NMR Spectral Assignment of Per-substituted Key-Intermediates of β-Cyclodextrin and Implications in the Structures of the Derivatives

The compounds, 6-per-O-(t-butyldimethylsilyl)--cyclodextrin(1), 2,3-per-O-benzyl-6-per-O-(t-butyldimethylsilyl)--cyclodextrin(2), 2,3-per-O-benzyl--cyclodextrin (3),2,3,6-per-O-benzyl--cyclodextrin (4),2,3,6-per-O-benzoyl--cyclodextrin (5), are used as keyintermediates in the synthesis of selectively substituted -CD derivatives. Simple and assignable ¹H and ¹³C NMR spectra (chemical shifts and coupling constants) were obtained for compounds1–4 indicating C₇ symmetry, ⁴C₁ glucose conformation and major arrangement of H6, H6' atoms at the primary side. The derivative 5, however, gave very broad peaksat room temperature. The peaks could partially be assigned at 270 K, but the broadening was still present at 220 K. This implies that there exist several conformers of similar energyand C₁ symmetry that continuously interchange, since there is not a single type of stabilizing interaction thatpredominates. We attributed this phenomenon to the presence of the carbonyl group, which probablydisfavors - stacking and induces random arrangements of the aromatic rings.     

Classification of edible and lampante virgin olive oil based on synchronous fluorescence and total luminescence spectroscopy

Total luminescence and synchronous fluorescence spectroscopies were tested as regards their ability to differentiate edible from lampante virgin olive oils. Total luminescence spectra were recorded by measuring the emission spectra in the range 350-720 nm at excitation wavelengths from 320 to 535 nm. The synchronous fluorescence spectra of 41 edible and 32 lampante virgin olive oils were acquired by synchronous scanning the excitation and emission monochromator maintained at an offset value of 80 nm. Classification of virgin olive oils based on their synchronous fluorescence spectra was performed by hierarchical cluster analysis and principal component analysis using the spectral range of 429-545 nm. Principal component analysis provided better discrimination between the two classes, without any classification error, while hierarchical cluster analysis allowed 97.3% correct classification. These results indicate the capability of fluorescence techniques to differentiate virgin olive oils according to their quality.     

Car–Parrinello Molecular Dynamics Study of the Thermal Decomposition of Sodium Fulminate

Depending on the metal cation, metal fulminates exhibit a characteristic sensitivity with respect to heat and mechanical stress. In the present paper we study the high‐temperature reactions of bulk sodium fulminate using Car–Parrinello molecular dynamics simulations. We find that the initiating reaction is the formation of the fulminate dimer, while in earlier studies an electron transfer was assumed to be the first reaction step. The initial carbon? carbon bond formation is followed by fast consecutive reactions leading to polymerisation. The resulting species remain charged on the timescale of the simulations.     

Development and validation of an HPLC confirmatory method for the determination of tetracycline antibiotics residues in bovine muscle according to the European Union regulation 2002/657/EC

A high-performance liquid chromatographic method with diode-array detection, at 351 nm, was developed and validated for the determination of five tetracyclines (TCs): minocycline, tetracycline, oxytetracycline, chlortetracycline, and doxycycline in bovine muscle. Samples were macerated with a buffer solution, centrifuged, and purified using Abselut Nexus SPE cartridges. The separation of the examined TCs was achieved on an Inertsil ODS-3 5 microm, 250 x 4 mm analytical column, at ambient temperature. A multistep gradient elution was followed using 0.05 M oxalic acid and CH3CN, at a flow rate of 1.65 mL/min. The procedure was validated according to the European Union regulation 2002/657/EC determining selectivity, stability, decision limit, detection capability, accuracy, and precision. The results of the validation process demonstrate that the method can be readily applied to European Union statutory veterinary drug residue surveillance programmes. Mean recoveries of TCs from bovine muscle samples spiked at three concentrations (100, 250, and 400 ng/g) were in the range of 98.7-103.3%. Method's LOQ values achieved were 40 microg/kg for MNC, CTC, and DC and 25 microg/kg for OTC and TC. The decision limits (CCalpha) were in the range of 104.7-109.8 microg/kg, while the detection capability (CCbeta) was in the range of 108.4-116.7 microg/kg for all compounds.     

1,3-cycloaddition reactions of 2-oxo-2H-[1]benzopyran-4-carbonitrile N-oxide. Synthesis of several new 4-substituted coumarins

1,3-Cycloaddition reactions of new 2-oxo-2H-[1]benzopyran-4-carbonitrile N-oxide 2 with dipolarophiles, o-aminophenols and o-phenylenediamine resulted in 4-heterocyclic substituted coumarin derivatives. These derivatives are screened for antiinflammatory activity in vitro through their antiproteolytic activity, the interaction with 1,1-diphenyl-2-picrylhydrazyl and the ability to affect superoxide anion and to inhibit β-glucuronidase and soybean lipoxygenase.     

The Evaluation of Benign Glottic Lesions: Rigid Telescopic Stroboscopy Versus Suspension Microlaryngoscopy

Rigid telescopic strobo-video-laryngoscopy (RTS) is a primary clinical assessment methodology in the office evaluation of benign glottic lesions. However, diagnostic observations can be made only at the time of suspension microlaryngoscopy (SML). The records of 100 consecutive patients undergoing microlaryngoscopy for benign glottic lesions were retrospectively reviewed. Nine of 100 patients were found to have additional glottic lesions during SML. Sixteen additional lesions were noted in these nine patients. Fifteen of 16 lesions were sulci and/or mucosal bridges. Forty-five percent (4/9) of the patients with additional lesions underwent a management change intraoperatively. Three patients underwent additional surgical dissection, and one underwent less dissection than was planned. The discrepancy in diagnosis between rigid telescopic strobo-video-laryngoscopy and suspension microlaryngoscopy highlights certain key points: (1) During office endoscopy, tangential views of the medial surface of the glottis limit the diagnostic sensitivity. (2) Sulci and mucosal bridges are most subject to this limitation. (3) Informed consent should address the potential need for a change in intraoperative management. It is advisable to discuss the possibility for dissection in both vocal folds, even if a unilateral lesion is observed in the office. (4) Microlaryngoscopy is the final diagnostic step in the evaluation of glottic pathology. Meticulous inspection and palpation of the glottis are recommended during SML.     

A survey on the reactivity of phenyliodonium ylide of 2-hydroxy-1,4-naphthoquinone with amino compounds

The phenyliodonium ylide of 2-hydroxy-1,4-naphthoquinone reacts with aminoesters, ureas, aminoalcohols and aminophenols in refluxing dichloromethane to afford good yields of indanedione 2-carboxamido compounds, that in solution exist in an enol-amide form. The same reactants in a copper-catalyzed reaction afford mainly the corresponding N-arylo compounds. Arylhydrazines are mainly oxidized by the ylide and arylation occurs only in a low yield.