Synthesis and surface active properties of a novel linear dodecyl diphenyl ether sulfonate Gemini surfactant

Article abstract of DOI:10.1007/s11743-012-1349-9

The linear dodecyl diphenyl ether sulfonate gemini surfactant (C ₁₂-DLADS) has been synthesized by a new route from lauric acid according to a five-step reaction sequence consisting of acidification, Friedel-Crafts acylation, Clemmensen reduction, sulfonation and a neutralization reaction. The surfactant and intermediates were characterized by ¹H-NMR, HPLC/MS and elemental analysis. The properties have been studied by surface tension (_γCMC) and conductivity measurements. The thermodynamic parameters of micellization were calculated. The test results show that C₁₂-DLADS has lower critical micelle concentration (CMC) and better capability for lowering the _γCMC. The _γCMC and CMC are 36.04 mN/m and 6.03 × 10^-4 mol/L respectively at 45 °C. Moreover, with the increase in temperature, the conductivity of C₁₂-DLADS increased, while the counterion binding K₀ decreased. The thermodynamic data show that the micellization process for the surfactant C₁₂-DLADS is entropy driven. AOCS 2012.

Full text of DOI:10.1007/s11743-012-1349-9

J Surfact Deterg (2012) 15:703–707
DOI 10.1007/s11743-012-1349-9
ORIGINAL ARTICLE
Synthesis and Surface Active Properties of a Novel Linear
Dodecyl Diphenyl Ether Sulfonate Gemini Surfactant
•
Xu Hujun Liu Qicheng Chen Dandan Liu Xiaoya
•
•
Received: 13 June 2011 / Accepted: 16 March 2012 / Published online: 7 April 2012
Ó AOCS 2012
Abstract The linear dodecyl diphenyl ether sulfonate
gemini surfactant (C12-DLADS) has been synthesized by a
new route from lauric acid according to a five-step reaction
sequence consisting of acidification, Friedel–Crafts acyla-
tion, Clemmensen reduction, sulfonation and a neutraliza-
tion reaction. The surfactant and intermediates were
in the molecule, are a recent family of compounds [1–3]. In
the past decades, gemini surfactants have attracted con-
siderable interest because of their unique physicochemical
properties such as lower critical micelle concentration
(CMC), higher efficiency in reducing surface tension and
lowering the Krafft temperature than conventional mono-
meric surfactants [3–5]. Alkyl diphenyl ether sulfonate
gemini surfactants, which have been reported elsewhere
[6, 7], are one kind of gemini surfactant. Their intermedi-
ates have been obtained from diphenyl oxide and alkylate
reagent via the Friedel–Crafts alkylation reaction. How-
ever, the synthetic method has many shortcomings, for
example the alkylate has many isomers, i.e., it is a mixture
of linear and branched chain species. These shortcomings
have caused a bottleneck in the scientific research. In order
to study the relationship between structure and properties
of alkyl diphenyl ether sulfonate gemini surfactants, single
and highly purified model compounds must be synthesized.
Our new linear dodecyl diphenyl ether sulfonate gemini
surfactant (C12-DLADS) has been obtained from lauric
acid as the raw material in a five-step sequence of reac-
tions, according to Scheme 1.
1
characterized by H-NMR, HPLC/MS and elemental anal-
ysis. The properties have been studied by surface tension
(cCMC) and conductivity measurements. The thermody-
namic parameters of micellization were calculated. The test
results show that C12-DLADS has lower critical micelle
concentration (CMC) and better capability for lowering the
c
CMC. The cCMC and CMC are 36.04 mN/m and 6.03 9
10-4 mol/L respectively at 45 °C. Moreover, with the
increase in temperature, the conductivity of C12-DLADS
increased, while the counterion binding K0 decreased. The
thermodynamic data show that the micellization process for
the surfactant C12-DLADS is entropy driven.
Keywords Gemini surfactant ꢀ Synthesis ꢀ
Surface tension ꢀ Conductivity ꢀ Thermodynamic data
Introduction
Experimental Procedures
Gemini surfactants, which have two hydrophobic groups,
two hydrophilic groups, and a rigid or flexible spacer group
Materials
Lauric acid, diphenyl ether and chlorosulfonic acid of
chemically pure grade were obtained from Sinopharm
Chemical Reagent China. Thionyl chloride, anhydrous
aluminium chloride, hydrochloric acid and zinc dust of
analytical grade obtained from Sinopharm Chemical
Reagent China. Mercuric chloride of analytical grade
obtained from Tongren Chemicals China.
