Synthesis, characterization and surface properties of series sulfobetaine surfactants

Article abstract of DOI:10.1007/s11743-010-1212-9

A series of surface active sulfo-propane betaines and sulfo-butane betaines were synthesized with high yields by the reaction of an appropriate N,N-dimethyl alkylamine with an excess of 1,3-propane sultone and 1,4-butane sultone. The structures were characterized by ¹H-NMR spectroscopy and elemental analysis. The micellar properties of these compounds were determined by surface tension methods. Surface tension measurements also provide information about the dependence of the surface tension at the CMC (γ_cmc), pC₂₀ (negative logarithm of the surfactant molar concentration C₂₀ required to reduce the surface tension by 20 mN/m), the surface excess (Γ_max) at air/solution interface, the minimum area per surfactant molecule at the air solution interface (A).

Full text of DOI:10.1007/s11743-010-1212-9

J Surfact Deterg (2011) 14:31–35
DOI 10.1007/s11743-010-1212-9
ORIGINAL ARTICLE
Synthesis, Characterization and Surface Properties of Series
Sulfobetaine Surfactants
•
Guangmiao Qu Jiecheng Cheng Jijun Wei
•
•
•
•
Tao Yu Wei Ding Huoxin Luan
Received: 1 March 2010 / Accepted: 6 May 2010 / Published online: 5 June 2010
Ó AOCS 2010
Abstract A series of surface active sulfo-propane beta-
ines and sulfo-butane betaines were synthesized with high
yields by the reaction of an appropriate N,N-dimethyl
alkylamine with an excess of 1,3-propane sultone and
1,4-butane sultone. The structures were characterized by
1H-NMR spectroscopy and elemental analysis. The
micellar properties of these compounds were determined
by surface tension methods. Surface tension measurements
also provide information about the dependence of the
surface tension at the CMC (ccmc), pC20 (negative loga-
rithm of the surfactant molar concentration C20 required to
reduce the surface tension by 20 mN/m), the surface excess
(Cmax) at air/solution interface, the minimum area per
surfactant molecule at the air solution interface (A).
Introduction
Zwitterionic surfactants, which contain both positively and
negatively charged head groups, are interesting molecules
because of their many unique properties. In general, they
are mild to the skin and eyes, exhibit low toxicity, display
excellent water solubility, broad isoelectric ranges, high
foam stability, and resistance to hard water and to degra-
dation by oxidizing and reducing agents [1, 2]. Also,
changes in temperature, pH, and added electrolyte have
been found to have minimal effects on zwitterionic sur-
factants. Despite these desirable properties, their high
production cost, in comparison with other classes of sur-
factants, limits their industrial use [3].
Betaines are an important kind of zwitterionic surfac-
tants and are widely used as boosters because they stabilize
foams against the antifoaming action of the oil droplets
contained in commercial hair conditioners or shampoos [4].
Moreover, these surfactants reduce the irritation action of
the surfactants on the eyes and skin [5]. In spite of the wide
applications of betaine surfactants and their increasing
commercial use, it is clear from the literature, that their
theoretical aspects have received far less attention than
those of nonionic or ionic surfactants, especially on the
synthesis and basic air–water interface properties of sulfo-
propane betaines and sulfo-butane betaines have not been
reported systematically.
Keywords Zwitterionic surfactants Á
Critical micelle concentration Á Surface tension
G. Qu Á J. Wei Á T. Yu Á W. Ding Á H. Luan
Department of Chemistry and Chemical Engineering,
Northeast Petroleum University, Daqing 163318, China
In the present work, four kinds of sulfo-propane betaines
H-(CH2)mN?(CH3)2(CH2)3SO3
-
with m = 12,14,16,18
and four kinds sulfo-butane betaines H-(CH2)nN?(CH3)2
G. Qu
College of Petroleum Engineering,
China University of Petroleum, Beijing 100220, China
-
(CH2)4SO3 with n = 12,14,16,18 of high purities were
synthesized and their basic air–water interface proper-
ties studied. The synthesis route, chemical structures
and abbreviations of these surfactants are shown in
Scheme 1.
