Showing papers on "Tetrahydrofuran published in 1995"
TL;DR: In this article, the density, viscosity, refractive index for the sodium D-line, and speed of sound in binary mixtures of water with N,N-dimethylformamide, dimethyl sulfoxide, n,Ndimethylacetamide, acetonitrile, ethylene glycol, diethylene glyco-col, 1,4-dioxane, tetrahydrofuran, 2-methoxyethanol, and 2-ethoxy-ethanol have been determined at 298.15 K over the whole range of
Abstract: The density, viscosity, refractive index for the sodium D-line, and speed of sound in binary mixtures of water with N,N-dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, acetonitrile, ethylene glycol, diethylene glycol, 1,4-dioxane, tetrahydrofuran, 2-methoxyethanol, and 2-ethoxyethanol have been determined at 298.15 K over the whole range of mixture compositions. From these results, the excess molar volume, deviations in viscosity, speed of sound, molar refractivity, and isentropic compressibility have been calculated. The computed results are fitted to the Redlich-Kister polynomial equation to estimate the adjustable parameters and standard deviations. The observed negative VE values are compared with the available literature results.
321 citations
TL;DR: In this paper, the surface film formed on lithium immersed in propylene carbonate or {gamma}-butyrolactone containing 1.0 mol/dm{sup 3} LiBF{sub 4}(LiBF{ sub 4}/THF) for three days consists of LiF and a small amount of organic compounds.
Abstract: The surface film on lithium immersed in various electrolytes was analyzed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, and the potential sweep method. The surface film formed on lithium immersed in propylene carbonate or {gamma}-butyrolactone containing 1.0 mol/dm{sup 3} LiBF{sub 4}(LiBF{sub 4}/PC or LiBF{sub 4}/{gamma}-BL) for 3 days consists of LiF and a small amount of organic compounds. On the other hand, the surface film on lithium immersed in tetrahydrofuran (THF) containing 1.0 mol/dm{sup 3} LiBF{sub 4} (LiBF{sub 4}/THF) consists of a large amount of organic compounds and LiF. LiF and organic compounds are formed by the chemical reaction of LiOH, Li{sub 2}CO{sub 3}, and Li{sub 2}O with HF involved in the electrolyte plus the direct reaction of the solvent with the lithium metal, respectively. The amount of organic compounds produced was influenced by the kind of solvent. For the formation of organic compounds, solvents have to permeate the LiF layer on the lithium. Probably, the permeability of the solvent is related to the formation of organic compounds. The permeability of the electrolyte is estimated quantitatively from the surface tension and viscosity. The surface tension and viscosity were obtained using the capillary rise method and Ostwald`s viscometer, respectively.more » The surface tension and viscosity of LiBF{sub 4}/THF were much smaller than those of LiBF{sub 4}/PC or LiBF{sub 4}/{gamma}-BL. This indicates that THF is more permeable than PC and {gamma}-BL. THF may easily reach the lithium metal surface to form a large amount of, organic compounds. From these results, it can be concluded that the surface reaction of the lithium does not only depend on the chemical properties of the lithium surface and electrolyte, but also on the physicochemical properties of the electrolyte.« less
218 citations
TL;DR: In this paper, the behavior of graphite electrodes in various electrolyte solutions was explored using in situ x-ray diffraction in conjunction with chronopotentiometry, and the results revealed that graphite anodes behave reversibly in these solutions and are stable on Li intercalation−deintercalation cycling.
