Showing papers on "Tetrahydrofuran published in 1996"

Homogeneous synthesis of cellulose p‐toluenesulfonates in N,N‐dimethylacetamide/LiCl solvent system

Abstract: Pure cellulose p-toluenesulfonates (tosylates) with an insignificant formation of chlorodeoxy groups were prepared by reacting cellulose dissolved in a solution of N,N-dimethylacetamide and LiCI with tosylchloride (Tos-CI) in the presence of triethylamine within 24 h at 8°C. Various cellulosic starting materials with a degree of polymerization from 280 to 5 100 were used. The samples obtained were characterized by means of elemental analysis, FTIR and 13C NMR spectroscopy, and their intrinsic viscosities. The rise of the molar ratio of Tos-CI/anhydroglucose unit (AGU) from 0.6 to 9.0 leads to an increase in the degree of substitution (DS) from 0.4 up to a maximum value of 2.3. The cellulose tosylates are readily soluble in common organic solvents like dimethyl sulfoxide (within the whole DS range) and in N,N-dimethylacetamide, N,N-dimethylformamide, acetone, tetrahydrofuran and trichloromethane depending on DS. As revealed by 13C NMR spectroscopy a faster tosylation takes place at the O-6 atom of AGU compared with the O-2/3 atoms. This was additionally confirmed by analysis of the corresponding iododeoxy celluloses synthesized with NaI in acetylacetone. Furthermore, some important properties as stability against alkaline and heat were studied as well.

Impedance Spectroscopy of Li Electrodes. 4. A General Simple Model of the Li−Solution Interphase in Polar Aprotic Systems

Abstract: In this work Li electrodes were studied in a variety of electrolye systems using impedance spectroscopy. The Li electrodes were all prepared in situ by shearing the surfaces in the same solutions in which the experiments were performed. The electrolyte systems included propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), tetrahydrofuran (THF), 2Me−THF, and 1,3-dioxolane (DN) as the solvents, LiAsF6, LiClO4, LiBF4, and LiPF6 as the salts, and trace water up to a concentration of 200 ppm. The electrochemical behavior of these systems is controlled by films formed spontaneously on the Li surfaces in solutions through which Li ions migrate under an electrical field, and therefore, Li+ migration in fact determines the interfacial resistance measured. It is assumed that these surface films have a multilayer structure to which a “Voigt” type analog of RC circuits in series can be fitted. All the spectra could be modeled by five RC circuits in series (one of which also contains a “Warburg” ...

Preparation of a New Type of Phosphazene High Polymers Containing 2,2‘-Dioxybiphenyl Groups

Abstract: The direct reaction of [NPCl2]n with the difunctional reagent 2,2‘-dihydroxybiphenyl (HOC6H4C6H4OH) and K2CO3 in tetrahydrofuran gave soluble linear phosphazene high polymers instead of the expected cross-linked products. The reaction of [N3P3Cl6] with 1, 2, or 3 equiv of HOC6H4C6H4OH and K2CO3 in acetone gave the known spiro derivatives [N3P3Cl4(O2C12H8)], [N3P3Cl2(O2C12H8)2], and [N3P3(O2C12H8)3] without formation of bridging products, and the dichloro derivative reacted directly with para-substituted phenols HOC6H4R and K2CO3 in acetone to give the new compounds [N3P3(OC6H4R)2(O2C12H8)2] (R = Br, COC6H5, or OCH3), without signs of replacement of the bis(aryloxy) substituents. In an analogous manner, poly(dichlorophosphazene) [NPCl2]n reacted with HOC6H4C6H4OH and K2CO3 in THF without significant cross-linking to give, depending on the mole ratio, the soluble polymer [NP(O2C12H8)]n (Mw = 450 000, Tg = 160 °C) or the partially substituted polymers {[NP(O2C12H8)]0.35[NPCl2]0.65}n. The latter were subseque...

