Silica supported functional group

The major advantage of a bonded stationary phase is stability. Since it is chemically bonded, there is very little loss of stationary phase with column use. The siloxanes are the most widely used silica supports. Functional groups that can be attached as siloxanes are alkylnitriles (—Si—CH2CH2—CN),... 

Another type of silica-supported functional group has been prepared by coating silica gel with PS via free radical polymerization of styrene and divinylbenzene in the presence of silica gel which can in turn be further functionalized by the bromi-nation and reaction with KPPha to give sihca gel coated with phosphinated PS (Scheme 1.10) [180,181] ... 

FIGURE 10.2 Schematic representation of anchoring of organotitanium complexes to silica support functionalized with spaced amine groups. 

Support Silica gel Functional Group 5-methyl-8-hydroxy-quinoline Method/Coupling Agent Organic functional silane derivatives in solutions and surface Metal Ions Pb(ll), Cu(ll), Ni(ll), Cd(ll)... 

Previous studies by Sorokin with iron phthalocyanine catalysts made use of oxone in the oxidation of 2,3,6-trimethylphenol [134]. Here, 4 equiv. KHSO5 were necessary to achieve full conversion. Otherwise, a hexamethyl-biphenol is observed as minor side-product. Covalently supported iron phthalocyanine complexes also showed activity in the oxidation of phenols bearing functional groups (alcohols, double bonds, benzylic, and allylic positions) [135]. Besides, silica-supported iron phthalocyanine catalysts were reported in the synthesis of menadione [136]. 

Silica is the most commonly used solid support. Treatment with complexes bearing alkoxy- or chlorosilane functional groups is a common way to generate supported complexes on silica or any inorganic oxide containing surface silanol (Si-OH) groups (Scheme 7.2).23,24... 

Other covalently bonded catalysts are those on inorganic supports such as silica, molecular sieves (zeolites), and alumina, the complexes being held either directly via the oxygen of surface hydroxy groups or via an intermediate functional group, again especially phosphino. 

Figure 3.14 A supported reagent, in a manner similar to a scavenger, consists of a reactive functional group grafted onto insoluble silica. The spent reagent is easily removed by filtration.

---