四氢呋喃/环氧乙烷共聚醚与N-100固化反应机理(Ⅰ)──NMR研究催化活性与反应物的相互作用

Studies of Catalyzed Reaction Mechanism Between Co-polyether (THF/EO) and N-100 by NMR (Ⅰ)──Interaction and Complex Formation Between Reactants and Catalysts

采用高分辨核磁共振方法研究聚醚聚氨酯脲反应体系中四氢呋喃／环氧乙烷共聚醚和固化剂N－100及催化剂之间的相互作用．结果表明共聚醚的羟基和N－100的异氰酸酯基因之间存在相互作用，能够形成一种相对稳定的络合物．催化剂二月桂酸二丁基锡（DBTDL）能与共聚醚的羟基氧络合，从而使羟基氢活化；催化剂三苯基铋（TPB）及其乙氧基取代的衍生物与共聚醚羟基氢之间存在弱氢键作用．其强度随TPB乙氧基衍生物的碱性增强而增大．当DBTDL和TPB同时存在于反应体系中时，羟基上的氧和氢均被活化，表现为协同作用．

To elucidate the mechanism of the catalyzed reaction of co-polyether (EO/THF)with N-100, the interaction and complex formation between reactants and catalysts were in-vestigated by means of NMR spectroscopy. It is shown that the resonance peak of isocyanate carbon splits into two parts when the solutions of N-100 and co-polyether were mixed. The disappearing of proton resonance peak of hydroxyl group in NMR spectra when dibutyltin di-laurate(DBTDL) were added to the copolyether(THF/EO) solution indicates the complex formation. This interaction appears to be a bonding of tin to the oxygen of hydroxyl and make the hydrogen of the hydroxyl group very mobile and active, then exchange with other protons. In the case of triphenyl bismuth(TPB), the high field shift and intensity enhance-ment of proton peak were observed, which suggest a nucleophilic attack of the bismuth to the hydroxyl hydrogen.