Advances of the past 12 years in decarboxylation of biomass carboxylic acids to biofuels and high-value chemicals via photo- or electrocatalysis

Abstract

The utilization of renewable platform molecules as feedstocks for manufacturing high-value-added fine chemicals and liquid fuels has become crucial for green and sustainable chemistry and represents a rewarding challenge for today's society. Photochemistry and electrochemistry are effective and powerful tools for the transformation of biomass molecules through free radical intermediates under mild reaction conditions. Numerous direct decarboxylative reactions, without the need for prefunctionalization of carboxylic acids, by photocatalysis or electrocatalysis have been developed during the last few years, with more efficient, step-economical, and low energy consumption processes. In this review, we summarize recent advances in photochemical and electrochemical decarboxylative reactions for the synthesis of alkane fuels and high-value chemicals by utilizing biomass-derived free carboxylic acids as a sustainable source. These transformations can be categorized into four main types as follows: (1) decarboxylative reduction, (2) decarboxylative elimination, (3) decarboxylative coupling, and (4) decarboxylative oxidation. The scope and limitations of these conversions and mechanisms are discussed in detail. Finally, the challenges and perspectives for light or electrically driven decarboxylative transformation of renewable carboxylic acid feedstocks are proposed.