Synthesis of a novel betaine-type asphalt emulsifier and its investigation by online FTIR spectrophotometry

Article abstract of DOI:10.1007/s11164-012-0582-1

A novel betaine-type asphalt emulsifier, 3-(dodecyloxy)-2-hydroxypropan-N- carboxymethyl-N,N-dimethylammonium chloride, has been synthesized in a three-step reaction from lauryl alcohol, epichlorohydrin, dimethylamine, and chloroacetic acid. The optimum reaction conditions were obtained for synthesis of 2-(dodecyloxymethyl)oxirane in the first step. The yield reaches 75.7 % under the optimum conditions of reaction temperature 50 C, reaction time 5 h, feedstock mole ratio of epichlorohydrin to lauryl alcohol 1.4, basicity 33.3 %. The structures of the three products were identified by FTIR. Synthesis of 2-(dodecyloxymethyl)oxirane in the first step was monitored by online FTIR, and an intermediate was detected. On the basis of the experimental data, a plausible reaction mechanism was proposed for the reaction. The critical micelle concentration (CMC) of the final product is low, 8.8 × 10^-5 mol/L. The surface tension at the CMC is 21.2 mN/m. This product is an excellent emulsifier for asphalt. The prepared bituminous emulsion had high storage stability. The emulsifier is a rapid-set asphalt emulsifier.

Full text of DOI:10.1007/s11164-012-0582-1

Res Chem Intermed (2013) 39:597–614
DOI 10.1007/s11164-012-0582-1
Synthesis of a novel betaine-type asphalt emulsifier
and its investigation by online FTIR spectrophotometry
Chunlei Huai
•
Laishun Shi Na Li
•
Received: 5 March 2012 / Accepted: 26 April 2012 / Published online: 17 May 2012
Ó Springer Science+Business Media B.V. 2012
Abstract A novel betaine-type asphalt emulsifier, 3-(dodecyloxy)-2-hydroxypro-
pan-N-carboxymethyl-N,N-dimethylammonium chloride, has been synthesized in a
three-step reaction from lauryl alcohol, epichlorohydrin, dimethylamine, and
chloroacetic acid. The optimum reaction conditions were obtained for synthesis of
2
-(dodecyloxymethyl)oxirane in the first step. The yield reaches 75.7 % under the
optimum conditions of reaction temperature 50 °C, reaction time 5 h, feedstock
mole ratio of epichlorohydrin to lauryl alcohol 1.4, basicity 33.3 %. The structures
of the three products were identified by FTIR. Synthesis of 2-(dodecyloxymeth-
yl)oxirane in the first step was monitored by online FTIR, and an intermediate was
detected. On the basis of the experimental data, a plausible reaction mechanism was
proposed for the reaction. The critical micelle concentration (CMC) of the final
-
5
product is low, 8.8 9 10 mol/L. The surface tension at the CMC is 21.2 mN/m.
This product is an excellent emulsifier for asphalt. The prepared bituminous
emulsion had high storage stability. The emulsifier is a rapid-set asphalt emulsifier.
Keywords Asphalt ꢀ Emulsifier ꢀ Betaine ꢀ Synthesis ꢀ Online FTIR
Introduction
Surfactants to emulsify water and asphalt are called asphalt emulsifiers. The prepared
solution is called a bituminous emulsion. Compared with hot asphalt, use of a
bituminous emulsion has the advantage of stronger adhesive power with mineral
aggregate, lower energy consumption, and less pollution of the environment.
Bituminous emulsions are widely used as pavement and building materials [1–3].
C. Huai ꢀ L. Shi (&) ꢀ N. Li
School of Chemistry and Chemical Engineering, South Campus, Shandong University,
Jinan 250061, People’s Republic of China
e-mail: lshunsh@sdu.edu.cn
123

