The basicities of fifteen ortho-substituted benzoic acids and five benzophenone analogues have been measured with the aim of studying the effects of stereoelectronic factors on the strengths of very weak bases. The ortho effects of the substituents on the basicities of the benzoic acids have been estimated by two methods. The first method compares the pKβH⁺ values of the corresponding ortho- and para-substituted acids and uses the difference between them as a measure of the ortho effect on the assumption that the electrical effects of substituents are equal in the ortho and para positions. The second method is that of McDaniel and Brown (10). The ortho effects of alkyl substituents are base weakening and increase in the order methyl < ethyl < i-propyl < t-butyl. These effects are attributed to the bulk effect of the substituents, and in particular, to steric inhibition of resonance in the conjugate acid. The halogen substituents, on the other hand, appear to have base strengthening ortho effects in the order F > Cl > Br > I ≃ 0, which are attributed to stabilization of the protonated acid by intra-molecular hydrogen bonding. In a similar manner, oxygen containing substituents such as methoxyl and carboxyl are base strengthening. The basicities of these benzoic acids do not follow the linear relationships of either Taft (21) or Farthing and Nam (22) which have been developed to correlate the reactions of ortho-substituted benzene derivatives, a fact which serves to emphasize the high dependence of ortho effects upon the nature of the reaction. The basicities of benzophenone analogues in which the phenyl rings are rigidly held have also been studied. The basicities were found to be in the order 9-anthrone > 2,3;6,7-dibenzotropone > 2,3;6,7-dibenzosuberone > benzophenone > 9-fluorenone. The high basicity of anthrone is attributed to the planarity of the molecule which allows a high degree of resonance in both the unprotonated and protonated species. The low basicity of fluorenone is attributed to its similarity to cyclopentadienone in which the tendency of the carbonyl group to polarize in the usual direction, and so increase the electron density on oxygen, is greatly reduced through an effort to aromatize the ring. / Science, Faculty of / Chemistry, Department of / Graduate

Lai Chi-hung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1978. / Bibliography: leaves 80-82.

Thesis (M.Sc.)--York University, 2007. Graduate Programme in Chemistry. / Typescript. Includes bibliographical references (leaves 122-134). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR29309

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 167-179).

Thesis (Ph. D.)--University of Wisconsin, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The topic of this thesis is the catalytic and stoichiometric decarbonylation of aldehydes. A carbonylation reaction, the reaction of RuTPP(n-Bu₃P)₂ with CO gas was also studied. A catalytic decarbonylation system, using RuTPP(PPh₃)₂ as catalyst plus added excess tri-n-butylphosphine in acetonitrile-dichloromethane, was employed to decarbonylate several organic aldehydes. This system proved to be an effective decarbonylation agent, which also exhibited some selectivity. Some mechanistic studies were carried out in an attempt to elucidate the details of the reaction mechanism. From these and other findings in this laboratory, a tentative mechanism was proposed for the decarbonylation reaction. A radical mechanism, involving Ru(III) intermediates was favoured on the basis of e.s.r. data, spectral evidence and cyclic voltammetry studies. However, no intermediates were isolated. The full details of the mechanism, such as the precise nature of the postulated intermediates, have not been fully determined, although there are indications that solvated species, like RuTPP(CO)(CH₃CN), may be important. The stoichiometric reaction between RuTPP(n-Bu₃P)₂ and phenylacetaldehyde was also studied. The kinetic analysis indicated that the reaction, equation i, RuTPP(n-Bu₃P)₂ + C₆H₅CH₂CH0 --> RuTPP(CO)(n-Bu₃P) + n-Bu₃P + C₆H₅CH₃ equation i followed a pseudo-first-order rate law in the absence of excess phosphine, however, the actual k obsd values were found to be irreproducible. Some features of this reaction, such as the failure of the reaction to go to completion, and also the effect of trace oxygen on the reaction were investigated. The carbonylation of RuTPP(n-Bu₃P)₂ by CO gas was of interest, with respect to the catalytic reaction, which seems to involve pretreatment with CO (or aldehyde) to form a phosphine monocarbonyl. The reaction was found to follow a simple dissociative mechanism, which is similar to that observed for analogous M(porp)L₂, where M = Ru or Fe. A K value of 0.054 at 26°C was obtained and individual rate constants were calculated also. The temperature dependence of K was used to find the thermodynamic parameters ΔS° and ΔH° for the reaction. Some electrochemical studies were performed on RuTPP(n-Bu₃P)₂ and the corresponding monocarbonyl, RuTPP(CO)(n-Bu₃P). Electrochemical oxidation of RuTPP(CO)(n-Bu₃P) yielded a ir-cation radical, whereas bromine oxidation appeared to effect oxidation of the metal. / Science, Faculty of / Chemistry, Department of / Graduate

The structure of lycopodine was investigated in the neighbourhood of the carbonyl group. The results obtained enabled the elucidation of a large part of the peripheral structure of the alkaloid. / Thesis / Master of Science (MS)

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 118-133). Also available in electronic version.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy