic
phases in four ion-pairs. The ion exchange reaction
for TBAB is very fast with K2CO3 as compared with
other catalysts such as CTAB, TEAB and ETPPB.20
Tetrabutyl cation is more reactive as compared with
tetraethyl cations, when exchanged with large anions
of [R1 PhO− Q+](org). Further, in the case of ethyltriph-
enyl cation, it shows less activity due to the formation
of strong ion pairs with bromides.21 The order of the
catalyst for the conversion of phenol can be given in the
following sequence:
Q0 = total concentration of catalyst in organic phase,
mol/cm3
= [R1 PhO− Q+](org) + [Q+X−](org)
ꢀ
ꢁ
1
= [R1 PhO− Q+](org) 1 +
Ke
ꢀ
ꢁ
Ke + 1
=
[R1 PhO− Q+](org)
(17)
(18)
(19)
TBAB(max) > TBPB > TBAHS > CTAB
> TEAB > ETPPB.
Ke
Ke Q0
[R1 PhO− Q+](org)
=
(Ke + 1)
From the reactivity trend obtained, it is concluded that
TBAB gives the perfect balance between its lipophilic-
ity and structure size. A catalyst such as TEAB lacks
the lipophilic character to allow the ion pair to dissolve
in toluene and further react with the substrate. On the
contrary catalysts with bulkier alkyl group show steric
hindrance to form ion pair with the phenol. The reac-
tion was also studied without catalyst which showed
marginal conversion.
d[RX](org)
k2 Ke Q0
−
=
[RX](org)
dt
(Ke + 1)
The above equation is a typical pseudo-first order rate
equation.
Let XA = [RX] −[RX] , the fractional conversion of RX
0
[RX]
0
Then on integration, it leads to:
k2 Ke Q0
− ln(1 − XA) =
t = kQ0t = k1t
(20)
(Ke + 1)
Where
k1 = kQ0
and
94
90
(21)
(22)
81
k2 Ke
= k
66
(Ke + 1)
Thus, a plot of − ln(1 − XA) against t will give a slope
equal to k1. From the knowledge of the initial quantity of
catalyst, the rate constant k can be calculated. Order of
magnitude analysis suggests that the catalyst is mostly in
the [R1 PhO− Q+](org) form and thus Ke >> 1 leading
to [R1 PhO− Q+](org) ꢀ Qo. It was thus planned to test
the above model.
45
40
10
TPBP
TEAB
TBAB
ETPPB
CTAB
TBASH
NO
CATALYST
3.2 Effect of different phase transfer catalysts
Different PTC
Various nitrogen, phosphorous and sulphur based PTC
were screened for O-alkylation of CMP. Catalysts such
asTBAB, ETPPB, TBPB, TBAHSandTEABwereused
(Figure 1). In S-L PTC the entire quantity of the cata-
lyst is present in bulk organic phase (toluene) to form
active [R1 PhO− Q+](org) unlike the L-L PTC wherein
Figure 1. Effect of different PTC used for reaction of
4-chloro-2-methyl phenol (CMP). 4-Chloro-2-methyl phenol
– 0.0028mol; Ethyl-2-chloropropionate – 0.003mol; K2CO3
– 0.0032mol; catalyst – 0.000014 mol/cm3; agitation speed
– 1200rpm; solvent (toluene) – 20ml; temperature −100 ◦C.

Insight into solid-liquid phase transfer catalyzed synthesis of Mecoprop ester
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
0
100
200
300
400
0
100
200
300
400
Time (min)
Time (min)
Figure 2. Effect of the speed of agitation on conver- Figure 3. Effect of quantity of K2CO3 on conver-
sion of CMP. 4-Chloro-2-methyl phenol – 0.0028mol; sion of CMP. 4-Chloro-2-methyl phenol – 0.0028mol;
Ethyl-2-chloropropionate – 0.003mol; K2CO3 – 0.0032mol; Ethyl-2-chloropropionate – 0.003mol; K2CO3 – 0.0032mol;
catalyst –0.000014 mol/cm3;solvent(Toluene)–20mL; tem- catalyst–0.000014 mol/cm3;solvent (Toluene)–20mL;tem-
perature −100 ◦C. ( ) 800, ( ) 1000, ( ) 1200, ( ) 1400.
perature −100 ◦C ( ) 1:0.9, ( ) 1: 1, ( ) 1: 1, ( ) 1: 2.
Thus, all further reactions were studied using TBAB
as a catalyst as it showed enhanced activity, is inexpen-
sive and commercially available with high purity.
goes on increasing with increase in the quantity of base.
At lower mole ratio less conversion was observed and
this might be due to the insufficient quantity of K2CO3
which is available for reaction. From Figure 3, one can
note that a little more quantity of K2CO3 than stoichiom-
etry is enough to achieve the best conversion. Further,
the reaction was studied with fine powder and gran-
ular K2CO3. The fine powder gave a good rate and
conversion for the reaction which is explained later
(Figure 4).
