Synthesis of Wax Esters from α-Olefins

long-chain fatty acids (such as lauric acid (4), myristic acid (5), or palmitic acid (6)) in ... 50% conversion of the R-olefin, yielding the wax este...
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Synthesis of Wax Esters from r-Olefins Sukhprit Singh,* Avinash Bhadani, and Bhupinderpal Singh Department of Chemistry, Guru Nanak DeV UniVersity, Amritsar 143 005, India

R-Olefins (1-octadecene (1) and 1-hexadecene (2)), when reacted with N-bromosuccinimide (NBS (3)) and long-chain fatty acids (such as lauric acid (4), myristic acid (5), or palmitic acid (6)) in dichloromethane at room temperature, resulted in ca. 50% conversion of the R-olefin, yielding the wax esters: dodecanoic acid 1-bromomethyl heptadecyl ester (7a)/dodecanoic acid 2-bromomethyl octadecyl ester (7b); tetradecanoic acid 1-bromomethyl heptadecyl ester (8a)/tetradecanoic acid 2-bromomethyl octadecyl ester (8b); hexadecanoic acid 1-bromomethyl heptadecyl ester (9a)/hexadecanoic acid 2-bromomethyl octadecyl ester (9b); dodecanoic acid 1-bromomethyl pentadecyl ester (10a)/dodecanoic acid 2-bromomethyl hexadecyl ester (10b); tetradecanoic acid 1-bromomethyl pentadecyl ester (11a)/tetradecanoic acid 2-bromomethyl hexadecyl ester (11b); and hexadecanoic acid 1-bromomethyl pentadecyl ester (12a)/hexadecanoic acid 2-bromomethyl hexadecyl ester (12b). Introduction Wax esters are oxo esters of long-chain fatty acids esterified with long-chain alcohols. Wax esters have a variety of uses in industry. They can be used as high-pressure lubricants, as replacements for hydraulic oil, and in the pharmaceuticals, cosmetics, printing, leather, and food industries, as well as in candles and polishes. They fulfill a variety of quite diverse and important biological functions. These functions include protection from desiccation, ultraviolet (UV) light, and pathogens (e.g., plant epicuticular waxes), structural functions (e.g., beeswax), regulation of buoyancy and/or sound transmission (e.g., Spermaceti oil of sperm whales). Today, wax esters are mainly produced chemically or by biotechnological processes that use immobilized lipases.1 However, even the lipase-based biotechnological wax ester production is dependent on fatty alcohols as substrates, which currently must be synthesized chemically. Thus, there is still a strong demand for the production of inexpensive jojoba-like wax esters that are produced completely from inexpensive renewable resources such as fatty acids. There are some reports2-4 on the preparation of wax esters via the esterification of fatty acids with long-chain alcohols and in moderate-to-good yield via the interesterification (alcoholysis) of triacylglycerols or natural fats and oils with long- chain alcohols.5-7 Petersson et al.8 recently reported the production of wax esters via solvent-free energy-efficient enzymatic synthesis. The co-halogenation of alkenes with halogens and nucleophilic solvents such as water, diemethylsulfoxides, dimethylformamide, carboxylic acids, alcohols, nitriles, and ethers is well-documented.9 In our earlier work, we have reported the synthesis of β-haloethers,10 haloethoxylates,11 and β-halothioethoxylates12 from olefinic fatty methyl esters. In continuation of our research, an attempt has been made to prepare wax esters using the co-halogenation reaction of N-bromosuccinimide (NBS, 3) and long-chain fatty acids (such as lauric acid (4), myristic acid (5), or palmitic acid (6)) on the R-olefins (i.e., 1-octadecene (1) and 1-hexadecene (2)). Results and Discussion Co-halogenation has been proven to be very useful for diverse synthetic applications,13 and it has an important role in the functionalization of natural products. The present study at* To whom correspondence should be addressed. Mobile Telephone: +919855557324. E-Mail: [email protected]

Figure 1. Infrared spectra of 7a/7b.

