Synthesis and Properties of 4,4′-Di(n-Tetradecyl) Diphenyl Methane Disulfonate Salt

Article abstract of DOI:10.1007/s11743-016-1840-9

The gemini surfactant, sodium 4,4′-di(n-tetradecyl) diphenyl methane disulfonate, has been synthesized in four steps with high yield and only one isomer. The structures of intermediate products were analyzed by ¹H-NMR spectrometry and elemental

Full text of DOI:10.1007/s11743-016-1840-9

J Surfact Deterg (2016) 19:693–699
DOI 10.1007/s11743-016-1840-9
ORIGINAL ARTICLE
Synthesis and Properties of 4,40-Di(n-Tetradecyl) Diphenyl
Methane Disulfonate Salt
Kai Xu1,2 Danping Wang1,2 Hujun Xu1,2
•
•
Received: 3 November 2015 / Accepted: 25 May 2016 / Published online: 31 May 2016
Ó AOCS 2016
Abstract The gemini surfactant, sodium 4,40-di(n-te-
tradecyl) diphenyl methane disulfonate, has been synthe-
sized in four steps with high yield and only one isomer.
The structures of intermediate products were analyzed by
1H-NMR spectrometry and elemental analysis. Mass
spectrometry was applied to the analysis of the final
product. The Krafft point, surface tension, and critical
micelle concentration of the aqueous solution and the oil–
water interfacial tension were measured. The results indi-
cate that the gemini surfactant exhibits an ultra-low inter-
facial tension of 7.22 9 10-3 mN/m, which shows
potential applications for enhanced oil recovery.
one lipophilic group. Precisely because of its special
structure, gemini surfactants possess some special proper-
ties, which make them a hot topic in the field of surfactants
in recent years [1–7]. Surfactants flooding began in the
1930s, and they was widely used all over the world because
of low investment costs and high returns [8–14].
A gemini surfactant has significantly lower critical
micelle concentration (CMC) value and higher surface
activity, and it requires lower concentration to form
ultra-low interfacial tension, so it is possible to reduce
the oil–water interfacial tension efficiently. It also has
good solubilization and complexation. There is a great
prospect for gemini surfactants in chemically enhanced
oil recovery (EOR). Wang et al. [15] reported that
gemini surfactants, which have excellent rheological and
interfacial properties are expected to replace the alkali in
the alkali/surfactant/polymer (ASP) flooding system and
reduce the amount or replace the polymer in the system.
Zhou et al. [16] mentioned that anionic sulfonate gemini
surfactants are widely used in EOR. Anionic sulfonate
gemini surfactants not only have the advantage of high
cloud point, less adsorption on sandstone surface, high
interfacial activity, and good heat resistance, but also
optimal economic benefit due to lower costs. Gemini
surfactants not only share the properties of polymers in
oil flooding, but also the property of traditional surfac-
tant flooding agent, so it has great potential in the field
of EOR [17–21].
Keywords Gemini surfactant Á Clemmensen reduction Á
Double straight-chain alkyl diphenyl methane Á Enhanced
oil recovery Á Oil–water interfacial tension
Introduction
The typical difference between a gemini surfactant and a
traditional surfactant is that a gemini surfactant has two
hydrophilic groups and two lipophilic groups, and the
amphiphilic groups are linked by spacer chain, while a
traditional surfactant only has one hydrophilic group and
& Hujun Xu
xu6209@163.com
However, the presence of positional isomers in 4,40-
di(alkyl) diphenyl methane disulfonate salt synthesized by
the conventional alkylation reaction results in problems of
high interfacial tension and poor surface activity [22, 23].
To identify the relationship between the surfactant struc-
ture and properties, a single component product was syn-
thesized using the Clemmensen reduction reaction. The
1
School of Chemical and Material Engineering, Jiangnan
University, Wuxi 214122, People’s Republic of China
2
The Key Laboratory of Food Colloids and Biotechnology,
Ministry of Education, School of Chemical and Material
Engineering, Jiangnan University, Wuxi 214122, People’s
Republic of China
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Synthesis of 4,40-Di(n-Tetradecanoyl) Diphenyl
Methane
pure 4,40-di(n-tetradecyl) diphenyl methane disulfonate salt
obtained showed ultra-low interfacial tension.