The rate of solid-liquid mass transfer is dependent
upon the surface area provided by the number of par-
ticles and will be maximum if fine particles instead of
granular ones are used. In the current case the surface
area per unit volume of the particle is:
3.3 Effect of speed of agitation
Influence of mass transfer was determined by varying
the stirring speed from 800 to 1400rpm. The rate of the
reaction dramatically increases when stirring speed is
increased from 800 to 1200rpm (Figure 2). This might
be due to increase in interfacial area per unit volume
of dispersion which increases linearly with increase in
speed of agitation. However, there is a marginal dif-
ference in conversion between 1200 and 1400. Thus,
S-L mass transfer resistance at and above 1200rpm
is overcome and further experiments were studied at
1200rpm.
ꢀ
ꢁ
6
np
dp
3.4 Effect of K2CO3 quantity and particle size
where np and dp are a number of particles and parti-
cle diameter, respectively. Thus, with finer the particles
more surface area is provided. Thus, the solid-liquid
mass transfer coefficient can be given by the limiting
The effect of quantity of K2CO3 was studied for the con-
version of CMP to form the product. As the solid base
was added to the reaction, its concentration in organic
phase could not be varied. The quantity of K2CO3 to
CMP was varied in the ratio of 0.9 to 1.2. As stated
earlier, more quantity of K2CO3 helps in saturation of
organic phase as given by equations 1 and 3, and then
k
d
A
p
SL
D
Sherwood number, Sh =
= 2, which is far greater
than 2 in agitated vessels. DA is the diffusivity of dis-
solved K2CO3 in the liquid phase. The value of particle
6W
surface area per unit liquid volume is ap =
where
d
p
ρ
p
exchange with the quaternary cation leading to maxi- W, ρp and dp are solid loading (g/cm3), particle den-
mum of [R1 PhO− Q+](org) occurs. Conversion of CMP sity (g/cm3) and particle diameter respectively. Thus,

Ganapati D Yadav and Gunjan P Deshmukh
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
0
100
200
300
400
Time (Min)
Figure 5. Effect of catalyst loading on conversion of CMP.
4-Chloro-2-methyl phenol – 0.0028mol; Ethyl chloro propi-
onate – 0.0032mol; K2CO3 – 0.0032mol; agitation speed
0
100
200
300
400
Time (min)
Figure 4. Effect of size of K2CO3 on conversion of CMP. – 1200rpm; solvent (Toluene) – 20 mL; temperature
−100 C. ( ) 6.2 × 10−6 mol/cm3; ( ) 7.8 × 10−6 mol/cm3;
◦
4-Chloro-2-methyl phenol – 0.0028mol; Ethyl-2-chloro-
propionate – 0.003mol; K2CO3 – 0.0032mol; catalyst
– 0.000014 mol/cm3; solvent (Toluene) – 20mL; temperature
−100 ◦C. ( ) Granular K2CO3 ( ) Fine powder of K2CO3.
+
3
−5
3
( ) 9.31 × 10−6 mol/cm ; ( ) 1.1 × 10 mol/cm ; ( )
×
○
3
−5
3
1.24 × 10−5 mol/cm ; ( ) 1.39 × 10 mol/cm ; (
)
■
▲
1.55 × 10−5 mol/cm3.
3.5
the solid-liquid mass transfer rate is given by kSLap[BS]
where [BS] is the solid saturation concentration wherein
B forms an ion-pair with phenoxide species leading to
the formation of potassium salt with K and KHCO3. The
K+ is then exchanged with Q+X− (org) species to form
quaternary ion-pair and K+X− (solid). The concentra-
tion of the phenoxide ion will always be at its saturation
value for fine particles and the rate of solid-liquid mass
transfer will be far greater than reaction rate in the liq-
uid phase. Thus, after certain particle size, the rate of
reaction or conversion will be independent of particle
size as given in Figure 4.
y = 0.0054x
R² = 0.9969
3
2.5
2
y = 0.0049x
R² = 0.9984
y = 0.004x
R² = 0.9965
1.5
1
y = 0.0036x
R² = 0.9848
y = 0.0029x
R² = 0.9977
y = 0.0022x
R² = 0.9971
0.5
0
y = 0.0015x
R² = 0.9969
0
100
200
300
Time (min)
400
500
3.5 Effect of catalyst loading
Figure 6. Validation of model at different catalyst loadings.
