The growing demand of fossil fuel resources comes at a time of diminishing reserves of these non-renewable resources. To sustain modern civilization an alternative resource must be found to continue the supply of energy and chemicals. Being renewable, biomass is the only sustainable source of energy and organic carbon. Utilizing straightforward chemical methods, biomass can be transformed into 5-hydroxymethylfurfural (HMF), a platform chemical that can serve as an important intermediate to biofuels and commodity chemicals. 5-HMF is an important bio-sourced intermediate, formed from carbohydrates such as glucose and fructose. This thesis describes the reaction systems for the selective conversion of carbohydrates to HMF. First, acid catalyzed dehydration of glucose to HMF is addressed. Nano-?-Al 2 O 3 -SO 3 H, ?-Al 2 O 3 -SO 3 H catalysts prepared by sulfonation of Nano-?-Al 2 O 3 and ?-Al 2 O 3 were employed for glucose conversion. The basic structures of the prepared catalysts were characterized by BET, TEM, SEM, FT-IR and TGA techniques. The effect of process variables like initial D-glucose concentration (0.025–0.15 g/ml), reaction time (4–12 h), catalyst value (0.015-0.1 g) and reaction temperature (87–150 ?C) on the yield of HMF was examined. Highest yields of HMF (61 %) were obtained using D-glucose (0.05 g/ml), ?-Al 2 O 3 -SO 3 H (0.05 g) at a temperature of 100 ?C, DMSO solvent and reaction time of 12 h. Subsequently, acid catalyzed dehydration of fructose to HMF by Nano-?-Al 2 O 3 -SO 3 H, ?-Al 2 O 3 -SO 3 H is addressed. The effect of process variables like initial fructose concentration (0.025–0.15 g/ml), reaction time (4–15 h), catalyst value (0.015-0.1 g) and reaction temperature (87–150 ?C) on the yield of HMF was examined. Highest yields of HMF (81 %) were obtained using fructose (0.05 g/ml), ?-Al 2 O 3 -SO 3 H (0.05 g) at a temperature of 100 ?C, DMSO solvent and reaction time of 6 h. Finally, dehydration of sugars to HMF was conducted in DMSO, DMF, DMAc and isopropanol as solvents. The substituent effect on coupling constants and chemical shifts of 2-substituted 1, 4-dioxane derivatives was calculated. The relative energies and NMR parameters of axial and equatorial conformers of 2-substituted 1, 4-dioxanes were calculated by density functional theory (DFT/B3LYP) methods using 6-311++G(d,p) basis set. also, the substituent effect on NMR parameters of 2, 3- substituted 1, 4-dioxane derivatives was calculated.The contribution of resonance, hyperconjugation, inductive, steric, hydrogen bonding, electrostatic interaction and anomeric effect influences the NMR parameters.