Syntheses of fluorescent dyes. IX. New 4-hydroxycoumarins, 4-hydroxy-2-quinolones, 2H,5H-Pyrano[3,2-c]benzopyran-2,5-diones and 2H,5H-Pyrano[3,2-c]quinoline-2,5-diones

7-Substituted 4-hydroxycoumarins (2a-e) and 4-hydroxy-2-quinolones (2f-i) have been synthesized from the appropriate phenols or anilines and were converted to the enamines 3 using triethoxymethane and aniline. Condensation of 3 with nitriles 4a-h gave substituted 2H,5H-pyrano[3,2-c]benzopyran-2,5-diones (5a-r) or 2H,5H-pyrano[3,2-c]quinoline-2,5-diones (5s-x) , which exhibit both spontaneous and stimulated fluorescence with maxima between 418 and 549 nm. The marked influence of an electron withdrawing 3-substituent in 5 is demonstrated by the fluorescence spectra of 7a,b (synthesized from 2d,e and ethyl 3-oxobutyrate), whose maxima are sharply shifted to the blue as compared with compounds 21-r.     

Die Umlagerung substituierter Aminoacrylderivate. Präparative anwendungsbreite

The addition of carboxylic acids to dimethylamino-propinal ( 1a ) and 4-dimethyl-amino-but-3-in-2-on ( 1b ) gives, after rearrangement of the very instable primary adducts ( 2 ), Z-3-acetoxy-N,N-dimethylacrylamides and -crotonamides 3 to 8 in excellent yields and in a stereospecific manner. Similarly, the adducts of HCl and HBr to the alkynes 1a and 1b may be rearranged at low temperature by traces of acid to cis/trans equilibria of 3-halo-acrylamides and -crotonamides 9 and 10 . - On the other hand, treatment of 3-alkoxy-3-dimethylaminoacrolein with traces of acid yields alkylesters of E-3-dimethylaminoacrylic acid ( 12 , X = OR). - The preparative aspects of the rearrangement are discussed, and a brief outline of the spectroscopic properties of the compounds 3 to 8 is given.     

Optimization of a sodium ion-selective electrode for use in serum measurements

A sodium ion-selective polymeric membrane electrode has been optimized, especially with reference to serum measurements. For a given combination of polymer and ligand, the choice of membrane solvent is critical. Potentiometric measurements and electrodialysis experiments have shown that the dielectric constant and solubility parameter of the solvent influence the electrode selectivities, stability, slope and limit of detection. For use in serum measurements, it is essential to use an appropriate analytical technique, such as Flow Injection Analysis, which permits exposures to serum for only short periods of time.     

Thermoregulatoren, Thermostaten und Druckregulatoren

Ohne Zusammenfassung     

Determination of 1-vinyl-2-pyrrolidone in human serum by high-performance liquid chromatography

Summary A simple method is described which allows the quantification of 1-vinyl-2-pyrrolidone (NVP) in human serum. NVP is extracted from serum with diethylether and determined with HPLC/UV-detection. 1-Cyclohexyl-2-pyrrolidone serves as an internal standard. The detection limit is 0.1 mg/l. The method has shown that NVP can enter the organisms of workers occupationally exposed to this substance.