Functionalization polyethylene glycol

If mono-hydroxyl functionalized polyethylene glycol), HO-PEG, is added to Ca(NTMS2)2.THF2, then addition of LA affords the diblock PEG-b-PLA (Mn= 15,500, Mn calc = 15,500, Mw/Mn = 1.03).832 Using a similar strategy the reaction of CaFI2 with telechelic diol HO-(PEG)-OH, followed by polymerization of L-LA results in a triblock structure, PLA-b-PEG-b-PLA of narrow polydispersity (1.02-1.08).835 836 Triblock copolymers of morpholine-2,5-diones with PEO have also been prepared in this manner.837... 

PEG has been converted into a solid support by grafting functionalized polyethylene glycol chains onto polystyrene to form constructs such as TentaGel ... 

A very efficient catalytic system has been developed by He and coworkers using, under solvent-free conditions, quaternary ammonium bromide-functionalized polyethylene glycol (0.25 mol% 373 K, 8MPa, 5-20min) [68d]. The catalyst worked well for a variety of l-alkyl-2-aryl-substituted aziridines, and could be easily recovered by centrifugation and reused, without any significant loss of catalytic activity and selectivity. 

Miao C-X, He L-N, Wang J-Q et al (2009) Biomimetic oxidation of alcohols catalyzed by TEMPO-functionalized polyethylene glycol and copper chloride in compressed carbon dioxide. Synlett 20 3291-3294... 

Du Y, Wu Y, Liu A-H et al (2008) Quaternary ammonium bromide functionalized polyethylene glycol a highly efficient and recyclable catalyst for selective synthesis of 5-aryl-2-oxazolidinones from carbon dioxide and aziridines under solvent-free conditions. J Org Chem 73(12) 4709-4712... 

Wang X, Yang H, Feng B et al (2009) Functionalized polyethylene glycol)-stabilized palladium nanoparticles as an efficient catalyst for aerobic oxidation of alcohols in supercritical carbon dioxide/poly(ethylene glycol) biphasic solvent system. Catal Lett 132 34-40... 

Tian J-S, Miao C-X, Wang J-Q et al (2007) Efficient synthesis of dimethyl carbonate from methanol, propylene oxide and C02 catalyzed by recyclable inorganic base/phosphonium halide-functionalized polyethylene glycol. Green Chem 9(6) 566—571... 

In a subsequent investigation by the author [2] bi-functional polyethylene glycol derivatives, (II), were prepared. 

A hybrid between combinatorial synthesis on solid phase and in solution phase is the liquid-phase method characterized by the application of carrier polymers completely soluble in one solvent and insoluble in another solvent, for example functionalized polyethylene glycol [32,33]. 

Hydroxyapatite (CajQ(P04)g(0H)2) has also attracted considerable interest as a catalyst support. In these materials, wherein Ca sites are surrounded by P04 tetrahedra, the introduction of transition metal cations such as Pd into the apatite framework can generate stable monomeric phosphate complexes that are efficient for aerobic selox catalysis [99]. Carbon-derived supports have also been utihzed for this chemistry, and are particularly interesting because of the ease of precious metal recovery from spent catalysts simply by combustion of the support. Carbon nanotubes (CNTs) have received considerable attention in this latter regard because of their superior gas adsorption capacity. Palladium nanoparticles anchored on multiwalled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) show better selectivity and activity for aerobic selox of benzyl and cinnamyl alcohols [100, 101] compared to activated carbon. Interestingly, Pd supported on MWCNTs showed higher selectivity toward benzaldehyde, whereas activated carbon was found to be a better support in cinnamyl alcohol oxidation. Functionalized polyethylene glycol (PEG) has also been employed successfully as a water-soluble, low-cost, recoverable, non-toxic, and non-volatile support with which to anchor nanoparticulate Pd for selox catalysis of benzyl/cinnamyl alcohols and 2-octanol [102-104]. 

Francisco, A.T., Hwang, P.Y., Jeong, C.G., ling, L., Chen, J., Setton, L.A. Photocros-slinkable laminin-functionalized polyethylene glycol hydrogel for intervertebral disc regeneration. Acta Biomater. 10(3), 1102-1111 (2014)... 

Kandel, P. K. Fernando, L. R Ackroyd, P. C. Christensen, K. A. Incorporating functionalized polyethylene glycol lipids into reprecipitated conjugated polymer nanoparticles for bioconjugation and targeted labeling of cells. Nanoscale 2011, 3, 1037-1045. 

Zalipsky S (1993) Synthesis of an end-group functionalized polyethylene glycol-lipid conjugate for preparation of polymer-grafted liposomes. Bioconjug Chem 4 296-299... 

Karakhanov, E.A. Kardasheva, Y.S. Maksimov, A.L. Predeina, V.V. Runova, E.A. Utukin, A.M. (1996) Macrocomplexes on the basis of functionalized polyethylene glycols and copolymers of ethylene-oxide and propylene-oxide synthesis and catalysis, J. Mol. Catal A - Chem., 107,235-40. 

Tian, I Miao, C. Wang, J. Cai, F. Du, Y Zhao, Y He, L. Efficient Synthesis of Dimethyl Carbonate from Methanol, Propylene Oxide and COj Catalyzed by Recyclable inOrganic Base/Phosphonium Halide-Functionalized Polyethylene glycol. Green. Chem. 2007, 9, 566-571. 

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