tempted to evolve a new synthetic strategy for the production of wax esters using the co-halogenation reaction. The reaction has been applied to terminal olefins. The terminal olefins (12), when reacted with NBS (3) and long-chain fatty acids (i.e., lauric acid (4), myristic acid (5), or palmitic acid (6)) resulted in ∼50% conversion of the R-olefin to the respective wax esters (7-12). The structure of these wax esters has been established by their mass spectra, infrared (IR) spectra, and 1H and 13C nuclear magnetic resonance (NMR) analyses. The IR spectra (Figure 1) of the product 7a/7b gave a sharp peak at 1739 cm-1, representing the carbonyl of the ester. The C-O stretching was observed at 1250, 1160, 1115, and 1010 cm-1, along with C-Br stretching at 669 cm-1. Chromatographically inseparable positional isomers were formed in every instance. The formation of positional isomers was confirmed by the presence of double signals in both 1H NMR and 13C NMR spectra. However, the integration of peaks in the 1H NMR indicates that the amount of isomer involving antiMarkownikoff’s addition (i.e., dodecanoic acid 2-bromo-octadecyl ester (7b)) was much less, compared to the amount of isomer involving Markownikoff’s addition. A probable mechanism involving the formation of the carbonium ion should have led to a single isomer, dodecanoic acid 1-bromomethylheptadecyl ester (7a) (Markownikoff’s addition), but the formation of both positional isomers in both cases has been observed. This may be explained by the formation of a cyclic bromonium ion (Figure 2). The nucleophilic attack of the carboxylate ion

10.1021/ie0616592 CCC: $37.00 © 2007 American Chemical Society Published on Web 03/14/2007

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Figure 2. Proposed mechanism.

Figure 4. Figure 3.

1H

13C

NMR spectra of 7a/7b.

NMR spectra of 7a/7b.

onto the cyclic bromonium ion with steric factors resulted in the formation of dodecanoic acid 2-bromo-octadecyl ester (7b) (anti-Markownikoff’s addition), whereas the stabilization of an acyclic carbocation by the highly nucleophilic reagent (carboxylate ion) led to the Markownikoff’s addition (7a), thus forming both of the positional isomers. The proposed mechanism is supported by earlier reports.9,14 In the 1H NMR spectra (Figure 3) of product 7, the proton attached to C-2 was observed at its distinct position of δ 4.08-4.13 for CH-Br (product 7b) as a multiplet. However, the same was observed in the case of -CHOCO (product 7a), as a multiplet at δ 4.95-5.03. The isomer ratio of both isomers has been determined to be 1:2, from the ratio of the integration of the multiplet at δ 4.08 and δ 4.95. The protons attached to C-1 were observed at δ 4.3 for -CH2-O as a doublet of doublets and the protons attached to CH2Br appeared as AB-type quartets at δ 3.4, because of mutual splitting of the two-geminal protons. 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 51.68 (7b)

and CH-O at a chemical shift of δ 72.05 (7a; see Figure 4) in the 13C NMR. The nature of these carbons had been confirmed by the distortionless enhancement by polarization transfer (DEPT) experiment, where the polarities of both these signals were reversed (see Figure 5). The other peaks were observed at δ 67.54 for CH2-O, δ 35.10 for CH2-Br, and so on. The structure of compound 7a/7b has further been confirmed by fast atom bombardment (FAB) mass spectrometry, where the parent ion M+ and M+ + 2 has been observed at m/z 530 and m/z 532. The structures of other compounds have also been confirmed from their spectral data, as detailed in the Experimental Section. Experimental Section Octadecene and hexadecane was purchased from Sigma Aldrich. N-bromosuccinimide (NBS) and myristic acid was purchased from Central Drug House in New Delhi, India. Lauric acid was purchased from Sarabhai M. Chemicals in Baroda, India. Palmitic acid was purchased from Reanal Finomvegyszergya in Budapest, Hungary. Thin-layer chroma-

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Ind. Eng. Chem. Res., Vol. 46, No. 8, 2007 Scheme 1

Figure 5. DEPT NMR spectra of 7a/7b.

