Showing papers on "Tetrahydrofuran published in 1978"

A Novel Type of Polycondensation Utilizing Transition Metal-Catalyzed C–C Coupling. I. Preparation of Thermostable Polyphenylene Type Polymers

Abstract: Transition metal compounds including NiCl2(bpy) (bpy=2,2′-bipyridine), NiBr2(PPh3)2 (PPh3=triphenylphosphine), PdCl2(bpy), NiCl2, CoCl2, FeCl2, and FeCl3 catalyze polycondensation of di- and polyhalogenated organic aromatic compounds by dehalogenation with magnesium under mild conditions. Poly(p-phenylene), poly(m-phenylene), poly(oxybiphenylene), and poly(phenylenemethylene) were prepared from p-dihalobenzene, m-dichlorobenzene, bis(p-bromophenyl) ether, and α,p-dichlorotoluene. They have a high degree of polymerization and high thermal stability. Poly(p-phenylene), poly(oxybiphenylene), and poly(phenylenemethylene) have regularly repeated structures as proved by IR spectroscopy and X-ray powder diffraction. Polymerization of polyhalogenated aromatic compounds (1,3,5-trichlorobenzene and hexachlorobiphenyl) in tetrahydrofuran (THF) gave copolymers having aromatic nuclei and THF units. Polymerization of the haloaromatic compounds is considered to proceed through a mechanism in which consecutive cycles of ...

Isomerisation of allyl ethers catalysed by the cationic iridium complex [Ir(cyclo-octa-1,5-diene)(PMePh2)2]PF6. A highly stereoselective route to trans-propenyl ethers

Abstract: Allyl alkyl (and aryl) ethers are isomerised by H2-activated [Ir(cyclo-octa-1,5-diene)(PMePh2)2]PF6 in tetrahydrofuran or dioxan at room temperature to the corresponding trans-propenyl ethers (yields 95%; stereoselectivity 97%).

Synthesis and thermal decomposition of homoleptic tert-butyl lanthanide complexes

Abstract: The synthesis of a new class of stable, d-bonded organolanthanide complexes involving the tertiary-butyl ligand: LiLn(t-C/sub 4/H/sub 9/)/sub 4/(tetrahydrofuran)/sub x/ (Ln = samarium, erbium, x = 4; Ln = ytterbium, x = 3) is reported. Solubility in ethyl ether and THF are mentioned. Stability to air and moisture are discussed. Infrared spectra, variable-temperature magnetic susceptibility, and thermal stability of the complexes were used to study the ease of ..beta..-hydride elimination in this class of compound. Thermal decomposition of the samarium derivative was monitored via NMR and showed a decrease in the delta-0.79 singlet and appearance of absorptions for 2-methylpropane during a 12h period in THF at 40/sup 0/C. Decomposition was complete after 16 h. Only other major organic compound observed was 0.5 mol of ethylene.

Poly(styryl)bipyridine: synthesis and formation of transition-metal complexes and some of their physical, chemical, and catalytic properties

Abstract: Poly(styryl)bipyridine, 1, is produced from the reaction of lithiated polystyrene with bipyridine in tetrahydrofuran. Under our conditions, bipyridine becomes bound to 1615% of the phenyl residues. The reaction of 1 with a variety of transition-metal salts can be carried out in a variety of swelling solvents and results in formation of polymer-bound bipyridine transition-metal complexes. The extent of metal incorporation depends on solvent, metal ion concentration, and the identity of the metal species. Zerovalent metal complexes such as@-Ph-bpy-M(CO), (M = Cr, Mo, W) are readily prepared from the reaction of 1 with the metal hexacarbonyl complexes. (Poly(styry1)bipyridyl)palladium acetate is an active catalyst for the hydrogenation of olefins at ambient pressure and temperature. It can also be used to catalyze the acetoxylation of benzene; however, the percent conversion in this case is rather low.

