Copolymerization of 4-(diallylamino)pyridine and acid-base behavior of the copolymers

Abstract

4-(Diallylamino)pyridine (DAAP) cyclopolymerizes with free radical initiators yielding a polymer whose monomer units are identical with 4-pyrrolidinopyridine (PPY), a very active nucleophilic catalyst. It has been found that the catalytic activity of this polymer is higher than that of PPY in all reactions studied to date. We have synthesized copolymers of DAAP with neutral (JV^V-dimethylacrylamide), cationic (dimethyidiallylammonium chloride), and anionic (acrylic acid) monomers.The reactivity ratios were obtained at 60 °C and show that DAAP active chain ends react with the comonomer faster than with DAAP monomer. All comonomers displayed the opposite behavior. 13C NMR spectra show evidence of both cis and trans isomers in the five-membered ring of the DAAP repeat units. The acid-base properties of the copolymers were investigated with UV spectroscopy and show increasing basicity of the pyridine groups (higher pKa) with increasing comonomer content in the copolymers of DAAP with lV,lV-dimethylacrylamide and acrylic acid.No apparent dependence of pKa on composition was observed for the copolymers with dimethyidiallylammonium chloride.

Control of Substrate Specificity in Polymer-Catalyzed Solvolysis Reactions of p-Nitrophenyl Alkanoates by Changing the Buffer System

“…Macromolecule 1 is an amphiphilic polymer which contains distinct hydrophobic and hydrophilic regions, and it associates to form macromolecular aggregates by self-assembly in aqueous or methanol−water solution. − The control of aggregate morphology changes of small-molecule and macromolecular amphiphiles from spheres to rods, and to vesicles by increasing the hydrophobic effects in water and water−organic solvent mixtures has already been well-established. − For many years, the aggregate morphology changes of small-molecule amphiphiles from spherical micelles to micellar rods and vesicles have been known to be controlled by increases of their constituent concentrations in solution. − The gradual changes of aggregate morphology of polystyrene- b -poly(2-vinylpyridine) copolymers from spheres to rods, and to vesicles have also been demonstrated with increasing copolymer concentration . Consistent with the notion that salt-induced hydrophobic effects control aggregate morphology of amphiphiles, the aggregate morphology of these copolymers in water−organic solvent mixtures can also be changed from spheres to rods, and to vesicles by addition of salting-out agents such as NaCl and CaCl 2 .…”

“…4-(Dialkylamino)pyridine-functionalized polymers have been regarded as useful and simple model systems for obtaining a better understanding of the origins of enzymic efficiency and selectivity. − We have recently made an attempt to investigate such a model system to gain insight into the dominant control factors in solvolysis of p -nitrophenyl esters 2 ( n = 2−18) catalyzed by 4-(dialkylamino)pyridine-functionalized polymer 1 . − The mechanism of the reaction involves the attack by nucleophile 1 at the carbonyl group of substrates 2 and the formation of an N -acylpyridinium intermediate where the breakdown of the intermediate is the rate-determining step in the catalytic reactions . Strikingly, we have found ion-induced substrate specificity in the 1 -catalyzed solvolysis of 2 ( n = 2−18) in aqueous and methanol−water solutions. , Salting-in effects of the tris(hydroxymethyl)methylammonium ion in aqueous Tris buffer solution lead to the same substrate specificity for 2 ( n = 6) that is obtained with the enzyme, cholesterol esterase, for the same hydrolysis reaction …”

Polymeric catalysts based on 4-(diallylamino)pyridine

“…Characterization of most of the catalytic polymers was described in the previous paper of this series, and all copolymer identification numbers in the figure footnotes refer to materials given there.8 New copolymers described in Table II were synthesized at low conversions, and their compositions were calculated by using the reactivity ratios previously determined. 8 Buffered solutions were prepared according to standard procedures,17 and the pH was checked with a Model 701-A pH meter with an Orion combination pH electrode 91-55, which was calibrated with standard buffer solutions (pH 7 and 10 from Curtis Matheson Scientific).…”

“…Calculation of the approximate copolymer composition resulting in all DAAP units having DMDAAC1 monomer units on both sides is possible because this system was found to follow the first-order Markov copolymerization behavior. 8 The number-average sequence length of units of monomer 1 (rci) was calculated from eq 426 where…”

“…Figure8. Dependence of the rate of esterification of linalool with acetic anhydride on[DMAP] in toluene at 80 °C..250 r…”