Synthesis and Characterization of Bis(Isopropenylphenoxy)Alkanes and Bis(Vinylphenoxy)Alkanes: Two Classes of Highly Reactive, Photopolymerizable Monomers

Novel Photocurable Materials For Spinon Dielectric Films

Poly(indanes) can be prepared by the photoinduced cationic polymerization of a variety of diisopropenyl aromatic monomers. Typically, polymerization proceeds rapidly under UV irradiation catalyzed by diaryliodonium salt photoinitiators to give hard, transparent films. Investigations have shown that the polymerization proceeds mainly by a dimerization followed by a ringclosure process to yield indane structures along the polymer backbone. Film-forming mixtures containing either pure monomer or mixtures of monomers together with a poly(indane) prepolymer can be spin coated onto silicon wafers. Measurements made on the photopolymerized coatings give low dielectric constants. These coatings also display excellent thermal stability.

Generation and Synthetic Uses of Stable 4-[2-Isopropylidene]-phenol Carbocation from Bisphenol A

[reaction: see text] Stable 4-[2-isopropylidene]-phenol carbocation, IPP cation 1, was generated readily by addition of bisphenol A in concentrated sulfuric acid at ambient temperature, and the cation could be used for facile syntheses of 4-isopropenyl phenol (IPP), IPP dimers, and spiro-bisphenol derivatives.

Polytetrahydrofuran cross-linked polystyrene resins for solid-phase organic synthesis

Currently, divinylbenzene cross-linked polystyrene (DVB-PS) is the polymer of choice for use in solid-phase organic synthesis (SPOS). While much research has been directed toward the optimization of linker groups for the attachment of compounds to the polymer, the development of new polymers themselves has been relatively neglected. In an attempt to overcome the shortcomings of DVB-PS and to develop new polymers with optimum properties for use in organic synthesis, we have prepared a series of polystyrene polymers that incorporate flexible polytetrahydrofuran (PTHF) based cross-linkers. The objective of incorporating PTHF into the polymers was to slightly increase the overall polarity of the polymer and thus render the resins more organic solvent-like. Since the degree to which a resin swells in and absorbs a particular solvent correlates to how well substrates attached to the polymer are solvated, we compared the swelling of our new resins to commercially available DVB-PS resins. In all cases, we found that our resins swelled to a much greater extent than do DVB-PS resins, and their use should therefore allow for SPOS reaction conditions that more closely mimic homogeneous solution-phase conditions. It was also found that the PTHF chain length of the cross-linker does not affect the level of swelling since all of our cross-linkers afford resins with comparable levels of increased swelling. Furthermore, we have examined the utility of our resins in directed ortho-metalation reactions and found that the increased swelling of our resins allows for isolation of reaction products in yields comparable to what is achieved using standard solution-phase conditions.

Investigating resins for solid phase organic synthesis: the relationship between swelling and microenvironment as probed by EPR and fluorescence spectroscopy

The relationship between observed swelling of two cross-linked polystyrene resins and the microenvironment within polymer matrixes has been examined. Polystyrene cross-linked with either divinyl benzene (Merrifield resin) or 1,4-bis(4-vinylphenoxy)butane (JandaJel) was investigated with fluorescence and electron-paramagnetic resonance spectroscopy. Fluorescence spectroscopy revealed a superior correlation between observed swelling and solvation effects using a dansyl probe with JandaJel than with Merrifield resin. However, the internal viscosity of pre-swollen JandaJel is higher than Merrifield resin, as determined by EPR measurements. The combination of these two analytical methods provides insights into the physical differences observed between these two chemically similar resins and suggests caution should be used if using singular physical techniques to probe the microenvironment of polymeric matrixes.