tography (TLC) was performed on silica-gel-G-coated (0.25mm-thick) plates with petroleum ether/diethyl ether/acetic acid (in a ratio of 80:20:1 or 60:40:1) as the mobile phase. Spots were visualized by iodine. Instrumentation. FAB mass spectra were recorded on a JEOL model SX-102/DA-6000 mass spectrometer/data system using argon/xenon (6kV, 10 mA) as the FAB gas at the Central Drug Research Institute (CDRI) in Lukhnow, India. The accelerating voltage was 10 kV, and the spectra were recorded at room temperature. m-Nitrobenzyl alcohol (NBA) was used as the matrix. The matrix peaks were observed at m/z 136, 137, 154, 289, 307 in all cases. IR spectrum was recorded as a thin neat film on a Shimadzu model FT-IR 8400s (Kyoto, Japan) instrument. 1H and 13C NMR were recorded on a JEOL model FT-NMR 300 MHz system (AL-300; Tokyo, Japan) as a solution in CDCl3, using tetramethylsilane (TMS) as an internal standard. General Procedure. Lauric acid (4; 2.00 g, 10 mmol), myristic acid (5; 2.28 g, 10 mmol), or palmitic acid (6; 2.56 g, 10 mmol) was added to a stirred solution of 1-octadecene (1; 2.52 g, 10 mmol) or 1-hexadecene (2; 2.24 g, 10 mmol) and N-bromosuccinimide (3; 1.78 g, 10 mmol) in dichloromethane (50 mL). After the addition, the reaction mixture was stirred at room temperature. The reaction was monitored using TLC and reached an equilibrium after 1 h of stirring in all cases, as indicated by the minor variation in the TLC analysis, even after prolonged stirring up to 24 h. The crude reaction mixture was filtered. The filtrate was collected using a separating funnel, washed with water, and then dried over sodium sulfate. The evaporation and subsequent fractionation on a silica gel (60120 mesh) column chromatography using hexane or a hexane: chloroform mixture (at ratios of 90:10 to 50:50) (the stepwise increasing-polarity elution method) yielded, first, the unreacted R-olefin (ca. 50% of the actual amount taken for reaction in each case), followed by the respective wax esters (see Scheme 1, compounds 7-12). The percentage yields mentioned below are based on the amount of R-olefin that actually reacted in each case. Spectral Results Dodecanoic Acid 1-Bromomethyl Heptadecyl Ester (7a)/ Dodecanoic Acid 2-Bromomethyl Octadecyl Ester (7b). The spectral results for 7a and 7b are as follows: 1.96 g, 73.96%;

