Characterization of water/sucrose laurate/n-propanol/ allylbenzene microemulsions

Article abstract of DOI:10.1007/s11743-012-1344-1

Water/n-propanol/sucrose laurate/allylbenzene micellar systems were formulated and applied in the isomerization of allylbenzene in the presence of heterogenized derivatives of some platinum group catalysts. The ratio (w/w) of n-propanol/surfactant studied herewith was 2/1. Temperature insensitive microemulsions were found. The microemulsions were characterized by the volumetric parameters, density, excess volume, ultrasonic velocity, and isentropic compressibility. The densities increase with increases in the water volume fraction. Excess volumes of the microemulsions decrease for water volume fractions below 0.2, level off for water volume fractions between 0.2 and 0.6 then increase for water volume fractions above 0.6. Excess volumes of the studied micellar systems increase with temperature. Isentropic compressibilities increase with temperature for water volume fractions below 0.8 and decrease for water volume fractions above 0.8. Structural transitions from water-in-oil to bicontinuous to oil-in-water occur along the microemulsion phase. The particle hydrodynamic diameter of the oil-in-water microemulsions at the 0.95 water volume fraction was found to decrease with temperature. AOCS 2012.

Full text of DOI:10.1007/s11743-012-1344-1

J Surfact Deterg (2012) 15:505–512
DOI 10.1007/s11743-012-1344-1
ORIGINAL ARTICLE
Characterization of Water/Sucrose Laurate/n-Propanol/
Allylbenzene Microemulsions
•
Monzer Fanun Ziad Ayad Samer Mudalal
•
•
•
Shirel Dahoah Diana Meltzer Michael Schwarze
•
•
•
Reinhard Schomacker Jochanan Blum
¨
Received: 11 October 2011 / Accepted: 8 March 2012 / Published online: 22 March 2012
Ó AOCS 2012
Abstract Water/n-propanol/sucrose laurate/allylbenzene
micellar systems were formulated and applied in the
isomerization of allylbenzene in the presence of heterog-
enized derivatives of some platinum group catalysts. The
ratio (w/w) of n-propanol/surfactant studied herewith was
2/1. Temperature insensitive microemulsions were found.
The microemulsions were characterized by the volumetric
parameters, density, excess volume, ultrasonic velocity,
and isentropic compressibility. The densities increase with
increases in the water volume fraction. Excess volumes of
the microemulsions decrease for water volume fractions
below 0.2, level off for water volume fractions between 0.2
and 0.6 then increase for water volume fractions above 0.6.
Excess volumes of the studied micellar systems increase
with temperature. Isentropic compressibilities increase
with temperature for water volume fractions below 0.8 and
decrease for water volume fractions above 0.8. Structural
transitions from water-in-oil to bicontinuous to oil-in-water
occur along the microemulsion phase. The particle hydro-
dynamic diameter of the oil-in-water microemulsions at the
0.95 water volume fraction was found to decrease with
temperature.
Keywords Phase behavior ꢀ Ultrasonic velocity ꢀ
Density ꢀ Isentropic compressibility ꢀ
Hydrodynamic diameter
Introduction
Microemulsions are homogeneous, transparent, thermody-
namically stable dispersions of water and oil stabilized by a
relatively large amount of surfactant [1–3]. In order to
allow additional steric flexibility for surfactant rearrange-
ments, a cosurfactant (typically a short-chain alcohol) is
combined with the surfactant. A microemulsion system can
exist as water-in-oil, bicontinuous, or oil-in-water [1–3]
types. Microemulsions are considered to be ideal mic-
roreactors for various chemical and biochemical reactions
because of their ease of preparation and thermodynamic
stability [1–3]. However, to be used as microreactors,
detailed characterization of their properties is required.
This includes studies of the phase behavior (composition of
the mixture at which the microemulsion is formed), size of
the microemulsion droplets. Various spectroscopic and
scattering techniques have been employed for this charac-
terization [1–3]. Traditional spectroscopy (light scattering
techniques, NMR, etc.) employs the electromagnetic wave.
