Polymeric supports phenolic

Thus, phenols on a polymeric support can be converted into triflates using triflic anhydride. In the procedures outlined below, the triflation was performed on PS/ DVB-resin. 

The reason that a mixtiue of 80 vol % 1,4-dioxane and 20 vol % phosphate buffer is such a good compromise for the polymerization of phenols is probably up to the formation of aggregates consisting of phenols and 1,4-dioxane. With this solvent composition, the mole fraction of 1,4-dioxane is equal to that of water [83]. Experimental data have been pubUshed which clearly indicate the formation of phenol aggregates in a 1,4-dioxane/phosphate buffer mixture [83,84]. The stabiUzation of these aggregates is best with a composition of 80 vol % 1,4-dioxane and 20 vol % phosphate buffer [83]. It seems logical that the formation of aggregates could support the recombination of radicals and the electron-transfer step. 

Fuertes and co-woikers [12, 46 8, 78] investigated intensively the preparation of caibon membranes from PR precursors. According to Centeno and Fuertes [12], they coated a small quantity of liquid phenohc resin (Novolak type) on the finely polished surface of a porous carbon disk by means of a spin coating technique. The supported phenolic resin film was cured in air at 150°C for 2 h, and then carbonization was carried out in a vertical tubular furnace (Carbolite) at different temperatures (between 500 and 1,000°C) under vacuum. Figure 4.6 shows the SEM micrograph of the membranes. The polymeric film (Fig. 4.6a) coated on top of the porous substrate is dense and has a thickness of around 2 pm. The thickness of the carbon membrane shown in Fig. 4.6b is also about 2 pm. Figure 4.6c shows the top view of the fractured membrane. The top smface is veiy smooth. Helium gas permeance of membranes carbonized at different temperatures is shown in Fig. 4.7. 

To support a polystyrene onto the upper rim of ca-lix[4]arene (phenolic-O- of calix[4]arene) and 25,26,27-tribenzoyloxy-28-hydroxy, calix[4]arene was treated with chloromethylated polystyrene in the presence of K2CO3 (Scheme 7). Polymeric calix[4]arene (3a) thus obtained was hydrolyzed in the benzoyl groups prior to use for the extraction process. 

Zhang developed a monolithic poly(styrene-co-divinylbenzene) CEC column in which the EOF is supported by carboxyl groups of polymerized methacrylic acid [ 133]. Using benzene as a probe, column efficiencies of 90,000 -150,000 were observed within a flow velocity range of l-10cm/min (0.2-1.7 mm/s). Different families of compounds such as phenols, anilines, chlorobenzenes, phenylendi-amines, and alkylbenzenes were well separated typically in less than 5 min using 20 cm long columns. 

The third application is the oligomerization of phenol. By selecting solvent and supporting electrolyte, phenol is electro-oxidatively polymerized to yield poly (phenyleneoxide) as a tan-colored powder. 

The concept of using group I metal initiators was applied in order to minimize the toxicity generated by heavy metal residues in the end product PLAs when using metals like aluminum, tin, and lanthanides as initiators. In recent years, dinuclear lithium and macro-aggregates with phenolate ligands have attracted substantial interest, mainly due to uncommon strucmral feamres and their ability to catalyze formation of polyester and various other polymeric materials via ROP [28]. A series of lithium complexes supported with 2, 2-ethylidene-bis (4, 6-di-tert-butylphenol) (EDBP-H2) 2-6, (Scheme 6) are excellent initiators for the ROP of L-lactide in CH2CI2 at 0 °C and 25 °C [33-35]. In this case, the PDIs of the obtained PLAs were quite narrow (1.04—1.14) and a Unear relationship between and the monomer-to-initiator ratio ([M]o/[I]o) existed at 0 °C. Dimeric complexes 4 and 6 were the... 

Fig. 3 Bis(phenolate)-supported dimeric lithium and potassium L-lactide polymerization initiators [36-43]...

Nonoligomeric libraries. Peptide and peptoid libraries are examples of oligomeric (polymeric) libraries made up of repeating monomers (a-amino acids, A-substitutcd glycines). Random libraries composed of nonoligomeric compounds have been extensively explored. One illustration comes from the former laboratories at Organon (Fig. 1.6) (16). Thirteen different secondary amino-phenol inputs were attached to solid support by reaction with REM resin yielding resin-bound b-amino propionates. Two-site derivatization was then used to drive library diversity. The free phenolic OH was subjected to O-alkylation,... 

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