Dynamics of Pseudoliquid Phase of Heteropolyacids and Design of New Catalytic Reactions

本研究的目的是：(1)阐明伪液相在催化反应中的行为；(2)揭示分子在伪液相中的活化状态；(3)利用杂多化合物的伪液相构建新的催化反应体系。结果表明：(1)由于几乎所有的质子都参与了催化，所以伪液相对醇的脱水反应具有很高的催化活性。用红外光谱和固体核磁共振研究了乙醇在H_3PW_&lt；12&gt；O_&lt；40&gt；的伪液相中脱水反应机理。用固体核磁共振直接测定了质子化乙醇二聚体(乙醚中间体)、质子化单体和乙氧基(乙烯中间体).(3)[(C_5H_5N)_2H]_3PW_&lt；用单晶X-射线衍射法测定了其结构，其中吡啶分子配对形成(C_5H_5N)-H^-(NC_5H_5)阳离子。(4)通过伪液相大大提高了苯酚的液相烷基化反应活性。H3PW&lt；12&gt；O&lt；40&gt；比普通固体酸和H_2SO_4活性高得多。

The aims of this study are (i) to elucidate the pseudoliquid phase behavior in catalysis, (ii) to reveal the activated state of the molecules in pseudoliquid phase, and (iii) to construct the new catalytic reaction systems, utilizing the pseudoliquid phase of heteropoly compounds.The results are summarized as follows:(1) The pseudoliquid phase brought about the high catalytic activity for dehydration of alcohols, since nearly all protons in the bulk takes part in catalysis. In addition, unique selectivity for the reaction of polar molecules due to the pseudoliquid phase was obtained.(2) The reaction mechanism of dehydration of ethanol in the pseudoliquid phase of H_3PW_<12>O_<40> was elucidated by using IR and solid state NMR. Protonated ethanol dimer (intermediate for diethyl ether),protonated monomer, and ethoxy group (intermediate for ethylene) were directly detected by ^<13>C solid state NMR.(3) The crystal structure of the complex, [(C_5H_5N)_2H]_3PW_<12>O_<40> was determined by the single crystal X-ray diffraction method, where pyridine molecules are paired forming the (C_5H_5N)-H^+-(NC_5H_5) cation in the structure.(4) By the pseudoliquid phase, the activity of liquid-phase alkylation of phenol was greatly enhanced. H_3PW_<12>O_<40> was much more active than ordinary solid acids and H_2SO_4.