Synthesis of Gemini Surfactants from N-Halosuccinimide

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Ind. Eng. Chem. Res. 2007, 46, 983-986

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RESEARCH NOTES Synthesis of Gemini Surfactants from N-Halosuccinimide-Dimercaptoethane Cohalogenation of Olefinic Fatty Methyl Esters Sukhprit Singh* and Bhupinderpal Singh Department of Chemistry, Guru Nanak DeV UniVersity, Amritsar 143 005, India

Olefinic fatty methyl esters (undec-10-enoate (1), octadec-Z,9-enoate (2), methyl 12-hydroxyoctadec-Z,9enoate (3)), on reaction with N-halosuccinimides (4 and 5), i.e., N-bromosuccinimide (NBS, 4) or N-chlorosuccinimide (NCS, 5), and dimercaptoethane (6) in diethylether gave the gemini surfactants (β,β′dibromodithioethers) (7-12). Introduction

Scheme 1. Gemini Surfactants

Non-ionic hydrophilic alkyl thiol surfactants are used in selfassembly films on gold surfaces,1 in stabilizing metal nanoclusters,2 and in self-assembled architectures of metal clusters.3 They also find applications in biotechnology4 and in chemical sensing.5 Geminis are used as promising surfactants in industrial detergency and have shown efficiency in skin care, antibacterial property, metal-encapped porphyrazine and vesicle formation, construction of high-porosity materials, antipollution protocols, analytical separations, nanoscale technology, biotechnology, enhanced oil recovery, and paint additives.6 They have also been used in the synthesis of new mesoporous zeolites for catalysis and adsorption applications.7 The cohalogenation of alkenes with halogens and nucleophilic solvents like water, diemethylsulfoxides, dimethylformamide, carboxylic acids, alcohols, nitriles, and ethers is well-documented,8 but little work has been carried out on sulfur containing nucleophiles forming the C-S bond. Few reactions have also been reported in the literature describing the incorporation of thiocynate or the sulfone functionality by cohalogenation of an olefin in the presence of thiocyanate9-12 or by using sodium benzene sulfonate.13 A recent report14 described the reaction of N-bromosuccinimide and dimercaptoethane in diethyl ether to form β,β′-dibromodithioethers from alkenes. In our earlier work, we reported a new synthetic strategy for the synthesis of β-haloethoxylates15 and β-halothioethoxylates16 from olefinic fatty methyl esters. In continuation of our research, an attempt has been made to prepare gemini surfactants using the cohalogenation reaction of N-bromosuccinimide (NBS) or N-chlorosuccinimide (NCS) followed by the addition of dimercaptoethane to the olefinic fatty methyl esters, i.e., undec-10-enoate, octadec-Z,9-enoate, and methyl 12hydroxyoctadec-Z,9-enoate. Results and Discussion The cohalogenation reaction of bifunctional substrates with olefins can be used to prepare molecules where the bifunctional substrates act as a spacer in the dimeric olefin. In the present study, we have made an attempt to apply the strategy on the terminally unsaturated (undec-10-enoic) and internally unsatur* To whom correspondence should be addressed. E-Mail: [email protected]. Phone: +919855557324.

ated (oleic and ricinoleic) acid methyl esters for the synthesis of gemini surfactants. The olefinic fatty methyl esters (undec10-enoate (1), octadec-Z,9-enoate (2), methyl 12-hydroxyoctadec-Z,9-enoate (3)) on reaction with N-halosuccinimides (Nbromosuccinimide; NBS, 4) or (N-chlorosuccinimide; NCS, 5) and 1,2-dimercaptoethane (6) in diethyl ether yielded the respective gemini surfactants 7a/7b-12a/12b (Scheme 1), the chromatographically inseparable isomeric mixture. The structure of these gemini surfactants has been established by their elemental analysis, mass, IR, and 1H and 13C nuclear magnetic resonance (NMR) spectroscopic analysis. The elemental analysis and mass spectroscopy confirmed the formation of dimer molecule. The CHNSO (carbon, hydrogen, nitrogen, sulfur, oxygen) analysis would have given different results if only the monomer had been formed. The elemental analysis of the product 7a/7b confirmed the dimeric molecular formula C26H48O4S2Br2. The IR spectra of the product 7a/7b gave a sharp peak at 1730 cm-1 for the carbonyl of the ester. The C-S stretching was observed at 1450, 1375, and 1225 cm-1. The C-O stretching occurs at 1174, 1110, and 1099 cm-1 along with

10.1021/ie061333t CCC: $37.00 © 2007 American Chemical Society Published on Web 01/09/2007

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Figure 1. Proposed mechanism.

