Tetrakis(4-N,N-dimethylaminobenzene)porphyrinato]manganese(III) acetate as a novel carrier for a selective iodide PVC membrane electrode.

[5,10,15,20-Tetrakis(4-N,N-dimethylaminobenzene)porphyrinato]Mn(III) acetate (MnTDPAc) was applied as an ionophore for an iodide-selective PVC membrane electrode. The influences of the membrane composition, pH of the test solution and foreign ions on the electrode performance were investigated. The sensor exhibited not only excellent selectivity to iodide ion compared to Cl- and lipophilic anions such as ClO4- and salicylate, but also a Nernstian response with a slope of -59.4 +/- 1.2 mV per decade for iodide ions over a wide concentration range from 1.0 x 10(-2) to 7.5 x 10(-6) M at 25 degrees C. The potentiometric response was independent of the pH of the solution in the pH range of 2 - 8. The electrode could be used for at least 2 months without any considerable divergence in the potential. Good selectivity for iodide ion, a very short response time, simple preparation and relatively long-term stability were the silent characteristics of this electrode. It was successfully used as an indicator electrode in the potentiometric titration of iodide ions, and also in the determination of iodide from seawater samples and drug formulations.     

Headspace SPME–GC Method for Acetone Analysis and its Biomedical Application

A new method for extraction and analysis of acetone in human urine based on headspace solid phase microextraction using a mixture of activated carbon and zeolite as sorbents in a PVC matrix coated on a silver wire and its application to the determination of ketone bodies is described. Unlike commercial fibers, which are coated on fused silica, the coating adheres strongly to the silver wire and is thermally stable up to 250 °C. After optimization of coating composition and microextraction conditions the fiber was used for the analysis of acetone in human urine.     

Synthesis of 2,2-Dimethyl-1,2-Dihydro-3H-pyrrol-3-one Preliminary Communication

The title compound 3g is obtained via two different routes, either in a multistep synthesis starting from 2-amino-2-methylpropionic acid (methylalanine) or by light-induced, oxidative dealkylation of the corresponding N-isopropyl derivative 3c .     

Poly(N‐Bromobenzene‐1,3‐Disulfonylamide), N,N,N′,N′‐Tetrabromobenzene‐1,3‐Disulfonylamide and DABCO‐Bromine Complex: As Novel Reagents for the Oxidative Coupling of Thiols to Disulfides

An efficient method for the oxidative coupling of thiols to their corresponding disulfides by new reagents poly(N‐bromobenzene‐1,3‐disulfonylamide) PBBS , N,N,N′,N′‐tetrabromobenzene‐1,3‐disulfonylamide TBBDA and DABCO‐bromine complex is described. The reaction was applicable to a variety of thiols with high chemoselectivity.     

Photochemistry of 2-Allyl-3-oxo-2,3-dihydro-1H-pyrrole-2-carboxyalates

On acetone-sensitized irradiation the title compounds 3a–c are converted to 2-allyl-3-hydroxy-1H-pyrrole-2-carboxylates 4 in reasonable yields.     

Synthesis and calcium channel antagonist activities of new derivatives of dialkyl 1,4-dihydro-2,6-dimethyl-4-(5-phenylisoxazol-3-yl)pyridine-3,5-dicarboxylates

The new analogues of nifedipine, in which 2-nitrophenyl group at position 4 is replaced by phenylisoxazolyl substituent, were synthesized. The symmetrical dialkyl 1,4-dihydro-2,6-dimethyl-4-(5-phenylisoxazol-3-yl)pyridine-3,5-dicarboxylates were prepared by classical Hantzsch condensation, and the asymmetrical analogues were synthesized using a procedure reported by Dagnino that involved the condensation of alkyl acetoacetate with alkyl 3-aminocrotonate and 5-phenylisoxazole-3-carboxaldehyde. The structure of all compounds was confirmed by IR, ¹H NMR and Mass spectra. In vitro calcium channel antagonist activities were evaluated as calcium channel antagonists using the high K⁺ concentration of guinea-pig ileum longitudinal smooth muscle (GPILSM) assay. These compounds exhibited moderate calcium antagonist activity (IC₅₀ = 10^?7 to 10^{? 5} M range) relative to the reference drug nifedipine (IC₅₀ = 1.10 ± 0.40 × 10^?8 M).     

Mild and Efficient Deprotection of 1,3‐Dithianes with N,N′‐ Diiodo‐N,N′‐1,2‐Ethanediyl‐Bis(p‐Toluenesulphonamide)

Aliphatic and aromatic 1,3‐dithiane are oxidized to the corresponding carbonyl compounds in good yields under mild conditions by N,N′‐diiodo‐N,N′‐1,2‐ethanediyl‐bis(p‐toluenesulphonamide) [NIBTS] and silver nitrate.