Another kind of wave that propagate through materials is
ultrasound [high frequency (above 100 kHz) acoustical
waves]. These waves explore the elastic rather than the
electric and magnetic properties of materials. As it trans-
verses a sample, compressions and decompressions in the
ultrasonic wave change the distance between molecules
within the sample, which, in turn, respond by intermolec-
ular repulsions and attractions. This ability of ultrasonic
waves to explore intermolecular forces allows access to
molecular levels of organization. Measurements of the
M. Fanun (&) ꢀ Z. Ayad ꢀ S. Mudalal
Colloids and Surfaces Research Center, Al-Quds University,
East Jerusalem 51000, Palestine
e-mail: Fanunm@gmail.com; mfanun@science.alquds.edu
S. Dahoah ꢀ D. Meltzer ꢀ J. Blum
Institute of Chemistry, The Hebrew University of Jerusalem,
91904 Jerusalem, Israel
¨
M. Schwarze ꢀ R. Schomacker
¨
Institut fu¨r Chemie, Technische Universitat Berlin,
Strasse des 17. Juni 124, 10623 Berlin, Germany
123

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J Surfact Deterg (2012) 15:505–512
scattering effects of ultrasonic waves allow distinction between
different structural organization within the microemulsion
phase [4–8].
(diphenyl-phosphine) iridium, palladium acetate and chlo-
rocarbonyl bis-triphenyl phosphine were purchased
from Strem. Hexachloroplatinic acid hexahydrate was
obtained from Alfa Aesar. Tetramethoxy silane (TMOS)
and n-octyltriethoxysilane (OTEOS) were purchased from
ABCR-Glest, Inc. The reference compounds (E)- and
(Z)-1-phenyl-1-propene were prepared as reported earlier
from allylbenzene and polystyrene-bound dichloro-bis
(triphenylphosphine) ruthenium (II) [17]. All compounds
were used as supplied without further purification. Triply
distilled water was used for all experiments.
In the course of our attempts to replace conventional,
but harmful solvents used in organic synthesis by benign
media, a three phase emulsion (or microemulsion)/solid
state transport system (EST) has been developed [9, 10].
This system which consists of a mixture of the organic
substrates and water, together with surfactants that solu-
bilize the reagents, has already proven useful in several
hydrogen transfer reactions [9–11] as well as in C–C
coupling processes [12–15]. Successful application of the
EST system requires careful studies on the various
parameters of the emulsions and microemulsions to be
employed. In the present paper we report on the properties
of aqueous microemulsions suitable for double bond
migration in allylic compounds by a heterogenized orga-
nometallic catalyst. Alkene isomerizations are involved in
the fabrication of fatty acids, terpenes, alkaloids and ste-
roids, and are also key steps in the preparation of Shell’s
higher olefin process and in the fabrication of a variety of
fragrances. Allylbenzene which is water-insoluble and can
be converted into the isomeric 1-phenyl-1-propenes by the
sol–gel supported ion pair [(C8H17)3NCH3][RhCl4] [16]
and by other heterogenized catalysts employed in the
framework of this study. Among the various surfactants
studied in connection with our isomerization in micro-
emulsions, we found sucrose laurate (L1695), together with
the co-surfactant n-propanol, of particular utility. Room
temperature measurements of the phase behavior, the vol-
umetric properties and droplet size should be a good
indication of the properties of the media applied at 107 °C
at which the catalytic double bond migration in allylben-
zene has been recorded (Scheme 1).
Methods
Sample Preparation for a Pseudoternary Phase Diagram
at Constant Temperature
The phase behavior of water, propanol, sucrose laurate, and
allylbenzene mixture is described in pseudoternary phase
diagrams in which the weight ratio of propanol/sucrose
laurate is fixed at two. The determination of the phase
diagram was performed in a thermostated bath (at 298, 310
and 318 0.1 K). Ten weighed samples composed of
mixtures of propanol; sucrose laurate and allylbenzene
were prepared in culture tubes sealed with viton-lined
screw caps at predetermined weight ratios of allylbenzene/
propanol/sucrose laurate. The initial composition of the
samples in grams before water titration is presented in
Table 1. The mixtures were titrated with water along
dilution lines by steps of 3 wt% each time drawn to the
aqueous phase apex from the opposite side of the triangle.