J. Cheng (&)
Daqing Oilfield Limited Company of Petrochina,
Daqing 163453, China
e-mail: qugm110@126.com
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J Surfact Deterg (2011) 14:31–35
Scheme 1 Synthesis routes of
sulfo-propane betaines and
sulfo-butane betaines
O
O
S
O
CH3
-
+
C
(CH2)3SO3
N
H
n
2n+1
acetone
CH3
Sb 16-3,Sb 18-3,
Abbreviation Sb 12-3,Sb 14-3,
CH3
CH3
N
C
H
n
2n+1
O
O
n=12,14,16,18
S
O
CH3
+
-
C
(CH2)4SO3
N
H
n
2n+1
acetone
CH3
Abbreviation Sb 12-4,Sb 14-4,
Sb 16-4,Sb 18-4,
Experimental Procedures
The surface tension was measured by the drop-volume
technique with a water thermostat control with a temperature
of 298 0.1 K. The time scale for one drop was 3–50 min
depending on the time required to attain equilibrium.
The surface tension was then measured three times for each
sample within a 3–50 min interval between each reading to
ensure equilibrium data. The surface tension (c) is given by
c = FVDqg/R, where R is the tip’s radius, Dq the difference
of the two phases, g the local gravity acceleration, V the
volume of one drop, F (R/V)1/3Dqg/R is a correction factor
which accounts for the nonsphericity of the drop. Each
surface tension value was determined from the average at
least five measurements. According to the Gibbs law applied
to equilibrium systems, the adsorption of surfactant at the
gas/liquid interface leads to a reduction in the surface ten-
sion of the solution. The surface excess concentration, C and
the surface area A, per surfactant was calculated using
the Gibbs equation C = -(1/nRT) (dc/dlnC)T = 1/ANA,
where R is the gas constant and T the temperature in Kelvin,
and n is a constant dependent upon the number of individual
ions comprising the surfactant, for zwitterionic surfactants n
is taken as 1. pC20 is the negative of the logarithm of the
surfactant concentration in the bulk phase required to pro-
duce a 20 mN/m reduction in the surface tension of the
solvent.
Materials
Dimethyldodecan-1-amine, dimethyltetradecan-1-amine, di-
methylhexadecan-1-amine, dimethyloctadecan-1-aminewere
from the Kangmanlin Chemical Industry Company (Nanjing
Jiangsu Province, China) and used without further purifica-
tion. 1,3-Propane sultone, 1,4-butane sultone were from the
Haiqu Chemical Company (Shanghai China). Acetone and
methanol were purchased from the Kemiou Chemicals
Company (Tian Jin China). All solvents were distilled prior to
use. The synthesis routes of sulfo-propane betaines and sulfo-
butane betaines were similar to each other, therefore, we will
describe only the synthesis procedure of Sb 12-3.
Synthesis of Sb 12-3
1,3-Propane sultone (0.25 mol) was dissolved in 50 ml
acetone and added to a stirred solution of dimethyldodec-
an-1-amine (0.05 mol) in 50 ml acetone, and the mixture
was refluxed for over 12 h. The end product Sb 12-3 was
produced as white solids; the solids were filtered and
washed with acetone, and then recrystallized from mixtures
of acetone and methanol. The solvent was evaporated
under reduced pressure. The yields were analyzed by a
Perkin Elmer Series II 2400 instrument with the following
results. Sb 12-3 had 89.67%, the yields for Sb 14-3, Sb
16-3 and Sb 18-3 were 92.55, 95.48 and 98.21%; similarly
the yields of Sb 12-4, Sb 14-4, Sb 16-4 and Sb 18-4 were
96.96, 96.60, 97.84 and 94.29%, respectively.
Results and Discussion
1H-NMR Characterization of the Products
The structures of sulfo-propane betaines and sulfo-butane
1
betaines were confirmed by H spectral analyses and ele-
Analytical Methods
mental analysis.
1H-NMR spectra were obtained with a Bruker FT-200
spectrometer using D2O as solvent. Chemical shifts (d)
were reported in ppm related to internal tetramethylsilane.