Abstract: The behavior of graphite electrodes in various electrolyte solutions was explored using in situ x‐ray diffraction in conjunction with chronopotentiometry The solvent systems studied included ethylene and diethyl carbonate mixtures (EC‐DEC), propylene carbonate (PC), tetrahydrofuran (THF), and dimethyl carbonate (DMC) These studies revealed that the above systems can be divided into three classes EC‐DEC and water contaminated DMC are solvent systems in which highly passivating and protective surface films are precipitated on the carbon at potentials much higher than the intercalation potentials Therefore, graphite electrodes behave reversibly in these solutions and are stable on Li intercalation‐deintercalation cycling An opposite case occurs with PC and THF, where the carbon is destroyed before or during the intercalation processes, and therefore graphite anodes behave totally irreversibly in these systems In an intermediate case (dry DMC is a good example), a passivating layer is formed on the carbon at a potential higher than where Li intercalation occurs, but it is not sufficient to protect the carbon totally and therefore the electrode is slowly destroyed by cycling
189 citations
TL;DR: In this paper, it is discussed that the reason for forming this ball-like structure is the saturation of four coordinated Al4O3(CH3)6 molecules on a surface of ice and the consequences for the formation of the catalytically active structure together with metallocene are discussed.
Abstract: Methylaluminoxane prepared from trimethylaluminium on a surface of ice mainly can be described as [Al4O3(CH3)6]4. This is shown through analysis, phase separation experiments with diethyl ether and molecular weight determinations in benzene, 1, 4-dioxane, tetrahydrofuran and trimethylaluminium. It is discussed that the reason for forming this ball-like structure is the saturation of four coordinated Al4O3(CH3)6. This molecule has a cavern which contains a solvent molecule or a molecule of trimethylaluminium. The consequences for the formation of the catalytically active structure together with metallocene are discussed.
127 citations
TL;DR: In this paper, Li, 15N, and I3C NMR spectroscopic studies of 6Li-15N labeled lithium hexamethyldisilazide ((6Li,'5N)- LiHMDS) are reported.
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.
107 citations
TL;DR: In this article, the authors demonstrate that the polymer-supported Mitsunobu reaction is useful for combinatorial library synthesis, and synthesize a number of model compounds and a simple three randomization step library composed of 4,200 different compounds.
93 citations
TL;DR: In this paper, the structure of a model protein, bovine pancreatic trypsin inhibitor (BPTI), in organic solvents has been examined using hydrogen isotope exchange/high-resolution NMR methodology.
Abstract: The structure of a model protein, bovine pancreatic trypsin inhibitor (BPTI), in organic solvents has been examined using hydrogen isotope exchange/high-resolution NMR methodology. When lyophilized deuterated BPTI is suspended in acetonitrile, tetrahydrofuran, ethyl acetate, or butanol, each containing 1% {sup 1}H{sub 2}O, several protein amide protons that are buried and strongly hydrogen bonded in aqueous solution are found to exchange with the solvent significantly within 24 h. When solid BPTI is prepared by different methods, such as rotary evaporation, acetone precipitation, or lyophilization from a dimethyl sulfoxide solution, and subsequently suspended in acetonitrile containing 1% water, the exchange intensities of the amide protons vary greatly among the preparations. These data combined suggest that the structure of BPTI in the four aforementioned organic solvents is partially unfolded, but not more so than in lyophilized powder, i.e., that these solvents cause little additional protein denaturation beyond that brought about by lyophilization. Using the same methodology, the BPTI structure also has been studied in several protein-dissolving solvents containing 1% water. In dimethyl sulfoxide, dimethylformamide, or methanol, the same amide protons exchange almost completely within 24 h, while in glycerol they do not. 33 refs., 3 figs., 2 tabs.
87 citations
Patent•
03 Mar 1995TL;DR: Improved hydrogenation catalysts consisting essentially of highly dispersed, reduced ruthenium and rhenium on carbon support and methods of making and using the same are discussed in this paper.
Abstract: Improved hydrogenation catalysts consisting essentially of highly dispersed, reduced ruthenium and rhenium on carbon support and methods of making and using the same. Such catalysts exhibit high conversion rates in aqueous solution hydrogenation of hydrogenatable precursors (e.g., maleic acid, succinic acid, γ-butyrolactone, etc.) to tetrahydrofuran, 1,4-butanediol and mixtures thereof.
