Mechanochemistry of Lignin Model Compounds in Relation to Bleaching of Mechanical Pulp

Abstract

1. As shown in Fig. 1, changes in the amounts of coniferyl aldehyde groups in both GP and TMP were shown by the treatment with aqueous H202 or ethanolic H202.2. Mechanochemical conversions of t-CAMe are shown in Fig.3.3. One hr treatments for both guaiacyl glycerol-β-guaiacyl ether and veratryl glycerol-figuaiacyl ether with a CBM gave no significant product. Therefore, veratryl glycerol-β-vanillin ether (II) having high polarity was prepared and studied it's mechanochemistry. Treatment of this compound (II) with a CBM for lhr, splitting reaction of a large amounts of para-carbonyl phenol ether occurred to give 18.8, 4.8, 4.0, and 0%, respectively, as shown in Table 2.As shown in Fig.5 and 6, mechanochemical treatment of veratrylglycerol-β-vanillin ether with a CBM furnished at least seven kinds of products. In Fig. 7, chromophores were produced through mechanical pulping followed by alkaline H2O2-bleaching of wood lignin.Four types of phenyl coumarane model compounds IP-IVP were prepared as shown in Fig. 8, 9, and the following synthetic route of phenyl coumarones: 4and 5were also shown in Fig.9.As shown in Fig. 10, mechanochemical reactions of four kinds of phenyl coumarane model compounds (I-P-IV-P) proceed via compound (A) to stilbene type of compounds (II-S, IV-S). On the other hand, the intermediate compound (A) proceeds via (D) and (E) to give III-R and IV-R. The last one from (I-P-IV-P) affords (B) and (C) to give compounds (I-S, III-S). As is well-known, alkaline-H2O2 bleaching of (I-S, III-S) furnishes hydroquinone and quinone, respectively, as shown in Fig.11-15, respectively.As shown in the splitting reaction between Cα-Cβ bond in Compound [I], at least eight compounds were confirmed in Fig.20 and Table 6. In these cases, three radical species“·O2H, ·OH, and ·H” occurred to give ultrasonic waves as shown in Fig. 22.Treatment of creosol with HCHO furnished first to give condensation products [I], [II], and [III], respectively, as shown in Fig. 23 and Table 7.