Showing papers on "Tetrahydrofuran published in 1992"

A novel and practical preparation of .alpha.,.alpha.-difluoro functionalized phosphonates from iododifluoromethylphosphonate

Abstract: The addition reaction of iododifluoromethylphosphonate 1 with alkenes is catalyzed by tetrakis(triphenylphosphine) palladium or copper metal under mild conditions. A variety of functional groups, including alkyl, trimethylsilyl, hydrory, epoxy, acetory, ketone, and ester, in the alkenescould be tolerated under the reaction conditions. Reaction of 2 equiv of 1 with dienes gives the corresponding biphosphonates. Although the palladium complex fails to induce addition of 1 to cycloherene, the addition reaction proceeds readily with copper at 85 o C. With diallyl ether, a tetrahydrofuran derivative is obtained

Process for producing olefin based polymers and olefin polymerization catalyst

Abstract: Olefin polymerization is carried out in the presence of a catalyst comprising, as main components, the following Compounds (A) and (B): (A) a transition metal compound containing a transition metal selected from the IVB Group of the Periodic Table having the formula: M.sup.1 R.sup.1.sub.a R.sup.2.sub.b R.sup.3.sub.c R.sup.4.sub.d wherein M 1 is a Ti, Zr, or Hf atom; a, b, c, and d are independently an integer of 0 to 4; and R 1 , R 2 , R 3 and R 4 are selected from the group consisting of hydrogen atom, oxygen atom, halogen atom, C 1-20 alkyl, C 1-2 alkoxy, C 6-20 aryl, tolyl, xylyl, benzyl, C 1-20 acyloxy, allyl, trimethylsilyl, and (trimethylsilyl)methyl, acetylacetonate, substituted acetylacetonate, dimethyl ether, diethyl ether, tetrahydrofuran, tetrahydrothiophene, ethylbenzoate, acetonitrile, benzonitrile, trimethylamine, triethylamine, tributylamine, N,N-dimethylaniline, pyridine, 2,2'-bipyridine, phenanatholorine, triethylphosphine, triphenylphosphine, ethylene, butadiene, 1-pentene, isoprene, pentadiene, 1-hexene, benzene, toluene, xylene, cyclopheptatriene, cyclooctadiene, cyclooctatriene, and cyclooctatetraene; and (B) a boron compound wherein at least one of Compounds (A) and (B) is carried on a carrier; and an organoaluminum compound. According to the present invention, an olefin homopolymer or a copolymer of olefins having excellent properties such as high bulk density, can be effectively produced without using a great amount of an organoaluminum compound.

Synthesis and polymerization of N‐[4‐N′‐ (α‐methylbenzyl)aminocarbonylphenyl]maleimide

Abstract: A novel type of optically active N-[4-N′-(α-methylbenzyl)aminocarbonylphenyl]maleimide [(R)-MBCP] was synthesized from maleic anhydride, p-aminobenzoic acid, and (R)-methylbenzylamine. Radical homopolymerization of (R)-MBCP was performed in tetrahydrofuran (THF) at 50 and 70°C for 24 h to give optically active polymers having [α]25D = -141° and -129°, respectively. Anionic polymerization of (R)-MBCP with n-butyllithium in THF and N,N-dimethylformamide gave an optically active polymer having −78 to −81° of [α]25D. Radical copolymerizations of (R)-MBCP (M1) were performed with styrene (ST, M2) and methyl methacrylate (MMA, M2) in THF at 50°C. The monomer reactivity ratios (r1, r2) and the Alfrey-Price Q-e values were determined as follows: r1 = 0.009, r2 = 0.091, Q1 = 1.30, e1 = 1.87 in the (R)-MBCP-ST; r1 = 0.27, r2 = 1.21, Q1 = 0.93, e1 = 1.46 in the (R)-MBCP-MMA system. Chiroptical properties of the polymers were also investigated. © 1992 John Wiley & Sons, Inc.

