M. Jean Farrall

Functionalization of crosslinked polystyrene resins: 2. Preparation of nucleophilic resins containing hydroxyl or thiol functionalities

Abstract Crosslinked polystyrene resins containing thiol or hydroxyl functionalities on a fraction of their aromatic rings were prepared by reaction of crosslinked polystyryllithium with elemental sulphur or oxygen followed by reduction of the resulting polymer. Similarly, resins containing hydroxymethyl or thiomethyl functional groups were prepared from chloromethylated polystyrene by displacement of chloride in procedures involving three phase systems and the use of a phase transfer catalyst. The degree of functionalization could be controlled easily and the sulphur containing polymers were free of disulphide bonds.

FUNCTIONALIZATION OF CROSSLINKED POLYSTYRENE RESINS BY CHEMICAL MODIFICATION: A REVIEW

Functionalized crosslinked polystyrene resins have received much attention recently due to their numerous possible applications in chemistry and biochemistry. Three types of insoluble polymers with various degrees of cross-linking and different physical properties are used frequently as starting materials in the functional!zation reactions; these are popcorn polymers, solvent swellable beads and macroreticular beads. The reactions used in the chemical modification of these polymers are reviewed with emphasis on those reactions which introduce versatile, easily transformed functional groups which may serve to anchor the more specific functionalities of many special use resins. The following reactions of crosslinked polystyrene resins are reviewed: halogenation, chloromethylation, metalation, formylation, acylation, carboxylation, phosphination, nitration, amination and the introduction of hydroxyl, anhydride and sulfur containing functional groups. Finally, the analytical problems encountered in the characterization of the functionalized resins are reviewed.

Use of polymeric nucleophiles for the selective binding and removal of α-methylene-γ-butyrolactone allergens from complex mixtures.

Abstract An insoluble polymer containing primary amines selectively removed α-methylene-γ-butyrolactone allergens from solutions.

Chemically modified polystyrene containing pendant vinyl groups: a photosensitive polymer exhibiting chemical amplification

Abstract Soluble polystyrene, modified to contain pendant vinyl groups, was prepared in high functional yield from PStCH 2 Cl or PstCHO via Wittig reactions. The polymer was used to prepare a negative-working photosensitive resist in which absorbed light initiated a free radical crosslinking chain reaction.

Chemical modification of polystyrene

SummarySulfinate functional groups have been introduced on selected positions of the aromatic rings of soluble or crosslinked polystyrene via lithiation reactions followed by quenching with sulfur dioxide. The sulfinate polymers have good stability, can be stored at room temperature, and can be used for ion-exchange or as nucleophiles to produce polymer-bound sulfones. Good functional yields of polystyrene resins with sulfone pendant groups can be obtained by reaction of the polymeric sulfinates with various alkyl halides under phase transfer or classical conditions.

Pareparation of photosensitive polymers containing pendant cinnamic acid, ethyl cinnamate or cinnamaldehyde groups by chemical modification of polystyrene

SummarySoluble polystyrene was chemically modified to introduce pendant cinnamic acid, cinnamate ester, or cinnamaldehyde groups. The sensitivity of these polymers to crosslinking by ultraviolet light was studied by the adhesion method. Both the cinnamic acid and the cinnamaldehyde groups were found to crosslink more effectively than the cinnamate ester, the group which is commonly used in photoresists.

Polymeric reagents. IX Use of a polysterene-based amine oxide as a regenerable oxidizing agent for alkyl halides

Abstract A new polymeric reagent based on a crosslinked polysterene matrix modified to incorporate tertiary amine oxide residues is useful in the oxidation of primary alkyl bromides, alkyl iodides or benzylic halides into aldehydes. In all cases the yields are excellent and no overoxidation to form carboxylic acid is observed. The polymeric reagent can also be used to oxidize secondary alkyl bromides and iodides to the corresponding ketones, but these reactions are accompanied by significant side reactions which produce undersired alkenes. Unlike the corresponding low-molecular-weight reagents such as trimethylamine N-oxide, the polymer can be easily freed from impurities which cause significant side-reactions and does not require the use of scrupulously anhydrous reaction conditions for oxidation to occur. As expected, the use of the polymeric reagent also results in a simpler processing of the reaction mixtures, with filtration and evaporation of solvent as the isolation steps. The polymeric by-product of the reaction can be recovered quantitatively and be regenerated after washing, by treatment with hydrogen peroxide. The regenerated reagent is as effective an oxidizing agent as the starting polymer, and no significant loss of activity is observed after five reaction cycles.

Chemical Modification of Poly(Styrenesulfone)

The chemical modification of polystyrene sulfone has been investigated with the aim of replacing all the hydrogens located in positions α to the sulfone groups by methyl or other functionalities. Abstraction of two α hydrogens occurs readily in one single step by treatment of the polymer with two equivalents of n-butyl lithium at low temperature. Quenching of the bis-α-sulfonyl carbanion by addition of electrophiles such as methyl iodide, ethyl bromoacetate, carbon dioxide, or ethylene oxide, results in the introduction of two residues of the quenching agent in positions α to the sulfone groups. The last remaining α-hydrogen can subsequently be removed by a second abstraction-quenching reaction sequence to yield the fully substituted sulfone. In the case of quenching with methyl iodide, the final polymer contains SO2, α-methyl styrene and α-dimethyl styrene units. The substitution reactions can be monitored by NMR spectrometry and FT-IR difference spectroscopy. As expected, some chain degradation caused by the base treatment is observed.