Thesis (Ph.D. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2009.

A group of monomers based on disubstitued ethynylpyridine (3-PyCCPh-4-t-Bu, 2-PyCCR, R = 4-t-BuPh, 2-Py, n-Bu) and 4-tert-butyphenylethynyl (4-t-BuPhCCPh-p-OR, R = SiPh2-t-Bu, Si-i-Pr3) were prepared by Sonogashira cross-coupling reaction (PdCl2[(PPh3]2/CuI). All of these monomers were charakterized by IR, UV/vis and NMR spectroscopy. Ethynylpyridine based monomers were polymerised by quarternization (ethylbromid was used as a quarternization agent) and by Grubbs-Hoveyda 2nd generation catalyst. As a product of the quarternization were obtained oligomers compounded by 2 - 13 monomers units (Mw: 1600 - 6000, Y 70%). Only low molecular weight oligomers were also obtained by Grubbs-Hoveyda 2nd generation polymerization (Mw: 400 - 1500, Y 34 %). Monomers based on 4-tert-butyphenylethynyl were polymerized by TaCl5/Bu4Sn/Toluen catalytic system. In that case were obatined polymers (Mw: 64 000 - 200 000, IP = 2,3 -3,9, Y 75 %). Products of polymeryzations were charakterized by GPC, IR, UV/vis and NMR spectroscopy.

No description available.

Since the development of the ruthenium containing precatalysts Grubbs 1 (1) and Grubbs 2 (2), there was an increase in the development of new precatalysts. The NMR characterization could not cope with this. The NMR characterization mainly consists of 1H, 31P, COSY and rarely 13C. Due to the high natural abundance of 1H and 31P (99.98% and 100%), these experiments could be carried out quickly and easily. The only change that had to be made was to the spectral width, to accommodate the carbene signal (Ru=CH) between δ 20.02 and δ 17.32 ppm. The lack of 13C characterization is attributed to the low natural abundance of these nuclei that is only 1.10% and the lack of published parameters. Furthermore, the broad spectral width of 300 ppm increases the difficulty because the number of scans has to be increased to increase the sensitivity of the spectra and obtain useful data. In this study the precatalyst 1 was used to learn the NMR technique as well as to acquire the NMR parameters. 2 and two other commercial Grubbs-type precatalysts 3 and 4 underwent NMR characterization so that acquired values could be compared with the literature. Six other non-commercial Grubbs-type precatalysts 5-10 were synthesized and characterized. Due to the instability of the precatalysts and taking into account the duration of these experiments, the characterization was done over three steps. The first step was to do the following experiments: 1H, COSY, HSQC and HMBC, which took four hours. The next step was the DEPT135 experiment of three hours, and finally the 13C experiment of seven hours. The maximum amount of information could be obtained in this way. The combined NMR parameters for this study was obtained and used to characterize the Grubbs-type precatalysts 5-10 partially. Due to the large amount of overlapping peaks in the aromatic and alkane areas the resolution was not sufficient for full characterization. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

Since the development of the ruthenium containing precatalysts Grubbs 1 (1) and Grubbs 2 (2), there was an increase in the development of new precatalysts. The NMR characterization could not cope with this. The NMR characterization mainly consists of 1H, 31P, COSY and rarely 13C. Due to the high natural abundance of 1H and 31P (99.98% and 100%), these experiments could be carried out quickly and easily. The only change that had to be made was to the spectral width, to accommodate the carbene signal (Ru=CH) between δ 20.02 and δ 17.32 ppm. The lack of 13C characterization is attributed to the low natural abundance of these nuclei that is only 1.10% and the lack of published parameters. Furthermore, the broad spectral width of 300 ppm increases the difficulty because the number of scans has to be increased to increase the sensitivity of the spectra and obtain useful data. In this study the precatalyst 1 was used to learn the NMR technique as well as to acquire the NMR parameters. 2 and two other commercial Grubbs-type precatalysts 3 and 4 underwent NMR characterization so that acquired values could be compared with the literature. Six other non-commercial Grubbs-type precatalysts 5-10 were synthesized and characterized. Due to the instability of the precatalysts and taking into account the duration of these experiments, the characterization was done over three steps. The first step was to do the following experiments: 1H, COSY, HSQC and HMBC, which took four hours. The next step was the DEPT135 experiment of three hours, and finally the 13C experiment of seven hours. The maximum amount of information could be obtained in this way. The combined NMR parameters for this study was obtained and used to characterize the Grubbs-type precatalysts 5-10 partially. Due to the large amount of overlapping peaks in the aromatic and alkane areas the resolution was not sufficient for full characterization. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

