Novel synthesis of a new surfactant 4-((4-bromophenyl)(dodecyl)amino)-4- oxobutanoic acid containing a benzene ring using a copper catalyst cross-coupling reaction and its properties

Article abstract of DOI:10.1007/s11743-012-1423-3

A new surfactant 4-((4-bromophenyl)(dodecyl)amino)-4-oxobutanoic acid with a benzene spacer was synthesized via a novel copper catalyzed cross-coupling reaction. Its structure was confirmed by FTIR, ¹H-NMR, ¹³C-NMR and HRMS; its purity was checked by HPLC. Dynamic light scattering and an atomic force microscope showed that it forms an unusual large-diameter premicellar aggregation below the CMC.

Full text of DOI:10.1007/s11743-012-1423-3

J Surfact Deterg (2013) 16:581–585
DOI 10.1007/s11743-012-1423-3
ORIGINAL ARTICLE
Novel Synthesis of a New Surfactant 4-((4-Bromophenyl)
(dodecyl)amino)-4-Oxobutanoic Acid Containing a Benzene
Ring Using a Copper Catalyst Cross-Coupling Reaction
and its Properties
Minggui Chen
•
Xinqi Hu Meilong Fu
•
Received: 3 April 2012 / Accepted: 5 December 2012 / Published online: 15 December 2012
Ó AOCS 2012
Abstract A new surfactant 4-((4-bromophenyl)(dodecyl)
amino)-4-oxobutanoic acid with a benzene spacer was
synthesized via a novel copper catalyzed cross-coupling
aromatic surfactants is important for research into their
properties. In this paper, we synthesized a new carboxylate
surfactant with a benzene ring using a novel copper catalyst
cross-coupling reaction [9, 10], and its solution properties
were studied.
1
reaction. Its structure was confirmed by FTIR, H-NMR,
1
C-NMR and HRMS; its purity was checked by HPLC.
3
Dynamic light scattering and an atomic force microscope
showed that it forms an unusual large-diameter premicellar
aggregation below the CMC.
Preparation of the target compounds 4-((4-bromophe-
nyl)(dodecyl)amino)-4-oxobutanoic acid(C PhAm) is
1
2
illustrated in Fig. 1. First we designed the synthesis of the
gemini surfactant with a benzene spacer, but only one side
of the 1,4-dibromobenzene reacts with the amine, leaving
the para side bromide unreacted. The single substituted
secondary amine with the benzene ring was efficiently
constructed using a copper catalyst cross-coupling reaction
for C–N bond formation with a 56 % yield, followed by a
base-catalyst Michael addition of succinic anhydride to
give the final carboxylate surfactant C PhAm in 60 %
Keywords Surfactant with benzene ring ꢀ Cross-coupling
reaction ꢀ Synthesis ꢀ Property
Introduction
Surfactants containing an aromatic group have various uses
in industrial applications and fundamental chemical
research [1], their unique structure has found applications
in micellar catalysis [2–4], synthetic lipids and amphiphiles
1
2
yield.
[
5], and Enhanced Oil Recovery [6–8]. Thus, application of
Experimental
new synthetic methods to synthesize these kinds of
Materials
Electronic supplementary material The online version of this
article (doi:10.1007/s11743-012-1423-3) contains supplementary
material, which is available to authorized users.
Copper(I) iodide (99.5 %, fine powder), 1,4-dibromoben-
zene ([99 %), dodecane-1-amine ([99.5 %), succinic
anhydride ([99.5 %), anhydrous K PO ([99.5 %), anhy-
3
4
M. Chen (&) ꢀ M. Fu
drous Na SO , petroleum ether(PE) and ethyl acetate
2 4
Key Laboratory for Oil and Gas Drilling and Production
Engineering of Hubei Province, College of Petroleum
Engineering, Yangtze University, Jingzhou 434023,
People’s Republic of China
(EtOAc), toluene, acetic acid (AcOH), ammonium
hydroxide, Silica gel (230–400 mesh) were obtained from
commercial sources. N, N-dimethylformamide (DMF),
tetrahydrofuran (THF) and triethylamine (Et N) were
e-mail: cmgswpi@126.com
3
freshly distilled from CaH . All reactions were conducted
2
M. Chen ꢀ X. Hu
in an atmosphere of nitrogen and were monitored by thin
layer chromatography (TLC, illuminated by a ultraviolet
lamp).
