Thesis (Ph.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / Photographic X-ray diffraction data were used to determine the crystal and molecular structure of dimethyl sulfoxide near 5C. Of the total 868 unique X-ray reflections collected, 507 had measurable intensity, 270 were unobserved, and 91 were extinct. Near 5°C, dimethyl sulfoxide is found to be monoclinic with a = 5.303 +/- 0.005 A, b = 6.829 +/- 0.003 A, c = 11.693 +/- 0.010A, and B = 94°30' +/- 15'. The space group is P21/c with Z = 4. [TRUNCATED] / 2031-01-01

Thesis (M.Sc.) -- University of Adelaide, Dept. of Human Physiology and Pharmacology, 1976. / Typescript (photocopy).

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xvi, 240 p.; also includes graphics (some col.). Includes bibliographical references (p. 231-240). Available online via OhioLINK's ETD Center

Dimethylacetamide (DMA) solvent is oxidized catalytically to CH₃CON(CH₃)CH₂OOH and CH₃CON(CH₃)CHO under H₂/0₂ mixtures at 50°C in the presence of the dimethylsulfoxide complex RhCl₃(DMSO)₃ (I) at a rate which is much faster than peroxide-initiated autoxidation of DMA under O₂ alone. The hydroperoxide is thought to be the initial product, and the N-formyl derivative its decomposition product. An accompanying metal-catalyzed hydrogenolysis of 0₂ leads to H₂0₂ and H₂0. Hydrogen peroxide and CH₃CON(CH₃)CH₂OOH are the only products formed in the early stages of the catalytic reaction. The maximum rate of gas uptake in this initial region is independent of the partial pressure of 0₂, but shows linear dependences on Rh and H₂. Stoichiometry, rate and spectral data are consistent with an initiation reaction between complex I and H₂, and then 0₂ to give a catalytically active RhIII (0₂=) (DMA) species (II) (eq. 1) [formula omitted] The autoxidation of DMA and the hydrogenolysis of 0₂ are postulated to occur via independent pathways involving II (eqs. 2 and 3). [formula omitted] In the absence of H2, II degenerates to catalytically inactive species. The role of H₂ in the DMA autoxidation is thought to be the regeneration of Rh I species and hence II, from deactivated forms of II. Eventual slow, irreversible deactivation of the catalyst and the probable participation of the H₂0₂ product in peroxide initiated free-radical autoxidations complicate the interpretation of later stages of reaction. Diphenylsulfide (DPS) is catalytically oxidized to the sulfoxide by complex I under H₂/O₂ in DMA at 50°C, but accompanying oxidation of the solvent persists even in the presence of a 100-fold excess of DPS over Rh. Oxidation of the sulfide is thought to involve H₂0₂ liberated in the catalytic hydrogenolysis of 0₂. Complex I in CH₂C1₂ or C₂H₄CL₂ reacts with CO to give the dimethylsulfide complex RhCL₃(DMS)₃ via a facile reduction of DMSO ligands. Dimethylsulfoxide is reduced also by RhI species in CH₂CL₂ in the presence of two equivalents of acid to yield DMS, RhIII and H₂0. However, Rh I /2H⁺/DMS0 systems are relatively stable in DMA, because of the proton affinity of the solvent. Complex I reacts also with the strongly basic tertiary amine NEt₃ via a redox process in which the RhIII is reduced to Rh I with an accompanying dehydrogenation of the amine (eq. 4). RhCl₃ + 3NEt₃ → RhCl + 2NEt₃ HCl + CH₂=CHNEt₂ (4) The resulting ethenamine then reacts with I to give the ƞ¹-ylidic complex, RhCl₃(DMS̠O)₂(⁻CH₂CH=⁺NEt₂). Data from an earlier thesis, on a reaction between complex I and 1,8-bis(dimethylamino)naphthalene (or Proton Sponge), are reinterpreted in terms of a similar redox reaction that gives an N-carbene fragment (eq. 5),which is stabilized within the RhIII complex, RhCl₃(DMS̠O)₂(=CH-N(Me)-C₁₀H₆NMe₂•HCl). [formula omitted] / Science, Faculty of / Chemistry, Department of / Graduate

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Thesis (M.S.)--Oregon State University, 1987. / Typescript (photocopy). Includes bibliographical references (leaves 135-139). Also available on the World Wide Web.

The study of the reaction of cadmium and sulfur in dimethylsulfoxide (DMSO) is presented. Specifically, the reaction of dissolved molecular sulfur in DMSO at temperatures greater than 90°C with freshly precipitated metallic cadmium is followed by UV-visible spectrometry, atomic absorption spectrometry, and Raman spectrometry. Evidence for the formation of a new cadmium-sulfur species and S3- is discussed. In a second reaction, an equilibrium sodium polysulfide solution in DMSO is titrated with a solution of cadmium ion at room temperature and the reaction progress is followed by means of UV-visible spectrometry. A calculation of the average number of polysulfide charges reacting with each cadmium ion, n̄Q, was made using literature values of the molar absorptivities of the ions S3-, S8- 2, and S6- 2 and Beer's law. Likewise, the average number of sulfur atoms, n̄M, reacting with each cadmium ion was determined. A value of 4.8 polysulfide charges per cadmium ion was determined for n̄Q and a value of 18 sulfur atoms per cadmium ion was determined for n̄M. The significance of the possible formation of cadmium polysulfide complexes is discussed briefly in conjunction with the reaction mechanisms involved in the electrodeposition of CdS from a DMSO solution of CdCl2 and S8.

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The influence of solvent and steric hindrance on the conversion of thiolsulfinates to trisulfides with hexamethyldisilathiane was investigated and a new polar mechanism, based on acceleration of the reaction by polar solvents and by fluoride ions, was proposed. The mono and dialkylation of 2,2-disubstituted 1,3-dithiane-1-oxides was investigated. Whereas those derived from menthone form only one diastereomer which cannot be alkylated further, those derived from acetone form two diastereomers. Only one of them can be alkylated further. Dehydration of the diastereomeric tertiary alcohols derived from directed aldol-reaction of γ-butyrolactones and methyl ketones yields diastereomeric conjugated enes in high yield and d.e. Michael-addition of benzyl thiols to these gives good yields and d.e. of the Michael-adducts. Deprotection of PMB-protected thiols with concomitant formation of disulfides was achieved by bromine in methanol or CH2Cl2. A seven-membered cyclic disulfide which contains the carbon backbone of the Perophora viridis trisulfide, albeit with two stereocentres in the incorrect configuration, was prepared.