This paper concerns itself with the methods of identifying outliers in an otherwise normally distributed data set. Several significant tests and criteria designed for this purpose are described here, Peirce's criterion, Chauvenet's criterion, Grubbs' test, Dixon's test and Cochran's test. Deriving of the tests and criteria is indicated and finally the results of the use of the test and criteria on simulated data with normal distribution and inserted outlier are looked into. Codes in programming language R with the implementation of these test and criteria using existing functions are included. Powered by TCPDF (www.tcpdf.org)

Student Number : 0002306V - MSc dissertation - School of Chemistry - Faculty of Science / The first part of the dissertation involves the use of ring closing metathesis (RCM) and ruthenium mediated isomerisation-RCM tandem reactions to form a wide range of nitrogencontaining benzo-fused heterocycles. Those synthesized include the 6-membered isoquinolines, the 7-membered benzazepines and the 8-membered benzazocines. In order to put these compounds into perspective, a review of selected naturally occurring nitrogencontaining benzo-fused heterocycles is included along with some of their synthetic approaches. Of major significance is our utilization of the Wits methodology allowing one to access the 6-, 7- and 8-membered ring systems from a common synthetic intermediate. The 1,2,3,6-tetrahydro-2-benzazocines were all obtained after RCM in excellent yields (82-99%). We were also able to show that some ofthe protecting groups used were easily removed and that the ring could be hydrogenated after RCM to yield the 1,2,3,4,5,6-hexahydro-2- benzazocines. The isoquinolines were synthesized in 78% and 27% yield for the Ac- and Tsprotected compounds respectively, with no product isolated for the Boc- or SO2Bn-protected compounds. These poor results, caused a change to our strategy and we then used a “combinatorial-type” approach for the synthesis of the 2,5-dihydro-1H-2-benzazepines and the 2,3-dihydro-1H-2-benzazepines with yield of 9, 47, 58 and 82% and 8, 26, 39 and 82% obtained respectively for the RCM reaction Futhermore, we attempted the synthesis of the substituted 4-phenyl isoquinolines and 5-phenyl benzazepines, but we found that the systems would not undergo RCM even at high temperatures and with large amounts of Grubbs II metathesis catalyst. A short review is given in the second part of the dissertation concerning the naturally occurring and pharmaceutically useful indenols, indenones and indanones. It further highlights how our methodology was extended to include the synthesis of 4-isopropoxy-5- methoxy-1H-inden-1-ol (X), 4-isopropoxy-5-methoxy-1H-inden-1-one (X) and 4-isopropoxy- 5-methoxy-1H-indanone (X) through the use of ruthenium-mediated isomerisation and RCM from a similar common intermediate. We have shown the synthesis of 3-substituted indenols, indenones and indanones using the same synthetic procedure, but by changing the reaction temperature during RCM. This dissertation also answers many of the questions posed during the post-doctoral work of Coyanis. Namely, we were able to support our proposed mechanism that the conversion of the unsubstituted indenol to the indenone was occurring via a dehydrogenative-oxidation, through the use of 1H NMR studies that were coupled with an ICP-MS analysis. To the best of our knowledge, this is the first reported use of the Grubbs II catalyst (or its degradation products) in a tandem RCM-oxidation procedure by our group recently.

