Showing papers on "Tetrahydrofuran published in 1999"

New o-acyloxime photopolymerization initiator

Abstract: PROBLEM TO BE SOLVED: To obtain a new O-acyloxime useful as a photopolymerization initiator, having excellent heat stability and storage stability, capable of exhibiting high reactivity in photopolymerization technology, and capable of being easily synthesized and handled. SOLUTION: Compounds of formulas I-IV (R1 in phenyl or the like; R2 is a 2-12C alkanoyl or the like; R3 to R7 are each H, a halogen, a 1-12C alkyl or the like; R1' is a 2-12C alkoxycarbonyl or the like; R4' to R6' are each H, a halogen, a 1-12C alkyl, a cyclopentyl or the like; M is a 1-12C alkylene, cyclohexylene or the like), for example, 1-(4-phenylsulfany-phenyl)-butane-1,2- dione 2-oxime-O-benzoate. The compounds of formula I-IV each is obtained, for example, by reacting the corresponding oxime with an acyl chloride or anhydride in the presence of a base such as a tertiary amine in an inert solvent such as tetrahydrofuran or in a basic solvent such as pyridine.

Synthesis and Crystal Structure of UO2Cl2(THF)3: A Simple Preparation of an Anhydrous Uranyl Reagent

Abstract: Reaction of UO2Cl2·x(H2O) (x = 1, 3) with 6 equiv of ClSiMe3 in THF provides yellow UO2Cl2(THF)3. The single-crystal X-ray structure of the complex reveals a monomer in which the U is coordinated in a pseudopentagonal bipyramidal fashion by two apical oxo groups, three equatorial THF ligands, and two Cl groups. Upon drying the compound, dimeric [UO2Cl2(THF)2]2 is isolated. This compound is a suitable anhydrous starting material for a variety of uranyl coordination compounds.

2- (purin-9-yl) -tetrahydrofuran-3,4-diol derivatives

Abstract: There are provided according to the invention, novel compounds of formula (I) wherein R?1, R2 and R3? are as described in the specification, processes for preparing them, formulations containing them and their use in therapy for the treatment of inflammatory diseases.

Monomers for adhesive polymers, 2. Synthesis and radical polymerisation of hydrolytically stable acrylic phosphonic acids

Abstract: Acrylic groups containing phosphonic acids were synthesised by ether formation of ethyl a-chloromethylacrylate with hydroxyalkylphosphonates and subsequent hydrolysis to the corresponding phosphonic acid a-methyl-substituted acrylates. The structure of the synthesised monomers was confirmed by elemental analysis, IR, 1 H NMR, 13 C NMR and 31 P NMR spectroscopy. The monomers are stable in aqueous ethanol. The radical polymerisation of the monoacrylates in tetrahydrofuran with 2,2'-azobisisobutyronitrile (AIBN) results in soluble polymers, whereas a phosphonic acid diacrylate results in a cross-linked polymer.

Coupling of 2-Substituted 1-Fluorovinylstannanes with Organic Halides Catalyzed by Palladium(0)/Copper(I) Iodide. A Mild and Stereospecific Method to Monofluoroolefins.

Abstract: The palladium-catalyzed cross-coupling reactions of (E)- or (Z)-1-fluorovinylstannanes with aryl iodides and vinyl iodides provide good yields of stereoisomerically pure substituted fluoroolefins with retention of the double bond geometry. The reaction takes place with copper(I) iodide present as a cocatalyst at ambient temperature or in refluxing tetrahydrofuran and is tolerant of a variety of functional groups. Highly functionalized and stereoisomerically pure monofluorovinyl ketones also were obtained under mild conditions by the coupling of 1-fluorovinylstannanes with acid chlorides. 1H-{19F} NOE NMR experiments unequivocally established the stereochemistry of the coupling products E-14 and Z-14.

Selective Monodesulfonylation of N,N-Disulfonylarylamines with Tetrabutylammonium Fluoride

Abstract: The monodesulfonylation reaction of N, N-bis(methylsulfonyl)-, N, N-bis(phenylsulfonyl)-, and N, N-bis(p-tolysulfonyl)arylamines easily proceeded using tetrabutylammonium fluoride in tetrahydrofuran under mild conditions to give the corresponding N-monosulfonylarylamines in excellent yields.

