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.

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.

Orientadores: Daniela Zanchet, Regina Buffon / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-25T08:37:31Z (GMT). No. of bitstreams: 1 Aragao_IsaiasBarbosa_M.pdf: 4247291 bytes, checksum: 09937fc60abf375cebc0a59dc22ae39a (MD5) Previous issue date: 2014 / Resumo: Nanopartículas (NPs) e os ligantes em sua superfície vêm ganhando espaço como meio suporte devido a suas propriedades que aliam o comportamento da catálise homogênea com a heterogênea. Em longo prazo, imagina-se que o controle do ambiente local de espécies ancoradas na superfície destas NPs possa mimetizar o sítio catalítico de enzimas. Visando explorar a influência do ambiente local, foi avaliado o desempenho do catalisador de Grubbs de primeira geração em duas condições: encapsulado em matriz de sílica e na presença de NPs de ouro (NPs-Au). Apesar das reações de encapsulamento pelo método sol-gel serem rotas bastante exploradas, os resultados não foram encorajadores devido à desativação do complexo de rutênio nas condições de formação do gel, tanto pela via hidrolítica quanto não-hidrolítica. Com relação às NPs-Au, elas foram sintetizadas com misturas de ligantes (1-octanotiol e ácido 3-mercaptopropiônico), mostrando separação de fases dos ligantes, com a formação de domínios (raias). Nos estudos com catalisador de Grubbs em reações de metátese (autometátese do 1-hexeno e polimerização por abertura de anel do 1,5-ciclooctadieno), tanto a presença das NPs-Au como a de tiol livre tiveram influência negativa, levando a sua desativação prematura. Na presença de NPs-Au, houve queda da atividade, chegando a conversões nulas para razões mássicas maiores de que 1 mg de ouro/10 mg de catalisador, estando possivelmente associado à complexação das mercaptanas das NPs-Au com o complexo de rutênio. Buscando viabilizar o ancoramento do catalisador nas NPs-Au, sintetizou-se um ligante carbeno NHC com a funcionalização do esqueleto carbônico posterior do anel com um grupamento alil, que representa a primeira etapa para introdução de grupos funcionais e ancoramento em NPs / Abstract: The use of nanoparticles (NPs) and their protecting layer as support in catalysis start to be exploited, due to their unique characteristics at the interface of homogeneous and heterogeneous catalysts. At long term, the tuning of the local environment of catalytic species anchored on the surface of NPs may be a way to mimic the active site of enzymes. Aiming to explore the influence of the local environment, we evaluated the activity of the first generation Grubbs catalyst under two conditions: encapsulating it in a silica matrix and in the presence of gold NPs (NPs-Au). Although the heterogenization via the sol-gel method is a well-known and well-explored route, we could not obtain good results due to catalyst deactivation under gel formation in both hydrolytic and non-hydrolytic (nonaqueous) conditions. Considering the NPs-Au, they were synthesized with success using a mixture of ligands (1-octanethiol and 3-mercaptopropionic acid) that showed phase segregation and formation of stripes. The evaluation of the Grubbs catalyst on metathesis reactions (self-metathesis of 1-hexene and ring opening polymerization of 1,5-ciclooctadiene) showed premature deactivation in the presence of both NPs-Au and free thiol. In the presence of NPs-Au, the catalytic activity descreased, achieving null results when weight ratios bigger than 1mg of NPs-Au to 10 mg of catalyst were used, possibly associated to the interaction between the mercaptans and the ruthenium catalyst. To make possible the catalyst anchoring on the NPs-Au surface, a NHC carbene with an allyl group on its carbon backbone was synthesized, corresponding to the first step to introduce functional groups to the catalyst / Mestrado / Quimica Inorganica / Mestre em Química

In this study, we were particularly interested in looking at the possibility that cross metathesis of olefins in melt phase could be used to produce polydimethylsiloxane (PDMS) modified polypropylene (PP). The intention of this project was also to study and quantify relationships among the main experimental factors in the reaction: temperature, catalyst concentration and molar ratio of PP to PDMS, through a 2-level factorial statistical design. In order to examine if PP-PDMS copolymers were synthesized in the melt phase, measurement of the chemical, physical and viscoelastic properties of the synthesized copolymers was necessary. Techniques including proton (¹H)-nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), rheometry and scanning electron microscopy (SEM), were all used to characterize the synthesized copolymers. ¹H NMR measurements confirmed the presence of PDMS in the copolymers. They also provided a quantitative measurement of PP to PDMS molar ratio in copolymers by determining the integration of PP PDMS repeating unit signals in NMR spectra. Compared to virgin PP, a lower melting enthalpy of the PP phase in the copolymer was observed from DSC results. This implied that the PDMS component influenced the thermal behavior of the PP crystalline phase in the copolymers. Moreover, TGA measurements indicated that a higher thermal stability was obtained for PP-PDMS copolymers than that for virgin PP wax and this was expected since PDMS is known for its excellent stability at high temperature. Rheological analysis showed that the presence of PDMS in the copolymers gave lower complex viscosities and loss moduli, but higher storage moduli than those for virgin PP. Furthermore, the morphology of copolymers was examined by SEM and elemental analysis at the surface using an energy dispersive X-ray (EDX) analyzer on the SEM. It was found that micrographs of copolymers showed round domains on the surface, which were not observed in virgin PP wax and those round segments were confirmed to contain silicon. Torque values used in a batch mixer for polymerizations and the remaining weight % of copolymers at 350°C were used to conduct statistical analysis, through which models used to describe the relationships between experimental factors and these physical responses were determined.

In this study, we were particularly interested in looking at the possibility that cross metathesis of olefins in melt phase could be used to produce polydimethylsiloxane (PDMS) modified polypropylene (PP). The intention of this project was also to study and quantify relationships among the main experimental factors in the reaction: temperature, catalyst concentration and molar ratio of PP to PDMS, through a 2-level factorial statistical design. In order to examine if PP-PDMS copolymers were synthesized in the melt phase, measurement of the chemical, physical and viscoelastic properties of the synthesized copolymers was necessary. Techniques including proton (¹H)-nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), rheometry and scanning electron microscopy (SEM), were all used to characterize the synthesized copolymers. ¹H NMR measurements confirmed the presence of PDMS in the copolymers. They also provided a quantitative measurement of PP to PDMS molar ratio in copolymers by determining the integration of PP PDMS repeating unit signals in NMR spectra. Compared to virgin PP, a lower melting enthalpy of the PP phase in the copolymer was observed from DSC results. This implied that the PDMS component influenced the thermal behavior of the PP crystalline phase in the copolymers. Moreover, TGA measurements indicated that a higher thermal stability was obtained for PP-PDMS copolymers than that for virgin PP wax and this was expected since PDMS is known for its excellent stability at high temperature. Rheological analysis showed that the presence of PDMS in the copolymers gave lower complex viscosities and loss moduli, but higher storage moduli than those for virgin PP. Furthermore, the morphology of copolymers was examined by SEM and elemental analysis at the surface using an energy dispersive X-ray (EDX) analyzer on the SEM. It was found that micrographs of copolymers showed round domains on the surface, which were not observed in virgin PP wax and those round segments were confirmed to contain silicon. Torque values used in a batch mixer for polymerizations and the remaining weight % of copolymers at 350°C were used to conduct statistical analysis, through which models used to describe the relationships between experimental factors and these physical responses were determined.