Oxime sulfonate compound and acid generating agent for resist

Abstract: PROBLEM TO BE SOLVED: To obtain a new oxime sulfonate useful as an acid generating agent for resist capable of providing a resist pattern high in generation efficiency of an acid, excellent in pattern shape, dimensional fidelity, exposure margin, heat resistance, etc. SOLUTION: This oxime sulfonate compound is shown by formula I [R 1 and R 2 are each a (substituted) hydrocarbon] such as a compound of formula III. The compound of formula II is obtained, for example, by esterifying an oxime group-containing compound with a sulfonic acid chloride group-containing compound in a solvent such as tetrahydrofuran in the presence of a basic catalyst such as pyridine. An acid generating agent comprising the compound of formula I is mixed with a film-forming substance to prepare a photosensitive composition for resist. The amount of the photosensitive composition for resist blended is preferably about 1-30 pts.wt. based on 100 pts.wt. of the film-forming substance. COPYRIGHT: (C)1997,JPO

IR spectroscopy of neutral and ionic hydrogen-bonded complexes formed upon interaction of CH3OH, C2H5OH, (CH3)(2)O, (C2H5)(2)O and C4H8O with H-Y, H-ZSM-5 and H-mordenite: Comparison with analogous adducts formed on the H-Nafion superacidic membrane

Abstract: A complete assignment of the IR spectra of the ionic and neutral hydrogen-bonded species formed by interaction of a series of bases of increasing proton affinity [methanol, ethanol, dimethyl ether, diethyl ether and tetrahydrofuran (THF)] with H-Y, H-ZSM-5, H-mordenite (H-Mord) and H-Nafion is given. Special attention is devoted to the discussion of spectral manifestations associated with structures varying with continuity from the true neutral AH⋯B form (low B proton affinity) to the true ionic A–⋯HB+ forms (high B proton affinity) passing through intermediate situations characterized by proton potentials with a single broad minimum or two minima separated by a low barrier (hesitating proton) and substantial ionic character. The assignment is based more on the comparison of the whole series of spectra than on the minute analysis of the specific properties of each spectrum. The assignment is also based on the comparison of the spectra of the adducts in zeolites with the spectra of analogous species formed in homogeneous conditions between acids and bases of comparable base and acid strengths (used as models).The main conclusions are: (i) adducts formed in H-Y have neutral AH⋯B character (only at the highest filling condition are signs of formation of ionic dimeric B⋯HB+ species observed for methanol and ethanol); (ii) the species formed upon adsorption of methanol and ethanol on H-ZSM-5 and H-Mord are neutral at low coverage and prevalently ionic at the highest filling conditions [because of the formation of (B)n⋯HB+ oligomers: 1, 2, …, n]; (iii) owing to the larger basicity of the ethers and THF, monomeric hydrogen-bonded adducts characterized by nearly symmetric proton potentials and substantial ionic character are directly formed on H-ZSM-5 and H-Mord without the intervention of other adsorbed molecules; (iv) THF and diethyl ether do not enter the H-Mord channels because the strongly adsorbed forms formed at the pore entrances block further penetration; (v) on the superacidic H-Nafion membrane (used as a model of a superacidic solid) all substrates directly form very strong and nearly symmetric hydrogen bonds without the assistance of other basic molecules: consequently the formed species always have prevalently ionic character even at the lowest dosages.

