Facile and rapid decarboxylation of glutamic acid to γ-aminobutyric acid via microwave-assisted reaction: Towards valorisation of waste gluten

The growing trend towards the utilisation of biomass to produce fuels and chemicals has the potential to produce large quantities of protein-rich wastes that may be unsuitable for use as a feed. This protein waste could instead serve as a sustainable feedstock for the production of useful nitrogen-containing bio-based chemicals. We report herein the production of γ-aminobutyric acid from glutamic acid via a microwave-assisted decarboxylation reaction using isophorone as an inducer reagent. High yields of 63% can be achieved with only short reaction times (7 min) required. The influences of inducer loading, reaction time and hydrochloric acid concentration used for hydrolysis step of the work up were investigated at different scales. As a proof of concept, glutamic acid was facilely isolated from waste gluten, via microwave assisted hydrolysis, and subsequently decarboxylated with success. To the best of our knowledge this is the first organocatalytic route to γ-aminobutyric acid using glutamic acid as a reagent, and represents an alternative cleaner route to a valuable precursor for bio-based solvents, polymers and pharmaceuticals.