Facile and efficient preparation of phosphinate‐functionalized aromatic diamines and their high‐Tg polyimides

Two novel phosphorus‐functionalized aromatic diamines, 1,1‐bis(4‐aminophenyl)‐1‐(6‐oxido‐6H‐dibenz <c,e> <1,2> oxaphosphorin‐6‐yl)ethane ( 1 ) and bis(4‐aminophenyl)‐(6‐oxido‐6H‐dibenz <c,e> <1,2> oxaphosphorin‐6‐yl)phenylmethane ( 2 ), were prepared from 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide, 4‐aminoacetophenone, or 4‐aminobenzophenone in excess aniline using p‐toluenesulfonic acid monohydrate as catalyst by an efficient, one‐pot procedure. The effect of electron withdrawing/donating groups on the stabilization of the resulting carbocation seems critical for the success of the process and was discussed in detail. Based on diamines ( 1–2 ), a series of new polyimides, (5a–5d) and (6a–6d) , were prepared, respectively. Polyimides (5a–5d) are flexible and creasable. In contrast, polyimides (6a–6d) are brittle because of the structure rigidity, according to the analysis based on the NMR temperature‐dependent spectra of ( 2 ). Polyimides 5 displaying high T_g (318–392 °C), high moduli (3.39–4.49 GPa), low coefficient of thermal expansion (42–50 ppm/°C), and moderate thermal stability (T_d 5 wt % at 426–439 °C), are excellent high‐T_g and flame‐retardant materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2486–2499, 2009     

Modeling of drift-diffusion systems

We derive drift-diffusion systems describing transport processes starting from free energy and equilibrium solutions by a unique method. We include several statistics, heterostructures and cross diffusion. The resulting systems of nonlinear partial differential equations conserve mass and positivity, and have a Lyapunov function (free energy). Using the inverse Hessian as mobility, non-degenerate diffusivity matrices turn out to be diagonal, or – in the case of cross diffusion – even constant.     

The ratio of decay constants ƒB/ƒD

The result ƒ_B≈ƒ_D which had been obtained from sum rules and lattice calculations, and which contradicts the naïve prediction ƒ_p1/√M_p, is rederived using a simple argument based on semilocal parton-hadron duality. Is is argued that both here and in sum rules the key point is the use of semilocal duality instead of the bound-state wave functions.     

A rapid and reliable method for extraction and assay of tricyclic antidepressant drugs in serum or plasma

Because of their narrow therapeutic ranges and differing patient tolerances, the monitoring of tricyclic antidepressants (TADs) commonly prescribed for control of endogenous depression is highly desirable for the satisfactory treatment of patients. The majority of methods for analysis of TADs require multiple extractions from plasma with organic solvents, accompanied by obligatory centrifugation steps. We describe a simple procedure for the rapid extraction of serum TADs, with high recovery of the analyte drugs. It involves sample preparation using Analytichem 'BOND-ELUT' C-2 reverse phase columns, and analysis by gas chromatography using a nitrogen-phosphorus detector. The method offers a quick, inexpensive and low-maintenance assay which is applicable to all the common tricyclic class drugs.     

Flow of oil and water in a porous medium

The flow of two immiscible and incompressible fluids in a porous medium is described by a system of quasilinear degenerate partial differential equations. In this paper the existence of a weak solution by regularization is shown.     

Mikrochemie

Ohne Zusammenfassung