Synthetic routes to nucleoside analogs of N-substituted 1,3-thiazolidines

Abstract: Nucleoside analogs, namely 6-benzamido-9-(3-benzoyl-4(R))-methoxycarbonyl-2,2-dimethyl-thiazolidin-5(S)-yl)-9H-purine (7) and 6-chloro-9-[(3-benzoyl-2,2-dimethylthiazolidin-4(R)-yl)methyl]-9H-purine (8), were obtained from 3-benzoyl-5(S)-benzoyloxy-4(R)-methoxycarbonyl-2,2-dimethylthiazolidine (23) and 3-benzoyl-4(R)-hydroxymethyl-2,2-dimethylthiazolidine (24), respectively, the former, by treatment with 6-benzamidochloromercuripurine and titanium tetrachloride in 1,2-dichloroethane and the latter, by treatment with 6-chloropurine, triphenylphosphine, and diethyl azodicarboxylate in tetrahydrofuran. Compound 23 was obtained from 3-benzoyl-4(R)-methoxycarbonyl-2,2-dimethylthiazolidine (13) by treatment with benzoyl peroxide in refluxing benzene whereas compound 24 was obtained from 13 by borohydride reduction. The stereochemistry of the isomeric sulfoxides 18a and 18b, obtained from 13 by treatment with m-chloroperbenzoic acid, was assigned by means of 1Hmr spectroscopy. Reaction of the sulfoxides 18a and ...

Polymerization of tetrahydrofuran

Abstract: OF THE DISCLOSURE: Polytetrahydrofurans with molecular weights of from 3000 to 4,500 are manufactured by polymerization of tetrahydrofuran with a co-catalyst system of antimony penta-chloride and an organic carboxylic acid and/or a carboxylic acid anhydride.

Uranium(IV) poly(pyrazol-1-yl)borate complexes

Abstract: The uranium(IV) tetrakis[(pyrazol-1-yl)borates], U[HnB(pz)4 –n]4(pz = C3H3N2 and n= 1 or 2), and [UCl2{HB(pz)3}2] have been prepared. Some evidence for the formation of K[UCl2{H2B(pz)2}3],thf (thf = tetrahydrofuran) has also been obtained. The 1H n.m.r., i.r., and electronic spectra of these complexes are discussed.

Preparation of esters of poly-(tetramethylene ether) glycol

Abstract: Esters of poly(tetramethylene ether) glycol are prepared by polymerizing tetrahydrofuran in a reaction mixture which contains, in addition to the tetrahydrofuran, and acylium ion precursor such as acetic anhydride, a polymeric catalyst which contains sulfonic acid groups and, optionally, a carboxylic acid such as acetic acid.

The organometallic chemistry of the alkaline-earth metals. Part 3. Preparation and properties of alkylhalogenometal compounds and related species of calcium, strontium, and barium

Abstract: Alkyliodo-strontium and -barium compounds can be prepared in tetrahydrofuran (thf) solution at –78 °C in good yields, and solids of composition [MR(I)]·nthf (R = Me, Et, Prn, or Bun, M = Sr, n= 2 or 3; R = Et, M = Ba, n= 1) may be isolated. Characterisation of these products by analysis and other studies is reported. Co-condensation of alkyl halides with Ca, Sr, or Ba metal vapour at low temperature in vacuo gives products which contain solvent-free alkylhalogenometal species (10–25%) which are also investigated. Dicyclopentadienyl compounds, [M(cp)2](M = Ca, Sr, or Ba), and di-indenyl compounds, [M(C9H7)2](M = Sr or Ba), are prepared in high yield by co-condensation reactions. Reactions between various unsaturated organic molecules and iodo(methyl)-strontium and -barium compounds are reported and, except from Ph2CO, low yields of alkyl addition products are formed. The thermal decomposition of (ethyl)iodostrontium species produces a variety of hydrocarbon and other products, and studies on this system at 18 °C indicate the occurrence of some saturated C–C bond-cleavage reactions under mild conditions.

Method for preparing ester end-capped copolyether glycols

Abstract: Ester end-capped copolyether glycol is prepared by copolymerizing tetrahydrofuran and an alkylene oxide or cyclic acetal in a reaction mixture which contains, in addition to the tetrahydrofuran and alkylene oxide or cyclic acetal, (1) a polymeric catalyst which contains α-fluoro sulfonic acid groups, And (2) an acylium ion precursor such as acetic anhydride.

