The picryl ether of polyethylene glycol: Preparation, characterization, and reaction with n-propylamine

✍ Scribed by Julian M. Dust; J. Milton Harris

• Book ID: 105337543
• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 792 KB
• Volume: 28
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/pola.1990.080280719

✦ Synopsis

Abstract

A new electrophilic polymer, the picryl ehter of methoxypolyethylene glycol (M‐PEG‐OPi), was prepared by reaction of the lithium alkoxide of methoxypolyethylene glycol with picryl chloride. The resultant M‐PEG‐OPi was characterized by 200 MHz ^1^H and ^13^C‐NMR, microanalysis, and hydrolytic behavior. The rate constant for hydrolysis in pH 8.0 buffer is consistent with that expected for S~N~Ar hydrolysis of a polyethylene glycol picrate. Reaction of n‐propylamine with M‐PEG‐OPi in (CD~3~)~2~SO was followed by ^1^H‐NMR and UV‐visible spectroscopy. Evidence is presented for formation of a C‐1 Meisenheimer complex; no C‐3 adduct was observed in these experiments despite the steric bulk of the polymeric “group” on the picryl ring. Addition of a large excess of amine results in formation of a 2:1 dianionic complex, as shown by the UV‐visible spectrum. The possibility is discussed of using the reaction of M‐PEG‐OPi with protein amino groups as an analytical tool for measuring the number of available amino groups on protein chains.