Synthesis and characterization of the paramagnetic [Ag13Fe8(CO)32]4- tetraanion: a cuboctahedral Ag13 cluster stabilized by Fe(CO)4 groups behaving as 4-electron donors

Abstract: The new [Ag 13 Fe 8 (CO) 32 ] 4- paramagnetic cluster anion has been obtained in a mixture with other yet uncharacterized products from the reaction of Na 2 [Fe(CO) 4 ].xTHF with ca. 1.5 equiv of AgBF 4 or AgNO 3 in tetrahydrofuran and acetonitrile solution, respectively. It has been separated from the mixture via differential solubility of the tetrasubstitutred ammonium or phosphonium salts and isolated in a crystalline state as [NMe 3 CH 2 Ph] + and [N(PPh 3 ) 2 ] + salts.

Preferential solvation in mixed binary solvents: ultraviolet–visible spectroscopy of N-alkylpyridinium lodides in mixed solvents containing cyclic ethers

Abstract: Preferential solvation of N-ethyl-4-cyanopyridinium iodide and N-ethylpyrazinium iodide in binary solvent mixtures of cyclic ethers (1,4-dioxane and tetrahydrofuran) and cosolvents (water, monohydroxy alkanols and acetone) has been studied by monitoring the solvatochromic charge-transfer band of the solute. Protic solvents are preferred near the solute except in regions rich in water, methanol or ethanol where molecules of cyclic ethers are preferred over the protic component. This effect has been explained in terms of self-association of the protic solvent through hydrogen bonding. No preferential solvation of N-ethyl-4-cyanopyridinium iodide has been found to occur in 1,4-dioxane–propan-1-oI, 1,4-dioxane-propan-2-oI and 1,4-dioxane–tert-butyl alcohol. This has been explained in terms of specific solute–solvent interactions.

Process for the preparation of chlorosulfate and sulfamate derivatives of 2,3:4,5-bis-o-(1-methylethylidene)-beta-d-fructopyranose and (1-methylcyclohexyl)methanol

Abstract: A process for producing chlorosulfate and sulfamate esters of 2,3:4,5-bis-O-(1-methylethylidene)-β-D-fructopyranose and (1-methylcyclohexyl)methanol is disclosed. The process involves a two step procedure involving in the first step reacting of an alcohol with sulfuryl chloride in the presence of a tertiary or heterocyclic amine base in a solvent selected from the group consisting of toluene, t-butyl methyl ether or tetrahydrofuran to produce a chlorosulfate intermediate, which is preferably stabilized by an aqueous wash and/or treatment with a base, and in the second step reacting of the resulting intermediate with an amine in a solvent selected from the group consisting of t-butyl methyl ether, tetrahydrofuran and lower alkanol.

Organoamido- and Aryloxo-lanthanoids. IV. Synthesis and X-Ray Structures of Low-Coordinate [Yb(O-2,4,6-But3C6H2)3(thf)] and [Yb(O-2,4,6-But3C6H2)2(μ-OH)(thf)]2 (thf = Tetrahydrofuran)

Abstract: Reaction of Yb ( Otbp )2( thf )3( tbp = 2,4,6 But3C6H2; thf = tetrahydrofuran ) with TlOtbp in tetrahydrofuran at room temperature yields thallium metal and Yb( Otbp )3( thf ) (1), which was also obtained by redox transmetallation between TlOtbp and ytterbium metal in refluxing tetrahydrofuran . Some [ Yb ( Otbp )2( µ-OH) (thf)]2 (2) was also isolated from the first synthesis and is derived from hydrolysis of Yb ( Otbp )3( thf ) by traces of water. The X-ray crystal structure of (1) [triclinic, P1, a 21.78(1), b 13.89(2), c 10.461(4)A , α; 109.03(5), β 99.03(3), γ; 98.34(5)o, Z 2, No = 4354 'observed' data refined to R 0.0711 shows novel distorted tetrahedral four coordination for ytterbium [0-Yb-0 angles 90.6(5)-121.8(4)o, which is bonded more strongly to the aryl oxide [Yb-0 1.97(1), 2.02(1), 2.09(1) A ] than to thf [Yb-0 2.35(1) A. The X-ray structure of (2) [triclinic, P1, a 15.61(1), b 13.84(2), c 11.085(4) A, α 99.25(9),, β 94.46(4), γ 96.42(9), Z 1, No = 4718 'observed' data refined to R 0.050] indicates a centrosymmetric hydroxo -bridged dimer with a YbO2Yb core. Ytterbium has irregular five coordination with two bridging hydroxide oxygens [Yb-0 2.217(6), 2.199(6) A; 0-Yb-0' 70.2(2)o, Yb-O-Yb, 109.8(3)o, non-bonding Yb…Yb 3.614(2) A], two phenoxide oxygens [2.047(7), 2.073(6) A], and a more distant thf oxygen [2.363(8) A ].