The use of polymer supports for transition metal catalysts are very important and useful in synthetic organic chemistry as they make possible the separation and isolation of catalysts and products quite easy. These polymer-bound ligands/catalysts/reagents can, often, be recovered and recycled numerous times and typically yield products in high purity, negating the need for further purification steps (i.e. column chromatography). Because of this, interest in these systems has garnered international attention in the scientific community as being “Green”. Historically, insoluble, polymer-supports (i.e. Merrifield resin) were used to develop recoverable catalysts. This has the advantage of easy separation and isolation from products after a reaction; because of their insolubility, such supported catalysts can be easily removed by gravity filtration. However, these catalysts often have relatively poor reactivity and selectivity when compared to homogeneous catalysts. Because of this disadvantage, our lab has had interest in the development of soluble polymer-supports for transition metal catalysts. We have developed several separation methods for these soluble polymer-bound catalysts. These include thermomorphic liquid/liquid and solid/liquid as well as latent biphasic liquid/liquid separation techniques. This dissertation describes the use of both, latent biphasic liquid/liquid separation systems and thermomorphic solid/liquid separation systems. In order to perform a latent biphasic iii liquid/liquid separation, a polymer-bound catalyst must have a very high selectivity for one liquid phase over the other. Our lab has pioneered the use of polyisobutylene (PIB) oligomers as supports for transition metal catalysts. Previous work has shown that these oligomers are > 99.96 % phase selectively soluble in nonpolar solvents. This has allowed us to prepare PIB-supported salen Cr(III) complexes that can be used in a latent biphasic liquid/liquid solvent system. The synthesis of these complexes is quite straightforward and such species can be characterized using solution state 1H and 13C NMR spectroscopy. Also, these complexes can be used to catalyze the ring opening of meso epoxides with azidotrimethylsilane (TMS-N3) and can be recovered and recycled up to 6 times, with no loss in catalytic activity. To perform a thermomorphic solid/liquid separation, a polymer-bound catalyst that is completely insoluble at room temperature but soluble upon heating must be used. Our lab has pioneered the use of polyethylene oligomers (PEOlig) as supports for transition metal catalysts. Such PEOlig-supported catalysts are able perform homogeneous catalytic reactions at elevated temperatures (ca. 65 ○C), but, upon cooling, precipitate out of solution as solids while the products stay in solution. This process allows for the easy separation of a solid catalyst from the product solution. Described herein, is the development of PEOlig-supported salen-Cr(III) complexes and PEOlig-supported NHC-Ru complexes. The preparation of these complexes is also straightforward and such species can be characterized using solution state variable temperature (VT) 1H and 13C NMR spectroscopy. In the case of the PEOlig-supported salen-Cr(III) complex, it was found to be a recoverable/recyclable catalyst for the ring opening of epoxides with TMS-N3 and could be reused 6 times with no loss in activity. The PE-supported NHC-Ru complex was able to be used as a recyclable ring closing metathesis (RCM) catalyst and could be used up to 10 times.

The major subject of this thesis is the synthesis of enantiomerically enriched gamma and delta lactones via Ring Closing Metathesis (RCM). Furan and thiophene substituted aldehydes were transformed to the corresponding heteroaryl substituted allylic and homoallylic alcohols by using vinyl and allylmagnesium bromide, respectively and then resultant racemic alcohols were resolved by hydrolase type enzymes (PSC-II, Lipozyme, CAL-B) with high enantiomeric excess values. Since the absolute configuration of alcohols were known, it was possible to determine the configuration of the synthesized compounds. After the enantiomeric enrichment of the alcohols, subsequent acylation with acryloyl and methacryloyl chloride afforded feasible diene system that was subjected to ring closing metathesis reaction 1st and 2nd generation Grubbs&rsquo / catalysts were used. These lactones were used to test their biological activities.