Synthesis and properties of a novel linear alkylated diphenylmethane sulfonate gemini surfactant

Article abstract of DOI:10.1007/s11743-012-1407-3

The linear alkylated diphenylmethane sulfonate (C₁₂-DSDM) was synthesized by a four-step reaction with lauric acid, diphenylmethane and chlorosulfonic acid as raw materials. The structure of the final product was characterized by MS. The air-liquid surface tensions at various temperatures and salt solutions (NaCl) were measured by using the drop-volume technique and the thermodynamic parameters of the micellization were calculated. The results show that the critical micelle concentration (CMC) and γ _CMC of the surfactant are 1.452 mmol L^-1 and 38.49 mN m^-1 at 298 K. With an increase in temperature, the CMC gradually increases, the γ _CMC and the maximum surface adsorption capacity Γ_max decrease. The free energy of micelle formation is negative (-51.2 to -60.5 kJ mol^-1).

Full text of DOI:10.1007/s11743-012-1407-3

J Surfact Deterg (2013) 16:57–61
DOI 10.1007/s11743-012-1407-3
ORIGINAL ARTICLE
Synthesis and Properties of a Novel Linear Alkylated
Diphenylmethane Sulfonate Gemini Surfactant
•
Xu Hujun Geng Hui Kang Peng Chen Dandan
•
•
Received: 27 May 2012 / Accepted: 10 September 2012 / Published online: 2 November 2012
Ó AOCS 2012
Abstract The linear alkylated diphenylmethane sulfonate
(C12-DSDM) was synthesized by a four-step reaction with
lauric acid, diphenylmethane and chlorosulfonic acid as raw
materials. The structure of the final product was character-
ized by MS. The air–liquid surface tensions at various
temperatures and salt solutions (NaCl) were measured by
using the drop-volume technique and the thermodynamic
parameters of the micellization were calculated. The results
show that the critical micelle concentration (CMC) and cCMC
of the surfactant are 1.452 mmol L-1 and 38.49 mN m-1 at
298 K. With an increase in temperature, the CMC gradually
increases, the cCMC and the maximum surface adsorption
capacity Cmax decrease. The free energy of micelle forma-
tion is negative (-51.2 to -60.5 kJ mol-1).
CMCs found in the corresponding monomeric surfactants
[8–10].
A new kind of anionic gemini surfactant (C12-DSDM)
was synthesized with diphenylmethane as raw material in
four-step reaction sequence including a Friedel–Crafts
acylation, a Clemmensen reduction, a sulfonation and a
neutralization. Scheme 1 shows the whole process to attain
the new gemini surfactant.
Experimental Procedures
Materials
Lauric acid of chemically pure grade was obtained from
Sinopharm Chemical Reagent China, diphenylmethane
of industrial grade (98 % purity) from Jintan City Fine
Chemical Plant of China, and aluminium chloride, chlo-
rosulfonic acid of chemically pure grade from Sinopharm
Chemical Reagent China were used as received. Sodium
chloride of analytical grade from Sinopharm Chemical
Reagent China was baked at 773 K for 5 h before use.
Other chemicals used were all of analytical grade.
Keywords Linear alkylated diphenylmethane sulfonate ꢀ
Surface activity properties ꢀ Thermodynamic properties
Introduction
Gemini surfactants have two hydrophobic groups and two
hydrophilic groups in one molecule, and display a high
surface activity. In the past decade, there have been many
reports about cationic gemini surfactants but few about
anionic gemini surfactants which have a better surface-
active properties and a lower CMC [1–7]. The CMCs of
anionic gemini surfactants are the same as those of cationic
gemini surfactants, ten to twenty times lower than the
Synthetic Procedure
Synthesis of 4,40-di(Linear Lauroyl) Diphenylmethane(1a)
Diphenylmethane (11.53 g) and nitromethane (27.18 g)
were placed in a 250-ml, three-necked, round-bottomed
flask equipped with a mechanical stirrer, a dropping funnel
and a condenser with a calcium chloride drying tube which
was connected to a gas absorption device. The mixture was
stirred with the flask sitting in an iced salt bath, and then
anhydrous aluminium chloride (25.59 g) was added. After
X. Hujun ꢀ G. Hui ꢀ K. Peng ꢀ C. Dandan (&)
School of Chemical and Material Engineering, Jiangnan
University, Wuxi 214122, People’s Republic of China
e-mail: rabbit19820925@hotmail.com
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J Surfact Deterg (2013) 16:57–61
Scheme 1 Reaction scheme
AlCl3
O
O
C
C11H23COCl
C11H23
CC11H23
1a
ClSO3H
SO3H
HO3S
Zn(Hg)
Concentrated
hydrochloric
acid
C
12H25
H25C12
H25C12
C12H25
2a
SO3Na
NaO3S
NaOH
H25C12
C12H25
3a
1
1
the catalyst was completely dissolved, lauroyl chloride
(30 g) was added dropwise over about 0.5 h. Twenty
minutes after the addition, the reaction proceeded at room
temperature for 24 h. Then the reaction mixture was heated
to 70 °C for another 6 h until no more gas was given off.