Synthesis and Characterization of A New Conjugated Aromatic Poly(azomethine) Derivative Based on the 3‘,4‘-Dibutyl-α-Terthiophene Building Block

Abstract: A new conjugated aromatic poly(azomethine) derivative, poly(3‘,4‘-dibutyl-α-terthiophene−azomethine-1,4-phenylene−azomethine) (PBTPI), has been prepared by polycondensation of 2,5‘‘-diformyl-3‘,4‘-dibutyl-2,2‘:5‘,2‘‘-terthiophene with 1,4-phenylenediamine under the ethanothermal conditions. The red polycrystalline PBTPI was characterized by X-ray diffraction, NMR, FTIR, UV−visible−near-IR, photoluminescence, and ESR spectroscopies. PBTPI is partially soluble in tetrahydrofuran, giving an orange solution with an absorption maximum (λmax) of 457 nm. In the solid state, PBTPI has an optical band gap of 2.06 eV, which is one of the lowest among poly(azomethines), and is highly sensitive to a strong acid environment. Protonation yields a blue polymer with an optical band gap of 1.61 eV. The polymer is completely soluble in concentrated sulfuric acid and nitromethane containing Lewis acids (e.g., AlCl3), giving blue solutions with λmax of 656 and 638 nm, respectively. Iodine-doped PBTPI shows low electrical con...

Borate salt for photo polymerization initiator stable in acidic medium

Abstract: PROBLEM TO BE SOLVED: To obtain a new specific compound giving resist material, image recording material for holographic memory, etc., useful as photo polymerization initiator for ethylenically unsaturated compounds by composing a specific borate salt having stability in acidic medium. SOLUTION: The compound is a new borate expressed in formula [R 1 is a 1-20C (substituted)alkyl, a 3-12C (substituted)cycloalkyl, a 2-8C (substituted) alkenyl, etc., R 2 -R 4 are each a (substituted)phenyl, a (substituted) biphenyl; G is a functional group capable of forming a cation], [for example; tetraemthylammoniumbutyl-tris(2,6-difluorophenyl)borate, etc.] and is useful for a paint, printing ink, adhesive, resist, image recording material, etc., as photo polymerization initiator of ethylenic unsaturated compound. This compound is obtained by carrying out the reaction of tris(2,6-difluorophenyl) borane, etc., with butyl lithium in tetrahydrofuran then reacting the reaction product with tetramethylammonium chloride. COPYRIGHT: (C)1997,JPO

Anionic Synthesis of Narrow Molecular Weight Distribution Water-Soluble Poly(N,N-dimethylacrylamide) and Poly(N-acryloyl-N ‘-methylpiperazine)

Abstract: Water-soluble poly(N,N-dimethylacrylamide) (PDMA) and poly(N-acryloyl-N ‘-methylpiperazine (PAMP) were prepared in tetrahydrofuran at −78 °C by anionic polymerization in the presence of monofunctional initiators such as (triphenylmethyl)lithium, or -cesium or the difunctional initiators (1,1,4,4-tetraphenylbutyl)lithium, -potassium, or -cesium or cesium naphthalenide. Polymerizations initiated especially in the presence of cesium as counterion proceeded in a homogeneous manner and gave polymers having controlled molecular weights and narrow molecular weight distributions in quantitative yields. However, the polymerization results in polymers with a lower molecular weight and a broad molecular weight distribution at higher reaction temperatures. Size exclusion chromatography, 1H NMR spectroscopy, and intrinsic viscosity measurements support the clean anionic polymerization of DMA with few side reactions at −78 °C. Attempted anionic polymerizations of methacrylamide monomers such as N,N-dimethylmethacrylami...

Uranium-Mediated Ring Opening of Tetrahydrofuran. Crystal Structure of UI(2)(OCH(2)CH(2)CH(2)CH(2)I)(2)(Ph(3)P=O)(2)

Abstract: The synthesis and structure of the uranium(IV) compound UI2(OCH2CH2CH2CH2I)2(Ph3PO)2 (1) is described. Compound 1 is formed from the ring opening of THF from UI4(CH3CN)4.

Chiral Diselenides in the Total Synthesis of (+)-Samin

Abstract: Chiral selenium compounds are applied to stoichiometric as well as to catalytic reactions in the synthesis of substituted tetrahydrofuran derivatives: The selenium compound 1 was used in catalytic amounts for a rapid access to chiral diselenide 3. The efficient stereoselective addition to alkene 5 yields product 8 with a selenium functionality as a precursor for an intramolecular radical cyclization. In this way a short total synthesis of (+)-samin (11), a naturally occurring furofuran lignan, was achieved.

