Hydrogenolysis of Hydroxymatairesinol Over Carbon-Supported Palladium Catalysts
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Catalysis Letters Vol. 103, Nos. 1–2, September 2005 ( 2005) DOI: 10.1007/s10562-005-6514-6
Hydrogenolysis of hydroxymatairesinol over carbon-supported palladium catalysts Heidi Markusa, Pa¨ivi Ma¨ki-Arvelaa, Narendra Kumara, Natalya V. Kul’kovab, Patrik Eklundc, Rainer Sjo¨holmc, Bjarne Holmbomd, Tapio Salmia, and Dmitry Yu. Murzina,* Laboratory of Industrial Chemistry, Process Chemistry Centre, A˚bo Akademi University, Biskopsgatan 8, FIN-20500, A˚bo/Turku, Finland b Karpov Institute of Physical Chemistry, Moscow, Russia c Department of Organic Chemistry, Process Chemistry Centre, A˚bo Akademi University, Biskopsgatan 8, FIN-20500, A˚bo/Turku, Finland d Laboratory of Wood and Paper Chemistry, Process Chemistry Centre, A˚bo Akademi University, Porthansgatan 3, FIN-20500, A˚bo/Turku, Finland a
Received 11 March 2005; accepted 29 May 2005
The natural lignan hydroxymatairesinol was hydrogenolysed to a potential anticarcinogenic substance matairesinol over different carbon-supported palladium catalysts. The reaction was conducted in 2-propanol at 70 C under hydrogen flow in a stirred glass reactor. The catalysts were characterised by N2-physisorption, CO pulse chemisorption and pH measurement of aqueous catalyst slurries. The most active catalyst (Degussa-Hu¨ls) gave yields of matairesinol over 90% in 4 h. It was concluded that the acidity of the catalyst had a profound influence on the reaction rate. KEY WORDS: lignans; hydroxymatairesinol; matairesinol; hydrogenolysis; carbon-supported palladium catalyst.
1. Introduction Lignans, a group of plant phenols consisting of two b-b-linked cinnamic acid residues [1], can be found in many different plant parts, such as the wooden parts, roots, leaves, flowers, fruits, and seeds. Most plants contain only small amounts of lignans as glycosidic conjugates associated with fibre components, which makes the isolation process difficult [2]. Coniferous trees, on the other hand, contain exceptionally large amounts of lignans in unconjugated forms, which makes it easier to isolate them. Norway spruce (Picea abies) knots, i.e., the part of a branch that is embedded in the stem, contain large quantities of lignans, 6–24 wt.%, out of which hydroxymatairesinol is the most abundant, constituting 65–85 wt.% of the lignans [3]. There are two diastereomers of hydroxymatairesinol, (7R,8R,8¢R)(–)-7-allo-hydroxymatairesinol (HMR 1) and (7S,8R,8¢R)-(–)-7-hydroxymatairesinol (HMR 2), of which the latter is the major isomer [4]. Many different plant lignans are converted by the mammalian gut microflora to the mammalian lignans enterolactone and enterodiol [5]. In the beginning of the 1980s it was suggested that lignans may prevent breast cancer [6]. Several studies were made and the results showed that women who have breast cancer excrete smaller amounts of enterolactone than healthy women do, and that the urinary enterolactone excretion can be associated with the grain-fibre intake. It has also been * To whom correspondence should be addressed. E-mail: dmurzin@abo.fi
proposed that besides breast canc
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