The reaction was run in a 250 mL three-necked flask with a
stirrer, a condenser, and a dropping funnel. A tube containing
calcium chloride was connected to the condenser, and the gas
absorption device was connected to the tube. Tetradecanoyl
chloride used in the experiments was prepared in previous
work.
Experimental Procedures
Materials
Tetradecanoic acid was purchased from Cognis Chemicals
(China) Co., Ltd. and purified to greater than 98 %.
Diphenyl methane was obtained from Jintan Huakang Fine
Chemical Plant and purified to greater than 98 %. Nitro-
methane, aluminium trichloride, and hydrochloric acid was
purchased from Sinopharm Chemical Reagent Co., Ltd.
and their purity are all greater than 95 %. Thionyl chloride,
zinc, mercuric chloride, and chlorosulfonic acid of ana-
lytical grade was purchased from Sinopharm Chemical
Reagent Co., Ltd. Chloroform of analytical grade was
purchased from Shanghai Reagent Factory. Sodium
hydroxide, methyl alcohol, and calcium chloride of ana-
lytical grade were purchased from Shanghai Chemical
Reagent Co., Ltd. Crude oil having a viscosity of
87.5 mPa S and a density of 0.9342 g cm-3 at room tem-
perature was obtained from Shengli Oilfield Gudao Oil
Production Plant.
A certain amount of diphenyl methane was weighed
quickly and added into the three-necked flask, then an
appropriate amount of aluminum chloride was added. A
certain amount of tetradecanoyl chloride was added drop-
wise with the dropping funnel under stirring. The molar
ratio of diphenyl methane, tetradecanoyl chloride, anhy-
drous aluminum chloride, and nitromethane was
l:2.5:3.2:6.5. At the beginning, the reaction flask was
immersed in an ice bath to ensure the reaction temperature
was about 0 °C. The color of reaction liquid changed from
colorless to yellow, and aluminum trichloride was gradu-
ally dissolved with HCl gas escaping. After the addition of
tetradecanoyl chloride was completed (approximately
30 min), the reaction was continued in the ice bath for
20 min. Then, the bath was heated to room temperature,
and the reaction was carried out for 24 h. Next, the bath
was heated to 70 °C and the reaction continued for 6 h
until no additional HCl gas escaped. At this time, the color
of reaction liquid became dark green. The reaction liquid
was poured into the ice water, which was treated with
dilute hydrochloric acid under constantly stirring until the
ice was completely dissolved. After the reaction liquid
stratified completely, the organic layer was gathered and
washed with distilled water several times until pH was
about 7. The product yield was 93.4 %.
Synthetic Routes and Methods
Firstly, tetradecanoyl chloride was synthesized using
tetradecanoic acid and thionyl chloride. Then 4,40-di(n-te-
tradecanoyl) diphenyl methane was produced using
diphenyl methane and tetradecanoyl chloride via Friedel–
Crafts acylation reaction. After that, by means of Clem-
mensen reduction [24], sulfonation with chlorosulfonic
acid and neutralization with NaOH aqueous solution, the
final product was synthesized. The overall synthetic route
is shown in Scheme 1.
Purification of the 4,40-di(n-tetradecanoyl) diphenyl
methane: The raw product was soaked in ethanol and
heated to just boiling. Then, it was concentrated and the
Friedl-Crafts acylation
Clemmensen Reduction
CH3(CH2)12COOCL+
H2C(CH2)12CH3
OC(CH2)12CH
3 H3C(CH2)12CH2
SO3H
H2C(CH2)12CH3
H3C(CH2)12CO
HO3S
+
HSO3CL
NaOH
H2C(CH2)12CH3
H3C(CH2)12CH2
H3C(CH2)12CH2
NaO3S
HO3S
SO3H
H2C(CH2)12CH3
SO3Na
H2C(CH2)12CH3
+
H3C(CH2)12CH2
H3C(CH2)12CH2
Scheme 1 Schematic for the synthetic preparation of 4,40-di(n-tetradecyl) diphenyl methane disulfonate salt
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695
product was precipitated after the mixture cooled. After-
wards, the product was removed by filtration and treated by
vacuum drying (50–60 °C, 0.1 MPa). The purpose was to
remove unreacted tetradecanoyl chloride, diphenyl
methane, and nitromethane.
atmospheric pressure to remove the solvent and water. The
mass fraction of active matter was 90 % after it was dried.
