Quaternary ammonium ion dendrimers from methylation of poly(propylene imine)s

The poly(propylene imine) dendrimers DAB-dendr-(NH2)(8), DAB-dendr(NH2)(32) , and DAB-dendr-(NH2)(64), were fully converted with iodomethane to quatern ary ammonium ions at both chain ends and branch points and, with less iodom ethane, were partially converted to quaternary ammonium ions mainly at end groups. Amidation of the primary amine ends followed by treatment with iodo methane gave the first dendrimers with quaternary ammonium ions only at bra nch points. After an exchange of iodide counterions for chloride, all of th e quaternary ammonium ion dendrimers slightly increased the rate of decarbo xylation of 6-nitrobenzisoxazole-3-carboxylate ion in an aqueous solution. Similar quaternary ammonium ion dendrimers with more hydrophobic interiors or more hydrophobic chains on the ends were much more active catalysts for the decarboxylation. (C) 2001 John Wiley & Sons, Inc.