Pinosylvin monomethyl ether

Fig. 5-9. Radial variations in the content and composition of extractives in Scots pine (Pinus sylvestris) (Assarsson, 1969 see also Lindgren and Norin, 1969). 1, Total extractives 2, triglycerides 3, resin acids 4, fatty acids 5, pinosylvin + monomethyl ether.

The early chemotaxonomic studies of Erdtman (1952) showed that the heartwood of pines contained flavonoid (Ce-Cs-Ce) and stilbene (C6-C2-Ce) compounds, which could aid species identification. Although the two sections of the pine genus, Haploxylon and Diploxylon, both contain the stilbenes pinosylvin and pinosylvin monomethyl ether, the groups can be distinguished since the Diploxylon group (pines with two or three needles per cluster) contains only flavanones whereas... 

Pinosylvin (3,5-stilbenediol) ( )-form needles, insoluble in water, soluble in acetone. )- and (Z)-isomers occur together with the corresponding mono- and dimethyl ethers in pines, firs, and conifers. Pinosylvin has antifungal and antibacterial activities and protects the wood against rot, as a disinfectant it is 30-times stronger than phenol and is highly toxic for fish. As a result of condensation with lignin, pinosylvin prevents sulfite dissolution of wood. Pinosylvin monomethyl ether acts as an antifeedant for certain rabbit species. ... 

Pinosylvin and pinosylvin monomethyl ether are formed in the reaction zone in Pinus spp. as a response to fungus infections (57, 61). There is also an interesting correlation between the stilbene production in Pinus radiata and the presence of ethylene (plant hormone) in the wood (105, 106). The processes involved in heartwood formation and the formation of phenolic compounds in reaction zones have been extensively investigated and reviewed by Hillis (59). 

Plant phenolics of stilbene type are also reported to contribute to the insect resitance of the wood. Thus wood samples impregnated with pinosylvin monomethyl ether are resistant to the attack of the West Indian termite Cryp-totermes brevis (123, 124). Pinosylvin dimethyl ether and dihydropinosylvin were less effective. Sandermann and co-workers (103) have also found that pinosylvin and related hydroxystilbenes as well as some other phenolic wood extractives contribute to the termite and insect resistance of wood. However, our knowledge on this topic is still limited, and further studies shall reveal useful information. 

Loman A A 1970 Bioassays of fungi isolated from Pinus contorta var. latifolia with pinosylvin, pinosylvin monomethyl ether, pinobanksin and pinocembrin. Can J Bot 48 1303-1308... 

During acid sulfite pulping, lignin may also condense with reactive phenolic extractives. Pinosylvin and its monomethyl ether, present in pine heartwood, are examples of phenolic extractives of this type. Dual condensation of pinosylvin with lignin generates harmful cross-links. Consequently, pine heartwood cannot be delignified by the conventional acid sulfite method. 

Monomethyl ether, ClsH,4Or crystals, mp 122-123°. Uv max (ethanol) 303 nm (log e 4.26). More sol in benzene than pinosylvin. Also sol in methanol, glacial acetic acid. 

The first diflferentiation is used in various sectors of the wood-processing industry like the pulp and paper industry, as its chemical behaviour is defined by the polarity. Depending on the chemical pulping, certain extractives can show negative effects on the production, e.g. pinosylvin and its monomethyl ether during acid sulphite pulping. In contrast, other pine extractives (resin acids, terpenes, eic.) are useful by-products in Kraft pulping (see Section 9.4.3). 

A common oxygenation pattern of the natural stilbenes is the 3,5-dioxy substitution. Thus, the first natural stilbenes to be isolated from wood - pinosylvin and its monomethyl and dimethyl ethers-carry 3,5-dioxy substituents (35). 

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