In all of the samples tested, evaporative losses were neg-
ligible. All samples were equilibrated during a time inter-
val of up to 24 h. The different phases were determined
using visual and optical (crossed polarizers) methods. The
appearance of turbidity was considered as an indication for
Experimental
Materials
Table 1 Composition of the samples before water titration in grams
#
Sucrose laurate
(L1695)
n-Propanol
(n-PrOH)
Allylbenzene
(ALB)
Sucrose laurate (L1695) was obtained from Mitsubishi-
Kasei Food Corp. (Mie, Japan). Allylbenzene (ALB),
n-propanol, methyltrioctyl ammonium chloride (Aliquat
336), and rhodium trichloride trihydrate were obtained
from the Sigma-Aldrich Chemical Company. Dichloro-
tris(triphenylphosphine) ruthenium, di-l-chlorobis[(1,2,5,6,-
g)-1,5-cyclooctadiene] dirhodium, E-Chlorocarbonylbis
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
0.30
0.27
0.23
0.20
0.17
0.13
0.10
0.07
0.03
0.33
0.60
0.53
0.47
0.40
0.33
0.27
0.20
0.13
0.07
0.67
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
0.00
catalyst@hydrophobic sol-gel
L 1695 , H2O, PrOH, 107oC
3
1
2
Scheme 1 Catalytic double bond migration in allylbenzene
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J Surfact Deterg (2012) 15:505–512
507
phase separation. The phase behavior of such samples was
affirmed only after sharp interfaces had become visible.
The conclusion of this procedure was hastened by centri-
fuging the samples. Every sample that stayed clear and
uniform after energetic vortexing was considered as
belonging to a one-phase area in the phase diagram [18].
273 and 323 K in steps of 5 K. The particle hydrodynamic
diameter was calculated from the translational diffusion
coefficient (D) using the Stokes–Einstein relationship:
dH ¼ kBT=6pgD
ð1Þ
where dH is the hydrodynamic diameter, kB is Boltzmann’s
constant, T is the absolute temperature and g is the solvent
viscosity. The results are averages of 3 experiments.
Ultrasonic Velocity and Density
Catalytic Isomerization of Allylbenzene
The volumetric properties (ultrasonic velocity and density)
of the different microemulsion samples were measured
by means of a density and sound velocity analyzer (DSA
500M-Anton Paar, Austria) with a sound velocity resolution
A glass-lined mini-autoclave was charged with an oil-in-
water microemulsion composed of allylbenzene (0.18 ml,
0.81 wt%) sucrose laurate (L1695, 0.65 g, 3.30 wt%),
n-propanol (1.63 ml, 6.64 wt%), and triply distilled water
(TDW, 17.6 ml, 89.25 wt%) together with the sol–gel
encaged precatalyst (0.037 mmol), prepared by the method
described for the model catalyst [16]), TMOS (1.8 ml,
17 mmol), OTEOS (1.05 ml, 6.35 mmol)]. The mixture
was stirred magnetically (300 rpm) at 107 °C for the
desired length of time. The immobilized catalyst was
filtered off, washed and sonicated first with TDW (30 ml)
followed by CH2Cl2 (3 9 10 ml). The filtrate was treated
with NaCl (2 g) which caused a break down of the
microemulsion. The organic phase was separated and the
aqueous layer extracted with CH2Cl2 (20 ml) and analyzed
by gas chromatography as previously described [16].
of 0.5 ms-1 and density resolution of 5 9 10-6 g cm-3
.
A 3-ml degassed sample was introduced using Hamilton
glass syringe into a U-shaped borosilicate glass tube that was
being excited electronically to vibrate at its characteristic
frequency. The characteristic frequency changed depending
on the density of the sample. Through exact determination of
the characteristic frequency and a mathematical conversion,
the density of the sample can be calculated. The measuring
cell was closed by an ultrasonic transmitter on the one side
and by a receiver on the other side. The transmitter sent
sound waves of a known frequency through the sample.
