Synthesis of cyclic acetals (ketals) from oleochemicals using a solvent free method

Authors: Doll, Kenneth - Ken; Erhan, Sevim

Submitted to: Green Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2008
Publication Date: 6/3/2008
Citation: Doll, K.M., Erhan, S.Z. 2008. Synthesis of cyclic acetals (ketals) from oleochemicals using a solvent free method. Green Chemistry. 10(6):712-717.

Interpretive Summary: Despite the large growth in the bio-based fuel market, it is important not to neglect the development of new industrial products, such as lubrication fluids and surfactants. Starting from two bio-based materials, methyl oleate, and levulinic acid, we are able to make a complimentary set of materials. By changing the reaction conditions; we can favor the formation of either a branched ester, useful as a lubrication additive; or an acetal, useful as a controllable surfactant hydrophobe. Our methods are atom efficient and do not use organic solvent, which makes them favorable in green chemistry terms. This research benefits the vegetable oil industry by giving a new method where soybean oil can be turned into an industrial product with a potentially higher value, compared to the tumultuous fuel market.

Technical Abstract: We have studied the reaction selectivities of acid catalyzed ring opening reactions of epoxidized methyl oleate (methyl 9,10-epoxy stearate; EMO), to form either acetal or branched ester products. We have produced: methyl 9-(2-butyl-2-methyl-5-octyl-1,3-dioxolan-4-yl) nonanoate (hexanone methyl stearate acetal, HMSA), an oleochemically based acetal, in 83% isolated yield; from epoxidized methyl oleate and 2-hexanone. Utilizing our reaction chemistry, we have also been able to demonstrate the relative selectivities in competitive experiments by reacting EMO with 2-pentanone and octanoic acid. Finally, by controlling temperature and acid concentration, we were able to control the product distribution of the reaction of EMO with the bi-functional levulinic acid. We could favor either the acetal, or branched ester product in this work. This research may help lead to the formation of new hydrophobic molecules for the synthesis of new surfactants from oleochemicals.