“Anchor effect” in poly(styrene maleic anhydride)/TiO2 nanocomposites

Abstract: Multi-component composites or hybrid materials of inorganic matter and organic polymers have been reported recently [1–3]. It is well known that styrene and maleic anhydride usually copolymerize in an alternating way, resulting in a poly(styrene maleic anhydride) (PSMA) alternating copolymer with highly regular anhydride groups on backbone chains which may provide regular sites for combination with other substances. Nanocomposites of inorganic materials in organic matrices are of a particular interest, which combine typical properties of organic polymers (e.g., elasticity, transparency or specific absorption of light, dielectric properties) with the advantages of nanoparticles, particularly, the high specific surface and the high ratio of surface atoms to innersphere atoms. Among the nanostructured materials investigated, nanometer-sized TiO2 particles are technologically important in many applications, which greatly increases their activity as a catalyst and sensitivity as a sensor [4, 5]. However, a serious problem is its aggregation with varied ambient conditions. In this paper, we report the synthesis of PSMA/TiO2 nanocomposites via a multi-component solution. The PSMA can provide functional groups, which anchor TiO2 particles and prevent them from aggregating. The PSMA gives a 1 : 1 alternating structure consisting of styrene and maleic anhydride, as shown in Fig. 1 [6]. PSMA was dissolved in THF (tetrahydrofuran) with stirring at 40 ◦C for 12 h, then acacH (acetylacetone) and deionized water (mol ratio 1 : 25) were dropped into the polymer solution. The acacH was used to reduce the hydrolyzing rate of Ti(OBu-n)4 (tetrabutyl titanate). The pH value of the mixture was adjusted to about 1.7 with concentrated hydrochloric acid (37%). After stirring for 20 min, the precursor Ti(OBu-n)4 dissolved in THF was dropped into the mixture. After that, the reactant mixture was heated to 60 ◦C, and stirred at this temperature for 4 h. Finally, the homogeneous mixture was sealed in a baking oven and kept at room temperature for 4 days. Several punctures were made in the sealing adhesive tape with a pin to volatilize THF at 40 ◦C in flowing air, and thus orange-red and optically transparent samples of PSMA/TiO2 composites were obtained. The samples were dried under vacuum at 80 ◦C for 2 days. FT-IR spectra of the samples indicate the existence of absorbed water from air, which gave rise to an absorption band [7] at 1620 cm−1, and especially, the broad band around 3500 cm−1. The IR spectrum of PSMA (Fig. 2a) shows that the adsorption bands at 1858 and 1778 cm−1 which are characteristic bands of the copolymer of styrene maleic anhydride [8], which are attributed to asymmetrical and symmetrical νC=O (C=O stretching vibration) of the maleic anhydride moiety [9], respectively. The peaks at 1600, 1500 and 1450 cm−1 are the νC=C of the phenyl group on the backbone chain [9, 10]. The band at 1214 cm−1 is attributed to the νC–O–C of maleic anhydride units, for a five-numbered cyclo-anhydride shows a νC–O–C band at 1310∼1210 cm−1 wavenumber [7]. The band at 700 cm−1 is the δC=C (C=C bending vibration) of the phenyl group [10], which was used as an internal reference to offset differences in the thickness of IR samples. The spectrum of pure TiO2 (Fig. 2b) shows a strong and broad adsorption peak between 650 and 400 cm−1, which is accounted for by vibrations of Ti–O–Ti groups [11], and regarded as the characteristic peak for TiO2 [12]. The IR information of both

Amino or styryl compound and organic electroluminescent element using the same

Abstract: PROBLEM TO BE SOLVED: To obtain a new amino or styryl compound which gives organic electroluminescent elements having excellent heat resistance and long lives. SOLUTION: A compound of formula I (Ar1 is a 6-30C divalent or trivalent aromatic group; X1 and X2 are each styryl, a styrylaryl, a diarylamino or a diarylaminoaryl; (n) is 0 or 1; D1 is a 16-60C monovalent group having four or more carbon rings, when either of X1 or X2 is styryl or styrylaryl, or a 20-60C monovalent aromatic group having five or more carbon rings, when X1 and X2 are each the other). For example, a compound of formula II. The compound of formula I is obtained by preparing a Grignard reagent from a compound of formula III and then reacting the Grignard reagent with a compound of formula IV and Ni(dppp)Cl2 in anhydrous tetrahydrofuran.