C-Br stretching at 667 cm-1. The formation of a chromatographically inseparable positional isomeric mixture was as expected for internal olefinic ester but was surprising with terminal 10-undecenoate. The formation of positional isomers in the case of 10-undecenoate was confirmed by the presence of double signals in both the 1H and the 13C NMR spectrum. However, the integration of peaks in the 1H NMR indicates that the yield of isomer involving anti-Markovnikov’s addition, i.e., 10-bromo-11-[2-(2-bromo-10-methoxycarbonyldecylsulfanyl)ethylsulfanyl]undecanoic acid methyl ester (7a) was much higher as compared to isomer involving Markovnikov’s addition. A probable mechanism involving the formation of bromonium ion may have led to the isomer 7a. However, in the present study, the formation of both positional isomers has been observed in all the cases. This may be explained by the dual type of mechanism (Figure 1), i.e., the nucleophilic attack of dimercaptoethane on to the cyclic bromonium ion with steric factors leading to the formation of 10-bromo-11-[2-(2-bromo-10methoxycarbonyldecylsulfanyl)ethylsulfanyl]undecanoic acid methyl ester (7a) (anti-Markovnikov’s addition) with the stabilization of an acyclic carbocation by the highly nucleophilic reagent (dimercaptoethane) leading to the Markovnikov’s addition to give 11-bromo-10-[2-(2-bromo-10-methoxycarbonyldecylsulfanyl)ethylsulfanyl]undecanoic acid methyl ester (7b). The results in the present study are similar to those reported earlier by Younes et al.14 In the 1H NMR spectra of the product 7, the proton bonded to C-10 was observed at its distinct position of δ 4.1 for CH-Br (product 7a) as a multiplet, a singlet for 12 protons at δ 3.6 was assigned to CH3OCO, and the protons attached to C-11 (CH2-Br for product 7b) were observed at δ 3.37 as a doublet. Another multiplet at δ 2.97-3.01 was assigned to δ CH-S (product 7b). The protons attached to C-11 (CH2S, product 7a) were observed as a broad singlet at 2.7. The other protons have been observed at their normal positions. The formations of these isomers were further confirmed by the presence of a signal for both the carbons CH-Br at a chemical shift of δ 55.13 (7a) and CH-S at a chemical shift of δ 47.37 (7b) along with a signal at δ 174.30 for COOCH3. The nature of these carbons had been confirmed by the DEPT (distortionless

