The Interaction of Sulfite Ion with 2,4,6-Trinitrobenzaldehyde: Kinetic, Equilibrium, and Proton Magnetic Resonance Studies

1973 ◽  
Vol 51 (23) ◽  
pp. 3927-3935 ◽  
Author(s):  
Neven Marendic ◽  
Albert Richard Norris

Sulfite ion reacts with 2,4,6-trinitrobenzaldehyde in aqueous solution of ionic strength 0.14 M to yield a 1:1 σ-complex at low sulfite concentrations and a 2:1 σ-complex at high sulfite concentrations. The visible absorption characteristics of these two σ-complexes as well as equilibrium constants and relevant thermodynamic parameters for their formation have been determined. P.m.r. studies demonstrate that two isomeric forms of the 1:1 σ-complex occur in aqueous dimethylsulfoxide solution and two isomeric forms of the 2:1 σ-complex occur in water. In both the 1:1 and the 2:1 complexes isomers are found which contain sulfite ion attached to the C-1 carbon and one of the isomeric 2:1 σ-complexes is postulated to exist in cis and trans forms. Observations are presented concerning the kinetics of the very rapid formation of the 1:1 σ-complex in water.

1974 ◽  
Vol 52 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Erwin Buncel ◽  
Albert Richard Norris ◽  
Kenneth Edwin Russell ◽  
Peter Jura Sheridan

The kinetics of the reactions between sulfite ion and picramide, N-methylpicramide, and N,N-dimethylpicramide, to form 1:1 σ-complexes in aqueous solutions of constant ionic strength 0.14 M, have been investigated using a stopped-flow spectrophotometer. Specific rate constants for the formation and decomposition of these three complexes at 25.0 °C are 5.7 ± 0.2 × 104M−1 s−1 and 7 ± 1 s−1, 1.4 ± 0.1 × 104M−1 s−1 and 0.20 ± 0.02 s−1, and 4.1 ± 0.2 × 103M−1 s−1 and 0.14 ± 0.04 s−1, respectively. Enthalpies and entropies of activation characterizing the formation of the 1:1 σ-complexes have been determined. Equilibrium constants, determined spectrophotometrically at a number of temperatures, have been used to calculate the enthalpy (ΔH0) and entropy (ΔS0) changes associated with 1:1 and 2:1 σ-complex formation. These values are compared with corresponding ones for complex formation of sulfite ion with 1,3,5-trinitrobenzene and 2,4,6-trinitrobenzaldehyde. The extent of solvation of the σ-complexes is considered to play a primary role in determining the observed trends in the enthalpies and entropies of reaction.


1973 ◽  
Vol 51 (24) ◽  
pp. 4152-4158 ◽  
Author(s):  
Albert Richard Norris ◽  
James William Lennox Wilson

The hydrogen peroxide oxidation of thiocyanate ion in cis- and trans-[Coen2NH3NCS]2+ leads to the formation of the corresponding cis- and trans-cyanoammine- and diamminebis(ethylenediamine)cobalt-(III) complexes. The spectral properties of the previously unreported trans-[Coe2NH3CN]2+ are reported and compared to the spectral properties of the cis-isomer.Observations are made concerning the reaction conditions which favor a high percent conversion of trans-[Coen2NH3NCS]2+ to trans-[Coen2NH3CN]2+.


Author(s):  
Yasujiro Murata ◽  
Shih-Ching Chuang ◽  
Fumiyuki Tanabe ◽  
Michihisa Murata ◽  
Koichi Komatsu

We present our study on the recognition of hydrogen isotopes by an open-cage fullerene through determination of binding affinity of isotopes H 2 /HD/D 2 with the open-cage fullerene and comparison of their relative molecular sizes through kinetic-isotope-release experiments. We took advantage of isotope H 2 /D 2 exchange that generated an equilibrium mixture of H 2 /HD/D 2 in a stainless steel autoclave to conduct high-pressure hydrogen insertion into an open-cage fullerene. The equilibrium constants of three isotopes with the open-cage fullerene were determined at various pressures and temperatures. Our results show a higher equilibrium constant for HD into open-cage fullerene than the other two isotopomers, which is consistent with its dipolar nature. D 2 molecule generally binds stronger than H 2 because of its heavier mass; however, the affinity for H 2 becomes larger than D 2 at lower temperature, when size effect becomes dominant. We further investigated the kinetics of H 2 /HD/D 2 release from open-cage fullerene, proving their relative escaping rates. D 2 was found to be the smallest and H 2 the largest molecule. This notion has not only supported the observed inversion of relative binding affinities between H 2 and D 2 , but also demonstrated that comparison of size difference of single molecules through non-convalent kinetic-isotope effect was applicable.


1995 ◽  
Vol 60 (13) ◽  
pp. 4255-4257 ◽  
Author(s):  
Mario L. Aimar ◽  
Rita H. de Rossi
Keyword(s):  

Polyhedron ◽  
2000 ◽  
Vol 19 (26-27) ◽  
pp. 2565-2572 ◽  
Author(s):  
Ludmiła Szterenberg ◽  
Szczepan Roszak ◽  
Renata Matusiak ◽  
Antoni Keller

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