The velocity of sound was calculated by determining of the
period of received sound waves and by considering the
distance between transmitter and receiver. Due to the high
dependency of the density and velocity of sound values on
the temperature, the measuring cells had to be thermostated
precisely with two integrated Pt 100 platinum thermometers
together with Peltier elements that provided a precise
thermostating of the sample to within 0.01 °C. Viscosity-
related errors were automatically corrected over the full
viscosity range by measuring the damping effect of the
viscous sample followed by a mathematical correction of the
density value. The instrument automatically detected
gas bubbles in the density measuring cell by an advanced
analysis of its oscillation pattern and generated a warning
message. Measurements were made at 298, 310, 318 K.
Results and Discussion
Phase Behavior
Figure 1 presents the phase behavior of water/sucrose
laurate/n-propanol/allylbenzene systems at 298 K. As
PrOH/L1695=2/1
N80
Dynamic Light Scattering
1Φ
A Zetasizer Nano S (ZEN 1600) from Malvern Instruments
Ltd. (Worcestershire, UK) was used for the measurements
of the size of the dispersed particles. The equipment con-
sisted of a 4 mW, 633 nm He–Ne laser. The size mea-
surement range was between 0.6 nm and 6 lm, the size
measurement angle equaled 173°, the concentration range
for size measurement was between 0.1 ppm (0.00001
vol%)—40 wt% and the temperature measurement range
was between 275 and 363 K. A 1.5-ml microemulsion
sample was introduced into a disposable polystyrene cuv-
ette and measured over a temperature range between
MΦ
Water
ALB
Fig. 1 Pseudoternary phase diagram of the water/n-propanol/sucrose
laurate allylbenzene system at 298 K. The mixing ratio (w/w) of
n-propanol/surfactant is 2/1. The one phase region is designated by
1U, and the multiple phase regions are designated by (MU). N80 is
the dilution line where the weight ratio of (surfactant ? propanol)/
allylbenzene is 4/1
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J Surfact Deterg (2012) 15:505–512
shown in the figure, the transparent water-in-oil micro-
emulsion region appeared immediately on the first addition
of water to the mixture of surfactant and allylbenzene.
Similar findings on the behavior of sucrose laurate in the
presence of other aromatic oils have been reported else-
where [19, 20]. In these systems, temperature insensitive
microemulsions were observed, because no significant
change in the hydration of the surfactant head groups
occurred within the studied temperature range between 298
and 318 K. Similar behavior of nonionic sugar-based sur-
factants has been reported elsewhere [19, 21–24].
298 K
310 K
318 K
-1
-2
-3
-4
Volumetric Properties
0.0
0.2
0.4
0.6
0.8
1.0
water volume fraction(φ)
Figure 2 presents the variation in the density as a function
of the water volume fraction for the water/n-propanol/
sucrose laurate/allylbenzene microemulsions along the N80
dilution line presented in Fig. 1. The density increases with
the water volume fraction. For better understanding of the
variation of density as a function of the water volume
fraction, the excess volume of the microemulsions forma-
tion should be evaluated. The relation (2) can evaluate the
excess volume of microemulsions formation keeping in
view the additivity of volumes of the aqueous micellar and
Fig. 3 Variation of the excess volume as a function of the water
volume fraction for water/n-propanol/sucrose laurate/allylbenzene
micellar systems along the N80 dilution line at 298, 310 and 318 K
water volume fractions between 0.2 and 0.6, the excess
volumes are constant. For water volume fractions above
0.6 the excess volume increases. Negative values of excess
volumes indicate that the system contracts upon mixing.