trans-[Na(thf)][V(N2)2(Ph2PCH2CH2PPh2)2]: structural characterization of a dinitrogenvanadium complex, a functional model for vanadiumnitrogenase

Abstract: Reduction of VCl3(thf)3(thf = tetrahydrofuran) by Na in the presence of bis(phosphines) and N2 yields the complexes trans-[V(N2)2L2]–, which have been structurally characterized by X-ray crystallography for L = Ph2PCH2CH2PPh2, and in solution by 51V NMR spectroscopy for L = Me2PCH2CH2PMe2; 25% of the coordinated N2 is reductively protonated to NH3 and a small amount of N2H4 by HBr.

Deprotection of silyl ethers using 2,3-dichloro-5,6-dicyano-p-benzoquinone

Abstract: In the presence of a catalytic amount of 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), triethylsilyl (TES) and tert-butyldimethylsilyl (TBDMS) ethers are readily hydrolysed to the corresponding alcohols in MeCN–H2O (9 : 1) or tetrahydrofuran (THF)–H2O (9 : 1). TES ethers are cleaved to alcohols more easily than TBDMS ethers. tert-Butyldiphenylsilyl (TBDPS) ethers are stable under these reaction conditions.

Amidification of poly(styrene-co-maleic anhydride) with amines in tetrahydrofuran solution: A kinetic study

Abstract: The kinetics of the reaction between a styrene-maleic anhydride copolymer (SMA) and amines was investigated in tetrahydrofuran solution between 0°C and 40°C. This reaction converts the maleic anhydride (MA) into the corresponding amide-acid, while the consecutive reaction of the generated acid with amine forming a diamide or transformation of the acid-amide into the imide was not observed. The amine reactivity follows the order: 1-octylamine> >1-methyl hexylamine> >1,1-dimethyl propylamine or dibutylamine, demonstrating that the amine reactivity depends, to a large extent, upon its steric hindrance. This reaction is reversible as shown by IR at high temperatures, but the reverse reaction was undetectable between 0 and 40°C. The overall reaction involves spontaneous and autocatalytic reactions, and the overall reaction rate can be written as:-d[MA]/dt=k0[MA][-NH2]+k1[MA][-NH0]2. In the case of 1-octylamine below 0.02 M, the spontaneous reaction dominates (i.e, k0> >k1[-NH2]).

Organolanthanoids. XVII. The Synthesis of Bis(diphenylphosphinocyclopentadienyl)ytterbium(II) and Derived Heterobimetallic Complexes [Yb(thf)n(C5H4PPh2)2Z] [Z=Ni(CO)2, Mo(CO)4 or PtMe2; n = 1 or 2; thf = Tetrahydrofuran]. The X-Ray Crystal-Structure of [Yb(thf)2(C5H4PPh2)2Ni(CO)2]