white waxy solid, (hexane); IR νj (cm-1) neat: 670 (C-Br, str.), 1010, 1115, 1160, 1250 (C-O, str), 1740 (CdO, ester str.); 1H NMR (CDCl3): δ 0.86 (t, J ) 3.6 Hz, 12H, 4 X -CH3), 1.21.3 (br.s, 90H chain CH2), 1.6 (m, 4H, 2 X -CH2-CH2-CO2), 1.8 (m, -CH2-CHOCO), 2.3 (t, J ) 7.5 Hz, 4H, 2 X -CH2CO2), 3.4 (ab-q, -CH2-Br), 4.08-4.13 (m, CH-Br); 4.3 (dd, Jab ) 3.3 Hz, Jax ) 6.9 Hz -CH2-OCO), 4.95-5.03 (m, -CH-OCO); 13C NMR (normal/DEPT-135) (CDCl3): δ 14.05 (+ve, terminal CH3), 22.62, 24.85, 24.99, 27.02, 28.88, 29.05, 29.19, 29.23, 29.27, 29.29, 29.40, 29.45, 29.53, 29.59, 29.62, 31.86, 32.46, 34.09, 34.27, 34.35 (-ve, chain CH2), 35.10 (-ve, CH2-Br), 51.68 (+ve, CHBr), 67.54 (-ve, CH2-OCO), 72.05 (+ve, CH-OCO), 173.26 and 173.29 (+ve, -COO); MS m/z (relative intensity %): 530 M+ (13.15), 532 M++2 (13.15), 531/ 529 (31.56/28.9), 437 (2.6), 377/375 (2.6/2.6), 333/331 (47.34/ 67.12), 307/305 (5.3/2.6), 199 (2.6), 167 (5.3), 95/93 (absent) [R-cleavage ions for major isomer], 531/529 (31.56/28.9), 377/ 375 (2.6/2.6), 333/331 (47.34/67.12), 319/317 (1.3/1.3), 307/ 305 (5.3/2.6), 213 (2.6), 199 (2.6), 167 (5.3) [R-cleavage ions for minor isomer]. Tetradecanoic Acid 1-Bromomethyl Heptadecyl Ester (8a)/Tetradecanoic Acid 2-Bromomethyl Octadecyl Ester (8b). The spectral results for 8a and 8b are as follows: 1.90 g, 68.10%; white waxy solid, (hexane); IR νj (cm-1) neat: 670 (C-Br, str.), 1010, 1120, 1160, 1225 (C-O, str.), 1740 (CdO, ester str.); 1H NMR (CDCl3): δ 0.87 (t, J ) 6.6 Hz, 12H, 4 X -CH3), 1.2-1.3 (br. s, 98H chain CH2), 1.6 (m, 4H, 2 X -CH2-CH2-CO2), 1.8 (m, -CH2-CHOCO), 2.3 (t, J ) 7.5 Hz, 4H, 2 X -CH2-CO2), 3.42-3.51 (ab-q, -CH2-Br), 4.104.16 (m, CH-Br); 4.3 (dd, Jab ) 3.3 Hz, Jax ) 6.9 Hz, -CH2OCO), 4.99 (m, -CH-OCO); 13C NMR (normal/DEPT-135) (CDCl3): δ 14.04 (+ve, terminal CH3), 22.62, 24.85, 24.98, 26.66, 27.06, 28.74, 28.88, 29.05, 29.19, 29.29, 29.40, 29.46, 29.59, 29.62, 31.86, 32.46, 34.07, 34.21, 34.34, 35.11 (-ve, chain CH2), 36.21 (-ve, CH2-Br), 55.00 (+ve, CHBr), 67.53 (-ve, CH2-OCO), 72.04 (+ve, CH-OCO), 173.26 (+ve,

