Synthesis of β‐bromoethoxylates and β‐chloroethoxylates from olefinic fatty methyl esters

Abstract

Olefinic fatty methyl esters [undec-10-enoate (1 1), octadec-Z-9-enoate (2 2), methyl-12 hydroxy octadec-Z-9-enoate (3 3)], on reaction with an N-halosuccinimide (4 4--5 5)-i.e., N-bromosuccinimide (NBS; 4 4) or N-chlorosuccinimide (NCS; 5 5)-in the presence of diols such as mono-, di-, tri-, and tetraethylene glycols (6 6--9 9), gave the respective β-bromo-or β-chloroethoxylates (1 11 1--3 34 4).Paper no. S1476 in JSD 9, 51-56 (Qtr. 1, 2006)., ethylene glycols (mono-, di-, tri-, and tetra-), methyl esters, octadec-Z-9-enoic acid, polyethers, undec-10-enoic acid.Alkyl ethoxylates are well known for their use as nonionic surfactants (1). The ethoxylates also serve as starting materials for the formation of alkyl ether sulfate, a product used extensively for the manufacture of shampoos. These ethoxylates are generally prepared by an ethoxylation reaction of fatty alcohol with ethylene oxide. The cohalogenation of alkenes with halogens and nucleophilic solvents such as water, diomethylsulfoxides, dimethylformamide, carboxylic acids, alcohols, nitriles, and ethers is well documented (2). Dinulescu et al.(3) also reported the cohalogenation with ethereal solvents such as diethyl ether, tetrahydrofuran, dioxane, and ethylene oxide, leading to substituted β-haloether. A recent report by Younes et al. (4) describes the reaction of Nbromosuccinimide (NBS) and dimercaptoethane in diethyl ether to form β,β ′ -dibromodithioethers. To date, no reports have appeared on the utilization of cohalogenation reactions in fatty acid or vegetable oil chemistry. However, Ahmed and Singh (5) reported the cohalogenation of carboxylic acids on fatty methyl esters in a previous work. In the present study, we attempted to use the cohalogenation reaction of NBS and N-chlorosuccinimide (NCS) on olefinic fatty methyl esters to prepare potentially useful β-bromoethoxylates and β-chloroethoxylates. EXPERIMENTAL PROCEDURESMaterials and methods. Undec-10-enoic acid, octadec-Z-9-enoic acid, and NCS were purchased from Loba Chemicals (Mumbai, India). NBS was purchased from Central Drug House (New Delhi, India). 12-Hydroxy octadec-Z-9-enoic acid was isolated from castor oil using the partitioning method of Gunstone (6). Mono-, di-, tri-, and tetraethylene glycols were procured from M/S Sisco Chem. (Bombay, India) and were air-dried in an oven at a temperature of 120°C for 4 h, followed by cooling and storage in a desiccator. Thin-layer chromatography (TLC) was carried out on silica gel G-coated (0.25-mm 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. Infrared spectra were recorded on a Shimadzu FT-IR 8400s instrument. 1 H nuclear magnetic resonance (NMR) spectra were recorded on a Brucker-200 spectrometer, and 13 C NMR spectra were recorded on a Jeol FT-NMR spectrometer at 300 MHz (AL-300). Mass spectra were recorded on a Jeol SX-102 [electron impact/chemical ionization/fast atom bombardment (FAB)] at the Central Drug Research Institute (CDRI) in Lukhnow, India. G...

