DOI: 10.5176/2301-3761_CCECP.41

Authors: Hery Sutanto, M.Si., Dr.rer.nat. Widajanti Wibowo; Dr. A. Herry Cahyana


Modification of eugenol into its derivative compounds is an alternative way to enhance the economic value of clove oil, e.g. isoeugenol, [2–metoxy–4–(1–propenyl)phenol] has higher economic value than eugenol, [2–metoxy–4–(2–propenyl)phenol]. This isomerization of eugenol is generally carried out in a homogeneous medium using strong alkaline or transition metals as catalysts in a relatively high temperature. Since homogeneous catalytic reactions have some environmentally disadvantages regarding green process, this study on catalytic modification of eugenol was conducted using solid catalyst Na/NaOH/-Al2O3. This heterogeneous superbase catalyst Na/NaOH/-Al2O3 was prepared by first preparing -Alumina, in which an industrial waste in the form of aluminium scrap was used. This catalyst was then applied to produce the derivative compounds of eugenol at room temperature.

Since the OH-phenol of eugenol is very reactive towards oxidative coupling reaction, even at low temperature, methyl eugenol was used to compare the catalytic selectivity of Na/NaOH/-Al2O3 catalyst. Using methyl eugenol as the catalytic substrate, Na/NaOH/-Al2O3 has the activity to shift the double bond of 1-propenyl into 2-propenyl for 95.23{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} yield and 100{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} selectivity at room temperature for 2 h. Meanwhile, eugenol was transformed into 14.3{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} isoeugenol and 50.6{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} dehydrodieugenol over Na/NaOH/-Al2O3 under the same condition. Dimerization of eugenol occurs at the same time competitively with the generation of isoeugenol. The dimerization of eugenol identified by H-NMR and 13C-NMR spectra is evidence that the superbase catalyst may act as an oxidizing agent for eugenol continued by radical mechanism.

Keywords: eugenol ; methyl eugenol ; superbase catalyst Na/NaOH/Al2O3 ; isomerization ; dimerization

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