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31.
Alberto Bargagna Gaetano Bignardi Pietro Schenone Mario Longobardi 《Journal of heterocyclic chemistry》1983,20(4):839-843
The polar 1, 4-cycloaddition of phenylsulfene (generated in situ from phenylmethanesulfony] chloride and triethylamine) to N, N-disubstituted (E)-2-aminomethylenecyclohexanones I gave in general a mixture of N, N-disubstituted cis- and trans-4-amino-3, 4, 5, 6, 7, 8-hexahydro-3-phenyl-1, 2-benzoxathiin 2, 2-dioxides III and IV, which were separated by column chromatography and whose structural and conformational features were determined from uv, ir and nmr spectral data. In the case of N, N-diisopropylamino enaminone 1c, the cyclo-addition took place with elimination of an alkyl group as propene to give the adduct III?. 相似文献
32.
Monfrecola G Procaccini EM D'Onofrio D Roberti G Liuzzi R Staibano S Manco A De Rosa G Santoianni P 《Journal of photochemistry and photobiology. B, Biology》2002,68(2-3):147-155
Photodynamic therapy (PDT) with 5-aminolaevulinic acid (ALA) is an alternative tool for the treatment of superficial non-melanoma skin cancers. Recently ALA-PDT has been employed with encouraging results also for warts, condylomata and psoriasis. In this study the effects of topical ALA plus irradiation with visible light on intact human skin have been evaluated. Five skin areas (A, B, C, D, and E) on the inner upper part of the arms of five healthy volunteers (skin types III and IV) were treated with (A) ALA 20% in base cream without irradiation, (B) only the vehicle (base cream) without ALA, (C, D and E) ALA cream at the concentrations of 5, 10 and 20%, respectively; all treatments were applied with an occlusive dressing. Four hours after ALA or vehicle application areas B, C, D and E were irradiated with a fixed dose of 40 J/cm(2). ALA penetration through the intact skin was evaluated by in vivo fluorescence determination. The effects on healthy skin were evaluated by clinical and chromometric examinations, light microscopy, immunohistochemistry and electron microscopy. RESULTS: (1) in vivo fluorescence demonstrated that ALA is able to penetrate through the intact skin, when applied with occlusive dressing and induces a classical fluorescence peak due to Protoporphyrin IX (PpIX) formation, which is the active photosensitiser. (2) Skin areas receiving ALA plus irradiation showed erythema and swelling just after the irradiative session and hyperpigmentation 48-72 h later. (3) Colourimetric data confirmed significant skin colour changes: values a* (representing the erythematous changes) increased only on the skin areas where ALA+irradiation were applied and during the 48 h after irradiation, thereafter a* began to decrease; values L* (pigmentation) increased during the 2 weeks following treatment. (4) Histopathological, immunohistochemical (S100, HMB-45) and electron microscopic findings showed an absolute increment of the number of melanocytes, which appeared clearly activated. In conclusion the application of ALA cream followed by irradiation is able to induce a pigmentation response in healthy human skin, at least in skin types III and IV. This melanocytic activation could have a potential for the treatment of skin disorders characterised by hypopigmentation. 相似文献
33.
The reaction of sulfene with N,N-disubstituted 3-aminomethylene-2,3-dihydro-4-thiochromanones and-2,3,5,6-tetrahydro-4-thiopyranones gave 1,4-cycloadducts which are derivatives of new heterocyclic systems, namely 3,4-dihydro-5H-[1]benzothiopyrano[3,4-e]-1,2-oxathiin and 3,4,7,8-tetrahydro-5H-thiopyrano[3,4-e]-1,2-oxathiin, respectively. Furthermore, some pyrazole derivatives VII and VIII were prepared from 3-hydroxymethylene-2,3-dihydro-4-thiochromanone or 2,3,5,6-tetrahydro-4-thiopyranone and hydrazines. 相似文献
34.
The UV spectrophotometric analysis of a multicomponent mixture containing paracetamol, caffeine, tripelenamine and salicylamide by using multivariate calibration methods, such as principal component regression (PCR) and partial least-squares regression (PLS), was described. The calibration set was based on 47 reference samples, consisting of quaternary, ternary, binary and single-component mixtures, with the aim to develop models able to predict the concentrations of unknown samples containing as many as one-to-four components. The calibration models were optimized by an appropriate selection of the number of factors as well as wavelength ranges to be used for building up the data matrix and excluding any information about the interfering excipients included in pharmaceutics. The PCR and PLS models were compared and their predictive performance was inferred by a successful application to the assays of synthetic mixtures and pharmaceutical formulations. 相似文献
35.