Uranium(IV) bis(amido), imido and bis(acetylide) complexes: synthesis, molecular structure, solution dynamics and interconversion reactions

Abstract: Reactions of [UMe2(C5Me5)2] with primary aromatic or aliphatic amines led to the rapid formation of monomeric uranium(IV) complexes [U(C5Me5)2(NHR)2](R = 2,6-dimethylphenyl 1, Et 2 or But3). The compounds were characterized by standard techniques and for 1, by X-ray diffraction. In co-ordinating solvents like tetrahydrofuran (thf) compound 1 reacted intramolecularly releasing one primary amine and forming the imidouranium(IV)[U(C5Me5)2{N(C6H3Me2-2,6)}]·thf 4, whereas in non-co-ordinating solvents the base-free [U(C5Me5)2{N(C6H3Me2-2,6)}]5 was obtained. The thf in 4 was found not to be in equilibrium with bulk solvents, and different proton chemical shifts for the adducted base were observed as a function of temperature following a Curie–Weiss behaviour. σ-Bond metathesis reactions of the bis(amido) and/or imido complexes with terminal alkynes produced the bis(acetylide) complexes [U(C5Me5)2(CCR)2](R = Ph 6 or But7) active species for the regioselective oligomerization of terminal alkynes, which can be prepared also from the reaction of [UMe2(C5Me5)2] with 2 equivalents of the corresponding terminal alkyne. Reactivity studies show the possible interconversion among these bis(amido), imido and bis(acetylide) complexes.

Thion (RCSOH), Selenon (RCSeOH), and Telluron (RCTeOH) Acids as Predominant Species

Abstract: Thiocarboxylic acids, such as selenocarboxylic acids, exist predominantly in the thioxo form (RCSOH, thion acid) in polar solvents such as tetrahydrofuran (THF) at temperatures below −50 °C. Tellurocarboxylic acids (5) were observed for the first time by acidolysis of the corresponding cesium tellurocarboxylates with hydrogen chloride. The telluroic acids (6) exist predominantly in the telluroxo form (RCTeOH, telluron acid) in THF at temperatures below −70 °C. Telluron acids were reddish to blue violet for the aliphatics (R = alkyl) and dark green for the aromatics (R = aryl) and reacted with aryl isocyanates at −70 °C to give crystalline acyl carbamoyl tellurides in good yields.

Syntheses of Cationic, Six-Coordinate Cadmium(II) Complexes Containing Tris(pyrazolyl)methane Ligands. Influence of Charge on Cadmium-113 NMR Chemical Shifts.

Abstract: Treating a thf (thf = tetrahydrofuran) suspension of Cd(acac)2 (acac = acetylacetonate) with 2 equiv of HBF4·Et2O results in the immediate formation of [Cd2(thf)5](BF4)4 (1). Crystallization of this complex from thf/CH2Cl2 yields [Cd(thf)4](BF4)2 (2), a complex characterized in the solid state by X-ray crystallography. Crystal data: monoclinic, P21/n, a = 7.784(2) A, b = 10.408(2) A, c = 14.632(7) A, β = 94.64(3)°, V = 1181.5(6) A3, Z = 2, R = 0.0484. The geometry about the cadmium is octahedral with a square planar arrangement of the thf ligands and a fluorine from each (BF4)- occupying the remaining two octahedral sites. Reactions of [Cd2(thf)5](BF4)4 with either HC(3,5-Me2pz)3 or HC(3-Phpz)3 yield the dicationic, homoleptic compounds {[HC(3,5-Me2pz)3]2Cd}(BF4)2 (3) and {[HC(3-Phpz)3]2Cd}(BF4)2 (4) (pz = 1-pyrazolyl). The solid state structure of 3 has been determined by X-ray crystallography. Crystal data: rhombohedral, R3, a = 12.236(8) A, c = 22.69(3) A, V = 2924(4) A3, Z = 3, R = 0.0548. The cadm...