598
C. Huai et al.
Depending on the nature of the electric charge on the molecule, asphalt
emulsifiers are divided into anionic types, cationic types, zwitterionic types, and
nonionic types. Anionic emulsifiers, for example long-chain sulfonate, alkali metal
salts of an alkaline lignin, and carboxylic acid organic salts, were widely used in the
early stage of research [4–6]. Cationic emulsifiers replaced anionic emulsifiers later
because of their better emulsifying performance and excellent adhesive power with
mineral aggregate [7, 8]. The main cationic asphalt emulsifiers are organic amines,
quaternary ammonium salts, and imidazoline [9]. Peter Schilling studied the
emulsifying compositions of fatty amine and/or polyamine, lignin, and nonionic
surfactants. A preferred emulsifying composition can be produced by reacting
combinations of fatty amine and/or polyamine, lignin, and nonionic surfactant with
formaldehyde [10]. Gemini emulsifier is a kind of surfactant with more hydrophilic
groups and lipophilic groups, and it has stronger emulsifying ability [11–13]. Shi
et al. [14] studied the new Gemini cationic asphalt emulsifier bis[5-nonyl-2-
0 0
(
(2 -hydroxy-3 -triethyl ammonium chloride)propyl-oxy-benzyl)]methane, which
was synthesized by reaction of triethylamine, epichlorohydrin, and bis(2-hydroxy-5-
nonyl phenyl)methane, prepared from nonylphenol and formaldehyde. In addition,
combination of different asphalt emulsifiers can achieve the emulsifying ability
desired. Graf et al. [15] studied a medium set cationic bituminous emulsion
comprising asphalt, a cationic emulsifier and a nonionic water-soluble thickening
agent.
Zwitterionic emulsifiers, which can be mainly divided into betaine types and
amino acids, are another active research area of surfactants [16]. The hydrophilic
groups in the molecular structures contain both acidic and alkaline groups and their
charge properties depend on pH. The alkaline group of betaine emulsifier molecules
is quaternary ammonium whereas the acidic groups are mainly carboxyl and
sulfonic acid. A variety of research has been conducted on betaine emulsifiers
[
17–20]. They have good solubility, are less affected by pH than amino acids, and are
not precipitated at the isoelectric point. They have excellent emulsifying properties
and good compatibility with anionic, cationic, and nonionic surfactants [21, 22].
In previous work we studied different types of asphalt emulsifiers [14]. In this
study, a new betaine-type asphalt emulsifier with better emulsifying properties was
synthesized. The synthetic route to the emulsifier was optimized. The chemical
structures were characterized by FTIR. An intermediate was detected by online
FTIR analysis. A plausible reaction mechanism was proposed for the reaction.
Experimental
Materials
Lauryl alcohol was obtained from Sinopharm Chemical Reagent, Shanghai, China.
Chloroacetic acid was purchased from Tianjin DaMao Chemical Reagent Factory,
Tianjin, China. Epichlorohydrin and dimethylamine (33 %) were obtained from
XiLong Chemical Reagent, Guangzhou, China. All these reagents were of analytical
grade and used without further purification. The asphalt used was AH-90, which was
1
23

A novel betaine-type asphalt emulsifier
599
provided by Shengli Refinery of Qilu Petrochemical Company, Zibo, China. The
mineral aggregate was of marble stone mixture of different size.
Synthesis of betaine-type asphalt emulsifier
Scheme 1 shows the synthetic route to the asphalt emulsifier.
2-(Dodecyloxymethyl)oxirane (a): Lauryl alcohol (18.6 g, 0.10 mol) was
dissolved in 20.0 mL petroleum ether, then NaOH (5.0 g), tetrabutyl ammonium
bromide (0.8 g), and 10.0 mL water were added. Epichlorohydrin (13.0 g,
0
.14 mol) was then added dropwise and the mixture was stirred for 5 h at 50 °C
in a water bath. The resulting precipitate was rinsed three times with petroleum
ether and then the inorganic salt was removed. The final product was obtained by
vacuum distillation.
1-(N,N-Dimethylamino)-3-(dodecyloxy)propan-2-ol (b): 33 % Dimethylamine
aqueous solution (15.0 g, 0.11 mol) was added dropwise to 2-(dodecyloxymeth-
yl)oxirane synthesized above and the mixture was stirred for 6 h at 65 °C in a water
bath. The aqueous phase was removed by means of separatory funnel. The oil phase
was processed by vacuum distillation to remove the solvent, then recrystallized
from a mixture of ethyl acetate and petroleum ether. Product b was dried to a
constant weight under vacuum. The yield of product b was 50.6 %, which was
calculated from the weight obtained.
3-(Dodecyloxy)-2-hydroxypropan-N-carboxymethyl-N,N-dimethylammonium
chloride (c): Chloroacetic acid (11.5 g, 0.12 mol) was added to 1-(N,N-dimethyl-
amino)-3-(dodecyloxy)propan-2-ol (b) synthesized above and the mixture was
stirred for 6 h at 65 °C in a water bath. The reaction solution was processed by
vacuum distillation to remove the solvent and obtain the crude product. The crude
HCl
ClCH2CH
CH2
+
CH3(CH2)10CH2OH
CH3(CH2)10CH2OCH2CH
CH2
O
O
Product (a)
(
R1)
CH3(CH2)10CH2OCH2CH
CH2 + (CH3)2NH
O
CH3(CH2)10CH2OCH2CHCH2N(CH3)2
OH
Product (b)
(
R2)
CH3(CH2)10CH2OCH2CHCH2N(CH3)2 + ClCH2COOH
OH
CH3(CH2)10CH2OCH2CHCH2N(CH3)2 Cl
OH
CH2COOH
Product (c)
(R3)
Scheme 1 Synthetic route to 3-(dodecyloxy)-2-hydroxypropan-N-carboxymethyl-N,N-dimethyl
ammonium chloride
123

