Synthesis of oligoethylene glycol ethers from the seed oil of Vernonia anthelmintica

Abstract

The seed oil of Vernonia anthelmintica on reaction with diols (mono-, di-, tri-, or tetraethylene glycols) in the presence of boron trifluoride etherate, followed by saponification and esterification (methanol/H + ), gives the oligoethylene glycol ethers: methyl 12(13)-hydroxy-13 (12) [2-hydroxy-ethyl-1-oxy]-octadec-9-enoate; methyl 12(13)-hydroxy-13(12)-[5-hydroxy-3-oxapentyl-1-oxy]-octadec-9-enoate; methyl 12(13)-hydroxy-13(12)-[8-hydroxy-3,6-dioxaoctyl-1-oxy]-octadec-9-enoate; and methyl 12(13)-hydroxy-13(12)-[11-hydroxy-3,6,9-trioxaundecyl-1-oxy]-octadec-9-enoate. Methyl 12,13-dihydroxyoctadec-9-enoate is a co-product in all reactions. JAOCS 74, 609-611 (1997). KEY WORDS:Boron trifluoride etherate, ethylene glycols (mono-, di-, tri-, and tetra-), methyl esters, seed oil, synthesis, trivernolein, Vernonia anthelmintica.Oligoethylene glycols (1,2) are important building blocks in the synthesis of nonionic surfactants, crown ethers (3), di-and tetraester ligands (4), and aza-crown ethers (5).Vernonia anthelmintica is an annual herb. Air-dried seeds of the plant contain about 30% oil, whose major fatty acid is vernolic (cis-12,13-epoxy-cis-9-octadecenoic) acid (70-80%) (6). The high vernolic acid content of this oil makes it a viable starting material in oligoethylene glycol synthesis.Ayorinde et al. (7) reported that alkali-catalyzed transesterification of vernonia oil gave epoxy esters and that saponification of the oil with potassium hydroxide gave epoxy acids. In both reactions, the epoxy ring remained intact.In contrast, Kleiman et al. (8,9) reported that acid-catalyzed transesterification of the oil with methanol resulted in epoxide ring opening and gave the hydroxy methoxy methyl ester derivatives. Ayorinde and coworkers (10) also reported the synthesis of 12-hydroxy-13-alkoxy isomer as the major product in the acid-catalyzed alcoholysis of V. galamensis oil.In the present study, V. anthelmintica oil has been used for the synthesis of oligoethylene glycol ethers. Scheme 1 represents the reactant trivernolein, which is the major triacylglycerol present in V. anthelmintica oil. EXPERIMENTAL PROCEDURESIn Scheme 2, crude V. anthelmintica oil (1) was obtained by chloroform extraction of the crushed seeds. Mono-, di-, tri-, and tetraethylene glycols (2a-d) were procured from a commercial supplier (Sisco Chem., Bombay, India) and were dried in an oven at a temperature of 103 ± 2°C for 4 h and then cooled and stored in a dessicator. BF 3 -etherate was ob-

Fatty acids, fatty acid analogues and their derivatives

“…244 Reaction of the seed oil of Vernonia anthelmintica [which contains vernolic acid, 12-13-epoxy-18:1(9Z)] with diol-ethers in the presence of BF 3 -diethyl ether caused ring opening of the epoxy function to yield oligoethylene glycol ethers. 245 Oxidation of olefinic fatty esters to the corresponding keto derivatives was accomplished when the substrates were treated with palladium() chloride and p-benzoquinone in aqueous tetrahydrofuran under ultrasonic irradiation. For example, methyl oleate furnished a mixture of methyl 9(10)-oxostearate, while methyl 12-hydroxy-18:1(9Z) furnished methyl 12hydroxy-9-oxostearate exclusively.…”

Synthesis of tetrahydrofuran ring containing oligoethylene glycol ethers from the seed oil of Vernonia anthelmintica

“…Oligoethylene glycol ethers ([1a-c]; obtained as a mixture of positional isomers) were prepared by the previously reported method (8). BF 3 -etherate was purchased from Fluka (Buchs, Switzerland) and was used without further purification.…”

“…Air-dried seeds of the plant contain about 30% oil, whose major fatty acid is vernolic (cis-12,13-epoxy-cis-9-octadecenoic) acid (70-80%) (6). The high vernolic acid content makes it a viable starting material for making a number of industrial derivatives, such as oil-based paints, toughened epoxy resins, lubricants, adhesives, insect repellents (7), oligoethylene glycols (8), and 12aminododecanoic and 11-aminoundecanoic acids (9).…”

Synthesis of β-Amino Alcohols from Terminal Epoxy Fatty Acid Methyl Ester

“…In the industrial field, there has been competition between oleochemicals and petrochemicals. The ever-increasing cost of petrochemicals has diverted the attention of chemists to the synthesis of new oleochemicals derived from natural fats and oils. − Earlier several reports − have been published from our laboratory regarding reactions on fatty methyl esters for the synthesis of a variety of oleochemicals.…”