Characterization of the Product
Analysis and Characterization of 4,40-Di(n-Tetradecyl)
Diphenyl Methane
Synthesis of 4,40-Di(n-Tetradecyl) Diphenyl Methane
Step 1: Synthesis of zinc amalgam: 50 mL dilute
hydrochloric acid solution and 0.85 g mercuric chloride
were added to a 200 mL three-necked flask. After the
mercuric chloride dissolved completely, 12.2 g zinc was
added into the flask under magnetic stirring. The water was
removed by filtration after 5 min of stirring.
The resulting product was subjected to elemental analysis
using an Elementar Vario ELIII elemental analyzer (two
main elements are hydrogen and carbon). The results were
compared with the theoretical value to ascertain whether
1
the desired product was obtained. H-NMR spectra was
recorded on a Bruker 400 MHz instrument with CDCl3 as
solvent.
Step 2: Method of Clemmensen reduction reaction:
Clemmensen reduction is a chemical reaction described as
a reduction of ketones (or aldehydes) to alkanes using zinc
amalgam and hydrochloric acid. The synthetic route is
shown in Scheme 2.
Analysis and Characterization of 4,40-Di(n-Tetradecyl)
Diphenyl Methane Disulfonate Salt
Twenty grams of 4,40-di(n-tetradecanoyl) diphenyl
methane was added to a 250 mL three-necked flask that
was equipped with a mechanical stirrer and a reflux
apparatus. An appropriate amount of zinc amalgam pre-
pared in advance and 37.65 mL of hydrochloric acid were
then added. The flask was heated until the contents boiled
and reacted for 8 h (hydrochloric acid was supplemented
several times during the process of the reaction). After
cooling overnight, the paraffin-like supernatant was taken
out and dried. Finally 4,40-di(n-tetradecyl) diphenyl
methane was obtained and the product yield was 91 %.
Purification of the 4,40-di(n-tetradecyl) diphenyl
methane: the mixture was extracted with petroleum ether
because the product after reduction was soluble. In this
way, we removed unreacted 4,40-di(n-tetradecanoyl)
diphenyl methane.
Mass spectral peak of the sample was measured via an
electron impact (EI) method with water as substrate. The
equipment used was a Waters Platform ZMD 4000 mass
spectrometer.
Surface Properties
Measurement of Krafft Point (Tk)
The Tk of the gemini surfactant was measured using the
electrical conductivity method. A 0.1 g sample was
charged to a 20 mL bottle and dissolved in 9.9 g ultrapure
water to prepare a 1 wt % solution. The solution was
placed in a refrigerator in a sealed bottle and the temper-
ature maintained at about 1 °C. Once the solution appeared
cloudy, the solution was left refrigerated for more than
1 day. The solution containing precipitate was placed in a
cold water bath and the initial temperature was set at
0–2 °C. After the temperature of the bath stabilized, it was
heated up at intervals of 2 °C until the solution became
clear and transparent, and the conductance (K) was deter-
mined during the progress [26].
Synthesis of 4,40-Di(n-Tetradecyl) Diphenyl Methane
Disulfonate Salt
Seventeen grams of 4,40-di(n-tetradecyl) diphenyl methane
and 51 g chloroform were added to a 250 mL three-necked
flask equipped with a mechanical stirrer and a reflux
apparatus. Chlorosulfonic acid (7.07 g) was then added
slowly at room temperature, and the reaction lasted for 6 h
after the addition was complete [25]. The appropriate
amount of NaOH solution (10 %) was added in order to
adjust the pH to 9–10 and the product was distilled at
Measurement of Surface Tension
A series of concentrations of 4,40-di(n-tetradecyl) diphenyl
methane disulfonate salt aqueous solutions were prepared
with ultrapure water [27]. The surface tension was measured
Scheme 2 Schematic for the
Clemmensen reduction
R1
R1
Reflux
H+
R2
R2
Zn-Hg
R2
R2
O
O
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J Surfact Deterg (2016) 19:693–699
with a DCA-315 Automatic Interfacial Tension Meter
(Thermo Cahn Co., USA) by the pendant drop method at
45 °C. CMC of the product was obtained by means of surface
tension method.