College of Chemistry and Chemical Engineering,
Southwest Petroleum University, Chengdu 610500,
People’s Republic of China
1
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5
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J Surfact Deterg (2013) 16:581–585
Br
Br
HN (CH2)11CH3
d 1.28 (6H, t, J = 7.1 Hz), 3.51 (4H, d, J = 7.1 Hz), 6. 81
(1H, m), 6.97 (1H, d, J = 8.0 Hz), 7.25–7.33 (2H, m), 9.77
(1H, ws).
1
4
0mol%CuI,
0mol%L
CH (CH ) NH2
+
L=
Et N
3
2 11
OH
4eq K3PO4
DMF,N2
O
2
Br
4-Bromo-N-Dodecyl Aniline
O
OH
H3C(H2C)11 NH
O
H3C(H2C)11
N
In a flame-dried 50-mL round-bottom flask equipped with
a stirring bar was added 1,4-dibromobenzene (2.36 g,
10 mol), dodecan-1-amine (5.60 g, 30 mmol), K PO
(
C H ) N
O
2
5 3
+
O
THF,reflux
3
4
O
Br
Br
(8.48 g, 40 mmol), N, N-diethyl-2-hydroxybenzamide
0.77 g, 40 mmol) and Copper(I) iodide (0.38 g, 2 mmol).
(
Fig. 1 Synthetic method for the preparation of C12PhAm
Methods
The flask was sealed with a rubber septum immediately.
The tube was then evacuated and backfilled with nitrogen
(3 cycles). The degassed anhydrous DMF solution (20 mL)
was added with a syringe at room temperature. The color
turned from slightly green to yellow. The reaction mixture
was stirred at 120 °C for 80 h. The reaction mixture was
then allowed to cool to room temperature, then ethyl ace-
tate (20 mL), and water (100 mL) were added. The reac-
tion mixture was further extracted with ethyl acetate
Surfactant Characterization
FTIR spectra were obtained with a Perkin–Elmer Fourier
Transform Infrared Spectrometer. Experiments to obtain
1
13
H- and C-NMR spectra were carried out in the Chengdu
Institute of Organic Chemistry of Chinese Academy of
Science using a Bruker 300-MHz spectrometer for products
(3 9 20 mL). The combined organic phase was washed
with ammonium hydroxide (60 mL), saturated NaCl solu-
tion and dried over Na SO . Solvent was removed in vacuo
dissolved in CDCl with tetramethylsilane (TMS) as an
3
2
4
internal standard. Surfactant purity was checked by
Shimadzu HPLC using reversed C18 column. ESI HRMS
spectra were produced in the Agilent LC/MS TOF system.
and the residue was purified by flash column chromatog-
raphy on silica gel eluting with (PE/EtOAc = 100:1–80:1)
twice to give 2.49 g amine as a yellow solid (56 % yield),
an analytical pure product was recrystallized from EtOAc.
Surfactant Synthesis
-1
Rf = 0.69(PE/EtOAc = 20:1). FTIR (cm , KBr) 3,416,
2
8
,949, 2,922, 2,849, 1,684, 1,596, 1,504, 1,319, 1,178,
1
The key approach was to synthesize the copper ligand N,
N-diethyl-2-hydroxybenzamide, shown in Fig. 2. A mix-
ture of 2-hydroxybenzoic acid (30.0 g, 217 mmol) and
excess thionyl chloride (120 mL) was heated with reflux
for 2 h. After cooling, excess thionyl chloride was removed
by vacuum distillation; the residue was cooled to 0 °C in an
ice bath, and a solution of diethylamine (80 mL) was added
dropwise. After this addition, the resulting solution grad-
ually was heated to reflux for 20 h. Excess diethylamine
was removed under vacuum, and the residue was dissolved
in dichloromethane (300 mL). The organic phase was
washed with 1 mol/L hydrochloric acid (2 9 200 mL),
water (2 9 200 mL), dried (Na S0 ), filtered and the sol-
10, 724; H NMR (300 M Hz, CDCl ): d 0.88(3H, t,
3
J = 7.0 Hz), 1.26 (18H, m), 1.50 (2H, m), 3.03 (2H,
m),3.62 (1H, ws) 6.42 (2H, t, J = 10.9 Hz),7.15 (2H, ddd,
13
J = 18.2 Hz); C NMR (CDCl3): d14.10, 22.67, 27.14,
2
8.77, 29.58, 31.90, 43.98, 14.17, 131.85.
4
-((4-Bromophenyl)(dodecyl)amino)-4-Oxobutanoic Acid
The amine product (1.90 g, 4.26 mmol) was dissolved in
anhydrous THF (20 mL), succinic anhydride (1.28 g,
1
2.8 mmol) and anhydrous Et N were added subsequently.
