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  • 1
    Electronic Resource
    Electronic Resource
    Progress towards a generalized solvent polarity scale: The solvatochromism of 2-(dimethylamino)-7-nitrofluorene and its homomorph 2-fluoro-7-nitrofluorene (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 241-252 
    Details
    ISSN: 0947-3440
    Keywords: Polarity scale ; Solvatochromism ; Solvent polarity scale ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: More than 100 solvents and the gas phase were used to develop a solvent dipolarity-polarizability scale that combines the medium dipolarity and polarizability into a single parameter (SPP) calculated from the UV-visible spectra of 2-(dimethyl-amino)-7-nitrofluorene (DMANF) and its homomorph 2-fluoro-7-nitrofuorene (FNF). The proposed scale compares favourably for nonprotic solvents with existing solvent polarity scales including Kosower's Z, Dimroth and Reichardt's ET(30), Brooker's χR, Dong and Winnick's Py; Kamlet, Abboud, and Taft's π*, and Drago's S′ scale. When data are derived from electronic transitions, they provide an accurate description for the solvent effect in UV-Vis, IR, NMR, and fluorescence spectroscopy as well as in other chemical areas including thermodynamics and kinetics.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199519950234
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  • 2
    Electronic Resource
    Electronic Resource
    Electrochemical oxidation of dacarbazine and its major metabolite (AIC) on carbon electrodes (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 529-534 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical behavior of the antitumor agent dacarbazine (DTIC) and its major metabolite, 5-aminoimidazole-4-carboxamide (AIC), on carbon paste electrodes has been studied. Linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV) have been applied, showing that both molecules are active in oxidation. Both compounds are oxidized in a two-electron process, presenting a charge transfer coefficients (β) of 0.44 ± 0.03 and 0.48 ± 0.03 for DTIC and AIC, respectively, which indicate slow processes. The oxidation mechanisms proposed for each of these compounds seem to yield the same final product, the 5-hydroxyimidazol-4-carboxamide. DPV proved to be a valuable analytical technique that is suitable for distinguishing and analyzing both compounds when the most adequate medium (0.1 M HCIO4) and operating conditions are chosen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140010609
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and controlled release behaviour of dextran bioactive esters by direct reaction of dextran with the potassium salts of bioactive carboxylic acidsIn memoriam Dr. Antonio Macias (1997)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 3465-3475 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This work deals with the coupling of model bioactive carboxylic acids (1-naphthylacetic acid, 2-(6-methoxy-2-naphthyl)propionic acid (naproxen) and nicotinic acid) to dextran by direct reaction with their potassium salts using pyridine/sulfonyl chloride as activating agent. The structure of the resulting polymeric derivatives was determined by means of 1H and 13C NMR spectroscopy. The influence of the pyridine concentration, the type of sulfonyl chloride and the temperature on the reaction of dextran with potassium 1-naphthyl acetate was evaluated. The activation energy was found to be 65,7 kJ/mol. 13C NMR spectra at 75,4 MHz of partially modified dextran with 1-naphthyl acetate groups were studied in order to evaluate the selectivity of the reaction between dextran and potassium 1-naphthyl acetate. Analysis of the spectra of ring carbons in the anhydroglucose units shows that the reactivity of the individual hydroxyl groups decreases in the order C2 〉 C4 〉 C3. The hydrolysis in the heterogeneous phase of some dextran polymers partially modified with 1-naphthyl acetate groups shows that the release of the bioactive compound is dependent on the hydrophilic character of the polymer as well as the pH value of the medium.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1997.021981111
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  • 4
    Electronic Resource
    Electronic Resource
    Optimization of conditions for mercury-coated carbon fiber electrode formation and their influence on the cathodic stripping voltammetry of Se(IV) (1993)
    Weinheim : Wiley-Blackwell
    Electroanalysis 5 (1993), S. 455-460 
    Details
    ISSN: 1040-0397
    Keywords: Selenium ; Stripping voltammetry ; Carbon fiber ; Mercury film ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conditions for the deposition of mercury on the surface of carbon fibers to permit the sensitive and reproducible voltammetry of Se(IV) have been investigated. Several procedures employing both predeposition and in situ formation of a mercury film on the carbon fiber were evaluated, and the effect of the mercury concentration and plating time upon the sensitivity of the stripping response for Se(IV) was determined. Due to the steady-state diffusional mass transport characteristics exhibited by these electrodes, the need for stirred solutions, a specific deposition potential, and a deposition time period in the stripping voltammetric procedure was eliminated. This procedure gave rise to a linear response up to 3 ng/ml, a detection limit of 0.11 ng/ml, and a relative standard deviation (RSD) of 4.4% at 5 ng/ml (n = 5) for determination of Se(IV).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140050513
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  • 5
    Electronic Resource
    Electronic Resource
    A Generalized Solvent Basicity Scale: The Solvatochromism of 5-Nitroindoline and Its Homomorph 1-Methyl-5-nitroindoline (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1785-1794 
    Details
    ISSN: 0947-3440
    Keywords: Solvent basicity scale ; Solvent effects ; Solvatochromism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A total of 202 organic solvents and the gas phase were placed on a solvent basicity scale for hydrogen bond acceptor based on parameter SB. The value of such a parameter can readily be determined from the UV/Vis spectrum for an appropriate acid probe (5-nitroindoline) (NI) and its non-acid homomorph (1-methyl-5-nitroindoline) (MNI). The proposed scale can advantageously substitute the more widely used solvent scales such as Gutmann's donor number (DN), the Koppel-Palm B(MeOD) scale, and the Taft-Kamlet β scale. While data for the proposed scale are derived only from electronic transitions, they are accurately descriptive of solvent basicity in both spectroscopy (UV/Vis, IR and NMR) and miscellaneous chemical areas (thermodynamic, kinetics, and electrochemistry).
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961112
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  • 6
    Electronic Resource
    Electronic Resource
    Voltammetric determination of cocaine in confiscated samples (1991)
    Weinheim : Wiley-Blackwell
    Electroanalysis 3 (1991), S. 409-412 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical behavior of the abuse drug cocaine has been studied. Cocaine undergoes an irreversible oxidation process on carbon paste electrodes. It was calculated that 2 electrons were involved, and the value obtained for the charge transfer coefficient was 0.362 ± 0.006. Comparative voltammetric experiments yielded an estimated diffusion coefficient value for cocaine of 0.27 × 10-5 cm2 s-1. A linear calibration plot from 1.0 × 10-6 to 1.0 × 10-4M was obtained by using a scan rate of 50 mV s-1. A simple and reproducible procedure is proposed for the determination of cocaine in illegal dosage forms confiscated by police authorities; the results agree with those of a HPLC-UV method.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140030427
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