N‐halosuccinimide‐mercaptoethanol cohalogenation of olefinic fatty methyl esters: Synthesis of β‐halo thioethoxylates

“…The reaction has been applied to both terminal and internal olefinic fatty methyl esters. The olefinic fatty methyl esters (1-3), on reaction with NBS (4) or NCS (5) and 2-mercaptoethanol (6) furnished the respective 1,2-bromothioethoxylates or 1,2-chlorothioethoxylates (8)(9)(10)(11)(12)(13). The structure of these bromo/chloro thioethoxylates has been established by their IR and NMR ( 1 H and 13 C) spectroscopic analysis (detailed in experimental section).…”

“…The solution was dried over anhydrous sodium sulfate. The evaporation and subsequent fractionation on silica gel (60-120 mesh) column chromatography using hexane, hexane:chloroform (90:10 to 50:50), chloroform:methanol (98:2) (step-wise increasing polarity elution method) yielded a white crystalline mass having a melting point of 122°C, characterized as succinimide (7), followed by 1,2-dihalides (14)(15)(16)(17)(18)(19) as minor product and the respective β-bromothioethoxylates or β-chloroethioethoxylates (Scheme 1; [8][9][10][11][12][13] in quantitative yield. Inseparable positional isomers were formed in all cases.…”

“…1 H NMR (200 MHz, CDCl 3 ) δ ppm: 4.0 (m, 1H, -CH-Cl); 3.6 (s, 6H, 2 × CH 3 -O-CO); 3.4-3.5 (m, 6H, 2 × -CH 2 OH and CH 2 Cl); 2.9 (m, 1H, -CH-S); 2.6-2.7 (m, 8H, 3 × -CH 2 -S + 2 × OH); 2.3 (t, 4H, 2 × -CH 2 -CO 2 ); 1.6 (m, 4H, 2 × -CH 2 -CH 2 -CO 2 ); 1.2-1.3 (br.s, 24H chain CH2). 13 C NMR (300 MHz CDCl 3 ) δ ppm: 174.21 (COOCH 3 ); 61.08 and 60.71 (CH 2 OH); 63.11 (CH-Cl); 51.30 (COOCH 3 ); 48.05 (CH-S); 40.08, 36.60, 36.08 (CH 2 -S); 35.42 (CH2-Cl); 33. 98,31.33,29.44,29.10,28.90,28.72,25.98,25.45,24.70 (all CH 2 ).…”

“…A recent report (12) described the reaction of N-bromosuccinimide (NBS) and dimercaptoethane in diethyl ether to form β,β′-dibromodithioethers. In earlier work, we reported a new synthetic strategy for the synthesis of β-haloethoxylates from olefinic fatty methyl esters (13) and the comparative study of the neighboring group participation of NBS and N-chlorosuc-cinimide (NCS) on methyl isoricinoleate (unpublished results). This research was continued, attempting to prepare β-halothioethoxylates by using the cohalogenation reaction of NBS or NCS followed by the addition of 2-mercaptoethanol to the olefinic fatty methyl esters, that is, undec-10-enoate, octadec-Z -9-enoate, and methyl-12 hydroxy octadec-Z -9-enoate.…”

Comparative study of neighboring group participation in reactions of N‐bromoor N‐chlorosuccinimide on methyl isoricinoleate

“…The solution was dried over anhydrous sodium sulfate. The evaporation and subsequent fractionation on a silica gel (60-120 mesh) column chromatography using the series of solvents hexane, hexane:chloroform (90:10 to 50:50), and chloroform:methanol (98:2), in the stepwise increasing polarity elu-tion method, yielded a white crystalline mass having a melting point of 122°C, characterized as succinimide (8) and βhalo (chloro or bromo) 1,4-epoxide (9,10) and β-halo (chloro or bromo) ethoxylates (11)(12)(13)(14)(15)(16)(17)(18) IR ν (cm −1 ) neat: 3444 (OH, str); 1716 (C=O, ester str); 1217, 1182, 1132, 1085 (C-O, str); 759 (C-Br, str). 1 H NMR (200 MHz CDCl 3 ) δ ppm: 4.1(m, 2H, 2 × -CH-Br); 3.8 (m, 2H, 2 × -CH-OH); 3.6-3.7 (m, 20H, 6 × OCH 2 + 2 × CH 3 -O-CO + 2 × -CHO); 3.4-3.5 (m, 4H, 2 × -CH 2 OH); 2.8 (br.…”