3
The reaction was refluxed under a nitrogen atmosphere for
2 h (by TLC), the solvent was removed by vacuum dis-
2
4
7
vent was removed under vacuum. The residue was re-
crystallized 3 times from EtOAc to give a colorless plate
tillation, water (10 mL), and toluene (20 mL) were added.
The reaction mixture was further extracted with toluene
crystal product, whose purity was checked by TLC
1
Rf = 0.6, PE/EtOAc = 10:10) and H NMR (CDCl3):
(3 9 20 mL). The combined organic phases were washed
(
with water and dried over Na SO . Solvent was removed
2
4
by vacuum distillation, and the residue was purified by
flash column chromatography on silica gel eluting with
(PE/EtOAc/AcOH = 40:20:0.5–40:20:4) to give 1.64 g
acid product as colorless liquid which solidified upon
SOCl2
reflux
HNEt2
OH
COOH
OH
OH
COCl
standing (60 %yield). R = 0.36(PE/EtOAc/AcOH = 40:
f
Et N
O
2
-
0:2). FTIR (cm , KBr):3,424, 2,922, 2,852, 1,710, 1,651,
1
2
1
1,587, 1,487, 1,411, 1,274, 1,172, 844, 720; H NMR
Fig. 2 Synthesis of the copper ligand N, N-diethyl-2-hydroxybenzamide
1
23

J Surfact Deterg (2013) 16:581–585
583
(
300 M Hz, CDCl3): d 0.84(3H, t, J = 6.2 Hz), 1.21 (18H,
from D by the Stokes–Einstein equation R = k T/(6pgD)
h
B
ws), 1.45 (2H, ws), 2.26 (2H, t, J = 6.2 Hz), 2.63 (2H,
ddd, J = 12.6 Hz) 3.61 (2H, dd, J = 16.0 Hz),7.05 (2H, d,
J = 8.5 Hz), 7.54 (2H, d, J = 8.4 Hz),10.41 (1H, ws);
for spherical particles, where k represents the Boltzmann
B
constant, T is the absolute temperature, and g is the solvent
viscosity.
1
3
C-NMR (CDCl3): d 14.06, 22.62, 27.57, 28.75, 29.24,
9.31.84, 49.46, 129.79, 133.02, 171.07, 177.80; ESI
2
Atomic Force Microscope (AFM)
HRMS calc. 439.1,722, found: 439.4502. HPLC: 98 %
tR = 2.104 min, k = 254 nm, flow rate = 1.0 mL/min,
CH OH/H O/H SO = 20:1: 0.0, 024).
(
AFM was performed in air using a Nanoscope IIIa
microscope (Veeco Instruments, Santa Barbara, CA, USA)
in tapping mode to simultaneously collect height and phase
data. Images of 1–2 lm size were collected at a 1–3 Hz
scan rate and 512 9 512 pixel resolution. AFM cantilevers
were point probe plus tapping mode silicon probes (Agilent
Technologies, Tempe, AZ) with an &170 kHz resonance
frequency.
3
2
2
4
The synthesis of 4-bromo-N-dodecyl aniline on a
0-mmol scale was repeated six times, the yields were
3 % (60 h), 59 % (3d), 60 % (4d), 62.5 % (5d), 63.5 %
1
4
(
8d), 63 % (10d). It is recommended that the fatty amines
used should be of high purity (99 %) to give satisfactory
yields. The use of 1-octadecane amine with only a 90 %
purity gives a monomeric surfactant C PhAm yield of
1
8
1
1
3 %, H NMR (300 M Hz, DMSO): d 0.82 (3H, d, J =
.3 Hz), 1.22 (32 H, m, J = 10.5 Hz), 2.14 (2H, ms),2.38
6
Results and Discussions
(
2H, d, J = 4.5 Hz),3.57 (2H, s),7.25(2H, d, J = 7.5 Hz),
.64 (2H, d, J = 7.8 Hz). ESI HRMS: Calc. 540.2767
M ? H2O?); found: m/z = 540.2765.
7
Figure 3 shows the surface tension of CnPhAm (n = 12,
18) against their concentrations in pure water at 30 °C. The
surface tension of all the two surfactants decreases with
increasing surfactant concentration and then reaches a
break point, which is taken as the critical micelle concen-
tration (CMC).The amount of adsorbed surfactant (C) at
the air–water interface is given by Eq. (1), where R is the
gas constant (8.314 J/mol K), T is the absolute temperature
(K), C is the surfactant concentration(mol/L), and dc/logC
refers to the slope below the CMC in the surface tension
plots. The value of i that stands for the number of species at
the interface was taken as 1 for these surfactants, due to the
presence of excess sodium hydroxide [11].
