ISSN:
0887-624X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Studies have been carried out with the tosylate of the monomethyl ether of polyethylene glycol (MeO-PEG-OTs) and with low molecular weight models to assess whether the neighboring oxygen at position 3 or 6 provides the driving force for hydrolytic cleavage of these activated derivatives. Our results reveal that MeO-PEG-OTs undergoes hydrolysis by competitive pathways. Water directly displaces the tosylate group to give the original PEG alcohol and the oxygen at position 6 nucleophilically displaces the tosylate group to give a cyclic oxonium ion as an intermediate. This intermediate can react by three pathways. First, it can lead to the production of the original PEG alcohol by attack of water on a ring carbon; second, dioxane and a lower molecular weight PEG alcohol is produced by water attack at the nonring carbon next to the charged oxygen; and third dioxane can be displaced by the oxygen atom at position 6 in the chain.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pola.1990.080281213
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