enhancement by polarization transfer) experiment, where the polarities of both these signals were reversed along with a signal at chemical shift of δ 51.41 (OCH3). The other peaks were observed at δ 40.95, 40.20 for (CH2-S), δ 38.61 for CH2-Br, and so on. The structure of compound 7a/7b has further been confirmed by the electrospray mass spectrometry, where the parent ion M+ and M+ + 2 has been observed at m/z 648 and m/z 650, respectively. The major R-cleavage ions were observed at m/z 647, 558, 554, 479, 475, 383, 339, 337, 313, 311, 265, and 263 for major isomer 7a and m/z 647, 555, 553, 479, 475, 339, 337, 313, and 311 for minor isomer 7b. The CHNSO analysis and mass spectroscopy in the case of product 8a/8b again confirmed the formation of a dimer molecule with molecular formula C26H48O4S2Cl2. The IR spectra of the product gave a sharp peak at 1725 cm-1 for a carbonyl of the ester. The C-S stretching was observed at 1455, 1377, and 1215 cm-1. The C-O stretching occurs at 1170, 1150, and 1099 cm-1 along with C-Cl stretching at 759 cm-1. Similarly in the 1H NMR spectra of the product, the proton bonded to C-10 was observed at its distinct position of δ 4.01 for CH-Cl (8a) as a multiplet and at δ 3.0 as a multiplet for -CH-S (8b). A singlet at δ 3.66 has been assigned to CH3OCO, a doublet at δ 3.3 was assigned to CH2-Cl (8b), whereas another doublet merged with a triplet δ 2.76 was assigned to CH2-S (8a). The other protons have been observed at their normal positions. The 13C NMR spectra of the product gave structure-revealing signals at δ 54.34 for CH-Cl (8a), δ 46.15 for CH-S (8b), δ 40.73 and δ 40.34 for CH2-S, and δ 37.57 for CH2-Cl carbons. The other carbons have been observed at their normal chemical shifts. The structure of compound 8a/8b has further been confirmed by the electrospray mass spectrometry, where the parent ion M+ and M+ + 2 has been observed at m/z 559 and m/z 561, respectively. The major R-cleavage ions were observed at m/z 558, 469, 465, 386, 341, 325, 235, and 219 for major isomer 8a and m/z 558, 511, 509, 469, 465, 386, 325, and 235 for minor isomer 8b. The structure of the other compounds 9a/9b-12a/ 12b has also been assigned on the basis of elemental analysis, IR, 1H NMR, 13C NMR, and electrospray mass spectroscopic studies. Experimental Section Undec-10-enoic acid, octadec-Z,9-enoic acid, and N-chlorosuccinimide (NCS) were purchased from Loba Chemicals, Mumbai, India. N-Bromosuccinimide (NBS) and 2-mercaptoethanol were purchased from Central Drug House, New Delhi, India. Dimercaptoethane was purchased from HiMedia Laboratories, Pvt. Ltd., Mumbai, India. 12-Hydroxyoctadec-Z,9-enoic acid was isolated from seed oil of Ricinus Communis (castor oil) by the Gunstone partition method.17 Thin-layer chromatography (TLC) was carried out on silica-gel-G-coated (0.25mm thick) plates with petroleum ether/diethyl ether/acetic acid (80:20:1) or (60:40:1) as the mobile phase. Spots were visualized by iodine. Instrumentation. Elemental analysis was recorded on a Thermo Electron (U.K.) made Flash EA 1112 Series CHNSO analyzer. The electrospray mass spectra were recorded on a Micromass Quattro II (Manchester, U.K.) triple quadrupole mass spectrometer at Central Drug Research Institute (CDRI), Lukhnow (India). The samples (dissolved in methanol) were introduced into the electrospray ionization (ESI) source through a syringe pump at the rate of 5 µL/min. The ESI capillary was set at 3.5 kV, and the cone voltage was 40 V. The spectra were collected as printouts in six scans. The IR spectrum was recorded