(
Equilibrium Surface Tension
All the surfactant solutions were prepared by using twice-
distilled water from KMnO , neutralized, and the final pH
4
was adjusted to 12 by adding a small amount of NaOH. The
surface tension of the aqueous surfactant solution was
measured with an automatic surface tensiometer (BZY-1,
Shanghai Hengping Instrument Factory, Shanghai) with the
Wilhelmy plate technique. The platinum plate was rinsed
with redistilled water and flamed in a Bunsen burner before
measurement. For the surfactant only solution, it requires
about half an hour to equilibrate. The observations were
performed until the change in surface tension was less than
ꢀ
ꢁ
1
oc
CCMC ¼ ꢁ
ð1Þ
2
:303iRT o log C
T
-
1
0
.2 mN m over 3 min. The value obtained was a mean
value of three tests. All measurements were made at
5 ± 0.1 °C using a water circulating bath.
2
Dynamic Light Scattering
Dynamic Light Scattering measurements were performed
with a Brookhaven instrument BI-200SM at a wavelength
of 532 nm with a scattering angle of 90° and the experi-
mental temperature was 25.0 °C. The scattering spectrum
was measured through a band-pass filter and a pinhole
(
100 lm) with a photomultiplier tube. For light scattering
experiments, all solutions were filtered through a 0.22 lm
Millipore filter into the cylindrical scattering cells before
the experiment. The correlation function was analyzed
from the scattering data via the software NNLS method to
obtain the distribution of diffusion coefficient (D) of the
Fig. 3 Equilibrium surface tension versus log concentration of new
aromatic surfactant in H
O at 25 °C, pH = 12
solutes. The apparent hydrodynamic radius R was deduced
h
2
1
23

5
84
J Surfact Deterg (2013) 16:581–585
Table 1 Physical chemistry properties of surfactant C12PhAm solutions at the air/water surface
-
CMC (10 mol/L)
5
10
2
2
Surfactant
cCMC (mN/m)
10 C CMC (mol/cm )
A
CMC (nm )
pC20
CMC/C20
a
PhSAM
0.77
1.52
36.5
35.2
32.1
4.93
6.07
2.88
0.34
0.27
0.57
5.39
5.29
4.72
1.90
2.99
C
12PhAm
18PhAm
C
29.08
15.44
CMC critical micelle concentration, cCMC surface tension at CMC, CCMC maximum surface excess concentration at CMC, ACMC occupied area
per molecule at CMC, pC20 the efficiency of surface adsorption, CMC/C20 the relative effects of some structural or microenvironmental factor on
adsorption
a
Ref. [7], test at 25 °C;
CONH
m
OCH3
SO Na
n
PhSAM=
3
m+n=13
The area occupied by a surfactant molecule at the air/
solution interface was obtained from the saturated
adsorption as follows:
hydrophobic chain, they associate with each other to form
aggregates in dilute region (Table 1).
To confirm the CMC and premicellar aggregation
behavior of C12PhAm surfactant, a dynamic light scattering
014
NACCMC
1
ACMC
¼
ð2Þ
(DLS) experiment was carried out (Fig. 4).The R value
h
-
5
underwent a change at 1.5 9 10 mol/L; this indicates
structure change in surfactant solution, which can be
attributed to micelle formation. So the concentration was
its CMC. Above the CMC concentration, the surfactant has
mono distribution of a hydrodynamic radius of 60–80 nm.
However, below the CMC, at the concentration of
where N is Avogadro’s number, and UCMC is the maximum
surface excess concentration at CMC value.
The surface property of C PhAm surfactant was com-
2
1
parable to PhSAM, which have similar surfactant structure.