X. Hujun (&) ꢀ L. Qicheng ꢀ C. Dandan (&) ꢀ L. Xiaoya
School of Chemical and Material Engineering, Jiangnan
University, Lihu Avenue 1800, Wuxi 214122,
People’s Republic of China
e-mail: xu6209@163.com
C. Dandan
e-mail: rabbit19820925@hotmail.com
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J Surfact Deterg (2012) 15:703–707
O
C
O
C
Scheme 1 Synthesis
procedures of C12-DLADS
SOCl2
reflux
diphenyl ether
CH3NO2
CnH2n+1COOH
Zn(Hg)
CH3(CH2)10COCl
(CH2)10CH3
CH3(CH2)10
O
chlorosulfonic acid
Chloroform
CH3(CH2)11
O
(CH2)11CH3
hydrochloric acid
CH3(CH2)11
NaOH
(CH2)11CH3
O
CH3(CH2)11
(CH2)11CH3
O
SO3H
SO3H
SO3Na
SO3Na
Synthesis Procedure
separated by column chromatography is a white crystalline
1
species. The structures were confirmed by H-NMR spec-
troscopy and elemental analysis. 1H MNR (Bruker Avance
500 400 MHz CDCl3, TMS) for di(4,40-linear chain
dodecy) diphenyl ether: d: 0.862–0.879 [t, 6H, 2CH3CH2],
d: 1.256–1.300 [m, 40H, 2CH3(CH2)10CH2], d: 2.546–
2.585 [t, 4H, 2PhCH2], d: 6.893–6.914 [m, 3, 30, 5, 50-4H at
benzene ring], d: 7.103–7.124 [m, 2, 20, 6, 60-4H at benzene
ring]. Found %: C 85.25, H 11.60. Theory%: C 85.37, H
11.46. M.p. 35.2–36.0 °C.
Synthesis of 4,40-Di(lauroyl) Diphenyl Ether [1]
Lauryl chloride was synthesized by reacting lauric acid
and thionyl chloride under refluxing. Diphenyl ether
(0.088 mol) in nitromethane (30 mL) was placed in a
dried, 250-mL, three-necked, round-bottomed flask equip-
ped with mechanical stirrer, a condenser closed with a
calcium chloride drying tube and a dropping funnel. Then
anhydrous aluminium chloride (0.30 mol) was added. The
mixture was stirred and cooled to below room temperature
by an iced salt bath.
Synthesis of 4,4’-Di(linear dodecyl) Diphenyl Ether
Disulfoacid [3]
Then the lauroyl chloride (0.22 mol) was added drop-
wise for 0.5 h under stirring. After this addition, external
heating was applied and stirring was continued for 24 h.
The reaction continued for 20 min in ice bath, 24 h at room
temperature and 6 h at 70 °C successively. Then, it was
dumped in ice water that contained a small amount of
hydrochloric acid, stirred until the ice dissolved and laid
aside overnight. A white powdery solid of 95.6 % yield
was obtained by filtration, washing ordered with distilled
water and ethanol until a pH of around 7, and vacuum
drying.
4,40-Di(linear dodecyl) diphenyl ether (2 g) dissolved in
15 mL of chloroform was placed in a dried, 100-mL, three-
necked, round-bottomed flask equipped with a magnetic
stirrer, a condenser closed with a calcium chloride drying
tube and an addition funnel. Then, chlorosulfonic acid was
added. After 6 h of reaction, deionized water was added.
The resulting complex was poured into a separatory funnel
and two layers separated. The aqueous solution was
extracted three times with chloroform. The chloroform
extractions were all combined and concentrated. The
4,40-di(linear dodecyl) diphenyl ether disulfoacid separated
by column chromatography is a light yellow powder. The
structures were initially confirmed by elemental analysis.
Found %: C 64.98, H 8.66, S 9.74. Theory%: C 64.86, H
8.71, S 9.61.
Synthesis of 4,4’-Di(Linear Dodecyl)
Diphenyl Ether [2]
4,4’-Di(lauroyl) diphenyl ether (10 g) and hydrochloric
acid (30 g) were placed in a dried, 100-mL, three-necked,
round-bottomed flask equipped with a mechanical stirrer, a
condenser and an addition funnel. Then, the prepared zinc
amalgam was quickly added, and then external heating was
applied and refluxing was continued for 8 h. Moreover, the
appropriate hydrochloric acid was added after 1 h interval.
The resulting complex was poured into hot water (333 K),
and two layers separated. The aqueous solution was
extracted three times with mineral ether. The mineral ether
extracts were all combined and washed successively with
saturated sodium carbonate solution, deionized water, and
then dried over anhydrous calcium chloride. A light yellow
crude product was obtained by filtering and recovering
the mineral ether. 4,40-di(linear dodecy) diphenyl ether
Synthesis of C12-DLADS [4]
First 3 g of the appropriate 4,40-di(linear dodecy) diphenyl
ether disulfoacid dissolved in 5 mL of water was placed in a
dried, 100-mL, three-necked, round-bottomed flask equip-
ped with a magnetic stirrer, a condenser and an addition
funnel. The acids were neutralized with a sodium hydroxide
solution. Then, the sample solution was dried to constant
weight to attain the desired products. The surfactant was
characterized by high performance liquid chromatography
(HPLC) and mass spectrometry. HPLC indicated that the
mass fraction of C12-DLADS is 98.2 %. ESI–MS(negative):
m/z 332.18: [M-2Na]2–, 687.36: [M-Na]-.
