A conductive elastomer based on EPDM and polyaniline: II. Effect of the crosslinking method

Electrically conductive heterogeneous binary polymer blends based on ethylene-propylene-diene-monomer (EPDM) and polyaniline (PAni) were prepared in a Haake Rheocord 90 rheometer, coupled with an internal mixer (counter rotating cam rotors) using different amounts of PAni doped with dodecylbenzenosulfonic acid (DBSA). Blends were crosslinked using two methods: (i) phenolic resin (SP-1045) as crosslinking agent and (ii) electron beam irradiation. The last method avoids the interference of the acid dopant in the crosslinking process and produces blends with higher conductivity.     

Asymmetric Synthesis of 3-Hydroxyprolines by Photocyclization of N-(2-Benzoylethyl)glycinamides

The chiral N-(2-benzoylethyl)-N-tosylglycinamides 1a-c were prepared from the C₂-symmetric pyrrolidines 5a-c . Irradiation of these ketones 1a-c gave cis-3-hydroxyprolinamides 10-12 in moderate to good yields (Scheme 3). The de of the photocyclizations depended on the size of the substituents in positions C(2) and C(5) of the chiral pyrrolidine auxiliaries. In addition, the de varied with the reaction temperature, allowing the determination of activation-parameter differences. The structure of products 10-12 were established by NMR and X-ray analyses.     

Synthesis of some dibenzodiazepinone derivatives as potent and m2-selective antimuscarinic compounds

Two series of 5-[[4-[4-(dialkylamino)butyl]-l-cyclohexyl]acetyl], and 5-[(dialkylamino)acyl]-10,11-dihydro-5H- dibenzo[b,e][1,4]diazepin-11-ones were synthesized as potential m2-selective ligands 1,2. Their affinity and selectivity for the muscarinic cholinergic receptor m-AChR subtypes were determined. Replacing a nitrogen with CH in the piperidine ring of 5-[[4-[4-(dialkylamino)butyl]-l-piperidinyl]acetyl]-10,11-dihydro-5H-dibenzo-[b,e][1,4]diazepin-11-ones 3 significantly altered the affinity and selectivity to the muscarinic receptor subtypes.     

Determination of cisplatin and related platinum complexes in plasma ultrafiltrate and urine by high-performance liquid chromatography with on-line radioactivity detection

A reversed-phase ion-pair chromatographic method with on-line radioactivity detection for the simultaneous determination of 195mPt-labelled cisplatin and related platinum complexes has been developed. With this system a good resolution of various radiolabelled platinum complexes can be achieved. The detection limit of the radioactivity detector is 10 ng of cisplatin (specific activity of 15 MBq/mg cisplatin) per millilitre of urine or plasma ultrafiltrate. The detector response is independent of both the chemical structure of the platinum complexes and the matrix composition of the samples. This method may serve as a reference system for other high-performance liquid chromatographic systems with less specific and sensitive detectors.     

Stability study and quantitative determination of mebeverine hydrochloride in tablets by means of reversed-phase high-performance liquid chromatography

Summary A rapid and specific reversed-phase high-performance liquid chromatographic method (RPHPLC) is described for the determination of mebeverine hydrochloride in tablets. Elution was performed on an octyl silane column with a methanol-water mixture (75-25), containing 0.05% hexylamine as silanol-blocking agent, adjusted to pH 5.0 with phosphoric acid. The method gave accurate, precise and reproducible results. The mean recovery of the drug from six synthetic tablet mixtures was 100.0% with a relative standard deviation (RSD) of 0.94%. In order to test the specificity of the method, the interference of the degradation compounds of mebeverine hydrochloride and of the intermediates from the synthesis was investigated. None of them did interfere. By means of mass spectrometry and UV-spectrophotometry, the degradation compounds of mebeverine were identified as veratric acid and as 4-|ethyl-[2-(4-methoxyphenyl)-1-methylethyl]amino| 1-butanol. The stability study proved that mebeverine hydrochloride is very stable in tablets; the tablets still contain more than 95% of the declared drug potency after storage for more than one year at 50°C.Colofac; Duspatal; Duspatalin     

Syntheses and configurations of some heterocyclic amidoximes. X-Ray crystal structure of 3-phenyl-5,6-dihydro-2(1H)-pyrazinone-O-methyloxime