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as a thin neat film on a Shimadzu FT-IR 8400s (Kyoto, Japan) instrument. 1H and 13C nuclear magnetic resonance (NMR) were recorded on Jeol FT-NMR 300 MHz (AL-300; Tokyo, Japan) as a solution in CDCl3 using tetramethyl silane (TMS) as an internal standard. General Procedure The fatty acids undec-10-enoic, octadec-Z,9-enoic, and 12hydroxyoctadec-Z,9-enoic were esterified with dry methanol in the presence of concentrated sulfuric acid (as a catalyst) to obtain methyl undec-10-enoate (1), methyl octadec-Z,9-enoate (2), and methyl 12-hydroxyoctadec-Z,9-enoate (3), respectively. The esters were purified to a homogeneous product by column chromatography before further reaction. Dimercaptoethane (6; 0.94 g, 10 mmol) was added dropwise over 30 min to a stirred solution of methyl undec-10-enoate (1; 3.96 g, 20 mmol) or methyl octadec-Z,9-enoate (2; 5.92 g, 20 mmol) or methyl 12hydroxyoctadec-Z,9-enoate (3; 6.24 g, 20 mmol) and Nbromosuccinimide (4; 3.56 g, 20 mmol) or N-chlorosuccinimide (5; 2.44 g, 20 mmol) in diethyl ether (50 mL) at 0 °C under nitrogen. After addition, the reaction mixture was stirred at room temperature for 1 h. The crude reaction mixture was filtered. The filtrate was taken in a separating funnel and washed with water. The ether layer was dried over sodium sulfate. The evaporation and subsequent fractionation on a silica gel (60120 mesh) column chromatography using hexane, hexane/ chloroform (90:10 to 50:50), and chloroform/methanol (98:2) (stepwise increasing polarity elution method) yielded the respective non-ionic gemini surfactants 7-12 (Scheme 1) in >80% yield. Spectral Results 10(11)-Bromo-11(10)-[2-(2-bromo-10-methoxycarbonyldecylsulfanyl)ethylsulfanyl]undecanoic acid methyl ester (7). 3.52 g, 88.9%; pale yellow liquid, (hexane/chloroform, 50:50); IR νj (cm-1) neat: 667 (C-Br, str.), 1099, 1110, 1174 (C-O, str), 1225, 1375, 1450 (C-S, str.), 1730 (CdO, ester str); 1H NMR (CDCl3): δ 1.2-1.3 (br s, 48H chain CH2), 1.6 (m, 8H, 4X-CH2-CH2-CO2), 2.3 (t, J ) 7.5 Hz, 8H, 4X-CH2-CO2), 2.76 (br s, 8H, 4X-CH2-S), 2.88 (d, J ) 8.7 Hz, 4H, 2XCH2-S), 2.97-3.01 (m, 2H, 2X-CH-S), 3.37 (d, J ) 4.0 Hz, 4H, 2X-CH2-Br), 3.6 (s, 12H, 4X-CH3-O-CO), 4.05-4.09 (m, 2H, 2X-CH-Br); 13C NMR (normal/DEPT-135) (CDCl3): δ 24.59, 24.82, 25.61, 26.65, 27.22, 29.02, 29.24, 29.43, 31.17, 32.52, 33.17, 33.85, 34.02, 36.16 (-ve, chain CH2), 38.61 (-ve, CH2-Br), 40.20, 40.95 (-ve, CH2-S), 46.37 (+ve, CH-S), 51.41 (+ve, COOCH3), 55.13 (+ve, CHBr), 174.30 (+ve, COOCH3); MS m/z: 648 [M+], 650 [M+ + 2], 647, 558, 554, 479, 475, 383, 339, 337, 313, 311, 265, 263 (R-cleavage ions for major isomer), 647, 555, 553, 479, 475, 339, 337, 313, 311 (R-cleavage ions for minor isomer). Calcd for C26H48O4S2Br2: C, 48.15%; H, 7.46; and S, 9.89%. Found: C, 48.25%; H, 7.41%; and S, 9.97%. 10(11)-Chloro-11(10)-[2-(2-chloro-10-methoxycarbonyldecylsulfanyl)ethylsulfanyl]undecanoic acid methyl ester (8). 3.50 g, 88.4%; pale yellow liquid, (hexane/chloroform, 50:50); IR νj (cm-1) neat: 759 (C-Cl, str.), 1099, 1150, 1170 (C-O, str), 1215, 1377, 1455 (C-S, str.), 1725 (CdO, ester str); 1H NMR (CDCl3): δ 1.2-1.3 (br s, 48H chain CH2), 1.6 (m, 8H, 2X-CH2-CH2-CO2), 2.3 (t, J ) 7.5 Hz, 8H, 2X-CH2-CO2), 2.76 (br s, 8H, 4X-CH2-S), 2.86 (d, J ) 7.5 Hz, 4H, 2XCH2-S), 3.0 (m, 2H, 2X-CH-S), 3.3 (d, J ) 3.9 Hz, 4H, 2X-CH2-Cl), 3.66 (s, 12H, 4X-CH3-O-CO), δ 4.07 (m,