SB 12-3 1H NMR [300 MHz, (CDCl3)] d = 0.754–
0.842 (t,3H, –CH3), d = 1.135–1.370 (m,18H, –(CH2)9–),
d = 1.620–1.723 (m,2H, –CH2CH2–N?), d = 2.060–2.158
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J Surfact Deterg (2011) 14:31–35
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(m,2H, N?–CH2CH2CH2–), d = 2.824–2.892 (t,2H,
–CH2CH2–N?), d = 2.981–3.088 (s,6H, N?(CH3)2),
d = 3.201–3.264 (t,2H, N?–CH2CH2CH2–), d = 3.352–
3.441 (t,2H, N?–CH2CH2 CH2–);
CH2–CH2N?), d = 2.882–3.129 (s,6H, –(CH2)13–CH2–
CH2–N?CH2(CH2)2CH2–), d = 3.129–3.360 (t,4H, –N?CH2
(CH2)2CH2–SO3-);
Elemental analysis for SB 16-4: Calculated C 65.19% H
11.60% N 3.46%; Found: C 65.32%, H 11.67%, N 3.56%.
SB 18-4 1H NMR [300 MHz, (CDCl3)] d = 0.769–
0.830(t,3H, –CH3), d = 1.128–1.337(m,30H, –(CH2)15–),
d = 1.626–1.862(m,2H ? 4H, –(CH2)15–CH2–CH2–N?CH2
(CH2)2CH2–), d = 2.797–2.858(t,2H, –(CH2)15–CH2–
CH2N?), d = 2.989–3.094(s,6H, N?(CH3)2), d = 3.182–
3.313(t,4H, –N?CH2(CH2)2CH2–SO3-).
Elemental analysis for SB 12-3: Calculated C 60.90%, H
11.04%, N 4.17%; Found: C 60.95%, H 11.31%, N 4.21%.
SB 14-3 1H NMR [300 MHz, (CDCl3)] d = 0.728–
0.846 (t,3H, –CH3),d = 1.036–1.361 (m,22H, –(CH2)11–),
d = 1.598–1.732 (m,2H, –CH2CH2–N?), d = 2.049–2.168
(m,2H, N?–CH2CH2CH2–), d = 2.792–2.879 (t,2H,
–CH2CH2–N?), d = 2.982–3.101 (s,6H, N?(CH3)2), d =
3.188–3.283 (t,2H, N?–CH2CH2CH2–), d = 3.362–3.465
(t,2H, N?–CH2CH2CH2–).
Elemental analysis for SB 18-4: Calculated C 66.51% H
11.78% N 3.23%; Found: C 66.62%, H 11.85%, N 3.26%.
The results of 1H NMR and elemental analysis indicated
a high level of purity for all products.
Elemental analysis for SB 14-3: Calculated C 62.81% H
11.29% N 3.86%; Found: C 62.85%, H 11.35%, N 3.90%.
SB 16-3 1H NMR [300 MHz, (CDCl3)] d = 0.704–
0.835 (t,3H, –CH3), d = 1.108–1.380 (m,26H, –(CH2)13–),
d = 1.615–1.746(m,2H, –CH2CH2–N?), d = 2.037–2.178
(m,2H, N?–CH2CH2CH2–), d = 2.769–2.882 (t,2H,
–CH2CH2–N?), d = 2.966–3.098 (s,6H, N?(CH3)2),
d = 3.173–3.314 (t,2H, N?–CH2CH2CH2–), d = 3.314–
3.464 (t,2H, N?–CH2CH2 CH2–);
70
Sb 12-3
Sb 14-3
65
Sb 16-3
Sb 18-3
60
55
Elemental analysis for SB 16-3: Calculated C 64.45% H
11.51% N 3.58%; Found: C 64.55%, H 11.57%, N 3.60%.
SB 18-3 1H NMR [300 MHz, (CDCl3)] d = 0.757–
0.865 (t,3H, –CH3), d = 1.153–1.375(m,30H, –(CH2)15–),
d = 1.671–1.778 (m,2H, –CH2CH2–N?), d = 1.861–
1.927(m,2H, N?–CH2CH2CH2–), d = 2.552–2.618 (t,2H,
–CH2CH2–N?), d = 2.799–2.939 (s,6H, N?(CH3)2), d =
3.046–3.104 (t,2H, N?–CH2CH2CH2–), d = 3.219–3.326
(t,2H, N?–CH2CH2 CH2–).
