The multi-step conversion of sucrose to various C 5 -oxygenates and alkanes was achieved by integrating various homogeneous and heterogeneous catalytic systems. We have confirmed that the dehydration of sucrose to levulinic and formic acids is currently limited to about 30-40% in the presence of H 2 SO 4 , HCl, or Nafion NR50 in water. Performing the dehydration in the presence of a P(m-C 6 H 4 SO 3 Na) 3 modified ruthenium catalyst under hydrogen resulted in the in situ conversion of levulinic acid to c-valerolactone (GVL). Levulinic acid can be hydrogenated to GVL quantitatively by using P(m-C 6 H 4 SO 3 Na) 3 modified ruthenium catalyst in water or Ru(acac) 3 /PBu 3 / NH 4 PF 6 catalyst in neat levulinic acid. Formic acid can be used for the transfer hydrogenation of levulinic acid in water in the presence of [(g 6 -C 6 Me 6 )Ru(bpy)(H 2 O)][SO 4 ] resulting in GVL and 1,4-pentanediol. The hydrogenation of levulinic acid or GVL can be performed to yield 1,4-pentanediol and/or 2-methyl-tetrahydrofuran (2-Me-THF). The hydrogenolysis of 2-Me-THF in the presence of Pt(acac) 2 in CF 3 SO 3 H resulted in a mixture of alkanes. We have thus demonstrated that the conversion of carbohydrates to various C 5 -oxygenates and even to alkanes can be achieved by selecting the proper catalysts and conditions, which could provide a renewable platform for the chemical industry.

Polypentenamer was synthetized by equilibrium ring-opening metathesis polymerization (ROMP) using well-defined ruthenium catalyst systems. It was found that the equilibrium time is influenced by the catalyst loading or the catalyst activity, however as expected, the overall cyclopentene conversion is determined only by the applied reaction temperature. Equilibrium of the growing chain and monomer was observed and the activation enthalpy and entropy were determined as: DH ¼ À5.6 kcal mol À1 ;. So far these values are the lowest which are reported for cyclopentene polymerization catalyst systems. This unique feature of the equilibrium polymerization opens a way for the synthesis of durable, environmentally friendly elastomers where tires can be not only synthetized but also readily recycled by the same transition metal catalyst system.

Ring opening metathesis polymerization (ROMP) of a series of low-strain cyclic olefins and their hydroxyl derivatives using second generation Hoveyda-Grubbs catalyst has been investigated. Additionally, density functional theory (DFT) calculations were performed to evaluate the ring strain energies of the cyclic olefins and their hydroxyl derivatives, coupled with kinetic studies for the ROMP reactions. It was found that among different ring size monomers, Cy8 having a relatively moderate ring strain energy in comparison with the other cyclic olefins, exhibited the highest monomer conversion. The effect of temperature (0, 10, 15, and 25 8C) and monomer concentration (1 M; 2.5 M and 5 M for Cy5; and 1 M and 5 M for Cy7) for the cyclic olefins Cy5 and Cy7 were investigated. In general, the experimental results for the kinetic ROMP studies obtained using complex HG2 correlate really well with the DFT calculations determined for the ring strain energies of the cyclic olefins. For comparison, DFT calculations predicted the following trend for the ring strain energies Cy8 > Cy5 > Cy7 > Cy6, and the polymerizations carried out experimentally followed the same trend in terms of monomer conversion, with the exception of Cy5 and Cy7 at lower concentrations, which followed this trend Cy8 > Cy7 > Cy5 > Cy6.

Well-defined poly(vinyl alcohol-alt-propenylene) (4) was synthesized in one-pot reaction via equilibrium ring-opening metathesis polymerization (ROMP) or acyclic diene metathesis (ADMET) of nonprotected 3-cyclopentene-1-ol ( 2) and 1,6-heptadiene-4-ol using (1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)dichloro(phenylmethylene)(tricyclohexylphosphine)ruthenium ( 6) and (1,3bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)dichloro(oisopropoxyphenylmethylene)ruthenium ( 7) metathesis catalysts. The activation enthalpy and entropy of the equilibrium ROMP were determined as ΔH = −6.2 kcal mol −1 and ΔS = −18.9 cal mol −1 K −1 . The observed thermodynamic parameters were supported by computational studies. The calculated ring strain energy for 2 (−6.8 kcal mol −1 ) is comparable with the observed activation enthalpy for its equilibrium ROMP reaction catalyzed by 6 or 7. The cis:trans olefinic bond ratio analysis indicated a 20:80 cis:trans selectivity. The hydrogenation of 4 resulted in poly(vinyl alcohol-alt-propylene) (11) in high yield. Because of the similar ring strain energies of cyclopentene (1) and 2, the equilibrium copolymerization results in a polymer having randomly distributed dyads. In general, it means that the polymer formed contains approximately 50% alternating polymer, 25% 3, and 25% 4 homopolymer dyads as expected for a random polymerization.