71 citations
TL;DR: In this paper, poly (ether imide) segmented copolymers were prepared from polyether diamine and comonomer diamine with acid anhydride, and micro-phase-separated structure consisting of microdomains of rubbery polyether segments and of glassy polyimide segments.
58 citations
TL;DR: In this article, a comparison of column effiency and peak assymmetry measurements were made for 16 pyridine derivatives using approximately isoeluotropic mixtures of methanol, acetonitrile and tetrahydrofuran (THF) in combination with phosphate buffer at pH 7.0 on a RP-HPLC column suitable for the analysis of basic compounds.
56 citations
TL;DR: In this article, the initial formation of poly(aniline) and its derivatives was investigated for the electropolymerization of anilines in several nonaqueous solutions without proton donor to prepare the films effectively.
TL;DR: In this article, the excess molar enthalpies H{sub m}{sup E} measured at 298.15 K using a flow calorimeter were reported for 12 mixtures of methanol, ethanol, propan-1-ol, or propan 2-ol + tetrahydrofuran (THF), + tetrahexylhexyl tetramer (THP), or + 1,4-dioxane.
Abstract: Excess molar enthalpies H{sub m}{sup E} measured at 298.15 K using a flow calorimeter are reported for 12 mixtures of methanol, ethanol, propan-1-ol, or propan-2-ol + tetrahydrofuran (THF), + tetrahydropyran (THP), or + 1,4-dioxane. For all of the systems investigated, H{sub m}{sup E} is strongly positive over the whole mole fraction range and increase in the order methanol
TL;DR: In this article, an investigation of the reaction course and stoichiometry of the McMurry reaction of acetophenone utilizing [HTiCl(THF) 0.5]x (THF = tetrahydrofuran), TiCl3(DME)1.5Zn(Cu) (DME = 1,2-dimethoxyethane) and TiCl2 · LiCl as coupling reagents has been undertaken.
TL;DR: Dialkylborane catalyzed hydroboration of alkynes with an equimolar amount of 1,3,2-benzodioxaborole in tetrahydrofuran efficiently to provide 2-alkenyl-1.3, 2.2-bioxaborol under mild reaction conditions as mentioned in this paper.
TL;DR: In this article, the dilithiation of N,N′,N″-triphenylguanidine with n-butyllithium in tetrahydrofuran provides the first example of a triazatrimethylenemethane system [C(NPh)3]2], isoelectronic with both [CH2]2] and [CO3]
Abstract: The dilithiation of N,N′,N″-triphenylguanidine with n-butyllithium in tetrahydrofuran provides the first example of a triazatrimethylenemethane system [C(NPh)3]2–, isoelectronic with both [C(CH2)3]2– and [CO3]2–; the X-ray crystal structure of the dilithium salt shows it to exist as a dimer with planar CN3 structural units.
TL;DR: In this article, high-yield syntheses of the soluble, volatile complexes [{ML(Cl)}2][M = U or Th, L = N(CH2CH2-NSiMe3)3] have been achieved.
Abstract: High-yield syntheses of the soluble, volatile complexes [{ML(Cl)}2][M = U or Th, L = N(CH2CH2-NSiMe3)3] have been achieved. The molecular structure of the uranium complex shows it to be a dimer bridged by long U–(µ-Cl) bonds. These compounds are shown to be versatile starting materials for exploration of the chemistry of the amino(triamido) actinide fragment. Their reactions with Na[C5R5](R = H or Me) gave high yields of the monomeric complexes [ML(C5R5)] for which analogous non-chelate compounds are unknown. These species are fluxional and display apparent three-fold symmetry on the NMR time-scale in solution at room temperature, although an exchange process via a trigonal-bipyramidal transition state is postulated on the basis of variable-temperature NMR studies for the compound M = Th, R = Me. The molecular structure of the compound M = U, R = Me has been determined by X-Ray diffraction. Reaction of the chloro complexes with lithium tetrahydroborate in tetrahydrofuran (thf) gave high yields of [ML(H3BH)(thf)]. The uranium derivative has been structurally characterised and has distorted-octahedral geometry. Sublimation of these compounds in vacuo led cleanly to the base-free complexes [{ML(H3BH)}2]. The volatile dimeric alkoxide derivatives [{ML(OBut)}2] have been prepared similarly.
