Bromo Glycerol Monoethers from -Olefins - American Chemical Society

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Ind. Eng. Chem. Res. 2008, 47, 8090–8094

Synthesis of β-Bromo Glycerol Monoethers from r-Olefins Sukhprit Singh,* Avinash Bhadani, and Raman Kamboj Department of Chemistry, Guru Nanak DeV UniVersity, Amritsar 143 005, India

R-Olefins (1-decene (1), 1-dodecene (2), 1-tetradecene (3), 1-hexadecene (4), and 1-octadecene (5)), when reacted with N-bromosuccinimide (NBS (6)) and solketal (7) at 60 °C, followed by deprotection with 10% HCl, are converted into chromatographically inseparable isomeric mixtures of β-bromo monoethers of glycerol: 3-(2-bromoalkyloxy)propane-1,2-diol (13a-17a)/3-(1-bromoalkane-2-yloxy)propane-1,2-diol (13b-17b). Introduction Glycerol monoethers have copious applications and are a subject of a number of patents.1-12 These ecofriendly renewable compounds are encountered in several cosmetics, personal care, and laundry and cleaning formulations.1-4 Beside this, reports also suggest the use of such molecules as antimicrobial/antiseptics for skin preparations5 and also inhibitors of melanocyte, thus acting as skin whitening agents.6 Another report acknowledges its utilization for the treatment of allergies.7 Potent utility of such compounds also include transportation of lipids across mucosal membrane.8 Ink formulations for ink-jet printing containing C5-20 alkyl glycerol monoethers are claimed to have better redispersibility.9 Several reports have been published regarding the manufacture of glycerol monoethers, the majority of them being patented. These processes use olefin epoxide, glycidol, alcohols, epichlorohydrin, etc., as basic raw material for producing glycerol monoethers.10-13 A report also suggests etherification of glycerol catalyzed by ion-exchange resins.14 Using olefin epoxide as raw material for synthesis of such molecules necessitates initial conversion of the olefin to its epoxide. Linear alkyl alcohol synthesis using fatty acids (through hydrogenation) or by linear alpha olefins (through hydroformylation and hydrogenation) as raw materials is also expensive. Further, the temperature requirement in most of the cases is above 100 °C. Recently, Procter & Gamble Company of USA has patented a methodology for preparation of alkyl glycerol ethers using glycerol and an alkyl alcohol as the raw materials. The process requires a Bronsted acid/Lewis acid as catalyst and reaction temperature in the range of 70-250 °C. Direct etherification of glycerol using a catalyst at high temperature often leads to formation of many side products such as dialkyl glycerol ether, diglycerol, and dialkyl ether in considerable amounts apart from unreacted glycerol, alkyl alcohol, and catalyst which are usually left behind in the reaction vessel.15 Cohalogenation is a versatile reaction utilized successfully for the synthesis of important targets. Several cohalogenation reactions using alcohols as nucleophiles have been reported.16-19 Terminal olefins in the presence of N-bromosuccinimide (NBS), N-chlorosuccinimide (NCS), and N-bromoacetamide (NBA) give β-haloalkyl ethers when reacted with ethylene glycol.20 Haloglycoxylation of terminal aromatic or aliphatic olefins with ethylene glycol is well documented.21 Bromoacetylenic ethers are easily obtained by cohalogenation of olefins with NBS using 2-propyn-1-ol as solvent.22 In our previous work we have successfully utilized the cohalogenation reaction for the synthesis of β-haloethers,23 β-halothioethers,24 and wax esters.25 In the * Corresponding author. Tel: 911832258802-09, ext. 3211. Fax: 911832258820. E-mail: [email protected].