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COO); MS m/z (relative intensity %): 558 M+ (18.41), 560 M++2 (18.41), 559/557 (47.34/39.45), 465 (1.3), 377/375 (1.3/ 1.3), 335/333 (1.3/27.4), 333/331 (27.4/23.6), 227 (36.82), 195 (2.6), 95/93 (63.38/18.41) [R-cleavage ions for major isomer], 559/557 (47.34/39.45), 377/375 (1.3/1.3), 335/333 (1.3/27.4), 333/331 (27.4/23.6), 319/317 (1.3/1.3), 241 (2.6), 227 (36.82), 195 (2.6) [R-cleavage ions for minor isomer]. Hexadecanoic Acid 1-Bromomethyl Heptadecyl Ester (9a)/ Hexadecanoic Acid 2-Bromomethyl Octadecyl Ester (9b). The spectral results for 9a and 9b are as follows: 1.90 g, 64.74%; white waxy solid, (hexane); IR νj (cm-1) neat: 670 (C-Br, str.), 1010, 1100, 1160, 1230 (C-O, str.), 1745 (CdO, ester str.); 1H NMR (CDCl3): δ 0.86 (t, J ) 6.1 Hz, 12H, 4 X -CH3), 1.2-1.3 (br. s, 106H chain CH2), 1.6 (m, 4H, 2 X -CH2-CH2-CO2), 1.8 (m, -CH2-CHOCO), 2.3 (t, J ) 7.5 Hz, 4H, 2 X -CH2-CO2), 3.42-3.49 (ab-q, -CH2-Br), 4.084.13 (m, CH-Br); 4.3 (dd, Jab ) 3.3 Hz, Jax ) 6.9 Hz, -CH2OCO), 4.95-5.03 (m, -CH-OCO); 13C NMR (normal/DEPT135) (CDCl3): δ 14.03 (+ve, terminal CH3), 22.61, 24.84, 24.96, 26.82, 27.06, 28.87, 29.05, 29.18, 29.22, 29.28, 29.29, 29.36, 29.39, 29.46, 29.54, 29.58, 29.61, 31.85, 32.45, 34.08, 34.25, 34.35 (-ve, chain CH2), 35.11 (-ve, CH2-Br), 51.66 (+ve, CHBr), 67.53 (-ve, CH2-OCO), 72.06 (+ve, CHOCO), 173.27 and 173.31 (+ve, COO); MS m/z (relative intensity %): 587 M+ (39.45), 589 M++2 (39.45), 588/586 (13.15/26.30), 493 (3.9), 377/375 (2.6/2.6), 353/351 (1.3/2.6), 333/331 (16.52/13.15), 255 (15.78), 223 (2,6), 95/93 (49.57/ 15.78) [R-cleavage ions for major isomer], 588/586 (13.15/ 26.30), 377/375 (2.6/2.6), 353/351 (1.3/2.6), 333/331 (16.52/ 13.15), 319/317 (1.3/1.3), 269 (2.6), 255 (15.78), 223 (2,6) [R-cleavage ions for minor isomer]. Dodecanoic Acid 1-Bromomethyl Pentadecyl Ester (10a)/ Dodecanoic Acid 2-Bromomethyl Hexadecyl Ester (10b). The spectral results for 10a and 10b are as follows: 1.75 g, 69.72%; white waxy solid, (hexane); IR νj (cm-1) neat: 669 (C-Br, str.), 1010, 1120, 1160, 1230 (C-O, str.), 1730 (CdO, ester str.); 1H NMR (CDCl ): δ 0.86 (t, J ) 3.3 Hz, 12 H, 4 X -CH ), 3 3 1.2-1.3 (br.s, 82H chain CH2), 1.6 (m, 4H, 2 X -CH2-CH2CO2), 1.8 (m, -CH2-CHOCO), 2.3 (t, J ) 7.5 Hz, 4H, 2 X -CH2-CO2), 3.42-3.49 (ab-q, -CH2-Br), 4.10 (m, CH-Br); 4.3 (dd, Jab ) 3.3 Hz, Jax ) 6.9 Hz, -CH2-OCO), 5.00 (m, -CH-OCO); 13C NMR (normal/DEPT-135) (CDCl3): δ 14.03 (+ve, terminal CH3), 22.61, 24.84, 24.96, 25.06, 26.82, 27.06, 28.87, 29.04, 29.18, 29.26, 29.28, 29.32, 29.36, 29.38, 29.45, 29.52, 29.57, 29.61, 31.84, 32.46, 34.08, 34.26, 34.35 (-ve, chain CH2), 35.11 (-ve, CH2-Br), 51.68 (+ve, CHBr), 67.53 (-ve, CH2-OCO), 72.06 (+ve, CH-OCO), 173.28 (+ve, COO); MS m/z (relative intensity %): 502 M+ (23.67), 504 M++2 (23.67), 503/501 (58.33/55.55), 409 (1.3), 349/347 (2.6/ 2.6), 305/303 (31.56/31.56), 307/305 (2.6/31.56), 199 (15.78), 167 (2.6), 95/93 (57.86/13.15) [R-cleavage ions for major isomer], 503/501 (28.93/26.30), 349/347 (2.6/2.6), 305/303 (31.56/31.56), 307/305 (2.6/31.56), 291/289 (1.3/1.3), 213 (2.6), 199 (15.78), 167 (2.6) [R-cleavage ions for minor isomer]. Tetradecanoic Acid 1-Bromomethyl Pentadecyl Ester (11a)/Tetradecanoic Acid 2-Bromomethyl Hexadecyl Ester (11b). The spectral results for 11a and 11b are as follows: 1.72 g, 64.90%; white waxy solid, (hexane); IR νj (cm-1) neat: 670 (C-Br, str.), 1010, 1115, 1160, 1230 (C-O, str.), 1700 (CdO, ester str.); 1H NMR (CDCl3): δ 0.86 (t, J ) 6.3 Hz, 12H, 4 X -CH3), 1.2-1.3 (br. s, 90H chain CH2), 1.6 (m, 4H, 2 X -CH2-CH2-CO2), 1.8 (m, -CH2-CHOCO), 2.3 (t, J ) 7.8 Hz, 4H, 2 X -CH2-CO2), 3.40-3.49 (ab-q, -CH2-Br), 4.084.13 (m, CH-Br); 4.3 (dd, Jab ) 3.3 Hz, Jax ) 6.9 Hz, -CH2-

