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单宁-醛-胶原的反应——对植醛结合鞣机理的再认识

REACTION OF VEGETABLE TANNIN-ALDEHYDE-COLLAGEN ——A FURTHER UNDERSTANDING ON VEGETABLE TANNIN-ALDEHYDE COMBINATION TANNAGE

  • 摘要: 以黑荆树单宁为植物鞣剂,噁唑烷为醛鞣剂,较系统地研究了氢键、疏水键、胶原氨基在植鞣、醛鞣和植-醛结合鞣中的作用。证实了植-醛结合鞣的反应机理与已有的认识有很大的区别。醛类化合物即使在植鞣后加入,其主要的反应基团仍然是皮胶原的氨基。但是当单宁分子中含有亲核活性较高的反应基团时,醛类化合物可以在皮胶原和单宁分子之间形成交联键。这种交联作用可以对提高皮胶原的热稳定性产生协同效应,而且使单宁与皮胶原的结合稳定性进一步加强,能够抵御氢键破坏试剂和疏水键破坏试剂的作用。采用缩合类单宁时,容易形成胶原-醛-单宁交联键;但采用水解类单宁时,形成这种交联键的几率很小。

     

    Abstract: Using mimosa tannin as vegetable tanning agent and oxazolidine as aldehydic tanning agent,the effects of hydrogen bond,hydrophobic bond and side amino group of collagen on vegetable tanning,aldehyde tanning and vegetable-aldehyde combination tanning were investigated.Results indicated that aldehyde predominantly reacted with the side amino group of collagen even it was used after vegetable tanning.However,aldehyde could further react with vegetable tannin to form cross-linkage between collagen and vegetable tannin if highly nucleophilic sites in tannin molecules were available.As a result,the synergistic effect of the combination tanning in increasing hydrothermal stability of collagen fibers was achieved and the association between vegetable tannin and collagen was remarkably stabilized.This mechanism is appropriate for describing combination tanning with condensed tannins that contain nucleophilic sites.For hydrolysable tannins,however,no aldehydic cross-linkage between collagen and tannin could be observed.In (general),this research revealed the fact that the actual features of vegetable-aldehyde combination tanning should be different from the previously assumed one.With the mechanism suggested in this paper,all the phenomena in (vegetable) tannin-aldehyde-collagen interaction could be well understood.

     

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