COMPUTATIONAL STUDY OF PHOSPHINE-CATALYZED DIENE CARBOXYLATES SYNTHESIS OF REACTION MECHANISM FROM ?-VINIL ALLENOATE WITH DFT METHOD

• Main Author: Abdullah Hanif, Muhammad
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/59599
• Institution: Institut Teknologi Bandung

Diene carboxylates is family of carboxylates compound with double bond in ?-carbon and ?-carbon. Skeleton from diene carboxylates exist in various natural products and bioactive compounds that used as drug. Then, diene karboksilat can be used in various organic transformation. Currently, diene carboxylates can be synthesized with Wittig reaction, allene isomerization, and transition metal-catalyzed coupling reaction. Unfortunately, those methods still have some limitation such as, large quantity of byproducts, numerous steps, heavy-metal waste, and contaminated transition metal. Despite of that, a new method make it possible to synthesized diene carboxylates from ?-vinil allenoates that catalyzed by phospine. That method have far less byproduct, simpler reaction step, and free from dangerous heavy-metal. In this research, computational studies of phospine-catalyzed diene carboxylates synthesis from ?-vinil allenoat was conducted. Method used in this research are B3LYP/6-31G for geometry optimization, ?B97M-D3BJ/6-31G(d,p) for single point energy computation, and B3LYP/6-31G(d) with scale factorisation for free energy Gibbs correction. Study of reaction mechanism diene carboxylates syntesis from ?-vinil allenoates have been performed done. From 6 stable species that were predicted, only 5 species are stable when geometrically optimized, with 1 predicted species get splitted apart when geometrically optimized. It is then concluded that the reaction only have 4 reaction-step and doesn’t have 5 reaction-step as it was predicted. Vinil group influence on position reactivity in the reaction are succesfully discovered. Based on Loewdin atomic charge data, vinil group and catalyst steric effect will push reactive position from ?-carbon to ?-carbon. It also appears that Loewdin atomic charge data can explain reactvity in the referred experiments better than Mulliken atomic charge data. The thermochemistry aspects of the reaction are successfully determined. Every variation of reactions are exothermic reaction, with reaction in dichlorometane being more exothermic than reaction in chloroform. The kinetic aspects of the reaction have been successfully determined. Reaction with thiourea- derived bifunctional phospine catalyst has lower activation energy compared to reaction with triphenylphospine.