600
C. Huai et al.
product was recrystallized from ethanol (33 %), and dried to constant weight under
vacuum. The yield of product c was 96.7 %.
The yields (Y) of products a and c were obtained by the Mohr method. In reaction
R1, chloride ion was produced. 5.0000 g aqueous phase sample was weighed into a
conical flask, then approximately 50 mL distilled water and 0.1 mL of phenol-
phthalein indicator were added. The solution was titrated with 0.1 mol/L standard
nitric acid solution until complete loss of color. Then 1 mL 5 % potassium
chromate indicator was added and the solution was titrated with 0.1 mol/L standard
silver nitrate solution. The endpoint of the titration was identified as the first
appearance of the red–brown color of silver chromate. At the same time, a blank
titration was performed.
0
N ꢁ ðV ꢂ V0Þ ꢁ m
Y ¼
ꢁ 100%
1
000 ꢁ m ꢁ n
where V is the volume of AgNO standard solution consumed (mL), V is the
0
3
volume of AgNO standard solution consumed in the blank test (mL), m’ is the total
3
mass of the aqueous phase sample (g), m is the mass of the aqueous phase sample to
be titrated (g) N is the concentration of AgNO standard solution (mol/L), and n is
the number of moles of lauryl alcohol.
3
Surface tension and critical micelle concentration (CMC)
The surface tension of surfactant solutions decreases sharply with increasing
concentration, then hardly changes when the concentration reaches the CMC.
The surface tension of surfactant solutions was measured with a Kr u¨ ss (Hamburg,
Germany) Processor Tensiometer K12. The CMC and the surface tension at the
CMC were determined from the breaking point of the curve of surface tension
plotted against the logarithm of the concentration.
FTIR analysis
-
FTIR spectra were recorded in the wavenumber range 400 to 4,000 cm , with
1
-
1
averaging of 32 scans at a resolution of 4 cm , on a Bruker Tensor-27 FTIR
spectrophotometer.
UV–visible spectroscopic analysis
UV–visible spectroscopy was performed with a TU-1800PC UV–Vis spectropho-
tometer (Beijing Puxi Tongyong Instrument Company, Beijing, China). Complete
spectra of 0.5200 g lauryl alcohol or product c in 50 mL ethanol solution were
obtained in the range 200–1,000 nm.
Online FTIR analysis during synthesis of 2-(dodecyloxymethyl)oxirane
Online FTIR analysis was performed with a ReactIR 4000 spectrophotometer
(
Mettler–Toledo AutoChem, USA). FTIR spectra were recorded in the wavenumber
1
23

A novel betaine-type asphalt emulsifier
601
-
1
-1
at a resolution of 8 cm . Lauryl alcohol (18.6 g,
.10 mol) was dissolved in 20.0 mL petroleum ether. NaOH (5.0 g), tetrabutyl
range 650 to 4,000 cm
0
ammonium bromide (0.8 g), and 10.0 mL water were added. The solution was
stirred and heated to 50 °C in a water bath. The detector of the online FTIR analysis
system was immersed in the solution and the system then started to record the 3D
spectra. Epichlorohydrin (13.0 g, 0.14 mol) was added dropwise between 0 and
3
0 min. A magnetic stirrer was used during online FTIR measurement.
Preparation of bituminous emulsion
Emulsifier product c (10 g) was dissolved in 200 mL water. The pH of the aqueous
solution was adjusted to 2.0 by adding hydrochloric acid, and the solution was
heated to 60 °C. AH-90 asphalt (300 g) was heated to 120 °C. The bituminous
emulsion was prepared by mixing the aqueous solution containing emulsifier and
asphalt in a colloid mill for 1 min.
Mixing experiment
Mineral aggregate (200 g) and 30 g water were placed in a 500-mL bowl.
Bituminous emulsion (50 g) was then added, and the mixture was stirred at
60 revolutions per minute. The mixing time was recorded by observation of the
mixing performance.
Results and discussion
Optimization to synthetic route to 2-(dodecyloxymethyl)oxirane
Univariate analysis was used to optimize the synthetic route to 2-(dodecyloxym-
ethyl)oxirane. The factors feedstock mole ratio, reaction time, reaction temperature,
and basicity were studied.
Feedstock mole ratio
The reaction conditions were: reaction temperature 50 °C, reaction time 5 h,
basicity 33.3 %. Figure 1 shows a plot of the yield (Y) of product a versus feedstock
mole ratio (m) of epichlorohydrin to lauryl alcohol. As shown in Fig. 1, the yield
increases with increasing feedstock mole ratio then levels off for feedstock mole
ratio greater than 1.4. Therefore, the optimum feedstock mole ratio is 1.4.
Reaction time
The reaction conditions were: reaction temperature 50 °C, feedstock mole ratio of
epichlorohydrin to lauryl alcohol 1.4, basicity 33.3 %. Figure 2 shows a plot of
yield versus reaction time (t). As shown in Fig. 2, the yield increases with
123