This behavior of excess volume indicates that structural
transition in the microemulsion region occurs at 0.2 and at
0.6 water volume fractions. The values of the excess
volume increase with temperature. This behavior could be
related to breakage of hydrogen bonds or to the
dissociation of ionic head groups. Figure 4 presents the
variation of the ultrasonic velocity as function of the water
volume fraction for the water/n-propanol/sucrose laurate/
allylbenzene system. The ultrasonic velocity increases with
the water volume fraction up to 0.8, and thereafter
decreases. The variation in the values of ultrasonic
velocity as a function of the water volume fraction
provides information on the state of the water. At a low
oil phase,
X
VE ¼ Vmic
ꢁ
/iVi
ð2Þ
i
where VE is the excess volume, Vmic is the measured
specific volume of the solution, /i is the volume fraction of
component i in the micellar system and Vi is the specific
volume of component i. Figure 3 presents the variation in
the excess volume as function of the water volume fraction
at 298, 310 and 318 K. The excess volumes are negative
and decrease for water volume fraction below 0.2. For
1000
980
960
940
920
900
1550
1500
1450
1400
1350
1300
0.0
0.2
0.4
0.6
0.8
1.0
0.0
0.2
0.4
0.6
0.8
1.0
water volume fraction(φ)
water volume fraction (φ)
Fig. 2 Variation of the density as a function of the water volume
fraction for water/n-propanol/sucrose laurate/allylbenzene micellar
systems along the N80 dilution line at 298 K
Fig. 4 Variation of the ultrasonic velocity as a function of the water
volume fraction for water/n-propanol/sucrose laurate/allylbenzene
micellar systems along the N80 dilution line at 298 K
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J Surfact Deterg (2012) 15:505–512
509
water volume fraction the properties of water are very
different from those of the bulk (free water) indicating the
entrapment of water in the micellar core suggesting the
presence of water-in-oil microstructure. The increase in
the values of ultrasonic velocity upon addition of water
also indicates structural transitions along the water dilution
line. For a water volume fraction above 0.8, the ultrasonic
velocity approaches that of pure water indicating that water
is the continuous phase and an oil-in-water microstructure
is present. Since ultrasonic velocity is determined by the
change of physical properties at the interface between the
particle core and the continuous medium, the ultrasonic
velocity variation will also be correlated to the variation of
the size of the particle core. We analyzed the ultrasonic
velocity in terms of isentropic compressibility ks, which
represents a relative change of volume per unit of pressure
applied at constant entropy. ks is much more sensitive to
structural changes than the velocity and can provide
qualitative information about the physical nature of the
aggregates. The isentropic compressibility ks values were
evaluated with the help of the Laplace equation [25–27]:
6.5
6.0
5.5
5.0
4.5
4.0
φ = 0.19
φ = 0.38
φ = 0.89
295
300
305
310
315
320
Temperature (K)
Fig. 6 Variation of the isentropic compressibility as a function of the
temperature for water/n-propanol/sucrose laurate/allylbenzene micel-
lar systems along the N80 dilution line at 298 K
volume fractions below 0.8 while for water volume fractions
above 0.8 it decreases, indicating different structures in
these composition ranges. We suggest that at water volume
fractions below 0.2 water-in-oil microemulsions are present
while for water volume fractions between 0.2 and 0.6 it is a
bicontinuous morphology, and for water volume fractions
above 0.6 an oil-in-water microstructure is present. Figure 7
shows a schematic presentation of the suggested structural
transitions along the studied dilution line.
1
u2q
ks ¼
ð3Þ
Figure 5 presents the variation of the isentropic
compressibility ks as a function of the water volume
fraction. The isentropic compressibility decreases with the
water volume fraction below 0.8 and increases thereafter.
The variation in the values of isentropic compressibility as a
function of the increasing water volume fraction indicates
structural transitions from a water-in-oil to a bicontinuous
to an oil-in-water microstructure. Figure 6 presents the
values of the isentropic compressibility as a function of
temperature. It increases with the temperature for water
Diffusion Properties
At a water volume fraction of 0.95 and on the assumption
that exchange processes are negligible for the surfactant,
we can estimate the hydrodynamic diameter (dH) from
7.0
6.5
6.0
5.5
5.0
4.5
4.0
0.0
0.2
0.4
0.6
0.8
1.0
water volume fraction (φ)
Fig. 5 Variation of the isentropic compressibility as a function of the
water volume fraction for water/n-propanol/sucrose laurate/allylben-
zene micellar systems along the N80 dilution line at 298 K
Fig. 7 Schematic presentation of the suggested structural transitions
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J Surfact Deterg (2012) 15:505–512
11
10
9
Double Bond Migration Reactions
The catalytic isomerization of allylbenzene in solvent-free,
as well as in organic solvents, had already been shown to
depend strongly on the structural features of the catalyst
[28]. In this study, in the aqueous media, we noticed a
similar dependence of the reaction on the catalyst used.
