Tetrahydrofuran

About: Tetrahydrofuran is a research topic. Over the lifetime, 11778 publications have been published within this topic receiving 158241 citations. The topic is also known as: diethylene oxide & 1,4-epoxybutane.

Selective Production of Levulinic Acid from Furfuryl Alcohol in THF Solvent Systems over H-ZSM-5

Abstract: Furfuryl alcohol in high concentrations (1 M) was hydrolyzed to levulinic acid in high yields (>70%) using H-ZSM-5 zeolite as the catalyst in monophasic tetrahydrofuran (THF)–water solvent systems. Reaction kinetics studies using H-ZSM-5 were carried out, and combined with results obtained for other Bronsted acid catalysts, we suggest that the structural properties of H-ZSM-5, in conjunction with increased reaction performance using the polar aprotic solvent THF, are effective for furfuryl alcohol hydrolysis to levulinic acid while inhibiting furfuryl alcohol polymerization reactions. In addition, on the basis of results obtained for a wide range of THF–H2O solvent systems (19:1–1:2 w/w), we suggest that the hydrophobic nature of H-ZSM-5 alters the internal solvent microenvironment within the zeolite framework, allowing for high levulinic acid yields, even at low THF solvent concentrations (e.g., 1:2 THF–H2O w/w).

Platinum-containing hyper-cross-linked polystyrene as a modifier-free selective catalyst for L-sorbose oxidation.

Abstract: Impregnation of hyper-cross-linked polystyrene (HPS) with tetrahydrofuran (THF) or methanol (ML) solutions containing platinic acid results in the formation of Pt(II) complexes within the nanocavities of HPS. Subsequent reduction of the complexes by H2 yields stable Pt nanoparticles with a mean diameter of 1.3 nm in THF and 1.4 nm in ML. The highest selectivity (98% at 100% conversion) measured during the catalytic oxidation of l-sorbose in water is obtained with the HPS-Pt-THF complex prior to H2 reduction. During an induction period of about 100 min, l-sorbose conversion is negligible while catalytic species develop in situ. The structure of the catalyst isolated after the induction period is analyzed by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Electron micrographs reveal a broad distribution of Pt nanoparticles, 71% of which measure less than or equal to 2.0 nm in diameter. These nanoparticles are most likely responsible for the high catalytic activity ...

Ethereal solvation of lithium hexamethyldisilazide : unexpected relationships of solvation number, solvation energy, and aggregation state

Abstract: Li, 15N, and I3C NMR spectroscopic studies of 6Li-15N labeled lithium hexamethyldisilazide ((6Li,'5N)- LiHMDS) are reported. Mono-, di-, and mixed-solvated dimers are characterized in the limit of slow solvent exchange for a variety of ethereal ligands including the following: tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHl3 2,2-dimethyltetrahydrofuran (2,2-Me2THF), diethyl ether (EtzO), tert-butyl methyl ether (r-BuOMe), n-butyl methyl ether (n-BuOMe), tetrahydropyran (THP), methyl isopropyl ether (i-PrOMe), and trimethylene oxide (oxetane). The ligand exchange is too fast to observe bound and free diisopropyl ether (i-PrZO), tert-amyl methyl ether (Me2(Et)COMe), and 2,2,5,5-tetramethyltetrahydrofuran (2,2,5,5-Me4THF). Exclusively dissociative ligand substitu- tions occur at low ligand concentrations for all ligands except oxetane. Relative free energies and enthalpies of LiHMDS dimer solvation determined for eight ethereal ligands show an approximate inverse correlation of binding energy and ligand steric demand. Mixed solvation is found to be non-cooperative showing there exists little communication between the two lithium sites on the dimer. The different ethereal solvents display a widely varying propensity to cause formation of LiHMDS monomer. The often-cited correlation of reduced aggregation state with increasing strength of the lithium-solvent interaction receives no support whatsoever. The measured free energies of aggregation display a considerable solvent dependence that is traced to solvent-independent enthalpies of aggregation and solvent-dependent entropies of aggregation. LiHMDS monomer solvation numbers derive from solvent- concentration-dependent monomer:dimer proportions. Moderately hindered ethereal solvents afford LiHMDS monomers in trisolvated forms ((MesSi)zNLiS3) whereas THF and oxetane appear to afford considerable concentrations of five-coordinate tetrasolvates ((Me3Si)zNLiS4), The complex relationship between solvation energy and observable aggregation state is discussed in light of solvent-amide and solvent-solvent interactions on both the monomer and the dimer, the combined contributions of solvation enthalpy and entropy, and the complicating intervention of variable solvation numbers.

Selective Conversion of Cellulose to Hydroxymethylfurfural in Polar Aprotic Solvents

Abstract: Herein, we report a new reaction pathway to produce hydroxymethylfurfural (HMF) from cellulose under mild reaction conditions (140–190 °C; 5 mM H2SO4) in polar aprotic solvents (i.e. THF) without the presence of water. In this system, levoglucosan is the major decomposition product of cellulose, followed by dehydration to produce HMF. Glucose, levulinic acid, and formic acid are also produced as a result of side reactions with water, which is a by‐product of dehydration. The turnover frequency for cellulose conversion increases as the water content in the solvent decreases, with conversion rates in THF being more than twenty times higher than those in water. The highest HMF yield from cellulose was 44 % and the highest combined yield of HMF and levulinic from cellulose was 53 %, which are nearly comparable to yields obtained in ionic liquids or biphasic systems. Moreover, the use of a low boiling point solvent, such as THF, facilitates recovery of HMF in downstream processes.