present work we report a new methodology for the preparation of glycerol monoethers (13-17) using the cohalogenation protocol. Results and Discussion Today no efficient process is available to obtain glycerol monoethers directly from glycerol, as it often leads to formation of mixtures of mono- and polyethers which are difficult to purify. Most of the processes use modified glycerol (solketal) which is then reacted with fatty alcohol (or modified halogenated, mesylated, tosylated).26-30 A majority of the reactions take place in organic solvent. Long chain fatty alcohols are mainly derived from the hydroformylation process in which the linear alpha olefins are first reacted with carbon monoxide and hydrogen in the presence of a complex transition metal catalyst to obtain the corresponding aldehyde (formed as an isomeric mixture, and the ratio of isomers formed depends on the type of catalyst and process used). The purified fraction is then hydrogenated to afford the corresponding linear alkyl alcohol. The overall process requires lot of energy because it often requires high pressure and temperature. The process typically is accomplished by treatment of an alkene with high pressures (between 10 to 100 atm) of carbon monoxide and hydrogen at temperatures between 40 and 200 °C. This paper describes the synthesis of β-bromo glycerol monoethers from terminal olefins with a green approach that utilizes solketal as solvent as well as reactant. This offers a new strategy for the synthesis of such compounds that is less energy consuming, more specific, and simple. Terminal olefins (1decene (1), 1-dodecene (2), 1-tetradecene (3), 1-hexadecene (4), and 1-octadecene (5)) on reaction with N-bromosuccinimide (NBS (6)) and solketal (7) resulted in the formation of 1,3dioxolanes 8-12. The formation of chromatographically inseparable positional isomers as well as structural isomers has been observed in all the cases from 1H and 13C NMR spectroscopy. In the infrared (IR) spectra of these dioxolanes the stretching for C-Br was observed in the range 667 to 671 for the dioxolanes while the C-O stretchings were observed at 1047-1054, 1072-1085, 1112-1115, and 1216-1236. The structures revealing 13C and 1H NMR chemical shifts (δ ppm) of the products are shown in Figure 2. The methyl group (CH3) protons attached to C-2 of the 1,3-dioxolane were observed as two singlets at δ 1.36 and δ 1.42 respectively for 8a and 8b. The protons attached to C-5 of the dioxolane ring were observed as a pair of ABX quartets at δ 3.76-3.81 and δ 4.03-4.09 ppm, respectively, for both vicinal protons (Ha and Hb). The CHBr multiplet at δ 4.04-4.09 also merged with this signal.

10.1021/ie800718b CCC: $40.75  2008 American Chemical Society Published on Web 09/26/2008

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Figure 1. Proposed mechanism.

Similarly the CH2-O-CH2 protons were also observed as a pair of ABX quartets in the range δ 3.52-3.58 and δ 3.67-3.74. Clustering of all these signals in a narrow range gave a look of a broad multiplet. In the 13C NMR spectrum of 8-12 the C-2 carbon was observed at δ 109.2 to 109.5, while the ring carbon C-5 and C-4 were observed at δ 66.6 and 74.5, respectively. The oxy methyl carbon was observed at δ 71.9, and the C-1 of the alkyl chain was observed at δ 75.8 for the isomer suffixed a whereas the same carbon was observed at δ 35.12 for the isomer suffixed b. Similarly the C-2 of alkyl chain was observed at δ 53.47 for the isomer suffixed a and the same was observed at δ 79.6 for the isomer suffixed b. The 1,3-dioxolanes 8-12 were treated with 10% aqueous HCl to afford the given glycerol monoethers 13-17 in 70 to 75% isolated yield. The structure of these monoethers has also been established by their mass spectra, infrared (IR) spectra, and 1H and13 C NMR analyses. The IR spectra of the product 13a/13b gave a peak at 3380 cm-1, representing the hydroxyl group. The C-O stretchings were observed at 1047,1072, 1112, and 1216 cm-1, along with C-Br stretching at 667.32 cm-1. Two chromatographically inseparable positional isomers were formed (as expected) in every instance. The formation of positional isomers have been confirmed by the presence of double signals in both 1H NMR and 13C NMR spectra and was confirmed by 13C DEPT, 2 D COSY, and HETCOR experiments. A multiplet from δ 3.52 to 4.10 was observed for most of the structure elucidating protons for both type of positional isomers. The 13C chemical shifts and DEPT experiment were more informative and helpful in establishing the structure of the diols 13-17. The C-1 of alkyl chain appeared at δ 35.07 to 35.37 for the isomer having the bromide group attached to this carbon as a negative (-ve) signal, and at the same time the C-2 of the alkyl chain was observed at δ 51.6 to 53.6 as a positive (+ve) signal indicating the attachment of bromide to this carbon also. CH2-O carbons were observed at 63.73, 63.99, 71.89, 72.17, and 75.54 as the -ve signal, whereas positive signals for carbon attached to the oxygen appeared at δ 70.55, 70.33, and 79.40. The appearance of double signals for the carbon attached to the bromide and oxygen confirmed formation of positional as well as the structural isomers in all the cases. The formation of two isomers indicates that the most probable mechanism involves the formation of a cyclic bromonium ion as intermediate followed by nucleophilic attack of the hydroxyl ion from either side as shown in Figure 1. Experimental Section 1-Decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1octadecene were purchased from Sigma Aldrich. N-bromosuc-

Figure 2. 8b.

