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). 

Several of the polystyrene-based supports aim at increasing the size of the spacer-arm, thus making the attached peptide more easily accessible to the reagents. For example, several modified supports using a modified macroreticular polystyrene as a base have been reported (Inman et al., 1977). Amino groups for peptide attachment were located at the end of poly(ethylene glycol) units that were directly attached to the polystyrene core. 

SO3H) for cations, is the same in HPLC as in classical ion exchange chromatography. A variety of substrates ranging from cross-linked polystyrene, cross-linked polydextrans, cellulose and silica have been utilised. However, due to the problems of swelling, compressibility and mass transfer encountered with macroreticular polymeric supports and the limited pH stability of silica-based packings, the efficiencies achieved in lE-HPLC applications have been moderate. 

Rollman and co-workers have reported a study on Rh elution from polymer supports where the Rh was anchored to porous macroreticular polymer supports based on polystyrene cross-linked through divinylbenzene or ethyleneglycoldimethacrylate via dibutylphenylphosphine or AW-dimethyl-benzylamine groups. When a flow reactor at 85-100 °C and 5-10 MPa H2/CO was used Rh concentrations of 0.2-17 x 10 M were observed in the effluent. Increasing metal loadings, CO pressure, or the polarity of the solvent caused a corresponding increase in Rh loss while increasing temperature decreased metal loss. If these results are representative of the... 

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sieve zeolites, for example, crystalline aluminosilicates of group I and II elements, in which the latter have been replaced by protons.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. 

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