The solution was decanted into iced water which contained
a small amount of hydrochloric acid, and stirred until the
ice melted. The product was then put it aside, washed with
water and filtered several times until the pH was around 7.
After that, ethanol was used to wash the product. The
product was constantly stirred while being washed with
ethanol, heated to slightly boiling, then cooled to room
temperature, and filtered. Repeating the whole process
three times was sufficient. The product was dried to con-
stant weight with a yield of 91.1 %.
was confirmed by H-NMR spectroscopy. H NMR (Bru-
ker Avance 500 400 MHz CDCl3, TMS) for 4,40-di-linear
alkylated diphenylmethane: d: 0.88 [t, 6H, 2CH3CH2], d:
1.57 [dd, 4H, 2CH3CH2(CH2)9CH2], d: 1.28 [br, 36H,
2CH3CH2(CH2)9CH2], d: 2.56 [t, 4H, 2PhCH2], d: 7.08 [m,
8H, at benzene ring], d: 3.91 [s, 2H, PhCH2].
Synthesis of C12-DSDM(3a)
4,40-Di-linear alkylated diphenylmethane (20 g) and chlo-
roform (50 g) were placed in a dry, 250-mL, three-necked,
round-bottom flask equipped with a mechanical stirrer, a
dropping funnel and a condenser with a calcium chloride
drying tube which was connected to a gas absorption
device. Chlorosulfonic acid (11.55 g) was added dropwise,
and after that the reaction proceeded at room temperature
for 6 h. The product yield was 90 %. Adequate 15 %
sodium hydroxide was added until the pH was 9–10. The
chloroform and water were extracted in a rotary evaporator,
and the product was dried to constant weight.
Synthesis of 4,40-di-Linear Alkylated Diphenylmethane(2a)
Water (69.52 ml), hydrochloric acid (3.48 ml) and mer-
curic chloride (9.62 g) were placed in a 500-mL, three-
necked, round-bottom flask equipped with magnetic stir-
ring device. After the mixture had completely dissolved,
zinc powder (34.76 g) was added slowly. The mixture was
filtered 10 min later, and then the zinc amalgam was set
aside.
The mass spectrum (Fig. 1) shows a molecular ion peak
at m/z 685.4 (C37H58S2O6Na). The other salient peaks are
indicated in Scheme 2.
Measurements of Surface Tension
4,40-Di(lauroyl) diphenylmethane (28.3 g) was placed in
a 5500-mL, three-necked, round-bottom flask equipped
with mechanical stirrer and a condenser. Then hydrochloric
acid (96.91 g) and the previously prepared zinc amalgam
were added. External heating was applied and refluxing
was continued for 8 h. The upper level of the mixture was
4,40-di-linear alkylated diphenylmethane, and the zinc
amalgam was at the lower level. The product was dried and
purified by silica gel chromatography. The fixed phase was
200–300 eye silica gel, and the eluting agent was a mixture
of benzene and ethyl acetate with a volume ratio of 180:1.
The drops were collected in a beaker, the eluting agent was
dried out, and the pure product was obtained. The structure
The surface tension at various temperatures and salt con-
centration can be measured by using the drop-volume
technique. The surface adsorption Cmax and the minimum
area of each molecule Amin can be calculated using the
following equations. [11–12]
ꢀ
ꢁ
ꢁ1
oc
CMax
¼
ð1Þ
ð2Þ
2:303nRT o lg cMax
T
AMin ¼ ðNACMaxÞꢁ1 ꢂ 1014
where c is the surface tension in mN/, c is the concentration
of C12-DSDM in mol/L. is the thermodynamic
T
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59
Fig. 1 Mass spectrum of 3a
Scheme 2 Mass fragmentation
pattern of 3a
temperature in K, R the gas constant 8.31 J mol-1 K-1, NA
is the Avogadro number.
Results and Discussion
Surface Chemical Properties of C12-DSDM in Aqueous
Solutions
Thermodynamic Parameters of Micellization of C12-DSDM
in Aqueous Solutions
The surface chemical properties of C12-DSDM are listed in
Table 1. As shown in Table 1, the CMC and cCMC of C12-
DSDM in aqueous solution are 1.452 mmol L-1 and
38.49 mN m-1 at 298 K, indicating that this new gemini-
type surfactant has a very high surface activity.
