Síntese de acetais e de hemiacetais derivados de terpenos através da reação de hidroformilação catalisada por complexos de ródio modificados

Exportado OPUSMade available in DSpace on 2019-08-12T13:17:36Z (GMT). No. of bitstreams: 1 disserta__o_marina_caneschi_de_freitas.pdf: 5195332 bytes, checksum: be59b004b729b7897fb74965db1bc60e (MD5) Previous issue date: 8 A hidroformilação/acetalização tandem dos monoterpenos bicíclicos a-pineno, ß-pineno, 2-careno e 3-careno foi estudada empregando-se catalisadores de ródio modificados por PPh3 ou P(O-o-tBuPh)3 e etanol como solvente. A transformação tandem do ß-pineno, o qual possui dupla ligação exocíclica foi realizada com sucesso tanto nos sistemas promovidos por P(O-o-tBuPh)3 quanto nos sistemas contendo PPh3. Já os monoterpenos a-pineno, 2-careno e 3-careno, cujas duplas ligações são endocíclicas e estericamente impedidas, foram funcionalizados graças ao emprego do ligante P(O-o-tBuPh)3, que possui grande ângulo de cone e elevado parâmetro X. Os sistemas catalíticos desenvolvidos permitiram a síntese de acetais com bons rendimentos, sem a adição de co-catalisadores ácidos e empregando-se, como solvente, etanol, substância ambientalmente benigna e que pode ser obtida a partir de fontes renováveis. A hidroformilação do sesquiterpeno nerolidol catalisada por complexos de ródio modificados por ligantes de fósforo foi estudada tanto em soluções de tolueno quanto em soluções de etanol. Nos sistemas contendo tolueno como solvente, foram obtidos, como produtos majoritários, hemiacetais cíclicos, devido à ciclização intramolecular espontânea do aldeído previamente formado. Por sua vez, a hidroformilação do nerolidol em etanol permitiu a obtenção de acetais, sem a necessidade do uso de aditivos ácidos.Rhodium-catalyzed tandem hydroformylation/acetalization of -pinene, -pinene, 2-carene and 3-carene was studied in ethanol solutions in the presence of PPh3 or P(O-o-tBuPh)3 as auxiliary ligands. -Pinene, the only substrate containing exocyclic double bond, gave corresponding aldehyde and acetal in excellent combined yields in both systems. On the other hand, -pinene, 2-carene, 3-carene, which contain sterically encumbered trisubstituted endocyclic double bonds, showed good reactivity only in the Rh/P(O-o-tBuPh)3 systems. This ligand presents a large cone angle and a strong -acidity. The processes were performed in environmentally friendly ethanol as the solvent, in the absence of acid co-catalysts and the mixtures of fragrance acetals and aldehydes were obtained in nearly quantitative yields. Rhodium-catalyzed hydroformylation of sesquiterpene nerolidol was studied in toluene andethanol solutions in the presence of PPh3 or P(O-o-tBuPh)3 ligands. In toluene, the reaction gave with high selectivity a cyclic hemiacetal, which formally arises from the intramolecular cyclization of the primarily formed hydroxy aldehyde. In ethanol, the reaction gave a corresponding cyclic acetal in excellent yields even without additional acid co-catalysts

Synthesis of fragrance compounds from biorenewables : tandem hydroformylation–acetalization of bicyclic monoterpenes.

The Rhodium-catalyzed tandem hydroformylation–acetalization of the terpenes 3-carene, 2-carene, a-pinene, and b-pinene was studied in ethanol solutions in the presence of PPh3 or tris(O-tert-butylphenyl)phosphate, P(O-o-tBuPh)3, ligands. All these terpenes are constituents of turpentine oils obtained commercially from coniferous trees. b-Pinene gave the corresponding aldehyde and acetal in excellent combined yields in both systems. 3-Carene, 2-carene, and a-pinene, which contain sterically encumbered endocyclic double bonds, showed an extremely low reactivity with PPh3. The use of P(O-o-tBuPh)3 not only accelerated the hydroformylation of all four substrates remarkably but also increased the acetalization activity of the catalyst. In the Rh/P(O-o-tBuPh)3 system, various fragrance acetals and aldehydes were obtained from these renewable substrates in nearly quantitative combined yields. The process was performed under mild conditions, in environmentally friendly ethanol as a solvent, and in the absence of acid cocatalysts

Synthesis of fragrance compounds from renewable resources : the aqueous biphasic hydroformylation of acyclic terpenes.

The rhodium-catalyzed hydroformylation of acyclic terpenic compounds, i.e., ?-citronellene, linalool and nerolidol, was performed in a water/toluene biphasic system. The addition of the cationic surfactant cetyltrimethylammonium chloride remarkably increased the reaction rates, with the surfactant effect being substrate dependent. A water-soluble phosphine ligand was used to immobilize the rhodium catalyst in water, an environmentally benign solvent, whereas non-polar products were collected in the organic phase. A complete phase separation was easily achieved by switching the magnetic stirrer off and cooling the mixture to room temperature. Linalool and nerolidol gave cyclic hemiacetals with excellent stereoselectivity, whereas the hydroformylation of ?-citronellene resulted in two isomeric aldehydes with a linear-to-branched product ratio of approximately 85/15. Several fragrance compounds with pleasant sweet floral and woody scents were obtained in high yields through a simple and green one-pot procedure starting from the substrates easily available from natural bio-renewable resources

Complete genome sequence and analysis of Alcaligenes faecalis strain Mc250, a new potential plant bioinoculant.

Here we present and analyze the complete genome of Alcaligenes faecalis strain Mc250 (Mc250), a bacterium isolated from the roots of Mimosa calodendron, an endemic plant growing in ferruginous rupestrian grasslands in Minas Gerais State, Brazil. The genome has 4,159,911 bp and 3,719 predicted protein-coding genes, in a single chromosome. Comparison of the Mc250 genome with 36 other Alcaligenes faecalis genomes revealed that there is considerable gene content variation among these strains, with the core genome representing only 39% of the protein-coding gene repertoire of Mc250. Mc250 encodes a complete denitrification pathway, a network of pathways associated with phenolic compounds degradation, and genes associated with HCN and siderophores synthesis; we also found a repertoire of genes associated with metal internalization and metabolism, sulfate/sulfonate and cysteine metabolism, oxidative stress and DNA repair. These findings reveal the genomic basis for the adaptation of this bacterium to the harsh environmental conditions from where it was isolated. Gene clusters associated with ectoine, terpene, resorcinol, and emulsan biosynthesis that can confer some competitive advantage were also found. Experimental results showed that Mc250 was able to reduce (~60%) the virulence phenotype of the plant pathogen Xanthomonas citri subsp. citri when co-inoculated in Citrus sinensis, and was able to eradicate 98% of juveniles and stabilize the hatching rate of eggs to 4% in two species of agricultural nematodes. These results reveal biotechnological potential for the Mc250 strain and warrant its further investigation as a biocontrol and plant growth-promoting bacterium