A new and direct approach to functionalized biaryl α-ketophosphonic acids via aqueous Suzuki coupling on solid support

A new method for the synthesis of functionalized biaryl α-ketophosphonic acids has been developed. The key step involves the use of sodium bromobenzoyl phosphonates to react with polymer-bound boronic acids via microwave-assisted aqueous Suzuki coupling. This approach provides rapid access to a wide range of diverse biaryl analogues containing an α-ketophosphonic acid moiety.     

A new generation of track etched membranes for microfiltration and ultrafiltration. Part I. Preparation and characterisation

A new experimental apparatus for porous track etched membrane production has been designed, tested and installed near the core of the IEA-R1 nuclear reactor at IPEN-Sao Paulo. The thermal neutron flux close to the centre of the reactor core has been used to produce fission fragments from uranium sample which was deposited on a rod located at the centre of an evacuated aluminium chamber.     

Polyelectrolytes prepared from perfluoroalkylaryl macromolecules

The synthesis of a new generation of high-capacity oxidation-resistant ion-exchange resins and membranes is described which are sulfonic acid polyelectrolytes prepared from high molecular weight poly-α,β,β-trifluorostyrene. The difficult sulfonation of poly-α,β,β-trifluorostyrene is discussed in terms of the finding that this sulfonation must be effected upon an aromatic ring possessing a meta-directing substituent group. The oxidative stability of these new types of perfluoroalkyl aromatic sulfonic acid polyelectrolytes is both demonstrated and described with comparisons to their polystyrenesulfonic acid homologs. The difference in their oxidation–depolymerization stabilities is described in terms of benzylic carbon substituents.     

Normal‐stress differences and the detection of disclinations in nematic elastomers

We used a continuum model to investigate the isochoric radial expansion of a right circular cylindrical specimen composed of a nematic elastomer that is crosslinked in a uniaxial state and then annealed. Numerical solutions show that, above a certain radial expansion, the material has a definitive energetic preference for a state involving a disclination of strength +1 along the cylinder axis. Surrounding such a disclination is a core with radial dimension on the order of 10^?2 μm, which coincides with observations in conventional liquid‐crystal melts. Examination of the normal‐stress differences indicates that the first of these differences depends nonmonotically on the extent of radial expansion and possesses a local minimum at the point where a disclination becomes energetically preferred. This suggests a practical experimental method for testing the predictions of our model. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2098–2106, 2002     

High-load, oligomeric phosphonyl dichloride: facile generation via ROM polymerization and application to scavenging amines

A new ROMP-derived scavenging reagent, oligomeric phosphonyl dichloride (OPC), with high-load and selectivity is reported. This reagent can be readily generated via the ROM polymerization of bicyclo[2.2.1]hept-5-en-2-ylphosphonic dichloride, which is conveniently assembled from the Diels-Alder reaction of cyclopentadiene and vinyl phosphonic dichloride. The OPC has been exploited in the rapid, efficient scavenging of primary and secondary amines that are present in excess following a common benzoylation event at room temperature (30-60 min) or under microwave conditions in shorter duration (<5 min).     

The vacuum ultraviolet spectra of fluorine chlorine substituted trivalent phosphorus

The vapor phase absorption spectra of PF₃, PF₂Cl, PFCl₂, and PCl₃ are reported in the vacuum ultraviolet spectral region 2400—1200 A. These results are compared with information obtained from photoelectron spectra. A brief discussion of the spectra in terms of analogous absorption regions and results from CNDO/2 calculations are given.     

Proposal for radio-frequency spectroscopy of molecular ions

A method is proposed for the detection of low-frequency spectroscopic transition in gaseous molecular ions by monitoring the motion induced by inhomogeneous fields at the sum frequency of harmonic motion in an ion trap and the transition frequency. Numerical examples are given.     

Spin-orbit (core) and core potential integrals

Molecular integral formulas and corresponding computational algorithms are developed for the relativistic spin-orbit and core potential operators that are obtained from atomic relativistic calculations by means of the effective core potential procedure. Much use is made of earlier work on core potential integrals by McMurchie and Davidson. The resulting computer code has been made part of the ARGOS (Argonne, Ohio State) program from the C?OLUMBUS suite of programs, which computes the needed integrals over symmetry-adapted combinations of generally contacted Gaussian atomic orbitals.     

A phase-switch purification approach for the expedient removal of tagged reagents and scavengers following their application in organic synthesis

In this paper we wish to report on a variety of expedient chemical transformations and purifications achieved via a generic "catch and release" methodology, based on a synthetically inert bipyridyl chelating tag that can be selectively captured with a resin-bound copper(II) species. Utilising this approach we are able to derive many of the same benefits associated with both solid phase synthesis and supported reagent methods.