Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 2004
Publication Date: March 1, 2005
Citation: Piazza, G.J., Foglia, T.A. 2005. Preparation of fatty polyols using peroxygenase from oat seeds [abstract]. American Chemical Society National Meeting. Paper No. BIOT-313. Technical Abstract: There is increasing demand for biobased products that may substitute for those prepared from nonrenewable sources such as petroleum. Due to their ready availability fats and oils are starting materials for biobased materials. One common procedure is the epoxidation of the double bonds to produce a plasticizer. The epoxides can also be hydrolyzed to produce fatty polyols that have increased polarity, viscosity, and reactivity, which allow them to be precursors for a variety of functional fluids, greases, and plastics. The currently used epoxidation procedure is driven by peracid, formed by reacting hydrogen peroxide with formic or acetic acid in the presence of a strong acid catalyst. The procedure is potentially hazardous and must be conducted under anhydrous conditions. To improve the epoxidation procedure we have been investigating the use of a peroxygenase enzyme as a replacement for peracid technology. We have used a variety of isolation procedures, but have recently focused our efforts on using ground oat seeds as a source of peroxygenase to reduce the cost of epoxidation. We studied epoxidation of fatty amides and fatty acids because these are not affected by the lipase found in oat seeds. Additionally we developed epoxidation procedures for both aqueous and organic solvent reaction media. Typical reaction conditions for an aqueous medium were: 25 C, pH 7.5 buffer, molar ratio t-butyl hydroperoxide/fatty amide = 2.5, mass ground oats/mass fatty amide = 100/1, 24 h. Typical reaction conditions for an organic medium were: 15 C, hexane/isopropyl ether/ pH 7.5 aqueous buffer = 60/4/1 by volume, molar ratio t-butyl hydroperoxide/fatty amide = 1.3, mass ground oats/mass fatty amide = 67/1, 24 h. We have found that only cis internal double bonds are epoxidized, and that the resulting epoxide retains the cis configuration. Additionally we found that the epoxidation rate dropped when trying to epoxidize a double bond adjacent to an existing epoxide. Because of this rate drop, high yields of product are obtained containing only one or two epoxides from the amide of linoleate and the amide of linolenate, respectively. This reaction feature also was found using fatty acid derivatives. Conversion to epoxidized products typically is at the 85% level. The polyols that are prepared from the partially epoxidized fatty acids or amide derivatives are structurally different from those obtained from fully epoxidized materials. The reason for this is that when fully epoxidized linoleic acid, linolenic acid, or their chemical derivatives are hydrolyzed, the products are hydroxy tetrahydrofurans and not the 1,2-diols, the product obtained from spatially isolated epoxides. Thus, it is anticipated that bioproducts obtained from the hydrolyzed products of peroxygenase epoxidation will have physical properties that are different from those obtained from chemically prepared epoxides, and testing for useful properties of these enzymatically derived products is currently underway.