Upon application of different catalysts of the platinum
group elements, we found the following order of activity:
Heterogenized RuCl2(PPh3)3 [ [(C8H17)3NCH3][RhCl4] [
[Rh(cod)Cl]2 [ IrCl(CO)(PPh3)2 * Pd(OAc)2 [ H2PtCl2,
i.e., the catalytic potency depends both on the nature of the
metal and on the type of ligand. The isomerization of
allylbenzene by the aforementioned immobilized catalysts
is summarized in Table 2. As in organic solvents, the
ruthenium complex was shown to be the most efficient
catalyst also in microemulsions. After 2 h, the reaction
mixture was almost at equilibrium and the amounts of the
isomeric products did not alter thereafter. Slightly less
effective was the immobilized rhodium ion pair. After 3 h
the pair gave 8 % of the starting allylbenzene and 92 %
of the Z- and E-phenylpropenes. The heterogenized
[Rh(cod)Cl]2 reacted considerably slower than the ion pair.
Approximately 20 h was required at 107 °C to reach a state
of equilibrium. We recall that under solvent-free homo-
geneous conditions hardly any isomerization took place at
107 °C. Therefore in organic solvents, the experiments
were carried out at 160 °C [28]. Furthermore, in these
media, the addition of more than 15 % water to the reaction
mixture (in the autoclave) usually stopped the catalytic
reactions. The immobilized iridium and palladium catalysts
were found to have quite similar catalytic potencies. They
8
300
305
310
315
320
Temperature (K)
Fig. 8 Variation of the particle hydrodynamic diameter as a function
of the temperature for a water/n-propanol/sucrose laurate/allylben-
zene oil-in-water microemulsion system at 0.95 water volume fraction
along the N80 dilution line
Eq. 1. The variation in the values of the hydrodynamic
diameter (dH) at a water volume fraction of 0.95 along the
N80 dilution line for water/n-propanol/sucrose laurate/
allylbenzene microemulsions for different temperatures
was investigated. As shown in Fig. 8 the hydrodynamic
diameter decreases with temperature. It was shown that
isomerization reactions of allybenzene in microemulsions
depended on the droplet size of the system and that
sucrose laurate microemulsions with very small aggre-
gates were good systems for this isomerization reaction
[15].
Table 2 Isomerization of allylbenzene by some sol–gel encaged catalysts in aqueous microemulsions under comparable conditions
Entry
Sol–gel entrapped catalyst
Reaction time (h)
Composition of the final reaction mixture (%)a,b
1
2
3
1
2
RuCl2(PPh3)2
[(C8H17)3NCH3][RhCl4]
[Rh(cod)Cl]2
2
3
4
8
7
8
4
7
3
8
3
8
4
7
89
84
37
88
15
55
15
48
30
40
3
5
59
5
4
[Rh(cod)Cl]2
20
5
5
IrCl(CO)(PPh3)2
IrCl(CO)(PPh3)2
Pd(OAc)2
82
37
82
44
66
53
6
20
5
7
8
Pd(OAc)2
20
5
9
H2PtCl4ꢀ6H2O
H2PtCl4ꢀ6H2O
10
20
Reaction conditions: microemulsion of allylbenzene (1) (0.18 ml), sucrose mono laurate (0.65 g), n-propanol (1.63 ml), H2O (17.6 ml), sol–gel
material prepared from TMOS (1.8 ml) and trimethoxyoctylsilane (1.05 ml) and the appropriate metal complex (0.042 mmol); 107 °C
a
1–3 as shown in Scheme 1
b
Average of two reactions that did not differ by more than 2 %
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J Surfact Deterg (2012) 15:505–512
511
12. Tsvelikhovsky D, Blum J (2008) Three phase microemulsion/sol-
gel system for aqueous C–C coupling of hydrophobic substrates.