2H, 2X-CH-Cl); 13C NMR (normal/DEPT-135) (CDCl3): δ 23.78, 24.57, 24.75, 25.54, 26.05, 28.94, 29.57, 31.37, 31.80, 33.65, 33.89, 33.96, 36.13 (-ve, chain CH2), 37.57 (-ve, CH2Cl), 40.34, 40.73 (-ve, CH2-S), 46.15 (+ve, CH-S), 51.30 (+ve, COOCH3), 54.34 (+ve, CHCl), 174.27 (+ve, COOCH3); MS m/z: 559 [M+], 561 [M+ + 2], 558, 469, 465, 386, 341, 325, 235, 219 (R-cleavage ions for major isomer), 558, 511, 509, 469, 465, 386, 325, 235 (R-cleavage ions for minor isomer). Calcd for C26H48O4S2Cl2: C, 55.19%; H, 8.64%; and S, 11.46%. Found: C, 55.27%; H, 8.62%; and S, 11.55%.. 9(10)-Bromo-10(9)-[2-(2-bromo-9-methoxycarbonyl-1-octylnonylsulfanyl)ethylsulfanyl]octadecanoic acid methyl ester (9). 4.94 g, 83.4%; pale yellow liquid, (hexane/chloroform, 50: 50); IR νj (cm-1) neat: 669 (C-Br, str.), 1090, 1185 (C-O, str), 1248, 1385, 1460 (C-S, str.), 1730 (CdO, ester str); 1H NMR (CDCl3): δ 0.8-0.9 (t, J ) 6.9 Hz, 12H, 4X-CH3), 1.21.3 (br s, 96H, chain CH2), 1.6 (m, 8H, 4X-CH2-CH2-CO2), 2.3 (t, J ) 7.5 Hz, 8H, 4X-CH2-CO2), 2.7 (s, 8H, 4X-CH2S), 2.86-3.0 (m, 4H, 4X-CH-S), 3.67 (s, 12H, 4X-CH3O-CO), 4.06 (m, 4H, 4X-CH-Br); 13C NMR (normal/DEPT135) (CDCl3): δ 14.05 (+ve, terminal CH3), 22.61, 24.67, 24.87, 25.82, 27.33, 27.46, 27.70, 28.12, 28.56, 29.05, 29.16, 29.26, 29.64, 29.80, 29.90, 30.90, 31.83, 33.80, 34.03, 34.36 (-ve, chain CH2), 38.83 (-ve, CH2-S), 47.07 (+ve, CH-S), 51.40 (+ve, CO2CH3), 54.86 (+ve, CH-Br), 174.24 (+ve, COOCH3); MS m/z: 845, [M+], 847 [M+ + 2], 755, 751, 734, 730, 690, 686, 641, 639, 595, 593, 437, 435, 409, 407, 251, 249, 207 (R-cleavage ions for both isomers). Calcd for C40H76O4S2Br2: C, 56.86%; H, 9.07%; and S, 7.59%. Found: C, 56.95%; H, 9.10%; and S, 7.67%. 9(10)-Chloro-10(9)-[2-(2-chloro-9-methoxycarbonyl-1-octylnonylsulfanyl)ethylsulfanyl]octadecanoic acid methyl ester (10). 4.90 g, 82.7%; pale yellow liquid, (hexane/chloroform, 50:50); IR νj (cm-1) neat: 748 (C-Cl, str.), 1091, 1190 (C-O, str), 1265, 1375, 1458 (C-S, str.), 1735 (CdO, ester str); 1H NMR (CDCl3): δ 0.8-0.9 (t, J ) 5.1 Hz, 12H, 4X-CH3), 1.21.3 (br s, 96H, chain CH2), 1.6 (m, 8H, 4X-CH2-CH2-CO2), 2.3 (t, J ) 7.2 Hz, 8H, 4X-CH2-CO2), 2.88 (br s, 8H, 4XCH2-S), 3.01-3.09 (m, 4H, 4X-CH-S), 3.66 (s, 12H, 4XCH3-O-CO), 4.30-4.37 (m, 4H, 4X-CH-Cl); 13C NMR (normal/DEPT-135) (CDCl3): δ 14.00 (+ve, terminal CH3), 22.55, 24.12, 24.78, 26.91, 28.90, 28.98, 29.52, 31.72, 33.96 (-ve, chain CH2), 37.55, 38.80 (-ve, CH2-S), 47.07 (+ve, CH-S), 51.36 (+ve, CO2CH3), 61.09 (+ve, CH-Cl), 174.16 (+ve, COOCH3); MS m/z: 755 [M+], 757 [M+ + 2], 662, 641, 605, 603, 601, 597, 551, 549, 393, 391, 365, 363, 207, 205, 163, 161 (R-cleavage ions for both isomers). Calcd for C40H76O4S2Cl2: C, 63.54%; H, 10.13%; and S, 8.48%. Found: C, 63.59%; H, 10.21%; and S, 8.55%. 9(10)-Bromo-10(9)-{2-[2-bromo-1-(2-hydroxyoctyl)-9-methoxycarbonylnonylsulfanyl}-12-hydroxyoctanoic acid methyl ester (11). 5.30 g, 82.3%; pale yellow liquid, (hexane/ chloroform, 50:50); IR νj (cm-1) neat: 667 (C-Br, str.), 1050, 1090, 1180 (C-O, str), 1250, 1365, 1460 (C-S, str.), 1730 (Cd O, ester str), 3450 (OH, str); 1H NMR (CDCl3): δ 0.88 (t, J ) 5.2 Hz, 12H, 4X-CH3), 1.2-1.3 (br s, 88H, chain CH2), 1.6 (m, 8H, 4X-CH2-CH2-CO2), 2.3 (t, J ) 7.5 Hz, 8H, 4XCH2-CO2), 2.86 (br s, 8H, 4X-CH2-S), 3.01-3.09 (m, 4H, 4X-CH-S), 3.66 (s, 12H, 4X-CH3-O-CO), 3.80-3.88 (m, 4H, 4X-CH-OH), 4.18-4.22 (m, 4H, 4X-CH-Br); 13C NMR (normal/DEPT-135) (CDCl3): δ 14.05 (+ve, terminal CH3), 22.55, 24.61, 24.90, 25.49, 26.66, 27.28, 27.50, 28.47, 28.96, 29.30, 29.45, 31.73, 33.86, 35.26, 36.74, 37.88 (-ve, chain CH2), 43.00 (-ve, CH2-S), 47.44 (+ve, CH-S), 51.44 (+ve,