The thermodynamic parameters of micellization can be
calculated by the following equations. [13–16]
DG0m ꢃ RTfð1 þ ði=jÞK0Þ ln CMC þ ði=jÞK0 lnði=jÞg ð3Þ
For gemini surfactants i/j = 2 in the presence of excess
As shown in Table 1, under certain concentrations of
sodium chloride, the CMC gradually increases with
increasing temperature. The reason is that the structure
formed by water molecules around the hydrophobic groups
is destroyed by the increase in temperature, which is stops
the formation of micelles.
electrolytes, K0 = 1
À
ꢂ Á
DG0m T
o ln CMC
oT
DHm0 ¼ ꢁT2o
¼ ꢁ3RT2
ð4Þ
ð5Þ
oT
À
Á
1
DS0m ¼
DHm0 ꢁ DG0m
T
At a specific temperature, the CMC gradually decreases
with the increase in the concentration of sodium chloride,
and the reason is the electrostatic repulsion between
where DG0m, DHm0 , and DS0m are the free energy, enthalpy
and entropy of micellization.
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Table 1 Surface chemical properties of C12-DSDM
c(NaCl)/
mol L-1
T/K
CMC/mmol L-1
c
CMC/mN m-1
Cmax
/
Amin/nm2
C20
pC20
lmol m-2
0
298.0
303.0
308.0
313.0
298.0
303.0
308.0
313.0
298.0
303.0
308.0
313.0
1.452
2.363
3.551
3.972
0.635
0.659
0.681
0.701
0.215
0.232
0.251
0.261
38.49
38.36
38.28
38.20
36.68
36.54
36.21
36.14
36.19
35.68
35.63
35.59
1.86
1.86
1.84
1.84
1.86
1.86
1.77
1.77
1.77
1.74
1.71
1.63
0.89
0.89
0.90
0.90
0.89
0.89
0.94
0.94
0.94
0.95
0.97
1.02
6.1385
6.1392
6.1543
6.2631
7.1326
7.1485
7.2145
7.3267
7.1248
7.2261
7.2418
7.3109
3.21
3.21
3.21
3.20
3.15
3.15
3.14
3.14
3.15
3.14
3.14
3.14
0.10
0.20
Table 2 DG0m, DHm0 , DSm0 and TDS0m of micellization of C12-DSDM surfactants in aqueous solutions
DG0m kJ mol-1
DHm0 kJ mol-1
DS0m kJ mol-1 K-1
ꢁTDS0m kJ mol-1
c(NaCl)/
mol L-1
T/K
CMC/mol L-1
0.10
0.20
298.0
303.0
308.0
313.0
298.0
303.0
308.0
313.0
0.635 9 10-3
0.659 9 10-3
0.681 9 10-3
0.701 9 10-3
0.215 9 10-3
0.232 9 10-3
0.251 9 10-3
0.273 9 10-3
-51.28
-51.86
-52.47
-53.09
-59.33
-59.75
-60.14
-60.46
-16.24
-15.52
-14.98
-12.61
-34.47
-36.92
-28.88
-24.23
0.1176
0.1199
0.1217
0.1293
0.0834
0.0753
0.1014
0.1158
-35.04
-36.33
-37.48
-40.47
-24.85
-22.82
-31.23
-36.25
surfactant ions is weakened due to the presence of large
quantity of counterions, which greatly suppresses the
electric double layer, and make the monolayer more
compact and the micelles much easier to form.
which surround the surfactant molecules. Then the surfactant
molecules enter into the micelles and reduce the entropy.
Therefore, the micelle formation of this system is a thermo-
dynamically spontaneous process driven by the entropy.
Acknowledgments We would like to thank the Jiangnan University
Key Basic Research Program and the Geological and Scientific
Research Institute of the Shengli oilfield for financial support.
Thermodynamic Parameters of Micellization of C12-
DSDM in Aqueous Solutions
The thermodynamic parameters of micellization of C12-
DSDM in aqueous solutions at various temperatures are
shown in Table 2. It can be seen that the values of DG0m and
DHm0 are all negative at various temperatures [8], which
indicates the formation of micelles is spontaneous and exo-
thermic [9]. The entropy of micellization (DS0m) which reflects
the disorder of the system due to the formation of micelles is
always positive, which means the C12-DSDM molecules are
easy associated into the micelles. As shown in Table 2, the
values of DS0m decrease with the increase in temperature. This
is probably because with the increase of temperature, the
thermal motion of molecule increases, and at some level
destroys the ‘‘iceberg model’’ formed by water molecules
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Author Biographies
Xu Hujun is a Ph.D. graduate at the Wuxi Institute of Light Industry
and Nanjing University of Science & Technology. He has been
involved in surfactant and detergent science and technology for the
past 20 years.
Geng Hui graduated from Jiangnan University. He is currently
involved in research on gemini surfactant applications and synthesis
as a postgraduate at Jiangnan University.
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Light Industry Press, Beijing 66
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Acta Phys Chim Sin 11:450–453
Kang Peng graduated from Jiangnan University. He is currently
involved in research on gemini surfactant applications and synthesis
as a postgraduate at Jiangnan University.
Chen Dandan graduated from Jiangnan University. He is currently
involved in research on gemini surfactant applications and synthesis
as a postgraduate at Jiangnan University.
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123