4-Chloro-2-methyl phenol – 0.0028mol; Ethyl-2-chloro-
propionate – 0.0032mol; K2CO3 – 0.0032mol; catalyst
– 0.000014 mol/cm3; agitation speed – 1200rpm; solvent
Catalyst concentration plays an important role in S-L
PTC because the catalyst is a medium between reaction
between solid and organic phase. Increase in catalyst
concentration increases the rate of reaction. The cat-
◦
−6
+
(Toluene) – 20mL; temperature −100 C. ( ) 6.2 × 10
alyst concentration was varied from 6.2 × 10−6 to
mol/cm3; ( ) ×10−6 g/cm3; ( ) 9.31 × 10−6 g/cm3; (−5)
3
1.5×10−5 mol/cm (Figure 5). Even though the concen- 1.1 × 10−5 g/cm3; ( ) 1.24 × 10−5 g/cm ( ) 1.39 × 10
3
×
g/cm3; ( ) 1.55 × 10−5 g/cm3.
tration of the catalyst is increased the concentration of
Q+PhO− is the saturation value and therefore, the rate of
conversion remains the same. Thus, 1.4×10−5 mol/cm3
Figure 7 demonstrates the effect of catalyst concen-
was considered as optimum catalyst concentration. tration of the pseudo-rate constant k1. It gives a very
The experimental data were validated with the model good fit suggesting that as stated earlier Ke >> 1 and
(Figure 6).
hence [R1 PhO− Q+](org) ꢀ Qo.

Insight into solid-liquid phase transfer catalyzed synthesis of Mecoprop ester
0.006
0.005
0.004
0.003
0.002
0.001
0
100
90
80
70
60
y = 16.478x
R² = 0.972
50
40
30
20
0
0.00005 0.0001 0.00015 0.0002 0.00025 0.0003 0.00035
10
Catalyst loading (mol/cm3)
0
Figure 7. Effect catalyst concentration in organic phase on
pseudo-rate constant k1 (see Eq. 21).
0
100
200
Time (min)
300
400
Figure 9. Effect of temperature on conversion of CMP.
4-Chloro-2-methyl phenol – 0.0028mol; Ethyl-2-chloropro-
pionate – 0.0032mol; K2CO3 – 0.0032mol; catalyst
– 0.000014 mol/cm3; agitation speed – 1200rpm; solvent
(Toluene) – 20mL. ( ) 70 ◦C, ( ) 80 ◦ C, ( ) 90 ◦C ( )
100 ◦C.
100
90
80
70
60
50
40
30
20
10
0
3
y = 0.0085x
R² = 0.9915
2.5
y = 0.0078x
R² = 0.9985
2
1.5
1
y = 0.0035x
R² = 0.9997
0
100
200
300
400
y = 0.0016x
R² = 0.9958
Time (Min)
0.5
0
Figure 8. Effect of mole ratio on conversion of CMP.
4-Chloro-2-methyl phenol – 0.0028mol; Ethyl-2-chloropro-
pionate – 0.0032mol; K2CO3 – 0.0032mol; catalyst
– 0.000014 mol/cm3; agitation speed – 1200rpm; solvent
(Toluene) – 20mL; temperature −100 ◦C; ( ) 1: 0.9 ( ) 1:1,
( ) 1:1.1, ( ) 1:1.2.
0
50
100
150
200
250
300
350
Time (t)
Figure 10. Validation of model at different temperatures.
4-Chloro-2-methyl phenol – 0.0028mol; Ethyl-2-chloropro-
pionate – 0.0032mol; K2CO3 – 0.0032mol; catalyst
– 0.000014 mol/cm3; agitation speed – 1200rpm; solvent
(Toluene) – 20mL. ( ) 70 ◦C, ( ) 80 ◦ C, ( ) 90 ◦C ( )
100 ◦C.
3.6 Effect of mole ratio
The effect of variation in mole ratio was studied to
find out optimum concentration to achieve maximum
conversion and selectivity towards the product. Mole
3.7 Effect of temperature
ratio was studied from 1: 0.9 to 1.2 with reference to The effect of temperature on conversion of CMP was
CMP (Figure 8). The catalyst loading was kept 1.4 × studied at different temperatures from 80 to 110 ◦C
10−5 mol/cm3. It is concluded that the conversion goes under otherwise similar experimental conditions (Fig-
on increasing with increase in the concentration of CMP. ure 9). Increase in temperature results in an increase in

Ganapati D Yadav and Gunjan P Deshmukh
0
-1
-2
-3
-4
-5
-6
-7
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2-yl)acrylonitriles and a study of their antimicrobial
activities Synth. Commun. 43 2967
7. Yadav G D and Sowbna P R 2012 Process intensification
and waste minimization in liquid–liquid–liquid phase
transfer catalyzed selective synthesis of mandelic acid
Chem. Eng. Res. Des. 90 1281
the initial rate of reaction. The conversion also increased
subsequently.