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J Surfact Deterg (2012) 15:703–707
Surface-Active Properties
705
Electric Conductivity of C12-DLADS in Aqueous
Solutions [10]
Measurements of Surface Tension
The electric conductivity j of the surfactant solutions was
measured at 298.0 0.1, 308.0 0.1 and 318.0 0.1 K
respectively.
The surface tension of the surfactant solutions was mea-
sured using the drop-volume technique at 318.0 0.1 K
[8]. The surface tension of pure water was measured as
being 68.8 mN/m at 318.0 K.
Then the conductivity was plotted versus the surfactant
concentration in Fig. 2.
An anion gemini surfactant can associate into micelles
according to the following equilibrium
Measurements of Electric Conductivity
À
Á
nS2ꢁ þ 2nXþ $ SnX2nꢁ2p 2pꢁþ2pXþ
The electric conductivity of the surfactant solutions j was
measured using a DDS-11 digital conductivity meter
(Shanghai Tiancheng instrument company, Shanghai,
P. R.China) at 298.0 0.1, 308.0 0.1 and 318.0 0.1 K
respectively.
ð1Þ
where S2- are surfactant anions, X? are its counter ion, n is
aggregation number an(SnX2n-2p
2p- is the 2n - 2p coun-
)
terion, which is on the micelle surface.
Electric conductivity of the micelle surface is a = p/n.
In practice, a is defined by using the ratio of the slope
before and after the CMC.
Results and Discussion
Surface Tension of C12-DLADS in Aqueous Solution
a ¼ S2=S1
ð2Þ
where S1 is a straight slope under the CMC and S2 is a
straight slope above it. Thus, the counter ion binding
K0 = 1 - a.
In general, the critical micelle concentration (CMC) and
the surface tension at CMC (cCMC), which is usually taken
as the minimum surface tension achievable by a surfactant,
are the most important parameters to characterize the sur-
face activity of a surfactant [9].
Table 1 indicates that with the increase in temperature,
the conductivity and CMC of C12-DLADS increases, while
the counterion binding K0 decreases.
The surface tensions of aqueous solutions of C12-DLADS
was measured at 318.0 K with drop-volume technique.
We can see from Fig. 1 that the surface tension of a
C12-DLADS solution exhibits a sharp break corresponding
to the CMC at 6.03 9 10-4 mol/L at 318.0 K, which
indicates that this new gemini-type surfactants had very
high surface activity.
Thermodynamic Parameters of Micellization
of C12-DLADS in Aqueous Solutions
For C12-DLADS, the thermodynamic parameters of mic-
ellization, such as free energy (DG0m), enthalpy (DHm0 ), and
Fig. 1 Surface tension of C12-DLADS water solutions at 45 °C
Fig. 2 Plots of conductivit y (j) versus surfactant concentration (c)
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J Surfact Deterg (2012) 15:703–707
model’’ around surfactant molecules collapses, and the
disorder of the system is enhanced [11].
Table 1 Effects of temperature (T) on critical micelle concentration
(CMC) and properties of C12-DLADS solutions
The values of DS0m decreases with the increase of tem-
perature. Therefore, the micelle formation process of this
system is a thermodynamically spontaneous process driven
by the entropy [12].
C
12-DLADS
T (K)
10-4 CMC (mol L-1
298
308
318
)
2.899
210.2
62.1
0.30
0.70
3.179
225.9
72.4
0.32
0.68
4.986
225.0
83.2
0.37
0.63
S1
S2
a
Conclusions
K0
We proposed a new method to synthesize a linear gemini
anionic surfactant and characterized its properties, which
were found to be unusual. The CMC was about one order
of magnitude lower than those of conventional alkyl
benzene sulfonates, and lower than similar branched chain
anionic gemini surfactants [6]. Moreover, with the increase
in temperature, the conductivity of the C12-DLADS solu-
tion increased, while the counterion binding K0 decreased.
The thermodynamic data show that the micellization pro-
cess for the surfactant C12-DLADS is entropy driven.
entropy (DS0m) can be calculated from following equation
[10]:
DG ꢂ RTf½1 þ ði=jÞK0ꢃ ln CMC þ ði=jÞK0 lnði=jÞg
ð3Þ
for gemini surfactants, i/j = 2; in the presence of excess
electrolytes, K0 = 1. In the opposite case, K0 values are
measured by the conductivity method.
