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Kinetics parameters for Knoevenagel reaction: An NMR invetigation

Grant number: 17/08962-7
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): July 01, 2017
Effective date (End): January 31, 2019
Field of knowledge:Physical Sciences and Mathematics - Chemistry - Organic Chemistry
Principal Investigator:Claudio Francisco Tormena
Grantee:Luana Andrade Dutra
Home Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
Associated research grant:15/08541-6 - Nuclear magnetic resonance spectroscopy: beyond molecular structure assignment, AP.TEM

Abstract

Knoevenagel reaction is a condensation between aldehydes or ketones with activated methylene compounds in the presence of catalyst (usually an amine). The reaction product is an olefin that can be tri- or tetrasubstituted depending on the nature of carbonyl compound. The configuration for the C=C double bond can be E or Z and usually a preference between diastereoisomers is observed, favouring the less hindered isomer. However, the origin of this preference remaining unclear. In the current literature is proposed an explanation for this configurational preference based on the stability of transition state adopted by the iminium intermediate (generated by condensation of carbonyl compound with amine). However, the same preference is observed when non-nucleophilic amines or non-nitrogenated catalysts are used, in this case iminium intermediate cannot be formed. Based on that, the aim of this proposal is to evaluate the influence of different catalyst (amines) in the kinetics parameters for each reactional conditions and the origin of diastereoisomer preference observed for the Knoevenagel reaction. To achieve these objectives, the proposed reactions will be monitoring straightforward from their 1H NMR spectra to determine kinetics data. (AU)