Analysis of Humins Made in a Non-Aqueous Environment
MetadataShow full item record
The conversion of carbohydrates into levulinic acid via acid catalyzed hydrolysis results in the formation humins when done in an aqueous environment. It has been suggested that humins would not be formed in a non-aqueous solvent. When glucose hydrolysis was conducted using gamma-valerolactone as the solvent, humins were also produced. The humins formed in gamma-valerolactone were found to be have similar characteristics to those formed in water when comparing analytical results such as infrared spectra and differential scanning calorimetry. The production of humins in gamma-valerolactone is believed to be due to the accumulation of water produced by the reaction, and consequently the humins are thought to be the result of hydroxymethylfurfural, or HMF, hydration. In an attempt to prevent formation of humins from occurring in gamma-valerolactone, a Palladium catalyst was added to the reaction, as preliminary experiments shown that HMF along with formic acid produced 2,5-dimethylfuran, or DMF. DMF is not expected to react and produce humins. In these reactions 1,6-anhydro--d-glucopyranose (AGP) and 1,6-anhydro--dglucofuranose (AGF) were also produced, and it was found that when sorbitol was used instead of glucose, AGP and AGF were also produced, but in a very different ratio. This suggests that sorbitol is not an intermediate in the formation of AGP and AGF during palladium-catalyzed conversion of glucose.