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CO2CH3), 56.66 (+ve, CH-Br), 69.42, 71.58 (+ve, CH-OH), 174.33 (+ve, COOCH3); MS m/z: 877 [M+], 879 [M+ + 2], 787, 783, 750, 746, 722, 718, 657, 655, 611, 609, 453, 451, 425, 423, 251, 249, 223, 221 (R-cleavage ions for both isomers). Calcd for C40H76O6S2Br2: C, 54.78%; H, 8.74%; and S, 7.31%. Found: C, 54.87%; H, 8.71%; and S, 7.38%. 9(10)-Chloro-10(9)-{2-[2-chloro-1-(2-hydroxy-octyl)-9-methoxycarbonylnonylsulfanyl}-12-hydroxyoctanoic acid methyl ester (12). 5.30 g, 82.3%; pale yellow liquid, (hexane/ chloroform, 50:50); IR νj (cm-1) neat: 760 (C-Cl, str.), 1045, 1095, 1199 (C-O, str), 1278, 1380, 1460 (C-S, str.), 1735 (Cd O, ester str), 3435 (OH, str); 1H NMR (CDCl3): δ 0.88 (t, J ) 6.6 Hz, 12H, 4X-CH3), 1.2-1.3 (br s, 88H, chain CH2), 1.6 (m, 8H, 4X-CH2-CH2-CO2), 2.3 (t, J ) 7.5 Hz, 8H, 4XCH2-CO2), 2.88 (br s, 8H, 4X-CH2-S), 3.02-3.10 (m, 4H, 4X-CH-S), 3.66 (s, 12H, 4X-CH3-O-CO), 3.82-3.88 (m, 4H, 4X-CH-OH), 4.37-4.42 (m, 4H, 4X-CH-Cl); 13C NMR (normal/DEPT-135) (CDCl3): δ 14.04 (+ve, terminal CH3), 22.57, 24.84, 25.87, 26.85, 27.33, 29.04, 30.88, 31.74, 34.04, 35.32, 36.83, 37.60, 38.02 (-ve, chain CH2), 40.40 (-ve, CH2S), 48.64 (+ve, CH-S), 51.42 (+ve, CO2CH3), 61.06 (+ve, CH-Cl), 68.69 (+ve, CH-OH), 174.24 (+ve, COOCH3); MS m/z: 788 [M+], 790 [M+ + 2], 698, 694, 661, 657, 633, 629, 621, 567, 565, 409, 407, 381, 379, 207, 205, 179, 177 (R-cleavage ions for both isomers). Calcd for C40H76O6S2Cl2: C, 60.96%; H, 9.72%; and S, 8.14%. Found: C, 60.98%; H, 9.81%; and S, 8.19%. Conclusion In the present study, six new gemini surfactants have been synthesized and characterized. A new strategy has been described to synthesize the gemini surfactants from terminal and internal olefinic fatty methyl esters. Acknowledgment The authors are thankful to CSIR (Council of Scientific & Industrial Research), India, for providing a research grant for this work and CDRI (Central Drug Research Institute), Lucknow, for the mass spectra of the compounds. Literature Cited (1) Ulman, A. Formation and Structure of Self-Assembled Monolayers. Chem. ReV. 1996, 96, 1533-1554.

