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Phase selectively soluble polymer supports to facilitate homogeneous catalysisOrtiz-Acosta, Denisse 15 May 2009 (has links)
Soluble polymers that have phase selective solubility are useful in synthesis
because they simplify purification and separation. Such selectively soluble polymers
simplify catalyst, reagent, and product recovery and enable the use of Green chemistry
principles in homogeneous catalysis. However, while homopolymers have been
reported that have excellent thermal and phase-dependent solubility, less is known about
copolymers. Also, less is known about the phase selective solubility of polar aprotic
N,N-dialkyl polyacrylamides. This work describes a library synthesis of dye-labeled
poly(N-n-octadecylacrylamide-co-N-n-butylacrylamide) copolymers and study of the
effects of polymer composition in phase selective solubility of these copolymers. To
study the relative importance of n-octadecyl versus n-butyl groups, copolymers with
different ratios of n-octadecylacrylamide and n-butylacrylamide but with similar degrees
of polymerization and polydispersity were prepared by a split-pool synthesis using a
highly soluble poly(N-acryloxy-2-dodecylsuccinimide) as the precursor. Polymer
sequestrants were used to remove excess amines and the byproduct N-hydroxyl-2-
dodecylsuccinimide without fractionation of the polyacrylamides. Results demonstrated that poly(N-n-octadecylacrylamide-co-N-n-butylacrylamide) copolymers’ phase
selective solubility is equally dependant of the polar n-butyl and nonpolar n-octadecyl
groups on the copolymers.
Dye-labeled poly(N,N-dialkylacrylamide)s prepared by the polymerization of
N,N-dialkylacrylamides monomers with methyl, ethyl, propyl, butyl, hexyl, and dodecyl
N-alkyl groups in a variety of thermomorphic or latent biphasic polar/nonpolar solvent
mixtures were also prepared. Studies showed that poly(N,N-dialkylacrylamide)s have
phase selective solubility that is highly dependent of the size of the N-alkyl group.
Soluble polymers are known to be useful supports for catalysts. This thesis also
describes approaches to immobilization of a variety of catalysts on polyisobutylene
(PIB). The most effective of these catalysts were analogs of pyridyl N-oxides that have
been used as organocatalysts for the catalytic allylation of a variety of aromatic
aldehydes. PIB-supported N-oxide promoted the allylation of aldehydes in up to 99%
isolated yield. The products were isolated in the polar phase of a thermomorphic system
and the catalyst was recycled through five cycles.
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Studies of phase separable soluble polymersFuryk, Steven Michael 16 August 2006 (has links)
The technique of phase labeling has the ability to greatly enhance synthetic
protocol by simplifying purification and increasing efficiency. Traditional insoluble
supports offer efficient and simple recovery of the Âphase tagged material but suffer
from problems inherent to their heterogeneous nature. A solution to these problems has
been to utilize phase separable soluble polymers in the design of Âsmart responsive
systems that offer the option of homogenous reaction conditions with heterogeneous
separation conditions. The subject of this dissertation focuses on the application of
soluble polymeric phase tags in systems where the miscibility between solid-liquid and
liquid-liquid systems is thermally induced.
Low molecular weight poly(ethylene glycol) (PEG) oligomers were investigated
as phase anchors for SCS palladacycle catalysts. The oligomeric PEG chains were
sufficient to engender polar phase solubility in a heptane-DMA thermomorphic system.
Microwave irradiation of these thermomorphic mixtures of palladium complexes and
substrates was a viable scheme to recycle and significantly shorten reaction times for
simple Heck reactions of aryl iodides. Soluble polymeric supports possessing a lower critical solution temperature
(LCST) were utilized in the sequestration of the S-triazine herbicide, atrazine, from
contaminated water samples. The ability of poly(N-isopropylacrylamide) to sequester
hydrophobic guests like atrazine was examined. A functionalized PNIPAM derivative
containing secondary cyclic amines exhibited superior sequestration ability that was
credited to the covalent binding of the atrazine.
In order to facilitate the design of tailored, thermally responsive, smart polymers,
a high throughput temperature gradient microfluidic device was used to obtain LCST
data in a fast, accurate manner. The specific ion effects of various alkali metal halide
salts on the LCST of PNIPAM were investigated. The high precision in the
measurements enabled more subtle effects such as changes in solvent isotope, polymer
microstructure, molecular weight, and importance of end group effects on the LCST of
poly(N-alkylacrylamide)s to be evaluated.
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