602
C. Huai et al.
1
00
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
1
:1.0
1:1.1
1:1.2
1:1.3
1:1.4
1:1.5
1:1.6
1:1.7
1:1.8
m
Fig. 1 Plot of yield versus feedstock mole ratio
100
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
1
2
3
4
5
6
7
8
9
t (h)
Fig. 2 Plot of reaction yield versus reaction time
increasing reaction time and levels off after 5 h. Therefore, the optimum reaction
time is 5 h.
Reaction temperature
The reaction conditions were: reaction time 5 h, feedstock mole ratio of
epichlorohydrin to lauryl alcohol 1.4, basicity 33.3 %. Figure 3 shows a plot of
1
23

A novel betaine-type asphalt emulsifier
603
yield versus reaction temperature (T). As shown in Fig. 3, the yield increases with
increasing reaction temperature, and levels off after 50 °C. Therefore, the optimum
reaction temperature is 50 °C.
Basicity
The reaction conditions were: reaction temperature 50 °C, reaction time 5 h,
feedstock mole ratio of epichlorohydrin to lauryl alcohol 1.4. Figure 4 shows a plot
of yield versus basicity (B). As shown in Fig. 4, the yield increases with increasing
basicity, and levels off after 33.3 %. Therefore, the optimum basicity is 33.3 %.
Overall, the optimum reaction conditions were: reaction temperature 50 °C,
reaction time 5 h, feedstock mole ratio of epichlorohydrin to lauryl alcohol 1.4,
basicity 33.3 %. The yield reaches 75.7 % under the optimum conditions.
FTIR characterization
Figure 5 shows the FTIR spectrum of product a in Scheme 1. The absorption at
-
,320 cm (peak 1) is assigned to O–H stretching, which is attributed to ring
1
3
opening of product a. The absorption at 3,049 cm (peak 2) is assigned to C–H
-
1
-
stretching in the epoxy group. The absorption near 2,926 cm (peak 3) is assigned
1
-
to methylene unsymmetrical stretching. The absorption near 2,853 cm (peak 4) is
1
-
assigned to methylene symmetrical stretching. The absorption at 1,465 cm (peak
1
-
) and 1,375 cm (peak 6) is assigned to methylene unsymmetrical changing angle
1
5
vibration. The absorption at 1,250 cm (peak 7) originates from vibration of the
-
1
1
00
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
20
30
40
50
60
70
80
90
T(°C)
Fig. 3 Plot of reaction yield versus reaction temperature
123

604
C. Huai et al.
1
00
90
80
70
60
50
40
30
20
10
0
1
0
15
20
25
30
35
40
45
50
55
B (%)
Fig. 4 The plot of reaction yield versus basicity
-
1
epoxy group. The absorption at 1,114 and 1,065 cm (peak 8, 9) is assigned to
asymmetrical and symmetrical stretching vibration, respectively, of C–O–C. The
-
absorption at 950–810 cm (peaks 10, 11) is assigned to the epoxy group. The
1
-
1
absorption at 720 cm (peak 12) is assigned to methylene in-plane swing vibration.
Therefore, the FTIR spectrum agrees with the chemical structure of the target
compound of the synthesis, product a.
1
00
9
8
7
6
5
4
0
0
0
0
0
2
7
1
0
1
1
6
12
1
9
8
5
4
3
0
4
000
3600
3200
2800
2400
2000
1600
1200
800
400
-1
Wavenumber (cm )
Fig. 5 FTIR spectrum of product a in Scheme 1
1
23

