Design of Multifunctional Solid Superacid for Clean Chemical Processes

目前，大量的酸催化反应，如Friedel-Craft反应、酯化反应、水合反应和水解反应等都是用H_2SO_4和Al_1C_3等液体酸进行的，存在毒性大、腐蚀性大、催化剂浪费、催化剂用量大、分离回收困难等问题。用固体酸取代液态酸在化学和生命科学中变得更加重要，因为固体酸具有腐蚀性、安全性、减少浪费、可分离性和可回收等优点。耐水性是酸性Cs盐Cs_&lt；2.5&gt；H_&lt；0.5&gt；P_&lt；12&gt；O_&lt；40&gt；(缩写为CS2.5)的一种新功能。比较水和苯的吸附量，得出疏水性的顺序如下：HZSM-5(Si/Al=628)&GT；SiO_2&GT；CS3&GT；H-ZSM-5(Si/Al=40)[相似或相等]Cs2.5&GT；SiO_2-Al_2O_3&GT；Al_2O_3。由于Cs2.5的疏水性，它对水中的烯烃水合、酯和低聚糖的水解等有机反应具有很高的活性。此外，Cs2.5在过量水中也能有效地催化丁腈与醇反应合成AT-烷基酰胺。在两相反应体系中，H3PW&lt；12&gt；O_&lt；40&gt；对甲醛(甲醛水溶液)和苯合成二苯甲烷的反应具有极高的活性。

A huge number of acid catalyzed reactions such as Friedel-Crafts reactions, esterification, hydration and hydrolysis are currently performed using liquid acids such as H_2SO_4 and A1C1_3, having several problems of high toxicity, corrosion, catalyst waste, use of large amount of catalyst, difficult of separation and recovery. The replacement of the liquid acids with the solid acids is becoming even more important in chemical and life science, since the solid acids are green with respect to corrosiveness, safety, less waste, separability, and recoverability. Water-tolerancy is a novel function of an acidic Cs salt, Cs_<2.5>H_<0.5>P_<12>O_<40> (abbreviated as Cs2.5). Comparison of adsorption amounts of water and benzene led to the following order of hydrophobicity; HZSM-5 (Si/Al = 628) > silica > Cs3 > H-ZSM-5 (Si/Al = 40) 【similar or equal】Cs2.5 > silica-alumina > alumina. Owing to the hydrophobicity, Cs2.5 was highly active for organic reactions like hydration of alkene and hydrolysis of esters and oligosugars in water. Also, Cs2.5 was efficient for the reaction of nitrile with alcohol to AT-alkylamide even in excess water. In a bi-phasic reaction system, H_3PW_<12>O_<40> (in liquid state) was exceptionally active for synthesis of diphenylmethane from formalin (aqueous formaldehyde) and benzene.