13

C and 1H chemical shifts (δ ppm) of dioxolane isomers 8a and

cinimide (NBS) was purchased from Central Drug House, New Delhi, India. Solketal was prepared by a previously reported method26 by refluxing glycerol in 1:1 acetone and petroleum ether in the presence of catalytic amount of p-toluenesulfonic acid monohydrate. Thin-layer chromatography (TLC) was performed on silica-gel-G-coated (0.25-mm-thick) plates with hexane/ethyl acetate (in a ratio of 90:10 or 85:15) as mobile phase. Spots were visualized by iodine. Instrumentation. IR spectra were recorded as a thin neat film on a Shimadzu 8400s FT-IR (Kyoto, Japan) instrument. Mass spectra were recorded on Waters Micromass Q-Tof Micromass at Sophisticated Analytical Instrumentation Facility (SAIF), Panjab University, Chandigarh, India. 1H and 13C NMR were recorded on a JEOL AL-300 (JEOL Japan) FT-NMR 300 MHz system and Bruker Avance II (Switzerland) FT NMR 400 MHz system at the Sophisticated Analytical Instrumentation Facility (SAIF), at Panjab University, Chandigarh, India, as a solution in CDCl3, using tetramethylsilane (TMS) as an internal standard. General Procedure. 1-Decene (1; 2.80 g, 20 mmol), 1dodecene (2; 3.36 g, 20 mmol), 1-tetradecene (3; 3.92 g, 20

8092 Ind. Eng. Chem. Res., Vol. 47, No. 21, 2008 Scheme 1

techniques. These intermediates were helpful in understanding the mechanism of the reaction (Figure 1). Spectral Results

mmol), 1-hexadecene (4; 4.48 g, 20 mmol), or 1-octadecene (5; 5.04 g, 20 mmol) was added to stirred solution of solketal (7; 7.92 g, 60 mmol) and N-bromosuccinimide (6; 3.56 g, 20 mmol) at 60 °C. The reaction was stirred for 6 h at 60 °C. The progress of the reaction was monitored by thin layer chromatography, and the equilibrium stage was obtained in 6 h. The crude reaction mixture was cooled to 25 °C. Hexane (50 mL) was added to the reaction mixture, and it was stirred for 5 min and filtered to remove the precipitated succinimide. The filtrate was collected in a separating funnel and washed four times with 50 mL of water followed by removal of hexane by a rotary flash evaporator. The reaction mixture was treated with 20 mL of 10% HCl and vigorously stirred for 3 h. The content was transferred to a separating funnel. A 100 mL amount of both chloroform and water was added. The organic layer was washed till the pH of the water became 7. The organic layer was then dried with sodium sulfate. The evaporation and subsequent fractionation on a silica gel (60-120 mesh) column chromatography using hexane and then a hexane:ethyl acetate mixture (at ratios of 100:00 to 70:30) (the stepwise increasing-polarity elution method) yielded, first, unreacted olefins and then dibromides (5-10%) and traces of the dioxolanes, followed by the respective β-bromo glycerol monoethers 13-17 in 70-75% isolated yield as a pure fraction. This yield is calculated on the basis of the amount of R-olefins that actually reacted. The conversion per batch is 75-80% (Scheme 1). The intermediate 1,3-dioxolanes 8-12 were isolated separately through column chromatography after the removal of the succinimide and were characterized through spectroscopic