A novel betaine-type asphalt emulsifier
605
Figure 6 shows the FTIR spectrum of product b in Scheme 1. The broad absorption
-
at 3,280–3,380 cm (peak 1) is assigned to O–H stretching. The absorption at 2,926
1
-
and 2,853 cm (peaks 2, 3) is assigned to asymmetrical and symmetrical stretching
1
-
1
vibration, respectively, of methylene C–H. The absorption at 1,465 cm (peak 4) and
-
1
1
,385 cm
vibration. The absorption at 1,336 cm (peak 6) is attributed to in-plane deformation
(peak 5) is assigned to methylene unsymmetrical changing angle
-
1
-
1
vibration of O–H. The absorption around 1,195 cm (peak 7) is assigned to C–N
-
1
stretching. The absorption at 1,125 and 1,065 cm (peaks 8, 9) is assigned to
asymmetrical and symmetrical stretching vibration, respectively, of C–O–C. The
-
1
absorption at 722 cm (peak 10) is assigned to methylene in-plane swing vibration.
Therefore, the FTIR spectrum agrees with the chemical structure of the target
compound of the synthesis, product b.
Figure 7 shows the FTIR spectrum of product c in Scheme 1. The broad band at
-
,280–3,360 cm (peak 1) is assigned to O–H stretching. The absorption near
1
3
-
1
2
,926 cm
(peak 2) is assigned to methylene unsymmetrical stretching. The
-
1
absorption near 2,853 cm
stretching. The strong absorption at 1,740–1,760 cm (peak 4) originates from
(peak 3) is assigned to methylene symmetrical
-
1
-
1
C=O stretching in the carboxyl group. The absorption at 1,630–1,600 cm (peak 5)
-
is assigned to C=O stretching in carboxylate (–COO ). The absorption at
-
1
1
,465 cm
vibration. The absorption at 1,414 cm (peak 7) is attributed to the in-plane
(peak 6) is assigned to methylene unsymmetrical changing angle
-
1
-
deformation vibration of O–H. The absorption at 1,180 cm (peak 8) is assigned to
1
-
1
C–N stretching. The absorption at 1,125 cm (peak 9) is assigned to asymmetrical
-
1
stretching vibration of C–O–C. The absorption at 720 cm (peak 10) is assigned to
the methylene in-plane swing vibration. Therefore, the FTIR spectrum agrees with
the chemical structure of the target compound of the synthesis, product c.
1
00
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
1
0
6
7
9
8
4
3
1
5
2
0
4
000
3600
3200
2800
2400
2000
1600
1200
800
400
-
1
Wavenumber (cm )
Fig. 6 FTIR spectrum of product b in Scheme 1
123

606
C. Huai et al.
1
00
9
9
8
8
7
5
0
5
0
1
0
5
9
7
1
6
8
4
3
2
5
4
000
3600
3200
2800
2400
2000
1600
1200
800
400
-1
Wavenumber (cm )
Fig. 7 FTIR spectrum of product c in Scheme 1
UV–visible spectroscopic characterization
Lauryl alcohol does not have absorption peak in the range of 200–1,000 nm.
Product c has a strong absorption peak at 219 nm, which is attributed to the n ? p*
band of the carboxy group in the molecule. The molar absorptivity (e) of product c is
-
1
-1
6
3.3 L mol cm in ethanol at 219 nm.
Online FTIR analysis
The reaction used to synthesize 2-(dodecyloxymethyl)oxirane was monitored by
online FTIR. In the reaction, epichlorohydrin was added dropwise between 0 and
3
0 min and the reaction time was up to 6.5 h. Figure 8 shows the 3D online infrared
spectrum throughout the whole reaction process. It is apparent the spectrum changed
substantially. The most distinguishing change occurred after 40 min, which
indicated the reaction speed increased substantially. Figure 9 shows the online
infrared spectra at the beginning, middle, and end of the reaction, acquired at 0, 4.0,
and 6.5 h, respectively.
Five components were detected automatically during the online FTIR analysis;
their FTIR spectra are shown in Figs. 10, 11, 12, 13, and 14. In the FTIR spectrum
-
of component 1 (Fig. 10), the absorption at 2,963 cm (peak 1) is assigned to
1
-
1
methyl unsymmetrical stretching. The absorption near 2,926 cm
assigned to methylene unsymmetrical stretching. The absorption near 2,854 cm
(peak 2) is
-
1
(
peak 3) is assigned to methylene symmetrical stretching. The absorption at
-
,464 cm (peak 4) and 1,376 cm (peak 5) is assigned to methylene unsym-
1
-1
1
metrical changing angle vibration. The absorption at 1,252 cm (peak 6) originates
-
1
-
1
from vibration of the epoxy group. The absorption at 1,114 and 1,069 cm
1
23

A novel betaine-type asphalt emulsifier
607
Fig. 8 3D online FTIR spectrum during the reaction
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
3
2
1
0
4
000
3600
3200
2800
2400
2000
1600
1200
800
400
-
1
Wavenumber (cm )
Fig. 9 Online infrared spectra at different stages of the reaction (spectrum 1 at the beginning, spectrum 2
in the middle, spectrum 3 at the end)
(
respectively, of C–O–C. The absorption at 950–810 cm (peak 9) is assigned to the
peaks 7, 8) is assigned to the asymmetrical and symmetrical stretching vibration,
-
1
-
1
epoxy group. The absorption at 722 cm (peak 10) is assigned to methylene in-
plane swing vibration. Therefore, the spectrum of component 1 obtained by online
FTIR agrees with the chemical structure of the target compound of the synthesis,
product a.
-
1
In the FTIR spectrum of component 2 (Fig. 11), the absorption at 3,005 cm
peak 1) is assigned to C–H stretching in the epoxy group. The absorption near
(
-
1
2
absorption near 2,886 cm
,945 cm
(peak 2) is assigned to methylene unsymmetrical stretching. The
-
1
(peak 3) is assigned to methylene symmetrical
123

