The catalytic properties of bulky water-soluble salen complexes in the oxidation of isoeugenol(2-methoxy-4-(1-propenyl) phenol) have been investigated in aqueous ethanol solutions in order to obtain a mixture of polymeric compounds through dehydrogenative polymerization. The average molecular weight of dehydrogenated polymers (DHPs) was monitored by GPC and correlated to reaction conditions such as time, concentration of substrate, concentration of catalyst, type of oxidation agent, etc. The DHP synthesized by adopting the best reaction conditions was characterized by different analytical techniques (GPC, 13C-NMR, 31P-NMR and LC-MS) to elucidate its structure. The lignin-like polymer resulting from isoeugenol radical coupling possesses valuable biological activity and finds applications in a variety of fields, such as packaging industry and cultural heritage conservation.
References
[1]
Joo, H; Chae, HJ; Yeo, JS; Yoo, Y. Depolymerization of Phenolic Polymers Using Horseradish Peroxidase in Organic Solvent. J. Proc. Biochem？1997, 32, 291–296.
[2]
Kurek, B; Artaud, I; Pollet, B; Lapierre, C; Monties, B. Oxidative Degradation of in Situ and Isolated Spruce Lignins by Water-Soluble Hydrogen Peroxide Resistant Pentafluorophenyl Porphyrin. J. Agric. Food Chem？1996, 44, 1953–1959.
[3]
Pfeiffer, P; Breith, E; L？bbe, E; Tsumaki, T. Tricyclic Ortho-Condensed Partial Valence Rings. Justus Liebigs Ann. Chem？1933, 503, 84–130.
[4]
Minutolo, F; Pini, D; Petri, A; Salvatori, P. Heterogeneous Asymmetric Epoxidation of Unfunctionalized Olefins Catalyzed by Polymer-Bound (Salen)Manganese Complexes. Tetrahedron: Asym？1996, 7, 2293–2302.
[5]
Sheldon, R; Kochi, JK. Metal-Catalysed Oxidations of Organic Compounds; Academic Press: New York, NY, USA, 1981.
[6]
Haikarainen, A; Sipila, J; Pietikainen, P; Pajunen, A; Mutikainen, I. Synthesis and Characterization of Bulky Salen-Type Complexes of Co, Cu, Fe, Mn and Ni with Amphiphilic Solubility Properties. J Chem Soc., Dalton Trans？2001, 991–995.
[7]
Haikarainen, A; Sipila, J; Pietikainen, P; Pajunen, A; Mutikainen, I. Salen Complexes with Bulky Substituents as Useful Tools for Biomimetic Phenol Oxidation Research. Bioorg. Medicin. Chem？2001, 9, 1633–1638.
[8]
Sipila, J; Haikarainen, A; Brunow, G. Oxidative Delignification Chemistry, Fundamental and Catalysis; American Chemical Society: Washington, DC, USA, 2001.
[9]
Canevali, C; Orlandi, M; Pardi, L; Rindone, B; Scotti, R; Sipila, J; Morazzoni, F. Oxidative Degradation of Monomeric and Dimeric Phenylpropanoids: Reactivity and Mechanism Investigation. J. Chem. Soc., Dalton Trans？2002, 15, 3007–3014.
Terashima, N; Atalla, RH; Ralph, J; Landucci, LL; La Pierre, C; Monties, B. New Preparation of Lignin Polymer Models under Condition that Approximate Cell Wall Lignification. Synthesis of Novel Lignin Polymer Models and their Structural Characterization by 13C-NMR. Holzforschung？1995, 49, 521–527.
[12]
Shiba, T; Ling, X; Miyakoshi, T; Chen, CL. Oxidation of Isoeugenol and Coniferyl Alcohol Catalyzed by Laccases Isolated from Rhus Vernicifera Stokes and Pycnoporus Coccineus. J. Molecul. Catalysis B: Enzym？2000, 10, 605–615.
[13]
Yan, H; Ho, SH. Insecticidal Properties of Eugenol, Isoeugenol and Methyleugenol and their Effects on Nutrition of Sitophilus Zeamais Motsch. (Coleoptera: Curculionidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). J. Stored Product. Res？2002, 38, 403–412.