2,5-Diphenyl-3,4-bis(trimethylsilyl)-1-phosphacyclopentadienide as a Ligand at Calcium, Strontium, and Tin(II)

Abstract: The addition reaction of tetrakis(tetrahydrofuran)calcium or -strontium bis[bis(trimethylsilyl)phosphanide] with diphenylbutadiyne in toluene yields nearly quantitative amounts of slightly yellow tetrakis(tetrahydrofuran)calcium (1) and -strontium bis[2,5-diphenyl-3,4-bis(trimethylsilyl)phosphacyclopentadienide] (2). Due to the fact that the alkaline earth metal bis[bis(trimethylsilyl)amides] do not react with alkynes, colorless (tetrahydrofuran)calcium bis[2,5-bis(tert-butyl)-1-azacyclopentadienide] (3) was prepared by the transmetalation of N-trimethylstannyl-2,5-bis(tert-butyl)-1-azacyclopentadiene with distilled calcium. The metathesis reaction of 1 and 2 with SnCl2 gives yellow tin bis[2,5-diphenyl-3,4-bis(trimethylsilyl)phosphacyclopentadienide] (4).The phosphorus atoms of 1 and 2 are in a planar environment with long M−P distances, whereas in 4 the P atoms comprise a pyramidal coordination sphere. The tin−carbon distances are larger than observed in stannocenes which could be interpreted as a stann...

(Phosphine)gold(I) trifluoromethanesulfonates, trifluoroacetates and trichlorothioacetates†

Abstract: Stable, crystalline (phosphine)gold(I) trifluoroacetates of the type (R3P)AuOC(O)CF3 have been prepared in high yield from the corresponding chloro complexes with AgOC(O)CF3 in tetrahydrofuran for R = Me, Ph or o-Tol. The crystal structure of (Me3P)AuOC(O)CF3 features trimers with two short aurophilic Au· · ·Au contacts in an angular Au· · ·Au· · ·Au unit. Trichlorothioacetic acid has been aurated (in high yield) using {[(R3P)Au]3O}+BF4– and NaBF4 in dichloromethane to give equally stable compounds (R3P)AuSC(O)CCl3 with R = Me, Ph or o-Tol. In these products the trichlorothioacetate group is exclusively sulfur bonded to the gold atom. The methyl and o-tolyl compounds are dimers in the solid state, but association is based on only very long intermolecular Au· · ·S and Au· · ·Cl contacts, respectively. (Triphenylphosphine)gold thioacetate was prepared similarly, but the product is thermally unstable in both the solid and solution state. It thus appears that the presence of the halogen substituents is essential for the stability of the present compounds, which are useful aurating agents and can be employed for the controlled deposition of gold. [Tri(o-tolyl)phosphine]gold chloride was converted into the trifluoromethanesulfonate (triflate) in 95% yield by treatment with AgOS(O)2CF3 in tetrahydrofuran. The crystal structure determination of the CH2Cl2 solvate revealed non-ionic, molecular components [Au–O 2.110(3) A, S–O–Au 120.4(2)°], which are associated into dimers via hydrogen bonds [O· · ·H–C 170.2°, C–H 0.969 A, H· · ·O 2.575 A] with two CH2Cl2 molecules.

Rhodium-Promoted Linear Tetramerization and Cyclization of 3,3-Dimethylbut-l-yne.

Abstract: With tetrahydrofuran as the solvent [Rh(thf)(2)(cod)](+) promotes the selective coupling of tBuC(2)H to form triene-yne 1; at high alkyne concentrations, however, an unusual C-H activation process intervenes, leading to the formation of complex 2, which contains two linked five-membered rings. cod=1,5-cyclooctadiene.