608
C. Huai et al.
Peak 2
8
7
6
5
4
3
2
1
Peak 7 Peak 8
Peak 4
Peak 1
Peak 3
Peak 5
Peak 6
Peak 9
Peak 10
0
4
000
3500
3000
2500
2000
1500
1000
500
-1
Wavenumber (cm )
Fig. 10 The infrared spectrum of component 1 during the reaction
1
0
9
8
7
6
5
4
3
2
1
Peak 5
Peak 9,10,11,12
Peak 4
Peak 8
Peak 6,7
Peak 3
Peak 2
Peak 1
0
4
000
3500
3000
2500
2000
1500
1000
500
-
1
Wavenumber (cm )
Fig. 11 The infrared spectrum of component 2 during the reaction
-
1
-1
stretching. The absorption at 1,475 cm (peak 4) and 1,430 cm (peak 5) is
assigned to methylene unsymmetrical changing angle vibration. The absorption at
-
,265 cm (peak 6) is assigned to vibration of the epoxy group. The absorption at
1
1
-
,134 and 1,088 cm (peak 7, 8) is assigned to asymmetrical and symmetrical
1
1
stretching vibrations, respectively, of C–O–C. The absorption at 960–927 cm
-
1
-
peak 9, 10) is assigned to the epoxy group. The absorption near 852 cm (peak
1
(
1
23

A novel betaine-type asphalt emulsifier
609
Peak 1
1
0
9
8
7
6
5
4
3
2
1
0
Peak 8
Peak 7
Peak 4
Peak 5,6
Peak 2,3
4000
3500
3000
2500
2000
1500
1000
500
-
1
Wavenumber (cm )
Fig. 12 The infrared spectrum of component 3 during the reaction
8
Peak 12
Peak 10
7
Peak 1
6
5
4
3
2
1
Peak 3
Peak 9 Peak 11
Peak 4,5
Peak 2
Peak 7 Peak 8
Peak 6
0
4
000
3500
3000
2500
2000
1500
1000
500
-
1
Wavenumber (cm )
Fig. 13 The infrared spectrum of component 4 during the reaction
-
1
1) is assigned to C–Cl stretching. The absorption at 737–728 cm (peak 12)
1
is assigned to methylene in-plane swing vibration. Therefore, the spectrum of
component 2 obtained by online FTIR could be that of the by-product shown in
Scheme 2.
-
1
In the FTIR spectrum of component 3 (Fig. 12), the absorption at 3,389 cm
-
peak 1) is assigned to O–H stretching. The absorption near 2,951 cm (peak 2) is
1
(
assigned to methylene unsymmetrical stretching. The absorption near 2,886 cm
-
1
123

610
C. Huai et al.
6
5
4
3
2
1
0
Peak 1 Peak 2
Peak 4
Peak 3
Peak 7,8,9,10,11
Peak 5
Peak 6
4
000
3500
3000
2500
2000
1500
1000
500
-
1
Wavenumber (cm )
Fig. 14 The infrared spectrum of component 5 during the reaction
OH
CH (CH ) CH OH
CH (CH ) CH O + H2O
3
2 10
2
3
2 10
2
(
R4)
OH
-
OH
H
O
H + CH3(CH2)10CH2O
+
CH2
CHCH2Cl
CH3(CH2)10CH2OCH2CHCH2Cl
O
Component 4
(
R5)
OH
CH3(CH2)10CH2OCH2CHCH2Cl + OH
HO
H O
CH3(CH2)10CH2OCH2CHCH2 Cl
CH3(CH2)10CH2OCH2CH
CH2
+
Cl
+
H2O
O
Product (a)
(
R6)
-
HCl
CH (CH ) CH OCH CHOCH CH
CH2
CH3(CH2)10CH2OCH2CHCH2Cl + ClCH2CH
CH2
3
2
10
2
2
2
CH2Cl
OH
O
O
Component 4
Component 2
(
R7)
Scheme 2 The reaction mechanism for synthesis 2-(dodecyloxymethyl)oxirane
(
peak 3) is assigned to methylene symmetrical stretching. The absorption at
-
1
-1
1 (peak 4) and 1,347 cm
unsymmetrical changing angle vibration. The absorption at 1,236 cm (peak 6)
,460 cm
(peak 5) is assigned to methylene
-
1
-
1
originates from the deformation vibration of O–H. The absorption at 1,075 cm
1
23

