Oxygen Polyethylene glycol

In contrast to phosphorus esters, sulfur esters are usually cleaved at the carbon-oxygen bond with carbon-fluorine bond formation Cleavage of esteri nf methanesulfonic acid, p-toluenesidfonic acid, and especially trifluoromethane-sulfonic acid (tnflic acid) by fluoride ion is the most widely used method for the conversion of hydroxy compounds to fluoro derivatives Potassium fluoride, triethylamine trihydrofluoride, and tetrabutylammonium fluoride are common sources of the fluoride ion For the cleavage of a variety of alkyl mesylates and tosylates with potassium fluoride, polyethylene glycol 400 is a solvent of choice, the yields are limited by solvolysis of the leaving group by the solvent, but this phenomenon is controlled by bulky substituents, either in the sulfonic acid part or in the alcohol part of the ester [42] (equation 29)... 

Conder JR, Fruitwala NA, Shingari MK (1983) Thermal decomposition of polyethylene glycol 20 m and essential oils in gas—liquid chromatography and the effect of traces of oxygen. J Chromatogr A 269 171-178... 

O Neal DP, Meledeo MA, Davis JR, Ibey BL, Gant VA, Pishko MV, Cote GL (2004), Oxygen sensor based on the fluorescence quenching of a ruthenium complex immobilized in a biocompatible polyethylene glycol) hydrogel, IEEE Sensors Journal 4 728 - 734. 

IgE IgG IgM IL KLa KLH mAb PEG S-S TK tRNA Immunoglobin class E Immunoglobin class G Immunoglobin class M Interleukin Volumetric oxygen transfer coefficient keyhole limpet haemocyanin Monoclonal antibody polyethylene glycol Disulfide bridge thymidine kinase transcript of the RNA... 

Incidentally, C. J. Pedersen s first report on crown ethers and their complexes was published in the same year as the mechanism of the biological activity of valinomycin was clarified [2], Crown ethers are cyclic derivatives of polyethylene glycol of varying ring size, an example of which is also depicted in Figure 2.2.1. The structural relationship with the ionophores is clearly visible. It is thus not surprising that crown ethers also bind metal cations by coordination with the oxygen atoms [1, 3]. 

Moghimi, S. M., Hamad, I., Andresen, T. L., Jorgensen, K., and Szebeni, J. (2006), Methylation of the phosphate oxygen moiety of phospholipid-methoxy(polyethylene glycol) conjugate prevents PEGylated liposome-mediated complement activation and anaphylatoxin production, FASEB /., 20, 2591-2593. 

Synthesis from polyethylene glycol dibromides. Treatment of a poly (ethylene glycol) dibromide with Ba(OH)2 8H2O as a source of OH" and Ba followed by pyrolysis results in a crown ether. The Ba ion acts as a template. The present method requires only one building block (with one less oxygen than the crown ether formed). Highest yields (50%) are obtained with 18-crown-6. ... 

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