Banca de DEFESA: ALEXANDRE DAMIANI
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : ALEXANDRE DAMIANI
DATA : 02/09/2022
HORA: 13:30
LOCAL: Por participação remota - https://conferenciaweb.rnp.br/webconf/dalmo-2
TÍTULO:
Pseudoionone metathesis as a tool for mechanistic studies
PÁGINAS: 140
RESUMO:
Large-scale chemical production from renewable resources is expected to reach 113 million tons by 2050, corresponding to 38% of all organic chemical production. The metathesis reaction of such compounds has been used as an important tool in organic synthesis, whose obtention through other synthetic routes is complex. Ionones are natural products which have been identified in several plants but can also be easily produced from citral, a natural product largely found in plants as lemongrass. We studied the unprecedent metathesis of pseudoionone (6,10-dimethyl-3,5,9-trien-undeca-2-one) using homogeneous ruthenium as catalysts. The reactions were made under N2 atmosphere at different temperatures using decane or dimethylcarbonate, a green solvent. The products were characterized by mass-spectrometry and quantified by gas-chromatography. Commercial pseudoionone used in these experiments contained a mixture of the isomers 1a (3E, 5Z) and 1b (3E, 5E) in molar ratio 1a:1b = 29:71 and its metathesis was initially studied in decane, with two Ru based catalysts, Grubbs 2nd generation and Grubbs-Hoveyda 2nd generation. Since each carbon-carbon unsaturation can react in metathesis and pseudoionone has three of such double bonds, the number of different possible combinations among these unsaturations is elevated. Moreover, the resulting compound produced in the metathesis may react again, undergoing secondary metathesis, further complicating the study. This complexity enabled us to observe different reactivities among the olefinic double bonds in the pseudoionone molecule, from which we proposed mechanisms for the reactions, according to the Grubbs´ model for double bonds reactivity. We concluded that the reaction initiates by the coordination of the a-β-unsaturated bond conjugated to the carbonyl. The metal-carbene obtained reveals being strongly reactive to pseudoionone highly steric hindered prenyl group, another unusual reaction. Computational studies are needed to substantiate some of the proposals of this work..
MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1762430 - DALMO MANDELLI
Membro Titular - Examinador(a) Interno ao Programa - 1939561 - FERNANDO HEERING BARTOLONI
Membro Titular - Examinador(a) Externo ao Programa - 1805246 - PAULO DE AVILA JUNIOR
Membro Titular - Examinador(a) Externo à Instituição - ANA LUISA LAGE
Membro Titular - Examinador(a) Externo à Instituição - JESUS ALBERTO AVENDANO VILLARREAL - UFMG
Membro Suplente - Examinador(a) Interno ao Programa - 1766090 - MIRELA INES DE SAIRRE
Membro Suplente - Examinador(a) Externo ao Programa - 1802150 - MARCO ANTONIO BUENO FILHO
Membro Suplente - Examinador(a) Externo à Instituição - ANTÔNIO CARLOS FERREIRA BATISTA