50
45
40
35
30
25
20
1E-7
1E-6
1E-5
1E-4
1E-3
0.01
0.1
Elemental analysis for SB 18-3: Calculated C 65.87% H
11.69% N 3.58%; Found: C 65.92%, H 11.71%, N 3.60%.
SB 12-4 1H NMR [300 MHz, (CDCl3)] d = 0.710–0.857
(t,3H, –CH3), d = 1.094–1.388 (m,18H, –(CH2)9–), d =
1.584–1.886 (m,6H, –(CH2)9–CH2–CH2–N?CH2(CH2)2
CH2–), d = 2.760–2.915 (t,2H, –(CH2)9–CH2–CH2N?),
d = 2.915–3.102 (s,6H, N?(CH3)2), d = 3.102–3.323
(t,4H, –N?CH2(CH2)2CH2–SO3-).
concentration (mol/L)
Fig. 1 Plot of surface tension versus sulfo-propane betaine
concentration
75
70
65
60
55
50
45
40
35
30
25
Sb 12-4
Sb 14-4
Sb 16-4
Sb 18-4
Elemental analysis for SB 12-4: Calculated C 61.89% H
11.17% N 4.01%; Found: C 61.95%, H 11.75%, N 4.10%.
SB 14-4 1H NMR [300 MHz, (CDCl3)] d = 0.713–
1.035(t,3H, –CH3), d = 1.035–1.544(m,22H, –(CH2)11–),
d = 1.561–1.952(m,2H ? 4H, –(CH2)11–CH2–CH2–N?CH2
(CH2)2CH2–), d = 2.716–2.902 (t,2H, –(CH2)11–CH2–
CH2N?), d = 2.902–3.140(s,6H, N?(CH3)2), d = 3.140–
3.361(t,4H, –N?CH2(CH2)2CH2–SO3-).
Elemental analysis for SB 14-4: Calculated C 63.66% H
11.41% N 3.71%; Found: C 63.75%, H 11.55%, N 3.80%.
SB 16-4 1H NMR [300 MHz, (CDCl3)] d = 0.512–
0.883 (t,3H, –CH3), d = 0.883–1.569 (m,26H, –(CH2)13–),
d = 1.569–1.916 (m,2H ? 4H, –(CH2)13–CH2–CH2–
N?CH2(CH2)2CH2–), d = 2.543–2.882 (t,2H, –(CH2)13–
1E-7
1E-6
1E-5
1E-4
1E-3
0.01
0.1
surfactant concentration (mol/L)
Fig. 2 Plot of surface tension versus sulfo-butane betaine
concentration
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J Surfact Deterg (2011) 14:31–35
Table 1 Calculated parameters
of sulfo-propane betaines and
sulfo-butane betaines from
equilibrium surface tension
Surfactant
CMC (M)
cCMC (mN m-1
)
C (10-10 mol/cm2)
A (nm2)
pC20
Sb 12-3
Sb 14-3
Sb 16-3
Sb 18-3
Sb 12-4
Sb 14-4
Sb 16-4
Sb 18-4
1.61E-03
3.77E-04
2.90E-05
1.54E-06
2.20E-03
2.80E-04
2.30E-05
2.15E-06
32.79
31.84
30.46
28.06
31.48
29.68
32.06
31.83
1.59
3.32
1.05
0.50
0.43
0.05
0.40
0.42
0.15
0.04
4.910
4.485
5.517
5.945
3.518
4.540
4.957
5.752
3.85
31.8
4.17
3.96
10.95
42.02
Equilibrium Surface Tension Measurements
0
-1
-2
-3
-4
-5
-6
-7
of Sulfo-Propane Betaines and Sulfo-Butane Betaines
sulfo-propane betaine
Linear Fit
Surface tension behaviors of sulfo-propane betaine and
sulfo-butane betaine surfactants were investigated using
the drop-volume technique. All samples were prepared
using double distilled water as the solvent. All solutions
were clear and homogeneous at the measurement temper-
ature. The variation of the surface tension (c) with the
surfactant concentration (c) was determined and the results
are presented in a semi-logarithmic plot, in Figs. 1 and 2.