[14]
Evliya, H; Olcay, A. Oxidative Polymerization of Isoeugenol and Mild Oxidation of Synthetic Polymers with Alkaline Cupric Hydroxide. Holzforschung？1974, 130–135.
[15]
Quideau, S; Ralph, JA. Biomimetic Route to Lignin Model Compounds via Silver (I) Oxide Oxidation. Holzforschung？1994, 48, 124–132.
[16]
Orlandi, M; Agozzino, P; Donato, DI; Giachi, G; Toppa, EL; Zoia, L. Consolidation of Waterlogged Woods by in-situ Polymerisation of Isoeugenol; Conservation Science; Joyce, T, Ed.; Archetype Publications: London, UK, 2007; pp. 262–268.
[17]
Elegir, G; Kindl, A; Sadocco, P; Orlandi, M. Development of Antimicrobial Cellulose Packaging through Laccase-Mediated Grafting of Phenolic Compounds. Enzyme Microb. Technol？2008, 43, 84–92.
[18]
Sippola, V; Vilijava, TR; Vilonen, K; Krause, O. New Method to Follow the Dimerization Reaction Occurring During Oxidation of 4-Ethylguaiacol. Holzforschung？2002, 56, 601–606.
[19]
Sarkanen, KV. Lignin Precursors and their Polymerization. In Lignins: Occurrence, Formation, Structure, and Reactions; Sarkanen, KV, Ludwing, CH, Eds.; Wiley-Interscience: New York, NY, USA, 1971; pp. 95–163.
[20]
Canevali, C; Orlandi, M; Zoia, L; Scotti, R; Tolppa, EL; Agnoli, F; Morazzoni, F. Radicalization of Lignocellulosic Fibers, Related Structural and Morphological Changes. Biomacromolecules？2005, 6, 1592–1601.
[21]
Bortolomeazzi, R; Verardo, G; Liessi, A; Callea, A. Formation of Dehydrodiisoeugenol and Dehydrodieugenol from the Reaction of Isoeugenol and Eugenol with DPH Radical and their Role in the Radical Scavenging Activity. Food Chem？2010, 118, 256–265.
[22]
Granata, A; Argyropoulos, DS. 2-Chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane, a Reagent for the Accurate Determination of the Uncondensed and Condensed Phenolic Moieties in Lignins. J. Agric. Food Chem？1995, 43, 1538–1544.
[23]
Reale, S; di Tullio, A; Spetri, N; de Angelis, F. Mass Spectroscopy in the Biosynthetic and Structural Investigation of Lignins. Mass Spec. Rev？2004, 23, 87–126.
[24]
Evtuguin, D; Amado, F. Application of Electrospray Ionization Mass Spectrometry to Elucidation of the Primary Structure of Lignin. Macromol. Biosci？2003, 3, 339–343.
[25]
Evliya, H. Carbon-13 NMR Studies of a Dehydropolymer (DHP) from Isoeugenol; Comparison with Spruce Lignin. Holzforschung？1989, 43, 61–64.
[26]
Nenadis, N; Zhang, HY; Tsimidou, MZ. Structure–Antioxidant Activity Relationship of Ferulic Acid Derivatives: Effect of Carbon Side Chain Characteristic Groups. J. Agric. Food Chem？2003, 51, 1874–1879.
[27]
Rittstieg, K; Suurnakki, A; Suortti, T; Kruus, K; Guebitz, G; Buchert. Investigations on the Laccase-Catalyzed Polymerization of Lignin Model Compounds Using Size-Exclusion HPLC. J. Enzyme Microb. Technol？2002, 31, 403–410.
[28]
Himmel, ME; Tatsumoto, K; Oh, KK; Grohmann, K; Johnson, DK; Chum, HL. Molecular Weight Distribution of Aspen Lignins Estimated by Universal Calibration. In Lignin Properties and Materials; Glasser, WG, Sarkanen, S, Eds.; American Chemical Society: Washington, DC, USA, 1988; pp. 82–99.