Generation and Reactions of an Overcrowded Diaryldilithiosilane

Abstract: Exhaustive reduction of dibromo(2,6-diisopropylphenyl){2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}silane with excess amount of lithium naphthalenide (more than 4 molar amounts) in tetrahydrofuran at −78 °C gave the corresponding dilithiosilane, the effective formation of which was confirmed by the trapping experiments with a variety of electrophiles. The diaryldilithiosilane thus generated was found to be stable at −78 °C but undergo an intramolecular proton abstraction to give the lithium-migrated dilithiosilane.1

Coexistence of Activated Monomer and Active Chain End Mechanisms in Cationic Copolymerization of Tetrahydrofuran with Ethylene Oxide

Abstract: Cationic copolymerization of tetrahydrofuran (THF) with ethylene oxide (EO) in the presence of diols proceeds with simultaneous participation of secondary and tertiary oxonium ions. This process comprises therefore some features of the activated monomer (AM) and the active chain end (ACE) mechanisms. The mechanism of copolymer formation was evaluated, and the kinetics of competing reactions involving both secondary and tertiary oxonium ions with nucleophiles present in the system was studied. The apparent rate constants were derived, allowing the estimation of the influence of copolymerization conditions on the composition and microstructure of copolymers.

A Novel Breakable Cross-Linker and pH-Responsive Star-Shaped and Gel Polymers

Abstract: A bifunctional methacrylate monomer, namely, ethylene glycol di(1-methacryloyloxy)ethyl ether (1), was prepared through the addition reaction between ethylene glycol divinyl ether and methacrylic acid. 1 was used as a cross-linker in the preparation of a star-shaped poly(methyl methacrylate) [poly(MMA)], a branched soluble poly(MMA), and a polymer gel. The addition of 1 to an anionically prepared living poly(MMA) solution generated a star-shaped polymer with a central poly(1) gel core and several poly(MMA) arms. On the other hand, when MMA and 1 were simultaneously added to a tetrahydrofuran (THF) solution of an anionic initiator, a branched soluble poly(MMA) or a polymer gel was obtained, depending on the amount of 1. The cross-linking points in the above polymers could be easily broken by hydrolysis under acidic conditions, leading to linear polymers. In contrast to the common polymer gels, the present polymer gel could be broken to soluble polymers in an acidic medium. However, it was just swollen in a...

Synthesis and crystal structures of cationic lanthanide( III ) monoporphyrinate complexes

Abstract: Reactions of an excess of Ln[N(SiMe3)2]3·x[LiCl(THF)3], generated in situ from the reaction of anhydrous LnCl3 with 3 equivalents of Li[N(SiMe3)2] in tetrahydrofuran, with 5,10,15,20-tetrakis(p-methoxyphenyl)porphyrin (H2TMPP) in refluxing tetrahydrofuran–bis(2-methoxyethyl) ether solution (1∶6 v/v) gave the cationic monoporphyrinate complexes [LnIII(TMPP)(H2O)3]Cl (Ln = Yb; 1, Er, 2, or Y 3), and with 5,10,15,20-tetrakis(p-tolyl)porphyrin (H2TTP) gave [YbIII(TTP)(H2O)2(THF)]Cl 4. The structures of compounds 1–4 have been established by X-ray crystallography. Metathesis of 1 with an excess of AgBF4 gave the unexpected neutral monoporphyrinate complex [AgII(TMPP)] 5 whose structure was also determined. Compound 1 catalysed the cyclotrimerization of phenyl isocyanate.

A Non-Metallocene Hydride of Titanium(III)

Abstract: Several titanium(m) complexes incorporating the chelating diamidoamine ligand [(Me3SiNCH2CH2)2NSiMe3]2-[NN2] are described. The reaction between Li2[NN2] and TiCl3(THF)3 (THF = tetrahydrofuran) resulted in the formation of the dimeric titanium(III) chloride {TiCl[NN2]}2 1, from which the monomeric titanium(III) alkyl Ti{CH(SiMe3)2}[NN2] 2 could be synthesized via a salt metathesis route. The alkyl complex 2 was found to react with hydrogen gas to form the thermally stable, dimeric, diamagnetic titanium(III) hydride {TiH[NN2]}2 3; density functional calculations on a simplified model system of 3 indicated the presence of a weak Ti-Ti s- interaction. The solid-state structures of 1, 2, and 3 are described.