A novel betaine-type asphalt emulsifier
611
-
peak 7) is assigned to C–O stretching. The absorption at 753 cm (peak 8) is
1
(
assigned to methylene in-plane swing vibration. Therefore, the spectrum of
component 3 obtained by online FTIR agrees with the chemical structure of lauryl
alcohol.
-
1
In the FTIR spectrum of component 4 (Fig. 13), the absorption at 3,260 cm (peak
-
1
) is assigned to O–H stretching. The absorption at 2,962 cm (peak 2) is assigned to
1
methyl unsymmetrical stretching. The absorption near 2,926 cm
-
1
(peak 3) is
-
1
assigned to methylene unsymmetrical stretching. The absorption near 2,873 cm
peak 4) is assigned to methyl symmetrical stretching. The absorption near
(
-
,853 cm (peak 5) is assigned to methylene symmetrical stretching. The absorption
1
2
near 1,649 cm (peak 6) is assigned to the O–H bending. The absorption at
-
1
-
1
1
,465 cm
vibration. The absorption at 1,265 cm (peak 8) originates from the methylene out-
(peak 7) is assigned to methylene unsymmetrical changing angle
-
1
-
of-plane swing vibration. The absorption at 1,125 cm (peak 9) is assigned to
1
-
asymmetrical stretching vibration of C–O–C. The absorption at 1,075 cm (peak 10)
1
-
is assigned to C–O stretching. The absorption near 855 cm (peak 11) is assigned to
1
-
1
C–Cl stretching. The absorption at 721 cm (peak 12) is assigned to methylene in-
plane swing vibration. Therefore, the spectrum of component 4 obtained by online
FTIR could that of the intermediate shown in Scheme 2.
-
1
In the FTIR spectrum of component 5 (Fig. 14), the absorption at 3,002 cm
peak 1) is assigned to C–H stretching in the epoxy group. The absorption near
(
-
1
2
,829 cm
absorption at 1,570 cm
(peak 2) is assigned to methylene symmetrical stretching. The
-
1
-1
(peak 3) and 1,426 cm
methylene unsymmetrical changing angle vibration. The absorption at 1,265 cm
(peak 4) is assigned to
-
1
-
1
(
(
peak 5) originates from vibration of the epoxy group. The absorption at 1,190 cm
peak 6) is assigned to asymmetrical stretching vibration of C–O–C. The absorption
-
1
at 960–924 cm (peaks 7, 8) is assigned to the epoxy group. The absorption near
-1
8
-
48 cm (peak 9) is assigned to C–Cl stretching. The absorption at 760–735 cm
1
(peaks 10, 11) is assigned to methylene in-plane swing vibration. Therefore, the
spectrum of component 5 obtained by online FTIR could be that of epichlorohydrin.
Figure 15 shows the dependence of the relative concentrations (c) of components
–5 on reaction time. As shown in Fig. 15, the relative concentration of component
increases sharply 40 min after epichlorohydrin was added, then remains constant.
1
1
The relative concentration of component 1 decreases gradually with reaction time
after 3 h, which is because of the side reaction shown in Scheme 2. Therefore,
intermediate 1 could be the target compound of the synthesis, product a, in
accordance with the changing trend of concentration and the online FTIR spectrum
shown in Fig. 10.
The relative concentration of component 5 decreases sharply 40 min after
epichlorohydrin was added, then decreases gradually with reaction time. Compo-
nent 5 could be epichlorohydrin, in accordance with the changing trend of
concentration and the online FTIR spectrum shown in Fig. 14.
The relative concentration of component 3 decreases sharply 40 min after
epichlorohydrin was added, then keeps constant. Component 3 could be lauryl
alcohol, in accordance with the changing trend of concentration and the online FTIR
spectrum shown in Fig. 12.
123

612
C. Huai et al.
2
1
1
1
1
1
0
8
6
4
2
0
8
6
4
2
0
5
3
1
2
4
0
1
2
3
4
5
6
7
t (h)
Fig. 15 Dependence on time of the relative concentrations of components 1–5
The relative concentration of component 4 decreases gradually with reaction time
in the first stage, then keeps constant. Component 4 could be an intermediate, as
shown in Scheme 2, in accordance with the changing trend of concentration and the
online FTIR spectrum shown in Fig. 13.
The relative concentration of component 2 increases slightly with reaction time.
Component 2 could be a by-product, as shown in Scheme 2, in accordance with the
changing trend of concentration and the online FTIR spectrum shown in Fig. 11.
Reaction mechanism of synthesis 2-(dodecyloxymethyl)oxirane
For reaction R1 we proposed Scheme 2, as shown in reactions R4–R6, on the basis
of the spectra obtained by online FTIR (Figs. 10, 11, 12, 13, 14) and the trends of
the changing concentrations of the five components in Fig. 15. Component 4 is an
intermediate in the synthesis 2-(dodecyloxymethyl)oxirane. As shown in reaction
R4, lauryl alcohol is ionized in a highly basic environment. The alcohol anion is a
strong nucleophile, and attacks the less substituted carbon atom of epichlorohydrin
in an S 2 reaction (reaction R5). The intermediate component 4 is formed.
N
Cyclization of component 4 forms product a in reaction R6. Reaction R7 is a side
reaction producing component 2 from component 4.
CMC and surface tension
Figure 16 shows the plot of surface tension (r) versus the logarithm of the
concentration of product c at 298 K. The surface tension decreased sharply at first
-
then remained stable. The CMC has a lower value of 8.8 9 10 mol/L, which is
5
located at the turning point of the curve. The surface tension at the CMC is
2
1.2 mN/m.
1
23

