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  • 1
    Electronic Resource
    Electronic Resource
    Kinetic probe to study the structural behaviour of mixed aqueous - organic solvents. Effects of inorganic and organic salts on the kinetics and mechanism of intramolecular general base-catalysed methanolysis of ionized phenyl salicylate (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 129-141 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of inorganic and organic salts on the rates of methanolysis of ionized phenyl salicylate, PS-, were studied at 30°C in H2O-MeOH solvents. The observed pseudo-first-order rate constants, kobs, for methanolysis of PS- represent a non-linear incrrease with increase in methanol contents in mixed H2O-MeOH solvents. The observed data are explained in terms of the proposal that methanol molecules exist in monomeric, dimeric and in general polymeric forms in H2O-MeOH solvents. The rate constants, kobs, at alkanol [ROH (R = Me, HOCH2CH2)] contents of ca ≤ 55% (v/v), fit the relationship kobs = k [ROH]T/(1 + kA [ROH]), (1 + KA [ROH]), where k and KA represent the nucleophilic second-order rate constant for the reaction of ROH with PS- and the association constant for the dimerization of ROH, respectively, and [ROH]T is the total concentration of ROH. The rate constants, k, appear to be independent of total concentrations of inorganic salts [MX]T (M = Li, Na, K and X = OH, Cl), but the values of KA increase with increase in [MX]T and this increase varies in the order Li+ 〉 Na++ 〉 K+. The values of both k and KA show a decrease with increase in the total concentrations of organic salts, [R4MX]T (R = Et, Prn, Bun and X = Br, I). The effects of [MX]T and [R4MX]T on kobs versus content of ROH (%, v/v) profiles reveal the following inferences: (i) in the water-rich region of H2O-ROH solvents [at ca 〈 55% (v/v) ROH] the solvation shells of M+ and X- contain preferentially only water molecules whereas in the methanol-rich region [at ca 〉 55% (v/v) ROH] of solvents some cosolvent methanol molecules also enter into these solvation shells; (ii) the solvation shells of tetraalkylammonium ions, R4N+, contain some methanol molecules even in the water-rich region of the solvents; (iii) Li+ cause a methanol structure-making effect whereas Na+ and K+ ions show a methanol structurebreaking effect; and (iv) organic cations such as Et4N+, Prn4N+ and Bun4N+ reveal a methanol structure-breaking effect through an interaction mechanism different from that operating for Na+ and K+. Both k and KA show significant normal deuterium isotope effects in the reactions of MeOH and PS- which indicates the probable occurrence of proton transfer in the rate-determining step.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050305
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  • 2
    Electronic Resource
    Electronic Resource
    Salt and solvent effects on alkaline hydrolysis of N-hydroxyphthalimide. Kinetic evidence for ion-pair formation (1994)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 7 (1994), S. 412-419 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of the concentrations of LiCl, NaCl, KCl, CsCl, Na2CO3 and BaCl2 on the rates of reactions of hydroxide ion with ionized N-hydroxyphthalimide (NHP-) at 30°C and in H2O-MeCN solvents containing 10, 50, 60, 66, 70, 76 and 80% (v/v) MeCN reveal the formation of ion-pair complexes between cations of the salts, which probably exist in solvent-separated loose ion-pair forms (Mn+⃛Xk-) and NHP-. An increase in MeCN content from 2 to 76% (v/v) causes an increase in the association constants (K) by factors of 40, 21 and 9 for LiCl, NaCl and KCl, respectively, while the respective increase in the rate constants (k′s1) for the collapse of the ion-pair complexes to product is ca two-fold. The values of k′s1 remain almost unchanged whereas the values of K increase 7·5-fold with an increase in MeCN content from 2 to 70% (v/v) for CsCl. Ion-pair complex formation was not detected in the presence of Me4NCl at 70% (v/v) MeCN. The observed pseudo-first-order rate constants are highly sensitive to the valence state of cations and almost insensitive to the valence state of the anions of the salts.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610070805
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the cleavage of phthalimide in buffers of tertiary and secondary amines. Evidence of intramolecular general acid-base catalysis in the reactions of phthalimide with secondary amines (1991)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 4 (1991), S. 547-561 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction rates of the cleavage of phthalimide (PTH) were studied at 30°C in buffer solutions of trimethylamine, triethylamine, triethanolamine, carbonate, piperidine, dimethylamine, morpholine, piperazine and N-methylpiperazine at different pH values. The reactivity of carbonate, triethylamine and triethanolamine toward PTH could not be detected under the experimental conditions applied. However, triethylamine revealed nucleophilic reactivity toward non-ionized PTH (SH). The steric requirements of triethylamine and triethanolamine are ascribed to the absence of nucleophilic reactivities of these amines toward SH. Secondary amines show nucleophilic reactivity toward both SH and ionized PTH (S-). The absence of nucleophilic reactivity of trimethylamine and the