Synthesis, Reactivity, and Stability of Di- and Trivalent Samarium Amides

Abstract: SmCl3(THF)3 (THF = tetrahydrofuran) reacts with anionic dialkylamides R2N- [R = Cy (cyclohexyl), i-Pr (isopropyl), Ph (phenyl)] to give different products, depending on the nature of the R substituents. Reaction with Cy2NLi in a 1:2 molar ratio formed [(Cy2N)2Sm(μ-Cl)(THF)]2 (1) in 80% yield, whereas reaction with (i-Pr)2NLi under similar conditions gave [(i-Pr2N)2SmCl3(Li(TMEDA))2] (2). Partial loss of THF from complex 1 reorganized the molecule into the tetranuclear (Cy2N)6Sm4Cl6(THF)2 (3). Attempts to reduce complex 1 with a number of reagents gave [(Cy2N)3SmTHF]·toluene (5), while [(Cy2N)4SmLi(THF)] (4) was isolated upon alkylation reactions carried out with either NpLi or NfLi [Np = CH2C(CH3)3; Nf = CH2C(CH3)2Ph]. Direct synthesis of Sm(II) amides from SmI2(THF)2 starting material was successful only in the case of diphenylamide anion (Ph2N-). Depending on the stoichiometry, -ate (Ph2N)4Sm[Na(TMEDA)]2 (6) or neutral [(Ph2N)2Sm(THF)4]·THF (7) was obtained. The crystal structures of 1−7 were demonstrat...

Copper and Bismuth Complexes Containing Dipyridyl gem-Diolato Ligands: BiIII2[(2-Py)2CO(OH)]2(O2CCF3)4(THF)2 , CuII[(2-Py)2CO(OH)]2(HO2CCH3)2, and CuII4[(2-Py)2CO(OH)]2(O2CCH3)6(H2O)2, a Ferromagnetically Coupled Tetranuclear Copper(II) Chain

Abstract: The reactions of the singly deprotonated di-2-pyridylmethanediol ligand (dpmdH-) with copper(II) and bismuth(III) have been investigated. A new dinuclear bismuth(III) complex Bi2(dpmdH)2(O2CCF3)4(THF)2, 1, has been obtained by the reaction of BiPh3 with di-2-pyridyl ketone in the presence of HO2CCF3 in tetrahydrofuran (THF). The reaction of Cu(OCH3)2 with di-2-pyridyl ketone, H2O, and acetic acid in a 1:2:2:2 ratio yielded a mononuclear complex Cu[(2-Py)2CO(OH)]2(HO2CCH3)2, 2, while the reaction of Cu(OAC)2(H2O) with di-2-pyridyl ketone and acetic acid in a 2:1:1 ratio yielded a tetranuclear complex Cu4[(2-Py)2CO(OH)]2(O2CCH3)6(H2O)2, 3. The structures of these complexes were determined by single-crystal X-ray diffraction analyses. Three different bonding modes of the dpmdH- ligand were observed in compounds 1−3. In 2, the dpmdH- ligand functions as a tridentate chelate to the copper center and forms a hydrogen bond between the OH group and the noncoordinating HO2CCH3 molecule. In 1 and 3, the dpmdH- liga...

Effect of Temperature and Pressure on the Volumetric Properties of Branched and Cyclic Ethers

Abstract: The densities of liquid diisopropyl ether, 1,1-dimethylethyl methyl ether, 1,1-dimethylpropyl methyl ether, tetrahydrofuran, tetrahydropyran, and 1,4-dioxane have been determined from 288.15 to 328.15 K at pressures ranging from 0.1 to 8 MPa. The molar volumes (derived from densities) have been fitted to a polynomial as a function of temperature and pressure. Where available, the results have been compared to literature values.