Summary White crystalline complexes of general formula Cu2L4X2 (where X = Cl, Br and L = 1, 3-oxazolidine-2-thione, pyrrolidine-2-thione,N-methyl-1,3-imidazolidine-2-thione andN-ethyl-1,3-imidazolidine-2-thione) and CuLX (where L = 1,3-imidazolidine-2-thione) were prepared by reduction of copper(II) halides and studied by i.r. spectroscopy in the 4000–200 cm– range. Evidence for ligand coordination to the metal through sulphur was found in each case. The(CuCI) vibration in all the chloro derivatives falls atca. 240 cm–. 相似文献
36.
Gian Angelo Vaglio Paolo Volpe Lorenza Operti 《Journal of mass spectrometry : JMS》1982,17(12):617-619
The negative ion chemical ionization mass spectra, with ammonia and methane as reagent gases, of the (η6-arene)Cr(CO)3 complexes, where the arene is C6H5COCH3, C6H5COC2H5, C6H5COC3H7, C6H5COC(CH3)3, 2-CH3C6H4COC3H7, C6H5COOCH3, C6H5CH3, 1,3,5-(CH3)3C6H3 and C6H5CH2COC2H5, are reported. Similar behaviour is observed with the two reagent gases, but ammonia shows a much higher abundance for the ions produced by reactions of [NH2]? with sample molecules. The compounds containing the C6H5CO group display an abundant [M]? ˙, whereas the other compounds exhibit [M? H]? as base peak, produced by ion/molecule reactions. A comparison of the negative ion chemical ionization mass spectra of the (η6-arene)Cr(CO)3 complexes with those of the corresponding ligands shows the strong electron withdrawing power of the Cr(CO)3 group in the gas phase. 相似文献
37.
Giovanni Brigati Paola Franchi Marco Lucarini Gian Franco Pedulli Luca Valgimigli 《Research on Chemical Intermediates》2002,28(2-3):131-141
An EPR investigation of the kinetics of the exit, k -, and entrance, k +, processes in micelles of sodium dodecyl sulfate, hexadecyltrimethylammonium bromide and polyoxyethylene(6)decanol of a family of para-substituted benzyl tert -butyl nitroxides and para-substituted benzyl hydroxyalkyl nitroxides is reported. The inclusion of nitroxide probes in the hydrophobic environment of the micelle gives rise to a reduction of the value of both nitrogen and β-proton splittings, with the result that the resonance fields for the MI(2H β ) = ±1lines of the free and included species are significantly different. The rate constants were obtained by analyzing the EPR line shape variations as function of surfactant concentration and temperature. The experimental value of k + obtained from the study of benzyl tert-butyl nitroxide indicates that the association reaction is very close to being controlled by diffusion. The value of the exit rate, k -, instead, depends on the probe hydrocarbon chain length. A comparison of our results with those obtained by luminescence quenching techniques is also reported. 相似文献
38.
The protolysis equilibria of 2-hydroxybenzohydroxamic acid, H2SAX, have been studied at 25 degrees C in different ionic media by potentiometric titration with a glass electrode. The media were 0.513, 1.05, 2.21 and 3.5 mol/kg NaClO4. The constants beta(-p)(H2SAX<==>H(2-p)SAX(-p)+pH+), combined with salting effects of NaClO4 on H2SAX deduced from solubility determinations, were processed by the specific interaction theory, SIT, to give equilibrium constants at infinite dilution, log beta(-1)(o) = -7.655 +/- 0.013 and log beta(-2)(o) = -17.94 +/- 0.04, as well as specific interaction coefficients b(HSAX-,Na+) = 0.12 +/- 0.01 and b(SAX2-,Na+) = 0.17 +/- 0.02, molal(-1). 相似文献
39.
Lorenzo MalavasiPaolo Ghigna Gaetano ChiodelliGiorgio Maggi Giorgio Flor 《Journal of solid state chemistry》2002,166(1):171-176
The synthesis and structural properties of Mg1−xMn2+xO4, for 0≤x≤1 are described. Complete miscibility in the solid state exists for this system. For the material with the correct stoichiometry, i.e. MgMn2O4, the effect of temperature on the cation distribution was investigated= above 600°C the inversion degree (m) starts increasing. The electrical conductivity shows a small dependence on P(O2) which is consistent with the small oxygen non-stoichiometry determined by means of thermogravimetry. The main contribution to the transport properties arises from the inversion equilibrium. Two distinct conductivity regimes, below and above the inversion threshold, can be assumed to explain the electrical conductivity and thermoelectric power results. 相似文献
40.
Gaetano Dattolo Girolamo Cirrincione Anna Maria Almerico Enrico Aiello Isabella D'Asdia 《Journal of heterocyclic chemistry》1986,23(5):1371-1373
Pyrrolo[1,2-f]phenanthridines were prepared in good yields by the diazotization in acetic acid of the amines la,b and subsequent treatment with hypophosphorous acid. The necessity for hypophosphorous acid in the reaction was demonstrated. 相似文献