presence of nucleophilic reactivity of secondary amines toward S- are attributed to the occurrence of intramolecular general acid-base catalysis due to the presence of a mobile proton at the nucleophilic site of the nucleophile. Intermolecular general base catalysis was observed in the reactions of SH with all secondary amines except piperidine and such catalysis could be detected in the reactions of S- with morpholine, piperazine and N-methylpiperazine. Nucleophilic second-order rate constants for the reactions of secondary amines with SH (k1) and S- (k2) reveal the Brønsted plots of slopes of ca 0.8 and 0.3, respectively. Similarly, the general base-catalysed third-order rate constants (k4) for the reactions of secondary amines with SH yield a Brønsted plot of slope 1.2. These observations suggest the occurrence of diffusion-controlled trapping stepwise and pre-association stepwise mechanisms in the aminolysis of non-ionized and ionized phthalimide, respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610040905
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetic studies of the reactions of phthalimide with ammonia and pyrrolidine (1994)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 7 (1994), S. 518-524 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the nucleophilic cleavage of phthalimide (PTH) in buffer solutions of ammonia and pyrrolidine were determined. The reaction rates for ammonolysis of PTH revealed a buffer-catalysed second-order term in the rate law, but the reaction rates for pyrrolidinolysis of PTH showed buffer-catalysed second- and third-order terms in the rate law. Both ammonia and pyrrolidine revealed nucleophilic reactivity towards ionized PTH (S-) only within the pH range of the present study. This is attributed to the occurrence of intramolecular general base-acid catalysis. General base catalysis is detected in the reactions of pyrrolidine with both non-ionized PTH (SH) and S-. The general base-catalysed third-order rate constant for pyrrolidinolysis of SH is nearly 28 times larger than that of S-.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610070908
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  • 5
    Electronic Resource
    Electronic Resource
    Mechanism of the hydride transfer reaction of leuco crystal violet with cyanomethylene acceptors (1994)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 7 (1994), S. 218-220 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the hydride transfer of Leuco Crystal Violet to form the Crystal Violet, cation, the role of cyanomethylene acceptors was found to be essentially different from that of p-benzoquinones, both previously believed to act as π-acceptors in the same manner.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610070408
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  • 6
    Electronic Resource
    Electronic Resource
    Hydride transfer reactions of Michler's hydride with different π-accetors (1994)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 7 (1994), S. 309-315 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hydride transfer reactions of 4,4′-bis(dimethylaminophenyl)methane (Michler's hydride) with p-benzoquinones were studied. The rate of formation of Michler's Hydrol Blue was followed spectrophotometrically. The second-order rate constants and the activation parameters were estimated. The formation of a charge-transfer complex was observed at low temperatures. Stable and unstable paramagnetic species formed during the reactions were assigned by ESR spectroscopy. The observed kinetic behaviour and the stoichiometry were in line with those previously obtained for the systems involving Leuco Crystal Violet, Leuco Malachite Green and Leuco Bindschedler's Green. Hence the reaction is considered to proceed according to the so-far accepted multi-step mechanism. However, when tetracyano-p-quinodimethane or tetracyanoethylene was used as a π-acceptor, a comparatively stable radical ion pair was formed as a result of a one-electron transfer, followed by the gradual formation of Michler's Hydrol Blue. The kinetic behaviour and the stoichiometry of the reaction were examined, together with the enhanced kinetic effects of added triethylamine. A modified mechanism for these systems is proposed. The role of cyanomethylenes was found to be essentially different from that of p-benzoquinones, and therefore π-acceptors are divided into two groups of cyanomethylenes and p-benzoquinones.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610070607
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  • 7
    Electronic Resource
    Electronic Resource
    Solubility behaviour of copper(I) bromide in aqueous hydrobromic acid, potassium bromide and magnesium bromide. II (1970)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 375 (1970), S. 297-301 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Es wurde die Löslichkeit von CuBr in wäßrigen HBr-, KBr- und MgBr2-Lösungen bei unterschiedlicher Gleichgewichtskonzentration des freien Bromids er-mittelt. Aus den Löslichkeitsdaten wird auf die Spezies CuBr2- und CuBr32- in der flüssigen Phase des HBr- und des KBr-Systems geschlossen, und auf nur eine Spezies, CuBr32-, im MgBr2-System. Die ermittelten Werte der Gleichgewichtskonstante K1 · K2 · Kfest für das HBr- (50°C), KBr- (20°C) und MgBr2-System (20°C) sind: 3,16 · 10-1; 9,01 · 10-1 bzw. 4,78 · 10-1.