TL;DR: The strontium and barium tetrahydridridoborate complexes M(BH4)2 · 2 diglyme and M(bH4)-2 · 18-crown-6 (M = Sr, Ba) have been prepared from the solvates M(C4) 2 · 2 THF by ligand displacement as discussed by the authors, and X-ray structural analyses show molecular units in which BH4 group is in contact via three H atoms with the metal center.
Abstract: The strontium and barium tetrahydridoborate complexes M(BH4)2 · 2 diglyme and M(BH4)2 · 18-crown-6 (M = Sr, Ba) have been prepared from the solvates M(BH4)2 · 2 THF by ligand displacement. 11B-NMR and IR data reveal strongly polar bonding of the BH4 groups to the metal centers, and X-ray structural analyses of the diglyme and crown ether compounds show molecular units in which the BH4 group is in contact via three H atoms with the metal center. In contrast, M(BH4)2 · 2 THF compounds are chain polymers in the solid state, and each metal center is surrounded by 2 THF molecules in trans position and four BH4− groups each of which forms bridges with two metal centers. Estimations of the effective radius for the BH4 group indicate a high polarity for the M-BH4 interaction.
TL;DR: The lanthanide(II) aryloxide complexes [Yb(OC6H2But2-2,6-Me-4)2(OEt2)2]1, this paper ] have been synthesized by the reaction of 2 equivalents of the appropriate potassium arylsoxide with Ybl2 in diethyl ether (1) or thf (2 or 3) using Lnl2(thf) 2(Ln = Sm, Eu or Yb) in thf.
Abstract: The lanthanide(II) aryloxide complexes [Yb(OC6H2But2-2,6-Me-4)2(OEt2)2]1, [Yb(OC6H3But2-2,6)2(thf)3]2, [Yb(OC6H2But3-2,4,6)2(thf)3]3, [Sm(OC6H2But2-2,6-Me-4)2(thf)3]4, [Eu(OC6H2But2-2,6-Me-4)2(thf)3]·thf 5, [Yb(OC6H2But2-2,6-Me-4)2(thf)3]6 and [Yb(OC6H2But2-2,6-Me-4)I(thf)x]7(thf = tetrahydrofuran) have been synthesized Each of the complexes 1–3 was prepared by the reaction of 2 equivalents of the appropriate potassium aryloxide with Ybl2 in diethyl ether (1) or thf (2 or 3) Complexes 4–6 were prepared by the reaction of 2 equivalents of K(OC6H2But2-2,6-Me-4) with Lnl2(thf)2(Ln = Sm, Eu or Yb) in thf Reacting Ybl2 with 1 equivalent of K(OC6H2But2-2,6-Me-4) in thf yielded complex 7 as the main product, but 171Yb-{1H} NMR spectroscopy showed that 6 and [Ybl2(thf)4]8 were also formed The crystal structure of complex 5 reveals that it adopts a distorted trigonal-bipyramidal conformation with (i) apical thf oxygens [O(4)–Eu–O(5) 1786(2)°, Eu–O(4) 2590(5) and Eu–O(5) 2573(5)A]; (ii) the equatorial O(1), O(2) and O(3) thf coplanar; and (iii) Eu–O(1) 2321(5), Eu–O(2) 2337(5) and Eu–O(3) 2515(6)A The crystal structure of complex 8 showed there to be an octahedral arrangement around the metal, the molecule lying on a crystallographic inversion centre, with angles I–Yb–O(1) 901(2), I–Yb–O(2) 914(2) and O(1)–Yb–O(2) 889(3)°, and bond lengths Yb–I 3103(1), Yb–O(1) 2399(9) and Yb–O(2) 2373(8)A
TL;DR: Phenyl[tri(tent-butyl)phosphine]gold(I) has been prepared from tris(tri(tert)-butyl), tri-(tert-phosphines) gold(1))oxonium tetrafluoroborate and sodium tetraphenylborate in ethanol at ambient temperature.