Thiol−Thione Tautomerism in Thioformic Acid: Importance of Specific Solvent Interactions

Abstract: Attempts have been made to resolve a discrepancy in the recent literature concerning the thiol−thione tautomerism of monothioformic acid. Whereas Kato et al. (J. Am. Chem. Soc. 1996, 118, 1262) reported that the thione acid [RC(S)OH] exists predominantly in polar solvents at very low temperatures, Jemmis et al. (J. Phys. Chem. A 1997, 101, 7389) found, from ab initio calculations including continuum treatments of the solvent effect, that the thione forms HC(S)OH and CH3C(S)OH are less predominant, irrespective of the solvent polarity. However, both groups of authors have suggested specific solvation as a possible reason for the discrepancy and called for further studies. Indeed, the present work points out that specific interactions between polar and aprotic solvent molecules such as dimethyl ether and tetrahydrofuran and H atoms of the carboxylic function, giving strong hydrogen bonded O−H···O complexes, are likely to tip the balance in favor of the thione acids. This fact is supported by calculations ca...

Synthesis and characterization of novel poly(amide‐imide)s containing hexafluoroisopropylidene linkage

Abstract: A series of novel soluble poly(amide-imide)s were prepared from the diimide-dicarboxylic acid, 2,2-bis[N-(4-carboxyphenyl)-phthalimidyl]hexafluoropropane, with various diamines by the direct polycondensation in N-methyl-2-pyrrolidinone containing CaCl 2 using triphenyl phosphite and pyridine as condensing agents. All the polymers were obtained in quantitative yields with inherent viscosities of 0.78-1.63 dL g -1 . The polymers were amorphous and readily soluble in aprotic polar solvents such as N-methyl-2-pyrrolidinone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide as well as in less polar solvents such as pyridine and y-butyrolactone, and also in tetrahydrofuran. The polymer films had tensile strength of 84-129 MPa, an elongation at break range of 6-22%, and a tensile modulus range of 2.0-2.7 GPa. The glass transition temperatures of the polymers were determined by DSC method and they were in the range of 240-282°C. These polymers were fairly stable up to a temperature around or above 400°C, and lose 10% weight in the range of 450-514°C and 440-506°C in nitrogen and air, respectively.

Co-ordination chemistry of macrocyclic compounds with dangling phosphines. Unusual NMR shifts in metallo-calix[4]arenes†

