The Effect of Solvent Polarity on Autocatalytic Furfural Production Confirmed by Multivariate Statistical Analysis

Autocatalytic dehydration of xylose to furfural was studied in pure aqueous and monophasic organic/water mixtures to determine the effect reaction media and conditions have on conversion and yield. This study identified that the severity (Ro) of the reaction and polarity, as determined by the Hansen Solubility Parameter, δP, strongly correlate with xylose conversion and furfural yield. Increasing the Ro and δP increased both conversion and yield in pure aqueous and organic/water mixtures of sulfolane, γ‐butyrolactone, γ‐valerolactone, γ‐hexalactone, and tetrahydrofuran. Additionally, it was found that at a specified Ro and δP, similar conversions and yields were achieved using different combinations of time, temperature, and solvent mixture. Using principal component analysis and projection to latent structures, a semi‐empirical model was developed that provided estimates of xylose conversion and furfural yield over a range of experimental Ro and δP values. Solvent effect: Monophasic solvent systems with higher polarity significantly improved furfural yields in the autocatalytic dehydration of xylose. A semi‐empirical model was developed that confirms increased reaction severity and solvent polarity lead to higher furan yields. This increase is likely attributed to the stabilization of the carbocation that forms during the reaction.