Applying the principles of green chemistry to selected traditional organic chemistry reactions

Abstract

The primary objective of this project was to apply the principles of green chemistry to selected traditional synthetic organic chemistry reactions. The reactions studied in the lab were: amide formation, oxidation of alcohols with KMnO4 and LiCl/H2O2, oxidation of alkylarenes with KMnO4, reduction of β-ketoesters with yeast, and formation of esters by phase transfer catalysis. Microwave irradiation, biocatalysis, phase transfer catalysis, solvent-free conditions, and/or alternate solvents were used to accomplish these syntheses. Results were analyzed by the traditionally used percent yield calculations and selected green chemistry metrics. The main limitation of the results was that most products were not completely purified due to time constraints. For amidification it was found that results obtained using a commercial oven were better than results obtained using a domestic oven. Oxidation with KMnO4 gave higher yields at one week reaction time under solvent-free conditions than under reflux in dichloromethane for 1.5 h. The catalytic oxidation procedure using LiCl/H2O2 was found to be more wasteful than the stoichiometric procedure using KMnO4. Both methods showed preference for oxidation at benzylic as opposed to aliphatic positions. For the oxidation of alkylarenes it was found that dimethylcarbonate is not a suitable replacement for dichloromethane as an extraction solvent in this procedure. Also, higher yields were obtained at one week reaction time under solvent-free conditions than under reflux in dichloromethane for 1.5 h. product analysis for reduction of β-keotesters with yeast tend to suggest that steric factors may play a large role in the reaction with more sterically hindered substrates giving lower yields. Further work in this area is required to elucidate this hypothesis. Only a few esterification reactions were carried out but two of three results gave decent E-factors. Finally, it was shown that the majority of waste from each reaction was from the use of solvent. Therefore, recycling the solvent can have the biggest impact on reducing waste