Abstract: The chelating behaviour of three polyphosphines, cone-5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(diphenylphosphinomethoxy)calix[4]arene L1, cone-5,11,17,23-tetra-tert-butyl-25,26,27-tris(diphenylphosphinomethoxy)-28-methoxycalix[4]arene L2, and cone-5,11,17,23-tetra-tert-butyl-25,26-bis(diphenylphosphinomethoxy)-27,28-dihydroxycalix[4]arene L3, has been investigated. When [Mo(CO)3(C7H8)] and tetraphosphine L1 are heated together under reflux in tetrahydrofuran (THF) complex [Mo(CO)3L1] 1 is formed, for which the calixarene behaves as a fac-bonded tridentate ligand with one phosphine remaining free. Similar fac-chelating behaviour is found with [Mo(CO)3L2] 2, which is obtained from triphosphine L2. Formation of this latter complex is accompanied by the calixarene matrix adopting a partially flattened-cone conformation. In contrast, the conventional cone conformation is maintained in the trinuclear complex [(AuCl)3L2] 3, obtained quantitatively by treating L2 with [AuCl(THT)] (THT = tetrahydrothiophene). Reaction of L1 with [RuCl2(DMSO)4] (DMSO = Me2SO) in CH2Cl2 results in selective formation of the deep purple complex [RuCl2L2] 4 built around a fac-trigonal bipyramidal RuCl2P3 structure. Complex 4 reacts reversibly and stepwise with two equivalents of CH3CN. The calculated stability constants, as determined from a spectrophotometric titration, are log β1 = 9.1 and log β2 = 12.4. The proximally substituted calixarene L3 reacts with [PtCl2(COD)] (COD = cycloocta-1,5-diene) to afford the chelate complex cis-[PtCl2L3] 5. As revealed by an X-ray diffraction study, the P–Pt vectors point away from the calixarene axis in the solid state. The axial H atom of the C6H2CH2 group located between the two phosphine units of L3 undergoes a significant low-field shift upon complexation (δ 7.32 vs. 4.48 for free L3) presumably due to interaction with the lone pairs of the two neighbouring O-atoms. Complex 5 displays dynamic behaviour in solution, which can be rationalized as follows: (i) a fast flip-flop motion of the hydroxyl groups at low temperature, alternately forming hydrogen bonds with each of two neighbouring phenolic oxygens; (ii) a reversible inversion of the phenol ring through the lower-rim annulus, triggered by breakage of the hydrogen bonds at higher temperature. Reaction of [PtCl2(COD)] with one equivalent of L1, followed by in situ oxidation with NH2CONH2·H2O2, results in formation of a chelate complex, containing two proximal phosphines bonded to platinum as in 5 and two pending CH2P(O)Ph2 phosphine oxides. Stepwise reaction of [PtCl2(COD)] with one equivalent of L1 and two equivalents of [AuCl(THT)] gives a cis complex in which the platinum atom is again bonded to two proximal phosphines and the two AuCl units to the other two phosphine arms. As in 5, an anomalous low-field shift is observed for the axial C6H2CH belonging to the platinocycle of these complexes.

Optimizing lipase activity, enantioselectivity, and stability with medium engineering and immobilization for β‐blocker synthesis

Abstract: Lipase from Pseudomonas cepacia showed poor activity and moderate enantioselectivity (E) in pure aqueous systems for hydrolysis of a racemic mixture (+/-)-1-chloro-2-acetoxy-3-(1-naphthyloxy)-propane, which is a potential intermediate for beta-blocker synthesis. However, addition of polar organic solvents to the reaction can change both the activity and the enantioselectivity for this chiral reaction significantly. It was observed, in general, that the activity increases and the enantioselectivity decreases with the increase in the polarity of the organic solvent added to the medium. Among the six solvents chosen (i.e., dimethylsulfoxide [DMSO], 1, 4-dioxane, dimethylformamide [DMF], acetone, 1-propanol, and tetrahydrofuran [THF]), maximum activity and minimum enantioselectivity was obtained with DMSO, whereas minimum activity and maximum enantioselectivity was obtained with THF as the cosolvents. In the subsequent studies, native or polyethylene glycol (PEG)-modified lipase was immobilized by entrapping in Caalginate gel beads. In a fixed-bed continuous reactor containing these catalyst beads, the enzyme was found to be at least three times more enantioselective than the native form in a batch reactor. This fixed-bed reactor with the beads could be operated with high concentration of acetone (33% v/v) for about 1 month without a significant loss of enzyme activity and enantioselectivity.

Macrocycles, 8. Multiblock copoly(ether-esters) of poly(THF) andε-caprolactone via macrocyclic polymerization

Abstract: It has been demonstrated that the “polycondensation” of poly(tetrahydrofuran)-diols with dibutlytin dimethoxide in bulk yields tin-containing poly(THF) macrocycles and not linear polycondensates. These macrocycles were characterized by 1H and 119Sn NMR spectroscopy, by elemental analyses, viscosity measurements and mass spectroscopy. Furthermore, the stoichiometric insertion of γ-thiobutyrolactones was studied. The tin-containing macrocyclic poly(THF)-2 000 was used as macrocyclic initiator for the polymerization of e-caprolactone. The resulting macrocyclic block copoly(ether-esters) were reacted in situ with terephthaloyl chloride, succinyl chloride, or sebacoyl chloride. High temperatures proved to be advantageous for this polycondensation step. Number-average molecular weights (Mn's) up to 50 000 were obtained with polydispersity indices in the range of 1.6–1.7. The resulting tin-free multiblock copoly(ether-ester)s have the properties of thermoplastic elastomers and show good film-forming properties.