Resins polystyrene-based macroreticular

Macroreticular polystyrene-based resins with functional aminothiazole, imino-thiazole, or thiazoline groups exhibit a high selectivity for mercury(II). A thiazoline resin column has been used to concentrate mercury from sea water adjusted to pH 1 with hydrochloric acid. Maximum sorption capacity for mercury was found to be 2.8 mmole/g. The sorbed mercury is recovered quantitatively by eluting with 0.1 M HC1 containing 5 % thiourea 100). 

The most widely used catalysts for acid-catalyzed aldol condensations are the molecular sieve zeolites, for example, crystalline aluminosilicates of group I and II elements, in which the latter have been replaced by protons. The surface protons confer Br0nsted acidity. Among the acidic zeolites we can mention HZSM-5 (pentasil zeolite), HY (faujasite), or HM (mordenite). Recently, polystyrene-supported sulfonic acids such as those of the macroreticular strongly acidic cation-exchange resins (59) and acid-base functionalized mesoporous materials such as amine and sulfonic acid-containing SBA-15 (60) have been shown to promote the acid-catalyzed aldol condensation of aldehydes with ketones at low temperatures. 

---