Hydrogenation and hydrocracking with highly dispersed supported nickel catalysts

Abstract: This invention relates to a method for making supported nickel catalysts which are characterized as having the nickel in a highly dispersed state, the catalysts and use thereof in hydrogenation, reforming and hydrocarbon synthesis reactions, for example, Fischer-Tropsch reactions. Catalysts prepared by the method of the instant invention, wherein nonaqueous solutions are used in preparing the catalyst, are characterized as having a degree of dispersion of at least 10% greater than similar catalysts prepared by the prior art aqueous impregnation techniques and in some instances show an improved degree of dispersion of more than 50% over the catalysts prepared by the prior art methods. In the method of the instant invention the catalyst is prepared by slurrying a nickel metal precursor dissolved in a nonaqueous organic solvent with a high surface area support, for example, a refractory inorganic oxide, preferably selected from the group consisting of silica and alumina, removing the solvent to obtain a composite of said nickel metal precursor and said support and activating said composite by reducing in hydrogen at conditions sufficient to convert substantially all the nickel metal precursor to nickel metal. The nonaqueous solvent is preferably selected from the group consisting of aldehydes, ketones, ethers and organic nitrogen compounds, for example, acetone, acetonitrile, N-N-dimethyl formamide, hexamethyl phosphoramide, diethylether, tetrahydrofuran, dioxane, methylethyl ketone and acetaldehyde.

Graphite lamellar compounds. A new route to transition metal intercalates

Abstract: Potassium–graphite (C8K) reacts with transition metal salts [Ti(PriO)4, MnCl2·4H2O, FeCl3, CoCl2·6H2O, CuCl2·2H2O, or ZnCl2] dissolved in tetrahydrofuran to give the corresponding transition metal lamellar compounds of graphite; the insertion of the metal atoms between the carbon layers is established by X-ray diffraction methods and the formation of different insertion stages has been observed.

Catalysis and solvent participation in organometallic oxidative additions (Pt0→PtII and SnII→SnIV)

Abstract: The oxidative addition of (i) PhBr to SnR2 or Sn(NR′2)2, or (ii) BunCl to Sn(NR′2)2[R =(Me3Si)2CH, R′= Me3Si] is catalysed by a trace of the more reactive halide EtBr, and when tetrahydrofuran is the solvent, rather than C6H6, a larger proportion of the product is the SnIV-dihalide rather than the SnIV–1 : 1 adduct; the solvent effect is also shown in the [Pt(PPh3)3]–MeI system, and both catalysis (for Pt0[graphic omitted]PtII by azobisisobutyronitrile) and solvent effects are interpreted in terms of radical-chain processes

Preparation of diarenemetal complexes by potassium atom reduction

Abstract: Diarenemetal complexes, including bistoluenetitanium and bis(1-methylnaphthalene)molybdenum, are prepared by condensing potassium atoms into solutions containing metal halides and arenes in tetrahydrofuran at –100°C.

Polybutylene glycol carboxylic acid di:ester(s) - made by polymerisation of purified THF in the presence of carboxylic acid (anhydride) and catalyst

Abstract: Polybutyleneglycol carboxylic acid diesters R-CO-O-(-CH2CH2CH2CH2-O-)n-CO-R' (I) (in which R and R1 are alkyl, COOH-contg. opt. unsaturated aliphatic gp. or COOH-contg. aromatic gp. and n is a 2-200) are made by first treating tetrahydrofuran with strong mineral acids, organic sulphonic acids, silica gel and/or fuller's earth. The treated THF is then polymerised in the presence of >=1 carboxylic acid or carboxylic acid anhydride and a polymerisation catalyst to form the (I). The pretreatment of the THF removes traces of impurities present in technical THF and gives higher rates of polymerisation, reproducible molecular weights and avoidance of discoloured prods. The (I) can be transesterified e.g. with methanol to give the corresponding dihydroxy cpds., which are useful raw materials for the prodn. of polyurethanes.