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  • 1
    Electronic Resource
    Electronic Resource
    Cyanated liquid crystals with trans-stilbene structure: Syntheses and their cyclotrimerizations (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 313-321 
    Details
    ISSN: 0887-624X
    Keywords: liquid crystals ; cyanate ; cyclotrimerization ; liquid crystalline thermoset ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Liquid crystalline aromatic monocyanate (M) and dicyanates (D1 and D2) with trans-stilbene (—Ph—CH=CH—Ph—) structure were synthesized and their cyclotrimerization reactions were studied by differential scanning calorimetry and infrared spectroscopy. Monocyanate M underwent cyclotrimerization to yield a trimerized material with discotic properties. Dicyanate D2 and its cured product failed to exhibit any mesophase. In contrast, polycyclotrimerization of dicyanate D1 obtained a liquid crystalline thermoset with its schlieren texture prolonged over a wide temperature range. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330213
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  • 2
    Electronic Resource
    Electronic Resource
    Cure kinetics of a flexible aromatic dicyanate with schiff base structure (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 1585-1592 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polycyclotrimerization of a flexible aromatic dicyanate with a Schiff base structure was studied by means of differential scanning calorimetry (DSC). The study on dynamic DSC evaluated an apparent activation energy (Ea) of 75.8 kJ/mol and autocatalytic first-order kinetics with rate expression Af(α) = 1.96 X 105 (1 + 4.39 α) (1 - α) min-1. The kinetic feature can be explained by a proposed mechanism consisting of hydroxyl-catalyzed and autocatalytic paths. The lower value of Ea compared with other aromatic dicyanates is due to the electron-withdrawing linkage of the inherent imine ( - CH=N) structure. The kinetic feature is affected by the content of the residual impurities (e.g., phenols or absorbed water) in the corresponding sample. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070580922
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and Evaluation of 2-{[(2-Oxo-1H-quinolin-8-yl)oxy]methyl}-Substituted α-Methylidene-γ-butyrolactones (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1161-1168 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: O-Alkylation of 8-hydroxy-1H-quinolin-2-one (1) afforded 8-(2-oxopropoxy)-1H-quinolin-2-one (2) which was immediately cyclized to form the tricyclic 2,3-dihydro-3-hydroxy-3-methyl-5H-pyrido[1,2,3-de][1,4]benzoxazine,-5-one (3). The Reformatsky-type condensation of 3 furnished antiplatelet 8-[(2,3,4,5-tetrahydro-2-methyl-4-methylidene-5-oxofuran-2-yl)melhoxy]-1H-quinolin-2-one (4). Its counterparts 7a-f, Ph-substituted at C(2) of the furan ring, were obtained from 1 via alkylation and the Reformatsky-type condensation. Although compound 4 was less active against platelet aggregation than 7a-f, it was the only compound which exhibited significant inhibitory activity on high-K+ medium, Ca2+-induced vasoconstriction and was more active than most of its Ph-substituted counterparts against norepinephrine-induced vasoconstrictions.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800413
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  • 4
    Electronic Resource
    Electronic Resource
    α-Methylidene-γ-butyrolactones: Synthesis and evaluation of quinolin-2(1H)-one derivatives (1998)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 1038-1047 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As a continuation of our previous studies on the synthesis and antiplatelet activity of quinolin-2(1H)-ones with an α-methylidene-γ-butyrolactone substituted at O(8), the O(6)- and N(1)-substituted isomers were synthesized and evaluated for antiplatelet activity against thrombin (Thr)-, arachidonic acid (AA)-, collagen (Col)-, and platelet-activating-factor (PAF)-induced aggregation in washed rabbit platelets. These compounds were synthesized from 6-hydroxyquinolin-2(1H)-one via alkylation and Reformatsky-type condensation (Schemes 1 and 2). All of them were found to inhibit the platelet aggregation perfectly which was induced by AA and Col. 6-Substituted isomers 5b-g exhibited very strong inhibitory activities against AA- and PAF- induced aggregation and are approximately ten times more potent than their 8-substituted counterparts. However, the 1-substituted (11a and 11b) and the 1,6-disubstituted (6) counterparts were relatively inactive. Their effects on the Ca2+-dependent vasoconstriction induced by high K+, and the phasic and tonic vasoconstrictions induced by norepinephrine (NE) in rat aorta were also evaluated. Except 5g, all of them were found to have significant inhibitory activity on the NE-induced phasic and tonic vasoconstrictions. Compounds 6 and 11b also exhibited strong inhibitory activity on high-K+ medium, Ca2+-induced vasoconstriction.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19980810517
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of Coumarin Derivatives as Inhibitors of Platelet Aggregation (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 651-657 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a search for the inhibitors of platelet aggregation, certain coumarin derivatives were synthesized and evaluated for antiplatelet activity against thrombin(Thr)-, arachidonic acid(AA)-, collagen(Col)-, and platelet-activating-factor(PAF)-induced aggregation in washed rabbit platelets. These compounds were synthesized from 4-hydroxycoumarin (1) or naphthalen-1-ol via alkylation and Reformatsky-type condensation (Schemes 1-3). Among them, 4-[(2,3,4,5-tetrahydro-4-methylidene-5-oxo-2-phenylfuran-2-yl)methoxy]-2H-1-benzopyran-2-one (6b) showed potent antiplatelet effects on AA- and PAF-induced aggregation with IC50 values of 8.21 and 103.67 m̈M, respectively (see Tables 1 and 2). The antiplatelet potency of 6b against PAF-induced aggregation could be further improved by introducing a proper substituent at the 2-phenyl group of the lactone ring.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19960790308
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  • 6
    Electronic Resource
    Electronic Resource