These figures show that the surface tension values of
sulfo-propane betaines and sulfo-butane betaines decrease
rapidly when increasing the surfactant concentration before
reaching a plateau. A break is shown at a concentration
corresponding to the critical micelle concentration (CMC).
The parameters obtained from equilibrium surface tension
measurements are listed in Table 1. Comparing the sulfo-
propane betaines and sulfo-butane betaines, the normal
trends of a decreasing CMC with increasing alkyl chain
length is observed. The CMC decreases monotonously with
the number of hydrocarbon groups because of increased
molecular hydrophobic moiety.
-8
10
12
14
16
18
20
alkyl chain length
Fig. 3 Plot of CMC values versus alkyl chain length of sulfo-propane
betaines
0
sulfo-butane betaine
Linear Fit
-1
-2
-3
-4
-5
-6
-7
-8
The surface excess C at the air–water interface was
calculated by applying the Gibbs adsorption isotherm
equation. The area per molecule at the interface was esti-
mated from the corresponding value of C. Table 1 sum-
marized the CMC, cCMC, C, A, pC20 values. C is increased
with the hydrophobic length increase, this increases the
packing density at the gas–liquid interface. The area per
molecule at the interface A decreased (see Table 1) with
the increase in the alkyl chain length, while the head group
areas of Sb18-3 and Sb18-4 were much smaller, by almost
one order of magnitude.
10
12
14
16
18
20
alkyl chain length
Fig. 4 Plot of CMC values versus alkyl chain length of sulfo-butane
betaines
A convenient measurement of the efficiency of adsorp-
tion at the gas–liquid interface is the pC20 parameter
introduced by Rosen [6]. As shown in Table 1, pC20
increases as the hydrophobic chain length increases. The
results indicate that energetically speaking, the increases in
the hydrophobic chain length make the transfer of a sur-
factant molecule from the bulk to the interface more easily.
The CMC is a strong function of the length of the alkyl
chain; Rosen [6] reports that the variation of the CMC with
the number of carbons in the hydrophobic tail group (m)
can often be empirically described by the equation
Log(CMC) = A ? B 9 m, where A and B are constants,
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J Surfact Deterg (2011) 14:31–35
35
Chemical Engineering as a research chemist, and has been working on
the synthesis and applications of oil chemicals since then. He has
been enrolled in the oilfield exploration and development Ph.D.
program at the China University of Petroleum in Beijing, since 2007.
m is the carbon number of alkyl chains. For sulfo-propane
betaines the equation is Log(CMC) = 3.4884 - 0.5087 9
m, for sulfo-butane betaines the equation is Log(CMC) =
3.45773 - 0.5058 9 m. This means that the CMC
decreases roughly one order of magnitude for each addition
of two carbons in the surfactant tail group (Figs. 3, 4).
Jiecheng Cheng graduated in 1983 from Heilongjiang University in
Harbin, People’s Republic of China and in the same year joined the
Daqing Oilfield Limited Company of CNPC as a superior oilfield
engineer. He received his Ph.D. in 2000 from Dalian University of
Technology and his research work has been dedicated to the oil and
gas production, particularly enhanced oil recovery.
Acknowledgments This research has been financially supported by
the National Key Basic Research Development Program
(2005CB221305).
Jijun Wei has been studying for a master’s degree at Daqing
Petroleum Institute in Heilongjiang Province of the People’s Republic
of China since 2008, fields of interest are the structure and the
properties relationship of novel surfactants.
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Tao Yu graduated in 1977 and the same year began working at the
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Wei Ding graduated in 1985 and the same year started work at the
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He received his Ph.D. in 2005 from the Daqing Petroleum Institute in
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Author Biographies
Guangmiao Qu received a master’s degree in 2004 from the Daqing
Petroleum Institute in Heilongjiang Province of the People’s Republic
of China, and the same year joined the School of Chemistry and
123