Synthesis Of5-hydroxymethylfurfural And Its Deritives From Sugars Catalyzed By Salts And Inorganic Acids

The consumption of petroleum has surged during the20th century, at leastpartially because of the rise of the automobile industry. Today, fossil fuels such ascoal, oil, and natural gas provide more than three quarters of the world’s energy.Unfortunately, the growing demand for fossil fuel resources comes at a time ofdiminishing reserves of these non-renewable resources, such that the worldwidereserves of oil are sufficient to supply energy and chemicals for only about another40years, causing widening concerns about rising oil prices. Biomass can serve as asource for both energy and carbon, and being renewable it is the only sustainablesource of energy and organic carbon for our industrialized society.Unlike petroleum which contains limited functionality, biomass-derivedcarbohydrates contain excess functionality for use as fuels and chemicals, and thechallenge in this field is to develop methods to control the functionality in the finalproduct. Consider, for example, the selective dehydration of hexoses to produce5-hydroxymethylfurfural (HMF).In this thesis, the process of fructose dehydration to HMF and its deriveitives byusing ethanol and isopropanol as solvents and inorganic salts, acids, newBr nsted-acidic ionic liquid as catalysts was studied. And the reaction conditions,such as the amount of catalyst, temperature and time were optimized.Using inorganic salt as catalyst, fructose dehydration in ethanol and isopropanolwas investigated and studies showed that ammonium chloride had a better catalyticeffect than other salts. In an optimized process, fructose was converted into HMF andethoxymethylfurfural (EMF) in46%isolated yield at100°C for a reaction time of12h. Levulinic acid ethyl ester (LAEE) was formed as the only byproduct in less than2%yield. With the1:2mol ratio of ammonium chloride to fructose, the HMF yield reached68%at120oC for12h in isopropanol and3%of5-i-propoxymethylfurfuralwas obtained. The reaction in ethanol at100°C on a10g scale gave a total yield ofHMF and EMF of42%. No mineral acid such as sulfuric acid(H2SO4) and hydrogenchloride(HCl) are required.In addition, reaction intermediates during the experiment process were obtainedand analyzed, then the mechanism of fructose dehydration was elaborated.Next, the br nsted-acid ionic liquids, including [DMSO]~+[HSO4]~-,[DMSO]~+[Cl]~-,[DMSO]~+[I]~-,[DMSO]~+[CH3SO3]~-, were prepared and Hammatt acidity of thedifferent Ils was investigated in methanol using UV/Vis spectroscopy withp~-nitroaniline as the indicator and molecular probe. An effective transformation ofcarbohydrates to EMF and LAEE was developed in the presence of catalytic amountsof the br nsted-acidic ionic liquids. The effects of catalyst loading, reactiontemperature and reaction time in the dehydration reaction were investigated. For theconversion of fructose and inulin, EMF and LAEE, which can be used as fuels andfuel additives, were obtained in83%and80%total yields at140oC for a reactiontime of8h. The catalyst has been recycled efficiently and easily over seven timeswithout any significant loss in fructose conversion and the yield of product.Finally, A facile single-step conversion of fructose into EMF and LAEE in thepresence of acidic catalysts with microwave irradiation was described. Ethanol is anexcellent and environment friendly reaction solvent. The dehydration of fructose wereexamined with concentrated sulfuric acid as catalyst in ethanol at120oC undermicrowave irradiation. Under the same conditions, fructose conversion and overallyields of HMF, EMF and LAEE were higher for microwave heating than oil bathheating. A high EMF and LAEE yield of80%was obtained from fructose at120oC in5min. Good results were achieved when inulin, sucrose, glucose and agarose wereused as the feedstock.