    Antiplatelet α-Methylidene-γ-butyrolactones: Synthesis and evaluation of quinoline, flavone, and xanthone derivatives (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 1620-1626 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As a continuation of our previous studies on the synthesis and antiplatelet activity of coumarin derivatives of α-methylidene-γ-butyrolactones, certain quinoline, flavone, and xanthone derivatives were synthesized and evaluated for antiplatelet activity against thrombin (Thr)-, arachidonic acid (AA)-, collagen (Col)-, and platelet-activating factor (PAF)-induced aggregation in washed rabbit platelets. These compounds were synthesized from quinolin-8-ol, flavon-7-ol, and xanthon-3-ol, respectively, via alkylation and Reformatsky-type condensation (Schemes 1-3). By the comparison with comparison with coumarin α-methylidene-γ-butyrolactone 3a, flavone and xanthone derivatives, 3b and 3c, respectively, are more selective in which only AA- and collagen-induced aggregation are strongly inhibited. Most of the quinoline derivatives (9a-e) exhibited broad-spectrum antiplatelet activities.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19960790612
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis and Evaluation of α-Methylidene-γ-butyrolactone bearing flavone and xanthone moieties (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2337-2344 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a search for inhibitors of platelet aggregation, a number of α-methylidene-γ-butyrolactones 5 and 6 bearing flavone or xanthone moieties, respectively, were synthesized and evaluated for their antiplatelet activity against thrombin(Thr)-, arachidonic-acid(AA)-, collagen(Col)-, and platelet-activating-factor(PAF)-induced aggregation in washed rabbit platelets. These compounds were synthesized from 7-hydroxyflavone (1) or 3-hydroxyxanthone (2) via O-alkylation (→ 3 and 4, resp.) and Reformatsky-type condensation (Scheme). Most of the flavone-containing α-methylidene-γ-butyrolactones 5a-d showed potent antiplatelet effects on AA- and Col-induced aggregation, while xanthone derivatives 6c-e were found to have the same pharmacological profile than aspirin in which only AA-induced aggregation was inhibited (Table 1). However, 6c-e were approximately three to ten times more potent than aspirin (Table 2). For the vasorelaxing effects, 5a was the only compound which exhibited significant inhibitory activity on the high-K+ medium, Ca2+-induced vasoconstriction (Table3). Both 5a and 6a, with an aliphatic Me substituent at C(γ) of the lactone, were active against norepinephrine-induced phasic and tonic constrictions while their γ-aryl-substituted counterparts 5b-f and 6b-f were inactive.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800806
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of 3-aryl-2-(polystyryl)cyclopropenones via cyclopropenium ion substitution on polystyrene (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1-6 
    Details
    ISSN: 0887-624X
    Keywords: cyclopropenone ; cyclopropenium ; reactive oligomer ; polystyrene ; Friedel-Crafts ; TGA ; polymeric cyclopropenone ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrophilic substitution of cyclopropenium ions on aromatic polymers offers a unique opportunity to introduce polar functionality in a controlled manner to conventional, nonpolar polymers. Phenylcyclopropenone substituted polystyrene with predictable chemical composition and narrow molecular weight distribution were prepared. Size exclusion chromatography (SEC) analysis demonstrated the absence of branching or crosslinking in these functionalized polystyrenes during electrophilic substitution of the parent homopolymer. 13C-NMR confirmed that the degree of phenylcyclopropenone substitution was both highly efficient and predictable over a broad compositional range. The glass transition temperature (Tg) of the polymers was found to vary linearly with mole % phenylcyclopropenone substitution of the polystyrene. Thermal gravimetric analysis (TGA) indicated that thermal decarbonylation of the appended cyclopropenones occurred at approximately 180°C. Weight loss vs. temperature profiles correlated reasonably well with levels of substitution based on 13C-NMR analysis, confirming that decarbonylation of the calculated cyclopropenone substituents was the predominant thermal decomposition pathway. © 1995 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330101
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  • 9
    Electronic Resource
    Electronic Resource
    Maximum sum of binary-coded residuals (MASBR) regression as a robust procedure for treatment of spectral data (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 373-387 
    Details
    ISSN: 0886-9383
    Keywords: robust regression ; outliers ; spectroscopy ; calibration ; MASBR (maximum sum of binary coded residuals) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper, a novel robust regression method, the maximum sum of binary coded residuals (MASBR), is proposed. Instead of the sum of squared residuals used in least squares regression as the minimization criterion, MASBR regression maximizes the sum of binary coded residuals. MASBR regression is designed for cases where the conventional robust regression methods with breakdown points less than 50% fail. To circumvent the problem of being trapped in local optima, a stepwise-varying acceptable error limit (SVAEL) algorithm is proposed. Both numerical simulation and treatment of real analytical data demonstrate the feasibility of MASBR regression in conjunction with the SVAEL algorithm.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180090505
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  • 10
    Electronic Resource
    Electronic Resource
    Experimental study of wave propagation dynamics of binary distillation columns (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2743-2760 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: High-purity distillation columns are typically difficult to control because of their severely nonlinear behavior reflected by their sharp composition and temperature profiles. The dynamic behavior of such a column, as characterized by the movement of its sharp profile, was elucidated by a nonlinear wave theory established previously. With binary alcohol mixtures, this study provides an experimental observation of such wave-propagation dynamics of a 40-tray stripping column and a 50-tray fractionation column in response to step disturbances of feed composition, feed flow rate, and reboiler heat supply. Our experimental results have verified that the sharp profile in a high-purity column moves as a constant-pattern wave and that the nonlinear wave theory predicts its velocity satisfactorily with very simple mathematics. Our results also demonstrate the asymmetric dynamics of the transitions between two steady states.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421006
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