The Chemical Constituents Related to the Color of Sugi Heartwood and the Color Conditioning of the Heartwood by Chemical Modification.

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1. Methanol-Soloble coloring materials of sugi heartwood (2types:reddish colored heartwood and dark colored heartwood) were methylated or ethylated followed by oxidation with potassium permanganate in alkaline media. The results of GLC analysis of the oxidation products are summarized as follows: (1) Two types of the coloring materials were composed of the six partial structures: p-hydroxyphenyl group, 3,4-dihydroxyphenyl group, guaiacyl group, 3,4-dimethoxyphenyl group, 3-methoxy-4,5-dihydroxyphenyl group and guaiacyl group condensed at 6-position. (2) The dark colored heartwood contained 3-methoxy-4,5-dihydroxylhenyl group more than that of reddish colored heartwood. The existence of this partial structure in sugi heartwood was found for the first time in the present investigation. (3) The content of methoxyl group in the coloring material of the dark colored heartwood was higher than that of the reddish colored heartwood.2. Acetyl derivatives of agatharesinol and sequirin C were isolated from the extractives of acetylated dark colored heartwood, and identified by NMR and IR spectra. In the extractives, the substance possible to be polyphenol having 3-methoxy-4,5-dihydroxyphenyl group was detected by TLC, but not to be able to isolated.3. Color improvement of dark colored heartwood was conducted with various chemical treatnent. The treatment with ozone in dichloromethane: methanol (1:1)medium gave the most effective color improvement to the dark colored heartwood. Methylation of the wood diazomethane resulted in remarkable bleaching effect.