Synthesis, electrochemistry and photoconductivity of oligo- and poly-(1,1′-dihexylferrocenylenes)

Abstract: Oligo- and poly-(1,1′-dihexylferrocenylenes), more soluble than unsubstituted oligo- and poly-(1,1′-ferrocenylenes), were synthesized by reaction of dihexylfulvalene dianion with [FeCl2(thf)2](thf = tetrahydrofuran). Electrochemical properties of pentamers and a hexamer were revealed and compared with theory for a system with a linear combination of redox centres. Charge-transfer complexes of poly(dihexylferrocenylene)(M= 5000, M/Mn= 1.2) with tetracyanoethylene and 7,7,8,8-tetracyanoquino-dimethane exhibit photoconductivity.

Group 4 metal alkoxide complexes as catalysts for olefin polymerization

Abstract: The complexation of 3-tert-butyl-2-hydroxy-5-methylbenzaldehyde I with titanium or zirconium tetrachloride yielded two classes of complexes containing either one or two didentate alkoxide ligands. The structures of three monomeric, six-co-ordinate complexes, cis-dichlorobis(3-tert-butyl-5-methyl-2-oxobenzoyl)titanium(IV)1, cis-dichlorobis(3-tert-butyl-5-methyl-2-oxobenzoyl)zirconium(IV)2 and mer-trichloro(3-tert-butyl-5-methyl-2-oxobenzoyl)(tetrahydrofuran)zirconium(IV)3 were characterized by single-crystal X-ray diffraction. Compounds I and 3 crystallize in the monoclinic space group P21 with Z= 2, compound 1 in Cc with Z= 4 and compound 2 in orthorhombic space group Pbca with Z= 8. In the presence of methylaluminooxane complexes 1–3 give homogeneous catalysts, which for the polymerization of ethylene produced high molecular weight polyethylene with a broad molecular weight distribution.

Evidence for Reversible Ylide Formation: Equilibrium between Free Alkylidenecarbenes and Ethereal Solvent−Alkylidenecarbene Complexes (Oxonium Ylides)

Abstract: The free alkylidenecarbene, 2-butyl-1-hexenylidene 1 (R = Bu), generated by triethylamine-induced α-elimination of 2-butyl-1-hexenyliodonium tetrafluoroborate 7 in tetrahydrofuran undergoes regioselective 1,5-C-H insertions, 1,2-shifts of the butyl group, and electrophilic attack on the tertiary amine followed by protonation to give the cyclopentene 8, the alkyne 9, and the vinylammonium salt 10, respectively. In addition to these free carbene-derived products, the reaction affords the three-component coupling product, the vinyl ether 11, produced through nucleophilic attack of tetrahydrofuran on 1 (R = Bu) generating the oxonium ylide 2 (R = Bu), followed by protonation with subsequent ring-opening of the resulting cyclic oxonium salt 15 (R = Bu) by nucleophilic attack of triethylamine. Reactions were observed to be temperature dependent, as reflected in variations in the product profiles: decreasing the reaction temperature tended to decrease the yields of free alkylidenecarbene-derived products, i.e.,...

Phase diagrams for oil/methanol/ether mixtures

Abstract: One-phase transmethylations of vegetable oils with methanol to form methyl esters occur considerably faster than conventional two-phase reactions. Addition of simple ethers is an efficient method for producing a single phase. Ternary phase diagrams have been determined at 23°C for oil/methanol/ether mixtures; these are useful when applying the one-phase method across a wide range of conditions. Soybean, canola, palm, and coconut oils were used in combination with five ethers, namely, tetrahydrofuran (THF), 1,4-dioxane (DO), diethyl ether (DE), diisopropyl ether (DI), andtert-butyl methyl ether (TBM). All five ethers can produce miscibility for all methanol/oil compositions. The ether/methanol volumetric ratios required for miscibility at a methanol/soybean or canola oil volumetric ratio of 0.20 (5.4 molar ratio) at 23°C are: THF, 1.15; DO, 1.60; DE, 1.38 DI, 1.57; and TBM, 1.57. For THF, this results in one-phase mixtures that contain 65 vol% oil. Soybean and canola oil form identical diagrams. Palm oil requires slightly less ether at the lower methanol concentrations, but coconut oil requires considerably less across the whole concentration range. Acid-catalyzed reactions, when performed at the boiling point of the most volatile component, require less ether than predicted from the diagrams.