A novel betaine-type asphalt emulsifier
613
5
4
4
3
3
2
2
1
0
5
0
5
0
5
0
5
σ
-6.0
-5.5
-5.0
-4.5
-4.0
-3.5
lgc
Fig. 16 Plot of surface tension against the logarithm of the concentration of product c
Mixing performance
The emulsifier c is an excellent emulsifier for asphalt. The prepared bituminous
emulsion had higher storage stability. No separation of aqueous phase and asphalt
phase occurred after 5 days. The mixing time was 30 s, which indicates the
emulsifier is a rapid-set asphalt emulsifier. It can be designed to perform in a wide
variety of applications including tack coat, fog seal, and solventless cold mix
applications, for example recycling and base stabilization in asphalt pavement
construction.
Conclusions
A novel betaine-type asphalt emulsifier was synthesized in three steps by reaction of
lauryl alcohol, epichlorohydrin, dimethylamine, and chloroacetic acid. The
optimum reaction conditions were obtained for the first step, synthesis of
2
-(dodecyloxymethyl)oxirane. The intermediate was detected by use of online
FTIR analysis during the first step of synthesis of 2-(dodecyloxymethyl)oxirane. On
the basis of the experimental data, a plausible reaction mechanism was proposed
-
5
for the reaction. The product has a low CMC, 8.8 9 10 mol/L. The surface
tension at the CMC is 21.2 mN/m. The emulsifier of the product is a rapid-set
asphalt emulsifier. It can be designed to perform in a wide variety of applications
including tack coat, fog seal, and solventless cold mix applications, for example
recycling and base stabilization in asphalt pavement construction.
123

614
C. Huai et al.
References
1. H.I. Al-abdul Wahhab, I.M. Asi, Build. Environ. 32, 271–279 (1997)
2
. L.E. Ch a´ vez-valencia, E. Alonso, A. Manzano, J. P e´ rez, M.E. Contreras, C. Signoret, Constr. Build.
Mater. 21, 583–589 (2007)
3
4
5
6
7
8
9
. Y. Niazi, M. Jalili, Constr. Build. Mater. 23, 1338–1343 (2009)
. H.H. Moorer, USP 4088505, 9 May 1978
. W.T. Zdybak, USP 4427449, 24 Jan 1984
. M.W. Shuey, R. S. Custer, USP 5650000, 15 Jul 1997
. H.G. Schreuders, P. Schilling, USP 4447269, 5 May 1984
. A. Jada, C. Florentin, S. Mariotti, Adv. Colloid Interface Sci. 108–109, 127–132 (2004)
. H. Shirai, Y. Tsushima, J. Sasaya, K. Komiya, JP 2001329176, 27 Nov 2001
1
1
1
1
0. P. Schilling, USP 6077888, 20 Jun 2000
1. G.G.I. Moore, M.S. Terrazas, USP 7164041, 16 Jan 2007
2. D.J. Tracy, R.X. Li, M.S. Dahanayake, J. Yang, USP 6204297. 20 Mar 2001
3. Y. Tomokzau, B. Miri, M. Keisuke, H. Chikako, E. Kazutoyo, J. Colloid Interface Sci. 339, 230–235
(2009)
14. L. Shi, Z. Wan, L. Wang, Y. Xue, J. Shandong Univ (Eng Sc) 37, 122–126 (2007)
15. P.E. Graf, S.J. Agazzi, E.J. Vanderzanden, USP 4985079, 15 Jan 1991
1
6. M. Vel a´ zquez M, F. Ortega, F. Monroy, R.G. Rubio, S. Pegiadou, L. P e´ rez, M.R. Infante, J. Colloid
Interface Sci. 283, 144–152 (2005)
17. J.L. Bigorra, N.B. Gilabert, M.O. Hernandez, X.C. Cruxens, R.P. Subirana, USP 6015780, 18 Jan
2000
1
1
8. J.M. Gonzalez, M.J. Bermejo, R.M. Barcelo, J. Vilaret, N. Siscart, USP 6683033, 27 Jan 2004
9. M. Chorro, N. Kamenka, B. Faucompre, M. Lindheimer, R. Zana, Colloids Surf A 110, 249–261
(1996)
20. Y. Tomokazu, I. Tomoko, K. Megumi, E. Kunio, Colloids Surf A 273, 208–212 (2006)
21. E.J. Pancheri, M.H.K. Mao, USP 5167872, 1 Dec 1992
22. M. Hellsten, I. Harwigsson, USP 5902784, 11 May 1999
1
23