Eur J Org Chem 2008:2417–2422
13. Tsvelikhovsky D, Pessing D, Avnir D, Blum J (2008) Forcing a
cis-product by matrix imprinting: Heck reaction catalyzed by
Pd(OAc)2 entrapped within cis-imprinted sol-gel derived sili-
cates. Adv Synth Catal 350:2856–2858
14. Tsvelikhovsky D, Popov I, Gutkin V, Rozin A, Shvartsman A,
Blum J (2009) On the involvement of Pd nanoparticles in the
Heck and Suzuki reactions. Eur J Org Chem 2009:98–102
15. Rozin-Ben Baruch A, Tsvelikhovsky D, Schwarze M, Scho-
promote ca. 50 % conversion within 20 h. Hexachloro-
platinic acid is quite efficient at the beginning of the
isomerization process, but soon loses its catalytic power.
Conclusion
Temperature insensitive microemulsions were developed to
be used as microreactors with hydrophobic reagents that
will lead to a significant reduction in the vast amounts of
organic solvents used currently in organic syntheses, and
consequently increase the safety and diminish the cost of
chemical processes. Structural transitions from water-in-oil
to bicontinuous to oil-in-water were probed in the micro-
emulsion region. Since the particle size of the microemul-
sions is an important parameter in determining the yield of
isomerization reaction of allylbenzene, the results presented
in this study recommend performing these reactions at
water volume fractions above 0.80 at high temperatures.
¨
macker R, Fanun M, Blum J (2010) Dependence of the Heck
coupling in aqueous microemulsion by supported palladium
acetate on the surfactant and on the hydrophobicity of the sup-
port. J Mol Catal A Chem 323:65–69
16. Meltzer D, Avnir D, Fanun M, Gutkin V, Popov I, Schomacker R,
Schwarze M, Blum J (2011) Catalytic isomerization of hydro-
phobic allylarenes in aqueous microemulsions. J Mol Cat A
Chem 335:8–13
17. Zoran A, Sasson Y, Blum J (1981) Catalytic double bond isom-
erization by polystyrene-anchored RuCl2(PPh3)3. J Org Chem
46:255–260
18. Fanun M (2010) Formulation and characterization of micro-
emulsions based on mixed nonionic surfactants and peppermint
oil. J Colloid Interface Sci 343:496–503
Acknowledgments We gratefully acknowledge the financial sup-
port of this trilateral study by the Deutsche Forschungsgemeinschaft
(DFG) through grant SCHO687/8-1.
¨
19. Fanun M, Shakarnah A, Meltzer D, Schwarze M, Schomacker R,
Blum J (2011) Volumetric and diffusion properties of water/
surfactant/n-propanol/4-allylanisole micellar systems. Tenside
Surf Deterg 48:400–407
20. Fanun M (2008) Phase behavior, transport, diffusion and struc-
tural parameters of nonionic surfactants microemulsions. J Mol
Liq 139:14–22
References
21. Pes MA, Aramaki K, Nakamura N, Kunieda H (1996) Temper-
ature-insensitive microemulsions in a sucrose monoalkanoate
system. J Colloid Interface Sci 178:666–672
22. Kunieda H, Solans C (1996) How to prepare microemulsions:
temperature insensitive microemulsions. In: Solans C, Kunieda H
(eds) Industrial applications of microemulsions. Marcel Dekker,
New York
23. Fanun M (2009) Properties of microemulsions based on sugar
surfactants and peppermint oil. Colloid Polym Sci 287:899–910
24. Fanun M (2009) Microemulsion formation on water/nonionic sur-
factant/peppermint oil mixtures. J Dispers Sci Technol 30:399–405
25. Ye L, Weitz DA, Sheng P, Bhattacharya S, Huang JS, Higgins HJ
(1989) Dynamic rigidity percolation in inverted micelles. J Phys
Rev Lett 63:263–266
26. Wood AB (1941) A textbook of sound. G. Bell, London
27. Barret-Gultepe MA, Yeager EB (1983) Compressibility of col-
loids. 1. Compressibility studies of aqueous solutions of amphi-
philic polymers and their adsorbed state on polystyrene latex
dispersions by ultrasonic velocity measurements. J Phys Chem
87:1039–1045
1. Fanun M (ed) (2009) Microemulsions: properties and applica-
tions, surfactants science series, vol 144. CRC Press/Taylor and
Francis, Boca Raton
2. Stubenrauch C (ed) (2009) Microemulsion: background, new
concepts, applications, perspective. Wiley, New York
3. Kumar P, Mittal KL (eds) (1998) Handbook of microemulsions
science and technology. Marcel Dekker, New York
