DinÃmica direta e mecanismos das reaÃÃes de diels-alder e de desidrataÃÃo de Ãlcool

AUTOR(ES)

Marcus Vinicius Pereira dos Santos

DATA DE PUBLICAÇÃO

2008

RESUMO

The dynamics of dehydration of the protonated (R)-3,3-dimethylbutan-2-ol (pinacolylalcohol) isomer, [(CH3)3-C-CH(OH2)CH3]+, and of ethene + 1,3-butadiene cycloaddition were studied with the Born-Oppenheimer molecular dynamics (BOMD) technique for the direct dynamics using the AM1 method. The AM1 potential energy surface (PES) for the protonated pinacolyl alcohol presents two transition states related to the [(CH3)3C-CHCH3]+âââOH2 intermediate complex and to the CH3 migration leading to [(CH3)2C-CH(CH3)2]+âââOH2 product complex. The direct dynamics yielded negligible trajectories involving these complexes, since the momentum acquired by the H2O fragment led to a complete dissociation. Despite the concerted path (H2O dissociation and CH3 migration simultaneously) not being a minimum energy path in the AM1-PES a statistical significant number of trajectories involved this path. As for the Diels-Alder reaction, even when started from a symmetric transition state using the spin restricted AM1 wavefunction the dynamics yielded a large percentage of asymmetric paths toward cyclohexene. In both reactions, the dynamics revealed significant non-IRC (intrinsic reaction coordinate) reaction paths

ASSUNTO(S)

protonated pinacolyl bomd quimica non-irc bomd ethene + 1,3-butadiene protonated pinacolyl cycloaddition ethene + 1,3-butadiene non-irc cycloaddition

Documentos Relacionados

• The Diels-Alder reaction: an update
• Estudo sobre a síntese de furanoliangolidos pela Reação de Diels-Alder
• About the synthesis of furanoheliangolides through the Diels-Alder reaction
• Enantioselective Diels–Alder reactions catalyzed by hydrogen bonding
• A regioquímica das reações de Diels-Alder de N-tosil para-benzoquinona iminas