Inaug.-Diss.--Zürich. / Curriculum vitae. "Bibliographie": p. 51-53.

Thesis (Ph. D.)--Ohio State University, 1936. / Vita. Includes bibliographical references (leaves [81]-86). Available online via OhioLINK's ETD Center

Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

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

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 115-120).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. II. The metathesis and polymerization of terminal olefins catalyzed by molybdenum nitrosyl chloride - aluminum alkyl complexes. III. The stereoselective metathesis of cis-2-pentene to cis-2-butene catalyzed by molybdenum complexes of phosphines of different symmetry and aluminum alkyl cocatalysts. eContent provider-neutral record in process. Description based on print version record. Includes bibliographies.

An investigation was undertaken to examine some of the factors which may affect the thermodynamic position of equilibrium for a number of cis-trans olefin pairs. The positions of equilibrium were measured for selected aldehydes, ketones, nitriles and propenyl ethers. For these unsaturated compounds it has been found that their position of equilibrium may be attributed to four different factors. These factors are: i) a steric factor involving van der Waals repulsion between cis groups; ii) a polar repulsive term involving electrostatic repulsion between polar groups; iii) an effect termed differential resonance stabilization, which results from a conjugative stabilization by resonance which is greater in the trans isomer than in the cis isomer, where steric distortion from coplanarity of the carbonyl group and the double bond is present; and iv) an attractive interaction arising between cis substituents. The previously unreported Z isomers of crotonaldehyde and tiglaldehyde have been prepared as a mixture with the E isomers by photoisomerization of the E isomers. The presence of the Z isomers was readily detected by n.m.r. spectroscopy. Several β-halo α, β-unsaturated aldehydes have been prepared. The differential resonance stabilization, which resulted in >98% of the E isomer in the crotonaldehyde and tiglaldehyde equilibrium, was found to be partially compensated by an additional halogen-formyl polar repulsive term. The replacement of the β-methyl group in β-chlorocrotonaldehyde by a tert-butyl group increased the differential resonance stabilization effect such that the presence of the E isomer in the equilibrium was not detected. The effect of this tert-butyl group is partially compensated by the replacement of the β-halogen by methoxyl. The equilibrium positions for the series of aldehydes were compared to those of the corresponding ketones and esters. The preferential stabilization of a more polar isomer of a given isomer pair by a polar solvent has been investigated for several nitriles and haloölefins. The magnitude of the solvent stabilization effect in the above compounds was found to depend on the difference in polarity of the two solvents and the difference in polarity of the isomeric pair. With the above information, it was possible to extend the work of Gardner and McGreer on the additivity of free energy terms (multiplication of equilibrium ratios) to predict olefinic equilibria. In most cases correlation of the equilibrium ratio to a non-polar solvent, gave reasonable agreement between the predicted and experimental positions of equilibrium. / Science, Faculty of / Chemistry, Department of / Graduate

Thesis (Ph. D.)--University of Washington, 1993. / On t.p. ",̳" is superscript. Vita. Includes bibliographical references (leaves [179]-184).

Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: This study comprises the synthesis and characterization of propene/lower a-olefin copolymers and a-olefm homopolymers using metallocene catalyst systems. Incorporation of a-olefin comonomer into the polypropene backbone led to a change in properties such as microstructure and melting and crystallization temperatures. Synthesis of propene/a-olefin (J-butene, l-pentene, l-hexene and 4-menthyl-l-pentene) copolymers was carried out using the Me2Si(2-Methylbenz[e]indenyl)2ZrChIMAO catalyst combination. Copolymers were characterized by NMR, GPC, DSC and CRYSTAF. Comonomer incorporation was generally kept below 6 % to ensure crystallizable copolymers. Comonomer content influences tacticity. It was especially pronounced for propenell-butene copolymers and attributed to the formation of clusters. Melting and crystallization temperatures, (Tm (DSC), Tc (DSC) and Tc (CRYSTAF)), of propene/lower a-olefin copolymers decreased linearly with an increase in comonomer incorporation and strongly depend on comonomer type displaying a different behaviour compared to that of propene/ higher a-olefins (l-octene, I-decene, l-tetradecene, and 1- octadecene) copolymers. The melting and crystallization temperatures of propene/4- methyl-l-pentene copolymers occur between those ofpropene/l-pentene and propenellhexene. Poly-n-olefins (l-pentene, l-hexene, l-octene and l-decene) were prepared using a series of (R-115_C9H6)2ZrChIMAO[R = benzyl, phenyl and Si(CH3)3] and Me2C(115-C5H4-115- C9H6)ZrCh/MAO catalysts under different conditions. The resulting oligomers and polymers were characterized by GPC and NMR. Better conversions were obtained using catalysts with less bulky substituents and high MAO/catalyst ratios. Products ranged from dimeric oligomers to poly-u-olefins with molar masses between ca. 300 g.mol" and 6000 g.mol". Polydispersities, MwlMn, of poly-n-olefins synthesized at room temperatures were approximately 2, however, higher polydispersities were obtained at higher temperatures. Various end groups such as vinylidene, 1,2 disubstituted and 1,1,2 trisubstituted double bonds were observed and attributed to different propagation and termination reactions. The most important vinylidene end group corresponds to a specific 1,2 monomer insertion and termination by p-elimination. / AFRIKAANSE OPSOMMING: Hierdie studie behels die sintese en karakterisering van propeen/laer-a-olefien kopolimere en a-olefien homo-polimere wat berei is deur van metalloseen-katalisatore gebruik te maak. Die insluiting van 'n a-olefien ko-monomeer in die ruggraat van propileen het 'n verandering in eienskappe soos mikrostruktuur, smelting en die temperatuur van kristallisasie tot gevolg gehad. Die sintese van propeen/a-olefien (l-buteen, I-penteen, I-hekseen en 4-metiel-lpenteen) ko-polimere is uitgevoer met die katalisatorkombinasie Me2Si(2-Metielbenz[e] indeniel)2ZrClzIMAO. Daar is gepoog om die inkorporasie van die ko-monomeer tot <6% te beperk, om sodoende kristalliseerbare ko-polimere te verseker. Die komonomeerinhoud beïnvloed taktisiteit. Dit was veralopvallend in die propeen/l-buteen ko-polimere, en is toegeskryf aan die vorming van trosse (klusters) Die ko-polimere is gekarakteriseer deur van KMR, GPK, DSK en KRISTAF gebruik te maak. Die smelt-en kristallisasie-temperature (Tm (DSC), Tc (DSC) en Tc (CRYSTAF») van die propeen/Iaer-n-olefien ko-polimere het lineêr afgeneem met 'n toename in ko-monomeer inkorporasie en het sterk afgehang van van die tipe ko-monomeer. Die gedrag van laasgenoemde ko-polimere het verskil van dié van die propeenlhoër-a-olefien kopolimere (l-okteen, I-dekeen, I-tetradekeen, en l-oktadekeen). Die smelt- en kristallisasie-temperature van die propeen/4-metiel-l-penteen ko-polimere lê tussen dié van propeen/l-penteen en propeen/l-hekseen. Die poli-a-olefiene (l-penteen, I-hekseen,l-okteen en I-dekeen) is onder verskillende reaksiekondisies berei deur van die katalisatore (R-115-C9H6)zZrChIMAO [R=bensiel, feniel en Si(CH3)3] en Me2C(115-C514-115-C9H6)zrChIMAO.gebruik te maak. Die nuwe oligomere en polimere is met behulp van GPK en KMR gekarakteriseer. Katalisatore met kleiner substituente en hoër MAO/katalisator-verhoudings lewer beter omskakelings. Produkte het gevarieer vanaf dimeriese oligomere tot poli-a-olefiene met molêre massas tussen 300 en 6000 g.mol'. Die polidispersie van die poli-a-olefiene by kamertemperatuur gesintetiseer was ongeveer 2; hoër polidispersies is egter by hoër temperature verkry. Vinilideen, 1.2-disgesubstitueerde- en 1,1,2-trigesubsidueerde dubbelbindings is as eindgroepe waargeneem. Dit is toegeskryf aan verskillende voortplantings- en termineringsreaksies. Die belangrikste vinilideen-eindgroep stem ooreen met 'n spesifieke 1,2 monomeerinvoeging en terminering deur p-eliminasie.

No description available.