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J Surfact Deterg (2012) 15:419–431
efficiency of such agents is conditioned by their amphi-
philic nature. Various structural factors such as (1) struc-
ture and the chain length of the hydrophobic part [6–9], (2)
nature, number and the position of the hydrophilic part
[10], and (3) the hydrophobic-lipophilic balance (HLB) of
certain surfactants have been described. It has been shown
that the variety in the molecular structure of surfactants
leads to variations in their physicochemical properties [11,
12]. The secondary alkanesulfonates (SAS) are frequently
used as active matter in detergent formulations, as emul-
sifying agents and even in flotation. They are regarded as
specific anionic surfactants, because of their high chemical
stability, their better water solubility, their high compati-
bility with electrolytes, and their improved biodegradabil-
ity [13–15]. These surfactants are especially beneficial for
their lower critical micelle concentration (CMC), great
efficiency in lowering surface tension of water, excellent
detersive action and their efficacy to remove particulate
soils [16].
(Cmax) and the minimum molecular areas (Amin) at the air–
water interface were estimated. The hydrophilic-lipophilic
balance (HLB) values for the prepared compounds were
also calculated. The Krafft point, and foaming property
were systematically examined, and the effect of the length
of the hydrophobic part and the proportion of secondary
isomers on these properties were investigated.
Experimental Procedures
As mentioned in the previous work [19], high values of
conversion rate lead to good yields of the sulfochlorination
reaction, and a reduced chlorination molar ratio (RSO2Cl/
RCl). It was also noted that the best results were obtained
at a conversion rate of 80%. Also, the photosulfochlori-
nation of n-alkanes in the presence of aromatic solvent
leads to higher yields and reaction mixtures with high
percentage of secondary sulfochlorinated isomers [19, 20].
It is therefore interesting to apply these conditions set up
for n-tetradecane, n-hexadecane and n-octadecane.
The solubility is represented as a fundamental property,
and the most important attribute of the surfactant system is
its ability to efficiently reduce surface tension. Another
property to be considered is the foam power or foamability,
which is one of the essential characteristics for the for-
mulation of detergents, cosmetics, and similar composi-
tions. In most cases, nice, rich, and creamy foam is a signal
of efficacy [16]. Although, certain surfactants show a bad
foamability and foam stability in spite of their strong sol-
ubility in water, these characteristics are interesting for
applications requiring low foam, e.g. in products for dish-
washing machines. Furthermore, the Krafft point (KT), and
the Hydrophilic-Lipophilic Balance (HLB) are also
important, in order to know the temperature, and the field
of their applications as in solubilization, emulsification,
detergency, dispersion or wetting, respectively [17, 18].
In this paper, a homologue series of sodium salts of
secondary n-alkanesulfonates from n-alkanes with different
length chains (C14, C16 and C18), was prepared by a
photosulfo-chlorination process using sulfuryl chloride
with two different reaction conditions. The positional iso-
mers of n-alkanesulfonyl chlorides were analyzed simul-
taneously by gas phase chromatography (GPC) after
derivatization, and identified by gas chromatography cou-
pled to mass spectrometry using electronic impact mode
(GC-MS/EI). The chemical structures of synthesized sul-
fonates were confirmed by IR, and by liquid chromato-
graphy-electrospray tandem mass spectrometry (LC-ESI/
MS). Various isomeric distributions of these surfactants
having different length chains were obtained. Their critical
micelle concentrations (CMC) in aqueous solutions were
determined using specific conductivity and surface tension
measurements. Through surface tension isotherms, the
surface activity (cCMC), the surface absorption amount
Chemical Products
n-Tetradecane (Fluka, [99% pure), n-hexadecane (Fluka,
[99% pure), n-octadecane (Fluka, [97% pure), 1-chloro-
tetradecane (Aldrich, [98% pure), 1-chlorohexadecane
(Fluka, [98% pure), 1-chlorooctadecane (Fluka, [97%
pure), sulfuryl chloride (Aldrich, [97% pure), chloroben-
zene (Aldrich,[99% pure), pyridine (Fluka,[99.8% pure)
ethanol (Merck, 99.8%), N,N-diethylamine (Aldrich,[99.5%
pure), sodium hydroxide (Sigma-Aldrich, pure) and sodium
dodecylsulfate (Fluka, [98% pure). All others chemicals
were of commercial origin (Fluka), and were used without
further purification. Distilled water was used for preparing
solutions.
Instruments
IR spectra were recorded on a Perking Elmer Spectrometer
using KBr discs. GPC separations were recorded with a HP
Model 6890 gas chromatograph. A CPsil-5cb capillary
column 60 m 9 0.32 mm I.D, 25 lm film thickness was
used for the analysis with N2 as the carrier gas (0.36 ml/
mn). The gas chromatograph, HP Model 6800 was coupled
to an HP MSD Model 5973 mass spectrometer. The col-
umn used was a HP-INNOWax 60 9 0.25. I.D, 0.25 lm
film thickness with He as the carrier gas (0.7 ml/mn), and
the detection by EI (70 eV). Mass spectrometry was per-
formed in LC-MS/MS Waters ACQUIY (liquid chroma-
tography linked to tandem mass spectrometry) fitted with
an electrospray interface (ESI), and controlled by Mass-
Lynx software. The mass spectrometer was operated in the
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