However, onlymarginaldifferencewasobserved. The
model for each temperature was also tested to get good
statistical fit (Figure 10). Thus, the Arrhenius plot was
made and activation energy for the reaction was found
as 15.4 kcal/mol (Figure 11).
8. Yadav G D and Sowbna P R 2012 Modeling of
microwave irradiated liquid–liquid–liquid (MILLL)
phase transfer catalyzed green synthesis of benzyl thio-
cyanate Chem. Eng. J. 179 221
4. Conclusion
9. Yadav G D and Jain S S 2012 Novelties of low energy
microwave-irradiated tri-liquid phase transfer cataly-
sis (MILLL-PTC): halo-exchange of benzyl chloride
with sodium bromide Clean Technol. Environ. Policy 14
709
10. (a) Yadav G D and Tekale S P Selective 2010 O -
Alkylation of 2-Naphthol using Phosphonium-Based
Ionic Liquid as the Phase Transfer Catalyst Org. Pro-
cess Res. Dev. 14 722; (b) Yadav G D and Kadam A A
Atom-Efficient Benzoin Condensation in Liquid–Liquid
System Using Quaternary Ammonium Salts: Pseudo-
Phase Transfer Catalysis Org. Process Res. Dev. 16
755–763
A simple process was developed for the synthesis of
mecoprop ester from 4-chloro-2-methyl phenol (CMP)
and ethyl-2-chloropropionate using K2CO3 as a mild
base with >95% conversion under solid-liquid phase
transfer catalysis. Tetrabutylammonium bromide was
found as an excellent catalyst among all the catalysts
screened. A simple isolation process for the product was
developed. A new insight was provided into the reaction
mechanism and kinetics of the reaction. A complete the-
oretical analysis of the process involving one liquid and
two solid co-products was carried out to describe the
observed rate data for the first time in published litera-
ture on S-L PTC. The apparent activation energy for the
reaction is 15.4 kcal/mol.
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phase-transfer catalysis in the presence of potassium car-
bonate: alkylation of pyrrolidin-2-one J. Chem. Soc.,
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Acknowledgements
G D Yadav acknowledges support from R T Mody Dis-
tinguished Professor Endowment and J C Bose National
Fellowship of Department of Science And Technology, Gov-
ernment of India. G P Deshmukh acknowledges University
Grant Commission (UGC) for award of SRF under its UGC-
SAP green technology programme.
14. Jászay Z M, Petneházy I and Töke L 2004 Reaction of
chlorides of phosphoric, sulfonic, and carboxylic acids

Insight into solid-liquid phase transfer catalyzed synthesis of Mecoprop ester
on solid potassium carbonate surface under PTC circum-
stances Heteroatom Chem. 15 447
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sis: Alkoxylation of p-chloronitrobenzene Catal. Today
66 345; (f) Yadav G D and Paranjape P M 2005 Novel-
ties of solid–liquid phase transfer catalysed synthesis of
p-toluenesulfonyl fluoride from p-toluenesulfonyl chlo-
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Badure O P 2009 Liquid–liquid–liquid phase-transfer
catalysis for cleaner and selective etherification of p-
hydroxy-biphenyl with benzyl chloride to 1, 1ꢁ-biphenyl-
4-(phenylmethoxy) Clean Technol. Environ. Policy 11
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L 2002 O -Methylation of phenolic compounds with
dimethyl carbonate under solid/liquid phase transfer sys-
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based unusual alpha-amino acid derivatives under phase- 19. (a) Yadav
G D and Bisht P M 2004 Nov-
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tion of benzyl chloride with sodium acetate/benzoate:
Phase transfer catalysis in solid-liquid system Ind. Eng.
Chem. Proc. Des. Dev. 20 385; (b) Yadav G D and
Motirale B G 2008 Novelties of solid-liquid phase
transfer catalyzed synthesis of triclosan from potassium
2,4-dichlorophenolate and 2,5-dichlorophenol Ind. Eng.
elties of microwave irradiated solid-liquid phase
transfer catalysis (MISL-PTC) in synthesis of 2-
benzyloxyacetophenone J. Mol. Catal. A: Chem. 221
59; (b) Yadav G D and Bisht P M 2004 Syner-
gism of low energy microwave irradiation and solid-
liquid phase transfer catalysis for selective alkylation
of phenols to phenolic ethers Synth. Commun. 24
2285
Chem. Res. 47 9055; (c) Yadav G D and Haldavanekar B 20. Zhao Q, Sun J, Li J and He J 2013 Kinetics and mech-
V 1997 Mechanistic and kinetic investigation of liquid-
liquid phase transfer catalyzed oxidation of benzyl chlo-
ride to benzaldehyde J. Phys. Chem. A 101 36; (d) Yadav
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weakly acidic phosphonate in solid – liquid phase-
transfer catalysis system CATCOM 36 98
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