4-((2-Bromodecyloxy)methyl)-2,2-dimethyl-1,3-dioxolane (8a)/4-((1-Bromodecan-2-yloxy)methyl)-2,2-dimethyl1,3-dioxolane (8b). Light yellow liquid, mass (m/z): 373.2 and 375.2 (M + Na+ and M + 2 + Na+) parent ion (C16H31BrO3); IR (cm-1) neat: 671.18 (C-Br, str), 1051,1078, 1151, 1232 (C-O, str); 1H NMR (CDCl3) δ (ppm) 0.88 (t, J ) 6.3 Hz, 6H, 2 × terminal-CH3), 1.2-1.3 (br s, 24 H chain CH2), 1.36 (s, 6H, 2 × CH3 attached to C-2 of dioxolane ring), 1.42 (s, 6H, 2 × CH3 attached to C-2 of dioxolane ring), 1.57-1.60 (m, 4H, 2 × CH2 (C-3 of aliphatic chain)), 3.40-3.42 (m, 2H, CH2Br), 3.49 (m, 1H, BrCH2CHO), 3.52-3.58 (m, 4H, 2 × OCHaHb), 3.67-3.74 (m, 2H, OCHaHbCHBr), 3.76-3.82 (m, 2H, 2 × OCHaHb(proton attached to C-5 of the ring)), 4.03-4.09 (m, 3H, CHBr, 2 × OCHaHb(proton attached to C-5 of the ring)), 4.24-4.27 (m, 2H, 2 × CH-(methine proton of C-4 of the ring)); 13C NMR (normal/DEPT-135) (CDCl3) δ (ppm) 14.01(+ve, terminal 2 × CH3), 22.59, 25.18, 29.15, 29.32, 31.70, 32.30, 33.08, 34.21, 34.88 (-ve, chain CH2), 26.66, 26.81 (4 × CH3), 35.12 (-ve, CH2Br), 53.47 (+ve, CHBr), 66.59, 66.87, (-ve, 2 × C-5 of the ring), 74.54 (+ve, 2 × C-4 of the ring), 71.92, 71.17 (-ve, 2 × OCHaHb), 75.87 (-ve, OCH2CHBr), 79.67 (+ve, BrCH2CHO), 109.27, 109.38 (2 × C(CH3)2 observed in 13C). 4-((2-Bromododecyloxy)methyl)-2,2-dimethyl-1,3-dioxolane (9a)/4-((1-Bromododecan-2-yloxy)methyl)-2,2-dimethyl-1,3-dioxolane (9b). Slightly yellow liquid, mass (m/z): 401.2 and 403.2 (M + Na+ and M + 2 + Na+), parent ion (C18H35BrO3); IR (cm-1) neat: 667.32 (C-Br, str), 1054, 1085, 1155, 1217 (C-O, str); 1H NMR (CDCl3) δ (ppm) 0.85 (t, J ) 6.0 Hz, 6H, 2 × terminal-CH3), 1.2-1.3 (br s, 32 H chain CH2), 1.36 (s, 6H, 2 × CH3 attached to C-2 of dioxolane ring), 1.42 (s, 6H, 2 × CH3 attached to C-2 of dioxolane ring), 1.58 (m, 4H, 2 × CH2 (C-3 of aliphatic chain)), 3.40-3.42 (m, 2H, CH2Br), 3.50 (m, 1H, BrCH2CHO), 3.52-3.58 (m, 4H, 2 × OCHaHb), 3.67-3.74 (m, 2H, OCHaHbCHBr), 3.76-3.81 (m, 2H, 2 × OCHaHb-(proton attached to C-5 of the ring)), 4.05-4.10 (m, 3H, CHBr, 2 × OCHaHb-(proton attached to C-5 of the ring)), 4.26-4.29 (m, 2H, 2 × CH-(methine proton of C-4 of the ring)) 13C NMR (normal/DEPT-135) (CDCl3) δ (ppm) 14.05 (+ve, terminal 2 × CH3), 22.64, 25.21, 29.28, 29.52, 31.85, 32.30, 33.08, 34.21, 34.88 (-ve, chain CH2), 26.34, 26.68, (4 × CH3), 35.14 (-ve, CH2Br), 53.54 (+ve, CHBr), 66.64, 66.91, (-ve, C-5 of the ring), 74.56 (+ve, 2 × C-4 of the ring), 70.72, 71.00 (-ve, 2 × OCH2CHBr), 75.87 (-ve, OCH2CHBr) 79.70 (+ve, BrCH2CHO), 109.29, 109.41 (2 × C(CH3)2 observed in 13C). 4-((2-Bromotetradecyloxy)methyl)-2,2-dimethyl-1,3-dioxolane (10a)/4-((1-Bromotetradecan-2-yloxy)methyl)-2,2-dimethyl-1,3-dioxolane (10b). Slightly yellow viscous liquid, mass (m/z): 429.2 and 431.2 (M + Na+ and M + 2 + Na+), parent ion (C20H39BrO3); IR (cm-1) neat: 669.25 (C-Br, str), 1028,1053, 1115, 1234 (C-O, str); 1H NMR (CDCl3) δ 0.88 (t, J ) 6.4 Hz, 6H, 2 × terminal-CH3), 1.2-1.3 (br s, 40 H chain CH2), 1.36 (s, 6H, 2 × CH3 attached to C-2 of dioxolane ring), 1.42 (s, 6H, 2 × CH3 attached to C-2 of dioxolane ring), 1.57 (m, 4H, 2 × CH2 (C-3 of aliphatic chain)), 3.39-3.42 (m, 2H, CH2Br), 3.49 (m, 1H, BrCH2CHO), 3.52-3.58 (m, 4H, 2 × OCHaHb), 3.67-3.74 (m, 2H, OCHaHbCHBr), 3.76-3.82 (m, 2H, 2 × OCHaHb-(proton attached to C-5 of the ring)), 4.03-4.09 (m, 3H, CHBr, 2 × OCHaHb-(proton attached to

