An investigation of the acid catalysed conversion of carbohydrates to platform chemicals

Methods to obtain useful chemicals derived from sources other than fossil fuels is particularly challenging. The chemical conversion of biomass, a carbohydrate rich feedstock, into useful liquid products has thus become an intensely researched field. In this study, catalysis mediated by various acid catalysts such as Lewis acids, mineral acids and heterogeneous acid resins were investigated for the conversion of fructose, glucose, sucrose, cellulose as well as microalgae into useful chemical products. High yields of products were obtained in the short-chained alcohol solvents, polar aprotic solvents as well as a biphasic system under various reaction conditions. The one-pot synthesis of n-alkyl levulinates and 5-alkoxymethylfurfural in high yields was obtained in short-chained primary alcohol solvents. The solid resin Amberlyst-15 at moderate temperatures and under atmospheric pressure catalysed these reactions. High yields (~80 mol% ) of combined products were obtained from fructose and sucrose with product selectivity dependent on acid concentration and time. Importantly, good yields of 50 mol% of combined products were obtained from glucose under these reaction conditions. Furthermore, microwave irradiation reduced the time required to obtain such products. The production of levoglucosenone (LGN) from the acid catalysed thermolysis of cellulose was investigated in various polar aprotic solvents. Of the solvents investigated, the acid catalysed conversion using mineral acids was the most successful in sulfolane. Levoglucosenone, a valuable chemical intermediate, which can undergo further reactions, was found to convert into 5-chloromethylfurfural with high isolated yields of 72 mol%. Likewise, under the same reaction conditions high combined yields of n-alkyl levulinates and 5-alkoxymethylfurfural from fructose, glucose and sucrose, of >80 mol% were obtained from LGN. In the final component of this study, whole microalga Nannochloropsis sp., was subjected to a one-pot biphasic system for the carbohydrate component conversion to 5 chloromethylfurfural (CMF) alongside lipid extraction. Good isolated yields of CMF (44 mol%) were obtained after 3 hours. Model compounds from both macroalgae and microalgae were also investigated in this study, however these were found to give significantly lower yields of CMF