4. Mehta SK, Bala K (2000) Tween-based microemulsions: a per-
colation view. Fluid Phase Equilib 172:197–209
5. Mehta SK, Dewan RK, Bala K (1994) Percolation phenomenon
and the study of conductivity, viscosity, and ultrasonic velocity in
microemulsions. Phys Rev E 50:4759–4762
6. Mehta SK, Bala K (1995) Volumetric and transport properties in
microemulsions and the point of view of percolation theory. Phys
Rev E 51:5732–5737
7. Alberola C, Dederichs T, Emeis D, Moller M, Sokolowski T,
Witten KP (2007) Ultrasonic velocity measurements as a method
for investigating phase transitions of monoglyceride emulsifier
systems in pearlescent cosmetic creams. J Colloid Interface Sci
307:500–508
8. Hickey S, Lawrence MJ, Hagan SA, Buckin V (2006) Analysis of
the phase diagram and microstructural transitions in phospholipid
microemulsion systems using high-resolution ultrasonic spec-
troscopy. Langmuir 22:5575–5583
28. Blum J, Pickholtz Y (1969) Homogeneous catalytic isomerization
of allylbenzene and phenylbutenes by some platinum metal
complexes. Isr J Chem 7:23–33
9. Abu-Reziq R, Avnir D, Blum B (2002) A three-phase emulsion/
solid heterogenization method for transport and catalysis. Angew
Chem 114:4311–4313; Angew Chem Int Ed 41:4132–4134
10. Abu-Reziq R, Blum J, Avnir D (2004) Three-phase microemul-
sion/sol-gel system for aqueous catalysis with hydrophobic
chemicals. Chem Eur J 10:958–962
11. Abu-Reziq R, Avnir D, Blum J (2005) Three-phase microemul-
sion/sol-gel system for aqueous catalytic hydroformylation of
hydrophobic alkenes. Eur J Org Chem 2005:3640–3642
Author Biographies
Monzer Fanun received his Ph.D. in applied chemistry at the
Hebrew University of Jerusalem. He is a professor and head of the
Colloids and Surfaces Research Center at Al-Quds University, East
Jerusalem, Palestine. His research focuses on colloidal systems for
health care products and surfactant-based alternatives to organic
solvents.
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¨
Reinhard Schomacker received his Ph.D. in physical chemistry at
the University of Bielefeld. After a postdoctoral fellowship at the
Ziad Ayad completed his M.Sc. studies under the guidance of
Professor Fanun in the Applied and Industrial Technology Program at
Al-Quds University, East Jerusalem, Palestine.
¨
Max-Planck Institute of biophysical Chemistry in Gottingen and
6 years as senior scientist with the Bayer AG in Leverkusen he
became a professor of technical chemistry at the Technical University
Berlin. His research interests are catalysis, alternative reaction media,
integrated reactor and process concepts and the application of
colloidal systems in Chemical Engineering.
Samer Mudalal completed his M.Sc. studies under the guidance of
Professor Fanun in the Applied and Industrial Technology Program at
Al-Quds University, East Jerusalem, Palestine.
Shirel Dahoah is conducting her M.Sc. studies on industrially
important processes in aqueous microemulsions under the guidance of
Professor Blum at the Institute of Chemistry of the Hebrew
University.
Jochanan Blum is professor emeritus of organic chemistry at the
Hebrew University of Jerusalem. His current research interest is
directed to sustainable chemistry, including studies on the replace-
ment of organic solvents in chemical reactions by water, catalysis by
organometallics, new methods for catalyst recycling and domino
reactions.
Diana Meltzer completed her M.Sc. studies under the guidance of
Professor Blum at the Institute of Chemistry of the Hebrew
University. She is the recipient of numerous prizes for outstanding
achievements in her studies and research in the field of green
chemistry.
Michael Schwarze received his Ph.D. in technical chemistry at the
Technical University of Berlin. Since 2009, he has been a postdoc-
toral research fellow at the Technical University of Berlin and focuses
his research on integrated reactions, alternative reaction media,
membrane separation, and photocatalytic water splitting.
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