TL;DR: The cationic organouranium(IV) compounds [U(η-C5H5)3(thf) as discussed by the authors ] have been synthesized from neutral amide precursors by protonolysis of the UNR2(R = Et or Me) bond with NHEt3BPh4; the crystal structures of 2 and 8 have been determined.
Abstract: The cationic organouranium(IV) compounds [U(η-C5H5)3(thf)]BPh4(thf = tetrahydrofuran)1, [U(η-C5Me5)(NEt2)2(thf)2]BPh42, [U(η-C5R5)2(NEt2)(thf)]BPh4(R = H 3 or Me 4), [U(η-C5Me5)2(NMe2)(thf)]BPh45, [U(η-C8H8)(NEt2)(thf)2]BPh46, [U(η-C5R5)(η-C8H8)(thf)2]BPh4(R = H 7 or Me 8) have been synthesized from the neutral amide precursors by protonolysis of the U-NR2(R = Et or Me) bond with NHEt3BPh4; the crystal structures of 2 and 8 have been determined.
TL;DR: In this paper, Fourier transform infra-red spectra of poly(monomethyl itaconate) and poly(vinylpyridine) were used to study their hydrogen-bonding interactions.
TL;DR: In this paper, Friedel-Crafts acylation of 2,6-dimethylnaphthalene with 4-fluorobenzoyl chloride in nitrobenzene selectivity afforded 1 in 82% yield.
Abstract: Synthesis of 1,5-bis(4-fluorobenzoyl)-2,6-dimethylnaphthalene (1), polycondensation of 1 with Bisphenol A, and properties of the obtained polymer were studied. Friedel-Crafts acylation of 2,6-dimethylnaphthalene with 4-fluorobenzoyl chloride in nitrobenzene selectivity afforded 1 in 82% yield. X-ray single crystal structural analysis of 1 confirmed that the dibenzoylation proceeded regioselectively and two methyl groups sterically inhibited the coplanarity of the two aromatic planes. The polycondensation of 1 with Bisphenol A in toluene/N-methyl-2-pyrrolidone (NMP) mixed solvent in the presence of excess potassium carbonate as a condensation reagent was carried out at 180°C for 4 h to quantitatively afford the corresponding poly(arylene ether-ketone) (PEK) 3 with high molecular weight (M n ∼ 30,000) as a slightly yellow powder. As the reaction time was prolonged, both M n and MWD of 3 increased and the solubility of 3 in chloroform clearly decreased. By GPC-LALLS, M n of 3 obtained by the polycondensation for 16 h, was 85,000. The PEK 3 with high molecular weight was produced in a quantitative yield in a variety of solvents such as sulfolane. Water formed during the polycondensation hardly affected the yield and molecular weight of 3, although a small molecular weight decrease took place. To evaluate the special effect of the methyl groups of 3, polycondensation of 2,6-bis(4-fluorobenzoyl)naphthalene 2 with bisphenol A was carried out for comparison and the corresponding PEK 4 was quantitatively obtained. Whereas 3 was soluble in ordinary organic solvents such as tetrahydrofuran (THF), chloroform, and NMP at room temperature, 4 was insoluble in most solvents except for strong acids such as conc. sulfonic acid. The polymer 3 showed high glass transition temperature (238°C) and 5% weight loss temperature (457°C). Casting of the polymer from THF solution gave a transparent, tough, flexible, and amorphous film.
TL;DR: Arylboronic acids react with carbon monoxide (CO) at atmospheric pressure in methanol at 25°C in the presence of a catalytic amount (1−5 mol%) of tetrakis(triphenylphosphine)palladium(0) to give the corresponding methyl arenecarboxylates and diaryl ketones in moderate yield, where the addition of a base, especially sodium acetate, increases the selectivity for the esters as discussed by the authors.