Tetrahydrofuran Adducts of Bismuth Trichloride and Bismuth Tribromide

Abstract: The preparation and X-ray crystal structures of the bismuth trihalide−THF (THF = tetrahydrofuran) adducts [BiBr3(THF)3] and [BiCl3(THF)2] are described together with an X-ray powder diffraction derived structure of BiI3.

Method for preparation of aryl substituted alefinic secondary amino compounds

Abstract: Patients susceptible to or suffering from central nervous system are treated by administering an effective amount of an aryl substituted olefinic amine compound, such as (E)-metanicotine. (E)-metanicotine is provided from nicotine. Nicotine is reacted with ethyl chloroformate to produce ethyl N-methyl-N-[4-chloro-4-(3-pyridyl)butyl]carbamate, which then is reacted in the presence of potassium tert-butoxide, tetrahydrofuran and dimethylformamide to produce (E)-metanicotine N-ethyl carbamate, which then is subjected to hydrolysis using hydrochloric acid to produce a reaction mixture containing (E)-metanicotine. The reaction mixture containing (E)-metanicotine is adjusted to a slightly basic pH, and then contacted with dichloromethane. The resulting water immiscible phase then is separated from the aqueous phase. The aqueous phase, then is adjusted to a very basic pH, and then contacted with methyl tert-butyl ether. (E)-metanicotine is taken up by the methyl tert-butyl ether, and after separation of the methyl tert-butyl ether from the aqueous phase, the desired product is separated from the methyl tert-butyl ether.

Polymers of carbonic acid. XVII. Polymerization of cyclobis(tetramethylene carbonate) by means of BuSnCl3 and Sn(II) 2‐ethylhexanoate

Abstract: Dimeric cyclotetramethylene carbonate (TeMC)2 was polymerized in bulk at 185°C. Either nBuSnCl3 or Sn(II)2-ethylhexanoate (SnOct2) were used as catalysts. SnOct2 proved to be somewhat less reactive, but high yields (up to 93%) and high viscosities (νinh up to 0.85 dL/g) were obtained with both catalysts. Viscosity-average molecular weights (Mv) in the range of 50–75 × 103 were determined. The isolated crystalline poly(tetramethylene carbonate)s were characterized by IR, 1H- and 13C-NMR spectra, DSC measurements and WAXD powder pattern. CH2OH and octoate end groups were detected by means of 1H-NMR spectroscopy when SnOct2 was used as initiator, but ether groups were absent. DSC measurements revealed that poly(tetramethylene carbonate) is a slowly crystallizing polymer with a degree of crystallinity below 50% and a melting temperature in the range of 64–69°C depending on the molecular weight. Thermogravimetric analyses proved that polyTeMC decomposes completely between 240 and 340°C without leaving a residue. CO2 and tetrahydrofuran were the main degradation products. © 1996 John Wiley & Sons, Inc.

Autoionization of SmI3 in Tetrahydrofuran. X-ray Crystal Structure of the Ionic Complex [SmI2(THF)5][SmI4(THF)2]

Abstract: SmI3 can be prepared by the reaction of SmI2 with O2 in dry condition. It crystallizes as an ionic complex, [SmI2(THF)5][SmI4(THF)2], from THF, rather than the simple coordination compound SmI3(THF)3.