    Notes: The solubility of copper(I) bromide in aqueous HBr, KBr and MgBr2 solutions has been determined at varying free bromide equilibrium concentrations. On the basis of solubility data the presence of species like CuBr2- and CuBr32- is indicated in the aqueous phase in HBr and KBr systems, whereas in the case of MgBr2 the presence of only one species, CuBr32-, is concluded. The calculated values of the equilibrium concentration constant K1 · K2 · Ksol are 3.16 × 10-1, 9.01 × 10-1 and 4.78 × 10-1 for the HBr (50°C), KBr (20°C) and MgBr2(20°C) system, respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19703750312
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  • 8
    Electronic Resource
    Electronic Resource
    Solubility behaviour of copper(l) Iodide in potassium lodide acetone media. I (1970)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 375 (1970), S. 291-296 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Es wurde die Löslichkeit von CuJ in KJ/Aceton im Konzentrations bereich 0,05-0,2 M untersucht. Als einzige Komplexspezies sowohl in Lösung als auch im Bodenkörper wurde dabei CuJ2 - nachgewiesen. Auch konduktometrische Untersuchungen zeigen deren Existenz an. Bei 20°C hat die Konzentrationsgleichgewichtskonstante K1K2Ksol der Reaktion CuJ(sol) + J- → CuJ2- den Wert 1,65±0,2.
    Notes: The solubility behaviour of CuI was studied in KI-acetone media in the concentration range of approximately 0.05 to 0.2 M. Within this range of iodide concentration, Cul2- was the only complex species found to occur in the liquid as well as in the solid phase. Conductometric studies also indicated the existence of the same species. At 20°C, the concentration equilibrium constant K1K2Ksol for the reaction CuI (sol) + I- = CuI2- is 1.65±0.2.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19703750311
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis of cross linked platinum metal containing polyyne polymersDedicated to Professor Rudolf Hoppe on his 70th Birthday (1992)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 616 (1992), S. 121-124 
    Details
    ISSN: 0044-2313
    Keywords: cross-linked ; rigid-rod ; σ-acetylide ; π-conjugation ; electronic properties ; polyyne copolymer ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von vernetzten Platin-enthaltenden Polyyn-PolymererDie Umsetzung von Pt(PnBu3)Cl2 (1)oder Pt(AsnBu3)2Cl2 (2) mit berechneten Mengen von 1,3,5-Triethynylbenzol [1,3,5-(H—C≡ C—3C6H3] (3)ergibt monomere [1,3,5-(Cl(PnBu3)2Pt—C≡C—)3C6H3](4), [1,3,5-(Cl)(AsnBu3)2Pt—C≡ C—)3C6H3] (5) oder Polymere [1,3,5]- [(PnBu3)2Pt —C ≡ C—]3C6H3—{n (6),{1,3,5-[(AsnBu3)2Pt—C≡ C—]3C6H3}n (7) Komplexe. Die Umsetzung von (1) mit (3) und 2,5-Diethynyl-p-xylol,H—C≡ C—C6H2(CH3)2—C≡ C—H (8) unter Variation der molaren Anteile ergibt eine Reihe von hochmolekularen, vernetzten Platin-enthaltenden polyyncopolymerer.
    Notes: Reaction of Pt(PnBu3)2Cl2 (1) or Pt(AsnBu32Cl2 (2) with stoichiometric amounts of 1,3,5-triethynylbenzene, [1,3,5-(H—C≡C—)3C6H3] (3)yields monomeric, [1,3,5-Cl(PnBu3)2(Pt—C≡ C—)3C6H3] (4), [1,3,5-(C1)(AsnBu3)2Pt—C≡ C—3C6H3] (5) or polymeric, {1,3,5-[(PnBu3)2Pt—C≡C—]3C6H3—)n (6), {1,3,5-[(AsnBu3)2Pt—C≡ C—]3C6H3—}n (7) complexes. Treatment of (1) with (3) and 2,5-diethynyl-p-xylene,H—C≡ C—C6H2(CH3)2—C≡ C—H (8) in varying molar ratios yields a series of high molecular weight cross linked platinum metal containing polyyne copolymers.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19926161018
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  • 10
    Electronic Resource
    Electronic Resource
    Kinetic studies on general base-catalyzed cleavage of phthalimide (PTH) in 2-hydroxyethylamine and 2-methoxyethylamine buffers (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 28 (1996), S. 421-431 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Kinetic studies on the nucleophilic cleavage of phthalimide (PTH) in buffers of 2-hydroxyethylamine and 2-methoxyethylamine reveal nonlinear plots of kn vs. [Buf]T (at constant pH) where kn and [Buf]T represent apparent second-order rate constant and total amine buffer concentration, respectively. The nonlinear variation of kn against [Buf]T is attributed to the occurrence of a stepwise mechanism in the aminolysis of PTH. Intermolecular general base catalysis is detected in the reactions of both amines with nonionized PTH (SH) only within the pH range of the present study. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.4
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