OCO), 4.99 (m, -CH-OCO); 13C NMR (normal/DEPT-135) (CDCl3): δ 14.03 (+ve, terminal CH3), 22.61, 24.84, 24.95, 27.06, 28.87, 29.04, 29.17, 29.22, 29.28, 29.32, 29.38, 29.45, 29.54, 29.57, 29.60, 31.84, 32.45, 34.08, 34.25, 34.35 (-ve, chain CH2), 35.10 (-ve, CH2-Br), 51.66 (+ve, CHBr), 67.53 (-ve, CH2-OCO), 72.06 (+ve, CH-OCO), 173.31 (+ve, COO); MS m/z (relative intensity %): 530 M+ (18.41), 532 M++2 (18.41), 531/529 (47.34/42.08), 437 (5.26), 349/347 (1.3/ 2.6), 335/333 (2.6/1.3), 305/303 (28.93/31.56), 227 (52.6), 195 (2.6), 95/93 (71.01/21.04) [R-cleavage ions for major isomer], 531/529 (47.34/42.08), 349/347 (1.3/2.6), 335/333 (2.6/1.3), 305/ 303 (28.93/31.56), 291/289 (1.3/1.3), 241 (16.62), 227 (52.6), 195 (2.6) [R-cleavage ions for minor isomer]. Hexadecanoic Acid 1-Bromomethyl Pentadecyl Ester (12a)/Hexadecanoic Acid 2-Bromomethyl Hexadecyl Ester (12b). The spectral results for 12a and 12b are as follows: 1.70 g, 60.93%; white waxy solid, (hexane); IR νj (cm-1) neat: 669 (C-Br, str.), 1090, 1160, 1235 (C-O, str.), 1730 (CdO, ester str.); 1H NMR (CDCl3): δ 0.86 (t, J ) 3.9 Hz, 12H, 4 X -CH3), 1.2-1.3 (br. s, 98H chain CH2), 1.6 (m, 4H, 2 X -CH2-CH2CO2), 1.8 (m, -CH2-CHOCO), 2.3 (t, J ) 7.2 Hz, 4H, 2 X -CH2-CO2), 3.42-3.49 (ab-)q, -CH2-Br), 4.08-4.13 (m, CH-Br); 4.3 (dd, Jab ) 3.3 Hz, Jax ) 6.9 Hz, -CH2-OCO), 4.95-5.03 (m, -CH-OCO); 13C NMR (normal/DEPT-135) (CDCl3): δ 14.03 (+ve, terminal CH3), 22.61, 24.84, 24.96, 26.82, 27.06, 28.87, 29.05, 29.18, 29.22, 29.28, 29.36, 29.39, 29.46, 29.54, 29.58, 29.61, 31.85, 32.45, 34.08, 34.25, 34.35 (-ve, chain CH2), 35.11 (-ve, CH2-Br), 51.66 (+ve, CHBr), 67.53 (-ve, CH2-OCO), 72.06 (+ve, CH-OCO), 173.27 and 173.31 (+ve, COO); MS m/z (relative intensity %): 558 M+ (18.41), 560 M++2 (18.41), 559/557 (44.71/42.08), 465 (2.6), 353/351 (1.3/2.6), 349/347 (3.9/2.6), 305/303 (26.30/28.13), 225 (42.08), 223 (21.04), 95/93 (71.01/absent) [R-cleavage ions for major isomer], 559/557 (44.71/42.08), 353/351 (1.3/2.6), 349/ 347 (3.9/2.6), 305/303 (26.30/28.13), 291/289 (2.6/2.6), 269 (5.26), 225 (42.08), 223 (21.04) [R-cleavage ions for minor isomer]. Conclusion In the present study, six new wax esters have been synthesized in ca. 70% yield from R-olefins 1-octadecene and 1-hexadecene. The overall conversion of the R-olefins have been ∼50% in each case. Thus, in the present study, a new strategy has been described to synthesize the wax esters from terminal olefins. Acknowledgment The authors are thankful to CSIR (Council of Scientific & Industrial Research) India for providing the research grant for this work and CDRI (Central Drug Research Institute) in Lucknow for the mass spectra of the compounds. Literature Cited (1) Hills, G. Industrial use of lipases to produce fatty acid esters. Eur. J. Lipid Sci. Technol. 2003, 105, 601-607. (2) Hayes, D. G.; Kleiman, R. Lipase-catalyzed synthesis of lesquerolic acid wax and diol ester and their properties. J. Am. Oil Chem. Soc. 1996, 73, 1385-1392. (3) Wetje, E.; Costes, D.; Adlercreutz, P. Contineous lipase-catalyzed production of wax esters using silicone tubing. J. Am. Oil Chem. Soc. 1999, 76, 1489-1493. (4) Mukherjee, K. D.; Steinke, G.; Weitkamp, P.; Klein, E. High-yield preparation of wax esters via lipase-catalysed esterification using fatty acids and alcohols from Crambe and Cramelina oils. J. Agric. Food Chem. 2001, 49 (2), 647-651. (5) Schuch, R.; Mukherjee, K. D. Interesterification of lipids using an immobilized sn-1,3-specific triacylglycerol lipase. J. Agric. Food Chem. 1987, 35, 1005-1008.

