Electrochemical Conversion of Methyl Ketones to Esters

Abstract

The need for sustainable and efficient organic synthesis has inspired chemists to embrace classic technologies like electrochemistry and photochemistry. In addition to being an environmentally benign method to synthesize complex molecules, electrochemistry offers several other advantages due to relatively mild reaction conditions, high chemo and regioselectivity and the ease with which the reactions can be scaled up. Due to the aforementioned reasons, the surge in the field of electroorganic synthesis has been tremendous in the recent years. The industrial methods to synthesize esters majorly rely on first synthesizing acids using the haloform reaction and subsequently converting them into the corresponding esters using esterification reactions (for e.g., Fischer esterification method). The huge amounts of hazardous halogen used in these reactions poses a threat to the environment. Furthermore, the yields of the products are poor. Hence, the current methods of generating esters suffer from major limitations and deviate from the principles of atom and redox economy. Therefore, there is a need to explore alternatives to directly synthesize esters from the corresponding ketones. In this regard, electroorganic synthesis is a promising tool for efficient chemical transformations. The present thesis is directed towards the optimization of electrochemical parameters to synthesize methyl esters in good yields. Detailed study of five major parameters – solvent, supporting electrolyte, current density, charge, material of electrodes and substrate: electrolyte ratio, was carried out using galvanostatic techniques for substituted acetophenones. A robust electrochemical setup was employed and the reaction was scaled up to 6 g on multiple substrates.