Chemical Modification of Bark Extracts to Prepare High Quality Resins.

1)缩合单宁的性质用BF_3催化的标准苯基核交换法(NE-反应)和估算缩合单宁的常规方法相结合的方法，阐明了几种针叶树皮提取物和金合欢单宁的化学特征。2)缩合单宁的酚化和NE-反应。用由苯酚和酸性催化剂组成的试剂处理缩合单宁，在体系中以酚类为介质，通过NE-反应释放它们的组成核。实验结果表明，随着体系中水含量的增加，反应速率逐渐降低，水的抑制作用主要是由于体系的酸度降低所致。3)苯酚-水反应…对缩合单宁的化学修饰单宁在苯酚-水-酸体系中的酚化反应试图裂解黄酮醚环环，导致酚类化合物在C-2位上接枝，以避免分子的空间位阻。实验结果表明，酚化反应和NE-反应在化合物中同时发生，酚化反应速率随着酚类物质的电负性和体系酸度的增加而增加。4)单宁型木材胶粘剂的性能。由1摩尔的单宁和1.05摩尔的间苯二酚制备的间苯二酚-单宁加合物具有较好的冷固性。另一方面，酚化后的苯酚-单宁加合物具有较好的热定型能力。然而，要使天然树脂的耐久和快速固化达到合成树脂的水平，还需要进一步改进方法。较少

1) Characteristics of Condensed Tannins.Chemical characteristics of wattle and quebracho tannins and the bark extracts from some species of coniferous trees were elucidated by a method combining the standard phenyl nucleus-exchange method (the NE-reaction) using BF_3 catalyst and the conventional techniques for estimating of the general aspects of the tannin.2) Phenolation and the NE-reaction of Condensed Tannin.By the treatment of condensed tannins with reagents composed of phenol and acidic catalysts, their constituent nuclei were liberated by the NE-reaction, via phenolation with phenols added as a medium in the systems. From the experimental results used bronsted acid as a catalyst, decreasing the reaction rates was observed with increasing water contents in the systems and such inhibitory effects of water were estimated to be due to the decreasing the acidity, determined as an acidity function H_0, of the system.3) Chemical Modification of Condensed Tannin by Phenol-Water Reaction … More System.The phenolation of tannin in the phenol-water-acid systems was tried to cleave of flavonoid etherocyclic rings, leading to grafting of phenols in the systems at position C-2, for the purpose of leaving out of the steric hindrance of the molecule. The experimental results show that the phenolation and the NE-reaction took place in the compound at the same time, and the phenolation rate was increased with increasing the electronegativity of phenols used as medium and the acidity of the systems.4) The Property of Tannin-Based wood Adhesive.The properties of tannin-based resins as cold- or hot-setting adhesives prepared by chemical modification with resorcinol or phenol were tested. The resorcinol-tannin adduct prepared by 1 mole of tannin and 1.05 moles of resorcinol and exhibit a reasonable cold-setting properties. On the other hand, the phenol-tannin adduct by phenolation showed suitable hot-setting abilities. However, further improved approaches are necessary to make durable and fast curing natural resins corresponded to that of the synthetic resins. Less