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C-5 of the ring)), 4.25-4.27 (m, 2H, 2 × CH-(methine proton of C-4 of the ring)); 13C NMR (normal/DEPT-135) (CDCl3) δ (ppm) 14.19 (+ve, terminal 2 × CH3), 22.69, 25.18, 25.28, 27.20, 29.02, 29.35, 29.44, 31.92, 33.16, 34.78, 34.78 (-ve, chain CH2), 25.40, 26.79 (4 × CH3), 35.22 (-ve, CH2Br), 53.65 (+ve, CHBr), 66.71, 66.98, (-ve, C-5 of the ring), 74.64 (+ve, 2 × C-4 of the ring), 70.87, 71.15 (-ve, OCH2CHBr), 75.84 (-ve, OCH2CHBr) 79.79 (+ve, BrCH2CHO), 109.42, 109.53 (2 × C(CH3)2 observed in 13C). 4-((2-Bromohexadecyloxy)methyl)-2,2-dimethyl-1,3-dioxolane (11a)/4-((1-Bromohexadecan-2-yloxy)methyl)-2,2-dimethyl-1,3-dioxolane (11b). Slightly yellow viscous liquid, mass (m/z): 457.2 and 459.2 (M + Na+ and M + 2 + Na+), parent ion (C22H43BrO3); IR (cm-1) neat: 668.46 (C-Br, str), 1047,1072, 1112, 1216 (C-O, str); 1H NMR (CDCl3) δ 0.85 (t, J ) 6.0 Hz, 6H, 2 × terminal-CH3), 1.2-1.3 (br s, 48 H chain CH2), 1.36 (s, 6H, 2 × CH3 attached to C-2 of dioxolane ring), 1.42 (s, 6H, 2 × CH3 attached to C-2 of dioxolane ring), 1.58 (m, 4H, 2 × CH2 (C-3 of aliphatic chain)), 3.39-3.42 (m, 2H, CH2Br), 3.50 (m, 1H, BrCH2CHO), 3.52-3.58 (m, 4H, 2 × OCHaHb), 3.67-3.74 (m, 2H, OCHaHbCHBr), 3.76-3.82 (m, 2H, 2 × OCHaHb-(proton attached to C-5 of the ring)), 4.04-4.09 (m, 3H, CHBr, 2 × OCHaHb-(proton attached to C-5 of the ring)), 4.25-4.27 (m, 2H, 2 × CH-(methine proton of C-4 of the ring)); 13C NMR (normal/DEPT-135) (CDCl3) δ (ppm) 14.03 (+ve, terminal 2 × CH3), 20.16, 22.65, 27.15, 28.91, 29.65, 30.89, 31.88, 32.45, 33.08, 34.07, 34.12 (-ve, chain CH2), 25.18 (4 × CH3), 35.12 (-ve, CH2Br), 51.63 (+ve, CHBr), 66.62, 66.89, (-ve, C-5 of the ring), 74.56 (+ve, 2 × C-4 of the ring), 70.72, 71.00 (-ve, OCH2CHBr), 76.58 (-ve, OCH2CHBr) 79.76 (+ve, BrCH2CHO), 109.27, 109.28 (2 × C(CH3)2 observed in 13C). 4-((2-Bromooctadecyloxy)methyl)-2,2-dimethyl-1,3-dioxolane (12a)/4-((1-Bromooctadecan-2-yloxy)methyl)-2,2-dimethyl-1,3-dioxolane (12b). White waxy liquid, mass (m/z): 485.2 and 487.2 (M + Na+ and M + 2 + Na+), parent ion (C24H47BrO3); IR (cm-1) neat: 667.32 (C-Br, str), 1054, 1081, 1155, 1236 (C-O, str), 3380 (O-H, str); 1H NMR (CDCl3) δ (ppm) 0.85 (t, J ) 6.9 Hz, 6H, 2 × terminal-CH3), 1.2-1.3 (br s, 56 H chain CH2), 1.36 (s, 6H, 2 × CH3 attached to C-2 of dioxolane ring), 1.42 (s, 6H, 2 × CH3 attached to C-2 of dioxolane ring), 1.58 (m, 4H, 2 × CH2 (C-3 of aliphatic chain)), 3.39-3.42 (m, 2H, CH2Br), 3.49 (m, 1H, BrCH2CHO), 3.52-3.58 (m, 4H, 2 × OCHaHb), 3.67-3.74 (m, 2H, OCHaHbCHBr), 3.76-3.82 (m, 2H, 2 × OCHaHb-(proton attached to C-5 of the ring)), 4.05-4.09 (m, 3H, CHBr, 2 × OCHaHb(proton attached to C-5 of the ring)), 4.28-4.31 (m, 2H, 2 × CH-(methine proton of C-4 of the ring)); 13C NMR (normal/ DEPT-135) (CDCl3) δ (ppm) 14.14(+ve, terminal 2 × CH3), 22.63, 25.19, 26.62, 27.14, 29.30, 31.86, 33.10, 34.72, 34.85 (-ve, chain CH2), 25.41, 26.80 (4 × CH3), 35.14 (-ve, CH2Br), 53.58 (+ve, CHBr), 66.62, 66.89, (-ve, 2 × C-5 of the ring), 74.57 (+ve, 2 × C-4 of the ring), 70.72, 71.00 (-ve, OCH2CHBr), 74.57 (-ve, OCH2CHBr) 79.69 (+ve, BrCH2CHO), 109.27, 109.39 (2 × C(CH3)2). 3-(2-Bromodecyloxy)propane-1,2-diol (13a)/3-(1-Bromodecan-2-yloxy)propane-1,2-diol (13b). Yellowish viscous liquid; 3.29 g, 70.90%; mass (m/z): 333.1 and 335.1 (M + Na+ and M + 2 + Na+), parent ion (C13H27BrO3); IR (cm-1) neat: 667.32 (C-Br, str), 1047,1072, 1112, 1216 (C-O, str), 3380 (O-H, str); 1H NMR (CDCl3) δ (ppm) 0.88 (t, J ) 6.3 Hz, 6H, 2 × CH3), 1.2-1.3 (br s, 24 H chain CH2), 1.50-1.60 (m, 2H, CH2CH2CHBr), 1.80 (m, 2H, CHOCH2), 2.45 (bs, 2H, 2 × OH-1), 2.85 (bs, 2H, 2 × OH-2), 3.39-3.52 (m, 3H, CH2Br,