À
Á
DHm0 ¼ ꢁT2o DG0m=T =oT
¼ ꢁRT2ð1 þ 2K0Þo ln CMC=oT:
ð4Þ
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.
In order to calculate the enthalpy, CMC value can be
fitted by the following polynomials.
ln CMC ¼ a þ b T þ c T2 þ d T3
where a, b, c, d are matched coefficient of the enthalpy that
can be calculated by simultaneous equations (4) and (5).
ð5Þ
References
DHm0 ¼ ꢁRT2ð1 þ 2K0Þðb þ 2c T þ 3d T2Þ
ð6Þ
ð7Þ
1. Rosen MJ (1993) Gemini: a new generation of surfactants.
ChemTech 15:30–32
2. Zhu Y-P, Masuyama A, Okahara M (1990) Preparation and
surface active properties of amphipathic compounds with two
sulfate groups and two lipophilic alkyl chains. J Am Oil Chem
Soc 67:459
3. Song LD, Rosen MJ (1996) Surface properties, micellization, and
premicellar aggregation of gemini surfactants with rigid and
flexible spacers. Langmuir 12:1149–1153
4. Parreira HC, Lukenbach ER, Lindemann MO (1979) Physical
chemical properties of solutions of bis-(quaternary)ammonium
bromides. J Am Oil Chem Soc 56:1015–1021
À
Á
DHm0 ꢁ DG0m
DS0m
¼
:
T
The thermodynamic parameters of micellization for
C12-DLADS, at various temperature are shown in Table 2.
As show in Table 2, the values of DG0m, and DHm0 , are all
negative at the tested temperatures, indicating that the
formation of micelles is spontaneous and exothermic. The
entropy of micellization DS0m reflects the changes in dis-
order due to the formation of micelles. The values of DSm0
are all positive, which means the surfactant molecules are
likely to spontaneously associate into micelles. The reason
is that in aqueous solution, water molecules can form an
ordered area called the ‘‘iceberg model’’ around surfactant
molecules. With the formation of micelles, the ‘‘iceberg
5. Rosen MJ, Tracy DJ (1998) Gemini surfactants. J Surf Deterg
1:547–551
6. Xv HJ, Lv CX, Ye ZW (2005) Preparation and properties of
alkydiphenyl ether disulfonate. Fine Chem 22:19–22
7. Xiong KQ, Guo LM (2006) Preparation and properties of dial-
kyldiphenyl ether disulfonate. Leather Chem 23:25–29
8. Zhao GX (1991) Physical chemistry of surfactants. Beijing
University Press, Beijing, pp 13–18
9. Zhao GX, Zhu BY (2003) Principles of surfactant action. China
Light Industry Press, Beijing, p 66
10. Zhang YY, Zhao JX, Zheng O, You Y, Qiu Y (2001) Tempera-
ture dependence and enthalpy—entropy compensation of micel-
lization of gemini surfactants in aqueous solutions. Acta Chim
Sinica 59:690–695
Table 2 DG0m; DHm0 ; DSm0 ; TDS0m
C12-DLADS surfactants in aqueous solutions
of the micellization for
DG0m
DHm0
DS0m
ꢁTDS0m
T (K)
(kJ mol-1
)
(kJ mol-1) (kJ mol-1 K-1
)
(kJ mol-1
)
11. Zhao GX (1991) Physical chemistry of surfactants. Beijing
University Press, Beijing, pp 142–143
12. Milton JR, Zhu ZH, Gao TJ (1993) Synergism in binary mixture
of surfactants: mixtures containing mono- and disulfonated alkyl-
and dialkyl diphenyl ethers. J Colloid Interface Sci 157:254–259
298.15 -43.26
-13.13
-16.49
-20.30
0.094
0.078
0.061
-28.03
-24.04
-19.41
308.15 -40.46
318.15 -39.73
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707
Author Biographies
Chen Dandan graduated from Jiangnan University and is currently
involved in research with various aspects of surfactant application and
synthesis as a postgraduate fellow at Jiangnan University, P. R. China.
Xu Hujun is a Ph.D. graduate of the Wuxi Institute of Light Industry
and Nanjing University of Science & Technology, P. R. China. He
has been involved in surfactant and detergent research for over
20 years.
Liu Xiaoya is a professor in the Department of Materials Science and
the Key Laboratory of Food Science & Biotechnology. She received
her Ph.D. from Fudan University. Dr. Liu’s research focuses on the
macromolecular colloid and advance functional coating materials.
She has published over 60 papers in Angew Chem, Macromolecules,
JCIS., BBS., and has applied for 19 national and international patents.
Liu Qicheng graduated from Jiangnan University and is currently
involved in research dealing with gemini surfactant application and
synthesis as a postgraduate fellow at Jiangnan University, P. R. China.
123