(br, 44 H, long chain hydrocarbon), 0.85–0.90 (t,
J = 6.9 Hz, 6 H, terminal hydrogen of long carbon chain)
[29]. The spectra are consistent with the structure 4,40-di(n-
tetradecyl) diphenyl methane.
The molecular formula of the alkylated product is
C45H76. The experimental value and (theoretical value) of
the elemental analysis are: C 87.58 (87.66); H 12.34
(12.44). The data show that the C and H percentages are
close to the theoretical values, thus we can further confirm
that the product is 4,40-di(n-tetradecyl) diphenyl methane.
Measurement of Interfacial Tension
The interfacial tension of the sample solution was mea-
sured using a Dataphysics SVT20N Spinning Drop Inter-
face Tensiometer [28]. The spinning drop method is based
on a balance of centrifugal and interfacial tension forces. It
has a wide range of measurement, 1 9 10-6–2 9 103 mN/
m. Aqueous phase: the sample aqueous solution of 0.3 %
mass fraction with 300 mg/L hard water and 6 g/L salinity
was prepared. Hydrocarbon phase: crude oil.
Analysis and Characterization of 4,40-Di(n-Tetradecyl)
Diphenyl Methane Disulfonate Salt
Figure 2 is the mass spectrum analysis of 4,40-di(n-te-
tradecyl) diphenyl methane disulfonate salt. From Fig. 2,
m/z = 741.29 [M-Na]- is evidence for the existence of
Results and Discussion
disubstituted monosodium salt; m/z = 359.14 [M-2Na]2-
,
m/z = 639.37 [M-SO3Na2]- suggest the disubstituted dis-
odium salt. Thus, we can conclude that the main product is
disulfonate salt after sulfonating.
Characterization of the Product
Analysis and Characterization of 4,40-Di(n-Tetradecyl)
Diphenyl Methane
Surface Chemical Properties
The 1H-NMR spectra is shown in Fig. 1 (400 MHz,CDCl3).
d 7.07–7.24 (m, 8 H, hydrogen of benzene), 3.90 (s, 2 H,
hydrogen of benzene), 2.52–2.58 (t, J = 7.6 Hz, 4 H,
hydrogen of carbon chain benzyl), 1.55–1.60 (m,
J = 7.3 Hz, 4 H, b hydrocarbon of carbon chain), 1.25–1.30
Krafft point (Tk) is the temperature (more precisely, narrow
temperature range) above which the solubility of a sur-
factant rises sharply. At this temperature the solubility of
the surfactant is equal to the critical micelle concentration.
It is best determined by locating the abrupt change in slope
1
Fig. 1 H-NMR of 4,40-di(n-
tetradecyl) diphenyl methane
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J Surfact Deterg (2016) 19:693–699
697
Fig. 2 MS of 4,40-di(n-
tetradecyl) diphenyl methane
disulfonate salt
20101021-6 34 (0.142)
100
TOF MS ES-
6.64e3
359.14
359.64
353.15
360.14
360.64
719.31
741.29
124.96
96.94
742.29
639.37
631.41
671.14
799.25
182.91
0
m/z
50
100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900
70
65
60
55
50
45
40
200
150
100
50
0
-5.0
-4.5
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
0
10
20
30
40
50
log [C/(mol⋅L−1)]
T/(°C)
Fig. 3 Determination of the Krafft point of C14-DSDM
Fig. 4 Surface tensions of C14-DSDM aqueous solutions at different
concentrations at 45 °C
from a graph of the conductance K against T. Figure 3
shows the conductance K versus T plot of 1 wt % C14-
DSDM aqueous solution. We can see an obvious break,
which usually coincides with the temperature of full clar-
ification of the system, and the temperature corresponding
to the break is the value of Tk. As shown in Fig. 3, the
Krafft point of C14-DSDM (4,40-di(n-tetradecyl) diphenyl
methane disulfonate salt) is found to be 37.6 °C.