BrCH2CHO) 3.55-3.76 (m, 10H, 2 × OCHaHb, 2 × CHaHbOH, OCH2CHBr), 3.87 (m, 2H, 2 × CHOH), 4.10 (m, 1H, CHBr); 13 C NMR (normal/DEPT-135) (CDCl3) δ (ppm) 14.17 (+ve, terminal CH3), 22.66-32.92 (-ve, chain CH2), 35.17 (-ve, CH2Br), 53.18 (+ve, CHBr), 63.73, 63.99 (-ve, C1 CH2O), 70.53, 70.73 (+ve, C2 CHO), 71.09, 72.17 (-ve, C3 CH2O) 75.54 (-ve, OCH2CHBr) 79.40 (+ve, BrCH2CHO). 3-(2-Bromododecyloxy)propane-1,2-diol (14a)/3-(1-Bromododecan-2-yloxy)propane-1,2-diol (14b). Yellowish viscous liquid; 4.84 g, 74.17%; mass (m/z): 361.2 and 363.2 (M + Na+ and M + 2 + Na+), parent ion (C15H31BrO3); IR (cm-1) neat: 667.32 (C-Br, str), 1054,1085, 1114, 1220 (C-O, str), 3380 (O-H, str);1H NMR (CDCl3) δ (ppm) 0.85 (t, J ) 6.9 Hz, 6H, 2 × CH3), 1.2-1.3 (br s, 32 H chain CH2), 1.50-1.60 (m, 2H, CH2CH2CHBr), 1.82 (m, 2H, CHOCH2), 2.35 (bs, 2H, 2 × OH1), 2.75 (bs, 2H, 2 × OH-2), 3.38-3.52 (m, 3H,CH2Br, BrCH2CHO) 3.54-3.76 (m, 10H, 2 × OCHaHb, 2 × CHaHbOH, OCH2CHBr), 3.87 (m, 2H, 2 × CHOH), 4.10 (m, 1H, CHBr); 13 C NMR (normal/DEPT-135) (CDCl3) δ (ppm) 14.03(+ve, terminal CH3), 22.56-32.94 (-ve, chain CH2), 35.07 (-ve, CH2Br), 53.80 (+ve, CHBr), 63.75, 63.83 (-ve, C1 CH2O), 70.57, 70.76 (+ve, C2 CHO), 71.08, 72.41 (-ve, C3 CH2O) 75.54 (-ve, OCH2CHBr) 79.40 (+ve, BrCH2CHO). 3-(2-Bromotetradecyloxy)propane-1,2-diol (15a)/3-(1-Bromotetradecan-2-yloxy)propane-1,2-diol (15b). Yellowish viscous liquid; 3.50 g, 70.30%; mass (m/z): 389.2 and 391.2 (M + Na+ and M + 2 + Na+), parent ion (C17H35BrO3); IR (cm-1) neat: 659.51 (C-Br, str), 1047,1072, 1114, 1220 (C-O, str), 3386 (O-H, str);1H NMR (CDCl3) δ 0.88 (t, J ) 6.6 Hz, 6H, 2 × CH3), 1.2-1.3 (br s, 40 H chain CH2), 1.50-1.60 (m, 2H, CH2CH2CHBr), 1.81 (m, 2H, CHOCH2), 2.45 (bs, 2H, 2 × OH1), 2.86 (bs, 2H, 2 × OH-2), 3.31-3.51 (m, 3H, CH2Br, BrCH2CHO) 3.55-3.76 (m, 10H, 2 × OCHaHb, 2 × CHaHbOH, OCH2CHBr), 3.87 (m, 2H, 2 × CHOH), 4.09 (m, 1H, CHBr); 13 C NMR (normal/DEPT-135) (CDCl3) δ 14.1 (+ve, terminal CH3), 22.75-35.18 (-ve, chain CH2), 35.37 (-ve, CH2Br), 53.93 (+ve, CHBr), 63.99, 64.06 (-ve, C1 CH2O), 70.61, 70.73 (+ve, C2 CHO), 71.08, 71.46 (-ve, C3 CH2O) 75.54 (-ve, OCH2CHBr) 79.57 (+ve, BrCH2CHO). 3-(2-Bromohexadecyloxy)propane-1,2-diol (16a)/3-(1-Bromohexadecan-2-yloxy)propane-1,2-diol (16b). Yellowish viscous liquid; 3.92 g, 70.37%; mass (m/z): 417.2 and 419.2 (M + Na+ and M+ + 2 + Na+), parent ion (C19H39BrO3); IR (cm-1) neat: 667.32 (C-Br, str), 1047,1072, 1112, 1216 (C-O, str), 3388 (O-H, str);1H NMR (CDCl3) δ (ppm) 0.85 (t, J ) 6.0 Hz, 6H, 2 × CH3), 1.2-1.3 (br s, 48 H chain CH2), 1.50-1.60 (m, 2H, CH2CH2CHBr), 1.82 (m, 2H, CHOCH2), 2.21 (bs, 2H, 2 × OH-1), 2.79 (bs, 2H, 2 × CHOH), 3.37-3.53 (m, 3H, CH2Br, BrCH2CHO) 3.55-3.76 (m, 10H, 2 × OCHaHb, 2 × CHaHbOH, OCH2CHBr), 3.88 (m, 2H, 2 × H-2), 4.10 (m, 1H, CHBr); 13C NMR (normal/DEPT-135) (CDCl3) δ (ppm) 14.17 (+ve, terminal CH3), 22.66-35.06 (-ve, chain CH2), 35.33 (-ve, CH2Br), 53.74 (+ve, CHBr), 63.87 (-ve, C1 CH2O), 70.59 (+ve, C2 CHO), 71.01, 72.42 (-ve, C3 CH2O) 75.54 (-ve, OCH2CHBr) 79.51 (+ve, BrCH2CHO). 3-(2-Bromooctadecyloxy)propane-1,2-diol (17a)/3-(1-Bromohexadecan-2-yloxy)propane-1,2-diol (17b). Yellowish waxy solid; 4.52 g, 73.02%; mass (m/z): 445.2 and 447.2 (M + Na+ and M + 2 + Na+), parent ion (C21H43BrO3); IR (cm-1) neat: 669 (C-Br, str), 1047,1074, 1108, 1215 (C-O, str), 3390 (O-H, str); 1H NMR (CDCl3) δ (ppm) 0.85 (t, J ) 6.0 Hz, 6H, 2 × CH3), 1.2-1.3 (br s, 56 H chain CH2), 1.50-1.60 (m, 2H, CH2CH2CHBr), 1.79 (m, 2H, CHOCH2), 2.23 (bs, 2H, 2 × OH-1), 2.63 (bs, 2H, 2 × OH-2), 3.33-3.48 (m,