O-Methyl-α-ketophenylacetohydroximoyl chloride ( 1 ) was prepared by the reaction of O-methyl-α-methoxyphenylacetohydroximoyl chloride ( 5 ) with N-bromosuccinimide and concentrated hydrobromic acid. Reaction of 1 with ethylenediamine gave 3-phenyl-5,6-dihydro-2(1H)-pyrazinone-O-methyloxime ( 6 ). 3-Phenyl-5,6-cyclohexano-5,6-dihydro-2(1H)-pyrazininone-O-methyloxime ( 7 ) was prepared by reaction of 1 with trans-1,2-diaminocyclohexane. The X-ray structure of 6 has been determined. The crystals are orthorhombic, space group Pbca with a = 10.264(3), b = 18.262(4), c = 23.530(4)Å, V = 4411(2)ų, and Z = 16. The structure, which was refined to R = 0.038 using 1652 observed reflections, shows the amidoxime moiety to be the Z configuration. Reaction of benzohydroximoyl chloride with aziridine gave (Z)-aziridinylbenzaldoxime ( 16a ). Ultraviolet irradiation of a benzene solution of 16a gave a mixture of the Z and E isomers 16a and 16b . The E isomer 16b underwent thermal isomerization to 16a at 100°. Reaction of 16a with dimethyl sulfate in sodium hydroxide solution gave (Z)-O-methylaziridinylbenzaldoxime ( 17a ). Photoisomerization of a hexane solution of 17a gave a mixture of the Z and E isomers 17a and 17b which were separated by preparative glc. The isomers 17a and 17b are resistant to thermal Z = E isomerization. The mechanisms of thermal isomerization of benzamidoximes are discussed.     

Synthesis and photoluminescence of single crystals europium ion-doped BaF2 cubic nanorods

In this work, we used the hydrothermal method to synthesize Eu³⁺ ion-doped cubic BaF₂ nanorods, which is a luminescent material. The clubbed structures were well crystallized and exhibited face-centred cubic structures, as indicated by powder X-ray diffraction, scanning electron microscopy, electron diffraction, and transmission electron microscopy. The luminescent properties were studied, and local symmetry surrounding Eu³⁺ ions and electronic transition processes included. The results indicated that Eu³⁺ occupied only one C_4ν site in nanorods.     

Mass spectrometric identification of a candidate biomarker peptide from the in vitro interaction of epichlorohydrin with red blood cells

The reaction products of epichlorohydrin with human alpha- and beta- globins, obtained through in vitro incubation of these compounds and red blood cells, were determined by using reversed-phase high-performance liquid chromatography (RP-HPLC), electrospray ionization mass spectrometry and matrix-assisted laser desorption/ionization tandem mass spectrometry. The alpha-globin was much more reactive than the beta-globin. At low incubation ratios, approximating the order of magnitude of epichlorohydrin concentration as found in workplaces, the only modified peptide still detectable was the 62-90 belonging to the alpha-chain and carrying an incremental mass of 92 u on either His72 or His89. Given that the two peptides co-eluted in a single chromatographic peak during RP-HPLC separation, they could be chosen as suitable biomarkers for quantification in the setting up of a new methodology for the biological monitoring of persons occupationally exposed, replacing currently known procedures.     

Studies on crosslinking of EPDM-PE blends by thermoanalytical techniques

The effect of blend ratio and peroxide concentration on crosslinking characteristics of EPDM-PE blends were studied by Differential Scanning Calorimetry, Brabender plasticorder and Rheometer. Crosslinking of EPDM-PE blends follows first order reaction kinetics. The curing exotherm increases but activation energy decreases with increase in EPDM content in the blends. The same however increases with the increase in concentration of DCP upto a certain level, while the activation energy is almost independent of peroxide concentration. The cure rate increases whereas optimum cure time and energy consumption for curing decrease with increase in the EPDM-PE ratio. A method for determination of crosslinking efficiency in the case of blend systems was developed from high temperature modulus to predict the properties and the curing behaviour of the blends.

---

Zusammenfassung Mittels DSC, Brabender Plasticorder und Rheometer wurde der Einfluß von Mischungsverhältnis und Peroxidkonzentration auf den Vernetzungsverlauf von EPDM-PE-Gemischen untersucht. Die Vernetzung von EPDM-PE-Gemischen verläuft nach einer Reaktion erster Ordnung. Je höher der Anteil von EPDM im Gemisch, um so exothermer ist die Vernetzung und um so kleiner ist die dazugehörige Aktivierungsenergie. Mit dem Anwachsen der DCP-Konzentration bis zu einem gewissen Niveau wächst der exotherme Charakter, während die Aktivierungsenergie fast unabhängig von der Peroxidkonzentration ist. Mit dem Anstieg des EPDM/PE-Verhältnisses wächst die vernetzungsgeschwindigkeit, während die optimale Vernetzungszeit und der Energieverbrauch für die Vernetzung sinken. Es wurde ein Verfahren zur Bestimmung der Vernetzungseffizienz bei Mischsystemen entwickelt, um Eigenschaften und Vernetzungsverhalten von Gemischen voraussagen zu können.

     

On the synthesis of geometric isomers of 2-methyl (or phenyl)-4-[α-arylethylidene]-5(4H)-oxazolones

Several Z-2-methyl(or phenyl)-4-[α-arylethylidene]-5(4H)-oxazolones 3Z, 4Z were prepared. The results obtained were compared by diazomethane insertion and condensation procedure. In order to synthesize E-2-phenyl-4-[α-arylethylidene]-5(4H)-oxazolones 4E hydrogen bromide isomerization in dry benzene was used.