Abstract: Reaction of diphenylphosphinocyclopentadiene with Yb (C6F5)2 or with ytterbium metal and Hg(C6F5)2 in tetrahydrofuran ( thf ) gives, after workup with toluene, the phosphinoytter-bocene , [Yb (C5H4PPh2)2( thf )]. Treatment with thf or with N,N,N′,N′- tetramethylethane-1,2-diamine ( tmen ) yields [ Yb (C5H4PPh2)2L2] (L = thf or L2 = tmen ). Redox trans- metallation between ytterbium metal and Tl (C5H4PPh2) in l,2-dimethoxyethane ( dme ) gives thallium metal and [ Yb (C5H4PPh2)2(dme )]. The ytterbium-transition metal hetero-bimetallics [ Yb ( thf ) (C2H4PPh2)2Z]. nPhMe [Z = Ni(CO)2, Mo(CO)4 or PtMe2, n = 2/3 or 1] have been prepared by reaction of [ Yb ( thf )(C5H4PPh2)2] with Ni(CO)2(PPh3)2, Mo(CO)4( nbd ) ( nbd = norbornadiene ) or PtMe2(cod) (cod = cycloocta-1,5-diene) in toluene. Treatment of the heterobimetallics with tetrahydrofuran [Z = PtMe2 or Mo(CO)4] or a preparation in thf /toluene [Z = Ni(CO)2] yields [ Yb ( thf )2(C5H4PPh2)2PtMe2]. thf, [ Yb ( thf )2(C2H4PPh2)2Mo(CO)4]. thf and [ Yb ( thf )2 (C5H4PPh2)2Ni(CO)2]. The X-ray crystal structure of the last compound (triclinic, space group Pi, a 14.514(5), b 13.565(1), c 10.866(5) 93.11(2), β 104.65(3), γ 97.25(2)o, U 2045 A 3 , Z 2, 5141 data refined to R 0.031) reveals eight-coordinate ytterbium with a pseudo-tetrahedral arrangement of two thf ligands and the cyclopentadienyl ring centroids of two ή5 -diphenylphosphinocyclopentadienide ligands . The latter are also bonded through phosphorus to the Ni(CO)2 group, resulting in tetrahedral stereochemistry for nickel. Infrared spectroscopy suggests the presence of ytterbium- isocarbonyl bonding in solid [ Yb ( thf )(C2H4PPh2)2Z] [Z = Ni(CO)2 or Mo(CO)4].

Metallacyclohexadiene and metallabenzene chemistry. 6. Chemistry of an (.eta.6-metallabenzene)metal complex, [cyclic] [(.eta.6-Ir-CH-C(Me)-CH-C(Me)-CH)(PEt3)3]Mo(CO)3

Abstract: «Iridabenzene», (Ir-CH-C(Me)-CH-C(Me)-CH)(PEt 3 ) 3 (1), displaces p-xylene from (η 6 -p-xylene)Mo(CO) 3 in tetrahydrofuran solvent, producing (η 6 -iridabenzene)Mo(CO) 3 (2). The solid state structure of 2 has been determined by a single-crystal x-ray diffraction study (monoclinic, P2 1 /n)

The utility of (C5Me5)2Sm in isolating crystallographically characterizable zintl ions. X-Ray crystal structure of a complex of (Sb3)3–

Abstract: (C5Me5)2Sm reacts with Sb(Bun)3 in toluene to from [(C5Me5)2Sm]3(µ-η2:η2:η1-Sb3)(thf)(thf = tetrahydrofuran), which contains a bent (Sb3)3– ion [114.5(1)°] with an average Sb–Sb distance of 2.688(1)A.

Dalton communications. Desulfurization of thiophenes with ruthenium clusters

Abstract: The cluster [Ru3(CO)12] reacts with 2-methylthiophene in refluxing tetrahydrofuran to give products of oxidative addition by C–H cleavage, [Ru3(µ-H)(µ-C4H2MeS)(CO)10](exo and endo), as well as two compounds derived by S–C bond cleavage, [Ru2(µ-C4H3Me)(CO)6] and [Ru4(µ3-S)(µ-C4H3Me)(CO)11](X-ray structure determined), this being the first example of the fragmentation of a thiophene to leave both the inorganic and the organic fragments, S and C4H3Me, co-ordinated in the same organometallic compound.