(2) Hostetler, M. J.; Murray, R. W. Colloids and self-assembled monolayers. Curr. Opin. Colloid Interface Sci. 1997, 2, 42-50. (3) Shipway, A. N.; Katz, E.; Wilner, I. Photochemistry of chromophorefunctionalized gold nanoparticles. Chem. Phys. Chem. 2000, 1, 18-52. (4) Silin, V.; Weetall, H.; Vanderah, D. J. SPR Studies of the Nonspecfic Adsorption Kinetics of Human Ig G and BSA on Gold Surfaces Modified By Self-Assembled Monolayers (SAMs). J. Colloid Interface Sci. 1997, 185, 94-103. (5) Wohtjen, H.; Snow, A. W. Colloidal Metal-Insulator-Metal Ensemble Chemiresistor Sensor. Anal. Chem. 1998, 70, 2856-2859. (6) Diamant, H.; Andelman, D. Models of gemini surfactants. In Gemini Surfactants: Interfacial and solution phase behaViour; Zana, R., Xia, J., Eds.; Marcel Dekker: New York, 2004. (7) Bnjelloum, M.; Van Der Voort, P.; Cool, P.; Collart, O.; Vansant, E. F. Reproducible synthesis of high quality MCM-48 by extraction and recuperation of the gemini surfactant. Chem. Phys. 2001, 3, 127-131. (8) Rodriguez, J.; Dulcere, J.-P. Cohalogenation in Organic Synthesis. Synthesis 1993, 1177-1205. (9) Woodgate, P. D.; Lee, H. H.; Rutledge, P. S.; Cambie, R. C. Synthesis of Vicinal Iodothiocyanates, Iodoisothiocyanates, and Iodoazides using Phase-Transfer Reagents. Synthesis 1997, 462-464. (10) Cambie, R. C.; Lee, H. H.; Rutledge, P. S.; Woodgate, P. D. VicIodothiocyanates and Iodoisothiocyanates. Part 1. Preparation and Isomerisation. J. Chem. Soc., Perkin Trans. 1 1979, 757-764. (11) Cambie, R. C.; Larsen, D. S.; Rutledge, P. S.; Woodgate, P. D. Bromothiocyanation of Alkenes. J. Chem. Soc., Perkin Trans. 1 1981, 5863. (12) Cambie, R. C., Rutledge, P. S.; Strange, G. A.; Woodgate, P. D. Vic-Iodothiocyanates and Iodoisothiocyanates. Addition of Iodine- Thiocyanogen to Alkenes under Ionic and Radical Conditions. J. Chem. Soc., Perkin Trans. 1983, 553-565. (13) Harwood, L. M.; Julia, M.; Le Thuillier, G. Organic synthesis with SulphonessXV11: The Anti-Markownikoff Halosulphonylation of olefins via an ionic pathway, and a new method of preparing benzenesulphonyl iodide. Tetrahedron 1980, 36, 2483-2487. (14) Younes, M. R.; Mohamed, M. C.; Ahmed, B. N-Bromosuccinimidedimercaptoethane cobromination of alkenes: Synthesis of β,β′-dibromodithioethers. Tetrahedron Lett. 2003, 44, 5263-5275. (15) Singh, S.; Singh, B. Synthesis of β-bromoethoxylates and β-chloroethoxylates from olefinic fatty methyl esters. J. Surfactants Deterg. 2006, 9, 51-56. (16) Singh, S.; Singh, B. N-Halosuccinimide-mercaptoethanol cohalogenation of olefinic fatty methyl esters: Synthesis of β-halo thioethoxylates. J. Surfactants Deterg. 2006, 9, 191-195. (17) Gunstone, F. D. Fatty Acids. Part II. The Nature of Oxygenated Acid present in Vernonia anthelmintica (Wild.) Seed Oil. J. Chem. Soc. 1954, 1611-1616.

ReceiVed for reView October 17, 2006 ReVised manuscript receiVed December 7, 2006 Accepted December 23, 2006 IE061333T