However, C PhAm surfactant has an unusual surface
1
8
-
6
property with increased alkyl chain. A phenyl group in a
7.5 9 10 mol/L, there is a 535-nm large size distribu-
tion, this may come from some kind of premicellar
aggregate. The premicelle aggregation was also found by
Atomic Force Microscopy (Fig. 5).
linear hydrophobic chain equals to 3.5-CH -groups. The
2
branching in CnPhAm hydrophobic chain causes looser
packing of the surfactant molecules at the interface. When
the number of carbon atoms in the alkyl chains increase
from 12 to 18, there is a significant decrease in the effec-
tiveness of adsorption, which was attributed to coiling of
the long chain, with a consequent increase in the cross-
sectional area ACMC of the molecule at the interface. The
increase in the CMC upon increase the carbon length of the
bulky branch hydrophobic group in the molecule is pre-
sumably due to the difficulty of incorporating the bulky
hydrophobic group in the interior of a spherical or cylin-
drical micelle. The CMC/C20 ratio values of CnPhAm
surfactants increase with increasing hydrocarbon chain
length, implying that the long hydrophobic branching chain
makes the surfactant easy to adsorb at the air/water
interface.
The CnPhAm solution form premicellar aggregation
was seen in the surface tension plot, there is a turning point
in the surface tension decrease line region. Rosen [12, 13]
found that the Gemini surfactants with an aromatic spacer
have premicellar aggregates, attributed to the formation of
h
Fig. 4 Hydrodynamic radius (R ) distributions of the aggregates
formed in the aqueous solution of different C12PhAm surfactant
concentration at 25 °C, pH = 12
dimer species. Since C PhAm surfactants have two
n
1
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J Surfact Deterg (2013) 16:581–585
585
Fig. 5 AFM evidence of
premicelle aggregation in
surfactant C12PhAm solution,
2
5 °C, pH = 12
-6
-6
7
.5 × 10 mol/L
30 × 10 mol/L
Conclusions
6. Dai XH, Suo JH, Duan X, Bai ZW, Zhang L (2008) A study of
the technical route of the synthesis of alkylbenzenes for use as an
oil displacement agent. J Surf Deterg 11:111–115
We have synthesized a new surfactant containing a
benzene ring using a copper catalyst cross-coupling
reaction. We did not get the gemini surfactant with 1,
7
. Xu Z, Li P, Qiao W, Li Z, Cheng L (2006) Effect of aromatic ring
in the alkyl chain on surface properties of arylalkyl surfactant
solutions. J Surf Deterg 9:245–248
8
. Shaw JE (1984) Carboxylate surfactant systems exhibiting phase
behavior suitable for enhanced oil recovery. J Am Oil Chem Soc
4
-dibromobenzene, we speculate that the change of the
bromide group to the more reactive iodine group proba-
bly comes about by double substitution. However, this
approach has paved the way for the synthesis of surfac-
tant with benzene rings. Furthermore, we have shown that
the single chain carboxylate surfactant with a benzene
ring tends to form large premicellar aggregates. Further
study should focus on the application of this method to
the synthesis surfactants containing aromatic rings.
6
1:1395–1399
9. Kwong FK, Buchwald SL (2003) Mild and efficient copper-cat-
alyzed amination of aryl bromides with primary alkylamines. Org
Lett 5:793–796
0. Altman RA, Buchwald SL (2007) Cu-catalyzed Goldberg and
Ullmann reactions of aryl halides using chelating N- and O-based
ligands. Nat Protoc 2:2474–2479
11. Yoshimura T, Esumi K (2004) Synthesis and surface properties of
anionic gemini surfactants with amide groups. J Colloid Interface
Sci 276:231–238
1
1
2. Joann HM, Rosen MJ, Davenport L (2001) Fluorescence study of
premicellar aggregation in cationic gemini surfactants. Langmuir
Acknowledgments The authors thank Professor Han Lijuan and
Associate Professor Zhang Rui at the Southwest Petroleum University
for doing the DLS and AFM experiments. We thank the Natural
science foundation of Hubei Province (grant number: 2011CDA021)
for financial support.
1
7:6148–6154
1
3. Song LD, Rosen MJ (1996) Surface properties, micellization, and
premicellar aggregation of gemini surfactants with rigid and
flexible spacers. Langmuir 12:1149–1153
Author Biographies
References
Minggui Chen obtained his Ph.D. from the Department of Chemistry
and Chemical Engineering at Southwest Petroleum University in
1
2
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2
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. Santanu B, Kumar VP (2004) Evidence of enhanced reactivity of
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reactions in cationic gemini micellar media. J Org Chem
Engineering of Yangtze University. His current research includes
development of novel surfactants, petroleum colloid science and
petroleum recovery processes.
3
4
Xingqi Hu is a professor in the Department of Chemistry and
Chemical Engineering of Southwest Petroleum University. His main
field of research is the development of Gemini surfactants and water
soluble polymers.
6
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Meilong Fu is a professor in the Department of Petroleum
Engineering of Yangtze University. His main field research is in the
development of surfactants and polymers used in oilfields.
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