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3H,CH2Br,BrCH2CHO) 3.51-3.69 (m, 10H, 2 × OCHaHb, 2 × CHaHbOH, OCH2CHBr), 3.81 (m, 2H, 2 × CHOH), 4.04 (m, 1H, CHBr); 13C NMR (normal/DEPT-135) (CDCl3) δ (ppm) 14.12 (+ve, terminal CH3), 22.61-32.98 (-ve, chain CH2), 35.10 (-ve, CH2Br), 53.90 (+ve, CHBr), 63.78, 63.87 (-ve, C1 CH2O), 70.82 (+ve, C2 CHO), 71.18, 72.62 (-ve, C3 CH2O) 75.54 (-ve, OCH2CHBr) 79.43 (+ve, BrCH2CHO). Conclusion In the present study we have described a new protocol for the synthesis of β-bromo glycerol monoethers. Five new glycerol monoethers have been synthesized in ca. 70-75% isolated yield from R-olefins 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene via the cohalogenation method. Acknowledgment The authors are thankful to CSIR (Council of Scientific & Industrial Research) India for providing the research grant for this work and Sophisticated Analytical Instrumentation Facility (SAIF), Panjab University, Chandigarh for the 13C DEPT, 2D COSY, HETCOR, and mass spectra of the compounds. Literature Cited (1) Aoyama, H.; Ishii, D. Hair straighteners containing keratin-reducing agents and glycerin monoethers and hair straightening method using them. JP Patent 2007045801, Feb 22, 2007. (2) Kao Corp., Japan. Hair preparations containing glycerol R -monoethers. JP Patent 58083606, May 19,1983. (3) Inoue, T.; Tsukuda, K.; Morii, T. Liquid cleaning agent composition. JP patent 11256198, Sept 21, 1999. (4) Hasegawa, S.; Sakurai, O.; Uenuma, M.; Suetsugu, M.; Okawa, M. Method for manufacturing powder cosmetics. JP Patent 2008037844, Feb 21, 2008. (5) Shibuya, T.; Shimada, Y.; Hashimoto, S. Antiseptic agents comprising glyceryl ethers and glycerin esters. JP Patent 2007254342, Oct 4, 2007. (6) Kaburagi, T.; Ochiai, Y.; Okano, Y.; Masaki, H. Skin-whitening agent containing monoalkyl glyceryl ether and/or glycerin mono fatty acid ester, and skin-whitening cosmetic containing the same. JP Patent 2007063140, Mar 15, 2007. (7) Brohult, S.; Brohult, A. Use of glycerol ethers in the treatment of allergic diseases. US Patent 5173511, Dec 22, 1992. (8) Alexander, J.; Brewer, J. MD. Vesicles containing surfactant and transport molecule in vaccines. US Patent 5876721, Mar 2, 1999. (9) Inada, K.; Tsutsumi, T. Aqueous inks with high re-dispersing ability for ink-jet printing. JP Patent 2006176692, Jul 6, 2006. (10) Selifonov, S. Process for the preparation of glyceryl ethers for use as renewable biomass-based surfactants useful as detergents and emulsifiers. PCT Int. Appl. WO 2007062112, May 31, 2007.

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ReceiVed for reView May 3, 2008 ReVised manuscript receiVed August 17, 2008 Accepted August 24, 2008 IE800718B