TL;DR: In this article, a single electron transfer mechanism was proposed for the 1:1 addition with n-perfluoroalkyl iodides in the presence of a catalytic amount of Ti0 generated in situ.
TL;DR: In this paper, the correlation between Li cycling efficiency, Li morphology, Li surface chemistry, and the properties of the Li-solution inter-phase was investigated in the THF, 2Me-THF,2Me-Furan (MF), LiAsF{sub 6} electrolyte system.
Abstract: The correlation between Li cycling efficiency, Li morphology, Li surface chemistry, and the properties of the Li-solution inter-phase was investigated in the THF, 2Me-THF, 2Me-Furan (MF), LiAsF{sub 6} electrolyte system. Surface sensitive FTIR, EDAX-X-ray microanalysis, SEM, and impedance spectroscopy were used in conjunction with standard electrochemical techniques. Using THF as a cosolvent to 2Me-THF decreases the detrimental impact of contaminants such as water as it is more reactive toward lithium than 2Me-THF. The presence of MF (a few percent) influences the Li surface chemistry since its reduction to surface compounds with alloy groups suppresses solvent and salt reduction. However, its effect on Li morphology and cycling efficiency is marginal. It is concluded that the main positive impact of this additive reported in the literature is due to the stabilizing effect of the ethers by its possible reaction with trace Lewis acid contaminants in the solutions. The superiority of LiAsF{sub 6} as an electrolyte for these solutions is attributed to the precipitation of elementary arsenic and arsenic compounds (e.g., Li{sub 3}As, Li{sub x}AsF{sub y}) on lithium, which modifies Li deposition to become uniform and smooth.
TL;DR: Empirical solvent polarity parameters ET(30) were determined by UV-visible spectrophotometry using Dimroth-Reichardt's betaine dye, as a function of composition, for (aprotic + aprotic) and (aporetic + protic) binary solvent mixtures as discussed by the authors.
TL;DR: In this paper, a variety of monosubstituted γ-lactols 4−6 were prepared in good yields by DIBAL reduction of the corresponding γlactones 1−3.
Abstract: A variety of monosubstituted γ-lactols 4–6 were prepared in good yields by DIBAL reduction of the corresponding γ-lactones 1–3. The monophenyl-substituted lactols 4b–6b were transformed into disubstituted tetrahydrofuran derivatives by replacement of the hydroxyl group by the alkyl residue of organometallic compounds used as nucleophiles. The diastereoselectivity of the substitution was found to depend strongly on the substitution pattern of the γ-lactols. For the reaction of the 3- and 4-substituted derivatives 4b and 5b, respectively, good to excellent trans selectivity was observed, while the 5-substituted derivative reacted without any diastereoselectivity. These results were interpreted by means of the Felkin-Anh model.
TL;DR: In this article, an amperometric organic-phase phenol sensor was investigated in acetonitrile, acetone and tetrahydrofuran reaction media containing 20% v/v water.
TL;DR: In this article, the first zirconocene complex with an alkyl substituted alkyne without additional phosphine ligands Cp 2 ZrCl 2 with magnesium and t BuC 2 SiMe 3 in tetrahydrofuran was characterized by its IR and NMR spectra.
TL;DR: In this article, the high-resolution powder diffractometer (HRPD) was used for neutron diffraction of fully deuterated tetrahydrofuran (THF) and acetone clathrate hydrates.
Abstract: Neutron-diffraction studies of fully deuterated tetrahydrofuran (THF) and acetone clathrate hydrates have been performed with the high-resolution powder diffractometer (HRPD) at ISIS. Preferred orientations of THF and acetone molecules accommodated in the clathrate cages were determined by Rietveld analysis. The low-temperature phase of the THF hydrate was found to have a quasi-tetragonal structure with a complex local distortion causing strong broadening of the diffraction peaks.