Novel polynuclear Pt, Ag acetylide complexes. Crystal and molecular structure of [PtAg2(C6F5)2(C≡CtBu)2(CH3COCH3)2]2; a hexanuclear compound containing μ3-η2-bridging acetylide ligands

Abstract: The polynuclear complexes [PtAg 2 (C 6 F 5 ) 2 (C≡CR) 2 ] n (R=Ph Ia, t Bu IIa) have been obtained by reacting either the tetranuclear (NBu 4 ) 2 [Pt 2 Ag 2 (C 6 F 5 ) 4 (C≡CR) 4 ] or (NBu 4 ) 2 [cis-Pt(C 6 F 5 ) 2 (C≡CR) 2 ] with AgClO 4 in the appropriate molar ratio or by reacting cis-Pt(C 6 F 5 ) 2 (THF) 2 (THF=tetrahydrofuran) with [Ag(C≡CR)] n (R=Ph, t Bu) (Pt/Ag ratio 1:2) in acetone at room temperature.

Facile solution routes to hydrocarbon-soluble Lewis base adducts of thorium tetrahalides. Synthesis, characterization, and x-ray structure of ThBr4(THF)4

Abstract: The direct combination of thorium metal turnings with 2 equiv of elemental bromine or iodine in THF solution at 0 °C provides white crystalline ThX 4 (THF) 4 (X=Br, 1; X=I, 2; THF=tetrahydrofuran), in 70-80% isolated yield. These new compounds are soluble in hydrocarbon solvents and react readily with oxygen- and nitrogen-donor ligands in toluene solution to give ThBr 4 py 4 (3), ThI 4 py 4 (4), ThBr 4 (NCMe) 4 , (5), and ThBr 4 (DME) 2 (6) in high yield (py=pyridine, DME=1,2-dimethoxyethane)

Synthesis of ring‐shaped polyisoprene

Abstract: Cyclization of α,ω;-dilithiopolyisoprenes has been achieved in hexane solution in the presence of tetrahydrofuran (15% in volume) at −40 to - 50°C. Using as linking agent the non-conjugated diene 1,2-bis(isopropenyl-4-phenyl)-ethane, macrocyclic polyisoprenes could be obtained with yields of at least 90%, even for molecular weights as high as 30 000 mol g−1. With SiCl4 as coupling agent no gelation occurred and yields of about 70% in cyclic dimers, probably bicyclic, have been observed. These results are compared to those obtained by various authors with α,ω;-dilithiopolystyrenes or α,ω;-disodiopolystyrenes and are attributed mainly to the presence, in the polyisoprene case, of predominant cyclic aggregates even at low organolithium concentration.

Enhanced stability of potassium solutions in tetrahydrofuran containing 15-crown-5

Abstract: The process of potassium metal dissolution in tetrahydrofuran containing 15-crown-5 and the properties of the solution were studied. The changes in concentration of potassium anions and electrons as a function of time were determined by means of 39 K NMR and ESR spectroscopie. Enhanced stability of the solution with 15-crown-5 relative to that containing 18-crown-6 or 12-crown-4 was revealed

Organosamariums from Reaction of Alkyl Halides with Samarium(II) Derivatives

Abstract: Bis(cyclopentadienyl)samarium (SmCp2) and alkyl halides gave organosamariums stable at -10 °C and reactive towards electrophiles. Samariuim(II) iodide did not give stable alkylsamariums. However internal quenching with ethan[2H]ol provided high yields of the monodeuterated alkane. In the latter case, an unstable organosamarium species was formed which needed an in situ trapping agent. The samarium analogue of the Barbier reaction is discussed in the light of these results. Some additional Barbier experiments were performed in the presence of samarium(II) iodide in tetrahydrofuran. It is concluded that under standard conditions (in the absence or presence of hexamethylphosphoramide) an unstable and reactive organosamarium species is formed which is immediately trapped by the carbonyl compound.