on the surfactant aqueous solution, and the space occupied
by non-polar groups on the surface also increases. There-
fore, the surface tension of aqueous solution gradually
reduces when concentration increases. The chemical
composition on the outermost surface of the solution no
longer changes when concentration increases to a certain
value, at this time, surface tension of the solution no longer
changes [30]. CMC and the surface tension at the CMC
(ccmc) are two major parameters to characterize the surface
activity of a surfactant and they are determined from the
breakpoint of the surface tension isotherm. As is shown in
Fig. 4, the CMC of C14-DSDM at 45 °C is 1.00 9 10-3
mol/L, which is much smaller than that of sodium dodecyl
sulfate (SDS) 8.7 9 10-3 mol/L. The surface tension of
C14-DSDM at the CMC is 41.4 mN/m which is high
compared to SDS [31].
Surface Tension and CMC
The surface tension of C14-DSDM was measured with a
DCA-315 Automatic interfacial tension meter by the pen-
dant drop method at 45 °C. c versus log C curves are
shown in Fig. 4.
The surface adsorption on the surfactant aqueous solu-
tion is essentially the change of chemical composition on
the outermost surface of the solution, and it is a process of
water molecules that have a strong force gradually being
replaced by non-polar groups. When the concentration of
the solution increases, the surface adsorption also increases
Interfacial Tension
Surfactant molecules easily gather at the water–oil inter-
face. When the concentration of surfactant on the interface
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J Surfact Deterg (2016) 19:693–699
70 °C, which indicates that the novel gemini surfactants
are capable of reducing the interfacial tension to ultra-low
levels even at extremely high salinity and high degree of
mineralization, and it promises the basis for future
exploitation of oil fields.
0.018
0.016
0.014
0.012
0.010
0.008
0.006
Conclusion
4,40-Di(n-tetradecanoyl) diphenyl methane was produced
by using diphenyl methane and tetradecanoyl chloride as
raw materials by a Friedel–Crafts acylation reaction. Then
by means of the Clemmensen reduction, sulfonation with
chlorosulfonic acid and neutralization with NaOH aqueous
solution, the final product was synthesized.
The CMC of 4,40-di(n-tetradecyl) diphenyl methane
disulfonate salt aqueous solution is 1.00 9 10-3 mol/L,
and its surface activity is good enough. The interfacial
tension of 4,40-di(n-tetradecyl) diphenyl methane disul-
fonate salt aqueous solution reaches ultra-low values sug-
gesting t is a suitable surfactant for EOR applications.
40
45
50
55
60
65
70
T/(°C)
Fig. 5 Oil–water interfacial tension of C14-DSDM at different
temperature
is very small, the molecules can lie flat on the interface
[32]. The decrease of interfacial tension is caused by the
adsorption of surfactant molecules at the water/oil inter-
face. It usually takes time for surfactant molecules to dif-
fuse and adsorb at the interface. Therefore, the dynamic
interfacial tension will change over time [33]. Dynamic
interfacial tension often shows the lowest point corre-
sponding to the maximum amount of interfacial adsorption.
Aqueous samples of C14-DSDM gemini surfactant were
prepared in 300 mg/L hard water and 6 g/L salinity base
solution. The interfacial tensions between the solution and
crude oil were measured over a range of temperatures. The
most important thing worth attention here is that the
solution had an extremely high salinity (6 g/L) and a high
degree of mineralization (300 mg/L). Even under this
extreme condition, no precipitation or phase separation
happened for any of the test temperatures. In contrast,
conventional (monomeric) surfactants used in the petro-
leum industry today generally show poor aqueous solu-
bility/stability under such harsh conditions (high
mineralized degree or salinity). Thus, complex surfactant
formulations are studied in which a co-surfactant and/or
co-solvent are added to enhance the solubility [34]. This
unfortunately generates a lot of issues, including design
complexity, elevated cost, and chromatographic separation
[35].
Acknowledgments We are grateful for the financial support from the
Fundamental Research Funds for the Central Universities
(JUSRP51513).
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