No description available.

Crystals of the title compound are monoclinic with a= 8.314 (5), b= 22.723 (9), c= 12.589 (6) A, /3= 123.0 (2t, Z=4, space group P2dc. The structure was determined by Patterson and Fourier methods and refined by full-matrix least squares to a final R of 0.030 for 2043 independent reflexions. The U atom has pentagonal bipyramidal coordination and the N-methylacetylacetoneamine is bonded to U via O. There are two intramolecular N-H. . .0 hydrogen bonds which govern the geometry of the adduct molecule.

A calorimetric enthalpy of dilution technique was applied to the investigation of carboxylic acid self-association in organic solvents at 25°C. Data were analyzed in terms of the apparent relative molar enthalpy, Φ_L, and were found to fit adequately a monomer-dimer model. Values of the thermodynamic dimerization parameters K_2 and ΔH°_2 were obtained for several methyl-, halo-, and phenyl-substituted acetic and propionic acids in benzene. Some of the acids were also studied in toluene and carbon tetrachloride. Substituent effects on K_2 and ΔH°_2 were in general small and were explained adequately by an electrostatic model of the monomer-dimer interaction. Solvent effects were explained by considering an acid-solvent interaction. The effect on the results of small amounts of water in the solvent was found to be a function of aqueous acid strength. Acetic acid and other weak acids were unaffected by water in the solvent, but a significant affect was observed with stronger acids, such as the haloacetic acids.

No description available.

No description available.

The reactions of 4,6-dinitrobenzofuroxan, (DNBF) with aniline and six of its N- and ring- substituted derivatives have been studied. It is known that aniline usually reacts as a nitrogen nucleophile, forming nitrogen-bonded σ-adducts with trinitrobenzene, (TNB) in the presence of a strong base. However, in acidic solutions, a-adducts are formed with bonding between a ring carbon atom of the anilines and the 7-position of DNBF. A value of 2.0 for k(_H)/k(_D), the kinetic isotope effect, indicates that bond formation is largely rate determining in the substitution pathway. Estimates were made for the pK(_a) values relating to carbon protonation of the anilines. In solutions of aniline buffered with aniline hydrogen chloride it was possible to distinguish an initial, rapid reaction via the nitrogen centre to give anionic a-adducts. The thermodynamically more stable carbon-bonded σ-adducts were observed to form over time. In the presence of excess amine, these zwitterionic σ-adducts were in rapid equilibrium with the deprotonated forms. Equilibrium constants for this acid-base process were measured, and indicate that the negatively charged DNBF moiety is electron withdrawing relative to hydrogen. Kinetic and equilibrium studies are reported for the reactions of several aliphatic amines with a selection of nitrobenzofurazan derivatives in DMSO. Rapid reaction at the 5- position to yield σ-adducts was followed by slower formation of the thermodynamically more stable adducts at the 7-position. Proton transfer from the zwitterionic intermediates to a second molecule of amine was generally rapid, and the attack of the amine rate determining. This is in direct contrast with reactions involving TNB, where the proton transfer step is usually rate limiting. The reactions of four nitrobenzofurazan derivatives with sulfite have been studied in aqueous solutions. The stability of the initially formed 5-adducts was remarkably high in comparison with the corresponding σ-adducts formed from attack of sulfite on TNB. A slow isomerisation was observed to yield the thermodynamically more stable 7-adducts, except in the reaction with 4-nitro-7-chlorobenzofurazan, where attack at the 7-position would lead to nucleophilic substitution of the chloro-group to yield the substitution product. The mechanism of the isomerisation was found to occur via an intermolecular rearrangement, and not according to an intramolecular Boulton-Katritzky rearrangement. Sulfite attack on DNBF was also studied. A value for the equilibrium constant for the formation of a 1:1 adduct, K(_7) 1.1 x 10(^13) dm(^3) mol(^-1) was determined. This high value is a reflection of the high carbon basicity of the sulfite ion, and the highly electrophilic character of DNBF. Evidence was also obtained for the formation of 1:2 di-adducts in the presence of excess sulfite, which are present in the isomeric cis and trans forms.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 220-229).

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 226-231). Also available in electronic version. Access restricted to campus users.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 126-129).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 161-167).