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(6) De, B. K.; Bhattacharaya, D. K.; Bandhu, C. Enzymatic synthesis of fatty alcohol esters by alcoholysis. J. Am. Oil Chem. Soc. 1999, 76, 451453. (7) Decagny, B.; Jan, S.; Vuillemard, J. C.; Sarazin, C.; Seguin, J. P.; Gosselin, C.; Barbotin, J. N.; Ergan, F. Synthesis of wax esters through triolein alcoholysis: Choice of the lipase and study of the mechanism. Enzyme Microb. Technol. 1998, 22, 578-582. (8) Petersson, A. E. V.; Gustafsson, L. M.; Norblad, M.; Borjesson, P.; Mattiasson, B.; Patrick, A. Wax esters produced by solvent-free energyefficient enzymatic synthesis and their applicability as wood coating. Green Chem. 2005, 7, 837-843. (9) Rodriguez, J.; Dulcere, J. P. Cohalogenation in Organic Synthesis. Synthesis 1993, 1177-1205. (10) Ahmad, I.; Singh, S. Use of N-bromosuccinimide to obtain 1,2bromocarboxylates from olefinic fatty methyl esters. J. Oil Technol. Assoc. India (Kanpur, India) 1995, 27, 215-220.

(11) Singh, S.; Singh, B. Synthesis of β-Bromoethoxylates and βChloroethoxylates from olefinic fatty methyl esters. J. Surfactants Deterg. 2006, 9, 51-56. (12) Singh, S.; Singh, B. N-Halosuccinimide-mercaptoethanol cohalogenation of olefinic fatty methyl esters: synthesis of β-halo thiothloxylates. J. Surfactants Deterg. 2006, 9, 191-195. (13) Spargo, P. L. Organic halides. Contemp. Org. Synth. 1995, 2, 85. (14) Younes, M. R.; Mohamed, M. C.; Ahmed, B. N-Bromosuccinimidedimercaptoethane cobromination of alkenes: synthesis of β,β1-dibromodithioethers. Tetrahedron Lett. 2003, 44, 5263-5275.

ReceiVed for reView December 22, 2006 ReVised manuscript receiVed February 21, 2007 Accepted March 3, 2007 IE0616592