ARS | Publication request: Cross ketonization of Cuphea sp. oil with acetic acid over a composite oxide of Fe, Ce, and Al

Submitted to: Applied Catalysis A: Genera
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 27, 2012
Publication Date: June 1, 2012
Citation: Jackson, M.A., Cermak, S.C. 2012. Cross ketonization of Cuphea sp. oil with acetic acid over a composite oxide of Fe, Ce, and Al. Applied Catalysis A: Genera. 431-432:157-163.

Interpretive Summary: This work demonstrates that a sustainable supply of the fragrance compound and insect repellent, 2-undecanone, can be produced from the new row crop, Cuphea. The current source for this compound is wild tomatoes which results in an expensive mosquito repellent cream. We have shown that the seed oil from Cuphea can be reacted with acetic acid over the proper catalyst to yield 2-undecanone in such high yield that an acre of Cuphea could yield 160 lbs of the active ingredient. This could be used to produce just over a ton of effective insect repellent lotion. Beneficiaries of this work include growers and processors of small acreage crops, such as Cuphea, and manufacturers of natural insect repellent lotions.

Technical Abstract: The objective of this work was to demonstrate the viability of the cross ketonization reaction with the triacylglycerol from Cuphea sp. and acetic acid in a fixed-bed plug-flow reactor. The seed oil from Cuphea sp. contains up to 71% decanoic acid and the reaction of this fatty acid residue with acetic acid yields the fragrance compound and insect repellent 2-undecanone. To this end, we screened several ketonization catalysts taken from the literature including CeO2, CeO2/Al2O3, CeO2/ZrO2, MnOx/Al2O3. The catalysts were characterized by N2 adsorption/desorption, H2-TPH, CO2-TPD, and XRD. Each of these catalysts affected the conversion but the highest yield was found with a new coprecipitated mixed metal oxide of empirical formula Fe0.5Ce0.2Al0.3Ox. In a flow reactor, Fe0.5Ce0.2Al0.3Ox gave 2-undecanone at 91% theoretical yield with reaction conditions of 400°C, weight hourly space velocity of 2, molar ratio of acetic acid to Cuphea oil of 23, and N2 carrier gas flow of 125 ml/min at 2.4 bar. This high yield is attributed to the low rate of coke formation on the mixed metal catalyst. In the absence of acetic acid, coupling of the decanoic acid residues gives 10-ketononadecane.