Acylation of 2-methylfuran with fatty acid derivatives using heterogeneous catalysts

Abstract

Lignocellulosic biomass is a renewable source of furans that can be upgraded to commodity chemicals and fuels. Oleo-furansulfonate surfactants (OFS) are a new class of surfactants synthesized from furan and fatty carboxylic acid derivates (C8-C18) obtained from biomass and natural oils respectively. These biorenewable surfactants show potential for use in laundry detergents as they exhibit enhanced detergency properties and 100x stability in hard water compared to commercial linear alkylbenzene sulfonate surfactants. Friedel-Crafts acylation of furan for the formation of alkyl furan ketones is the key reaction involved in the tunable and selective synthesis of OFS surfactants. The alkyl furan ketone is formed using heterogeneous catalysts through direct acylation of fatty acids with furan, or indirectly with fatty acid anhydrides. There has been limited research on understanding the condensed phase reaction mechanism of furanic substrates, especially with long carbon chain acylating agents. In this thesis work, we investigate the reaction mechanism for the acylation of 2-methylfuran with a solid acid catalyst, Al-MCM-41, and n-octanoic anhydride as the acylating agent. The direct acylation pathway of furans with fatty carboxylic acids is preferred due to the formation of water as the only by-product. However, this reaction is prone to side reactions such as furan hydrolysis and acid self-ketonization. We evaluate the effect of different catalyst properties for the reaction of 2-methylfuran and acetic acid in an automated gas-chromatography reactor. The role of solvent structure is examined as another avenue for improving the direct acylation reaction rates and catalyst stability.