Showing papers on "Tetrahydrofuran published in 1982"

Highly Selective Carbon-Carbon Bond Forming Reactions Mediated by Chromium(II) Reagents

Abstract: A low valent chromium reagent is generated from chromium(III) chloride and a half mol of lithium aluminum hydride in tetrahydrofuran. The reagent behaves similarly to anhydrous chromium(II) chloride, which is commercially available, and reduces allylic halides to produce unisolable allylchromium species which add efficiently to aldehydes or ketones with high degree of stereo- and chemoselectivity. Particularly, high threo selectivity is observed in the reaction of aldehydes and 1-bromo-2-butene and is ascribed to a chair-like six-membered transition state. Simple reduction of allylic and benzylic halides produces biallyls and bibenzyls, while gem-dibromocyclopropanes afford the corresponding allenes in excellent yields.

The nature of dilute solutions of sodium ion in water, methanol, and tetrahydrofuran

Abstract: Monte Carlo statistical mechanics simulations have been carried out for dilute solutions of Na+ in water and tetrahydrofuran (THF) at 25 °C and 1 atm. The intermolecular interactions were described by Lennard‐Jones and Coulomb terms in the TIPS format including the TIPS2 parameters for water–water interactions. In conjunction with previous simulation results for Na+ in methanol, the present study provides detailed insights into the nature of ionic solvation by dipolar protic and aprotic solvents. In agreement with x‐ray data, the coordination number of Na+ in water is six, identical to the value obtained for Na+ in methanol. However, the coordination number of Na+ in THF fluctuates between five and six. Consistently, the ion–solvent interaction is less exothermic in THF compared to the other two solvents. However, the heat of solution which is the sum of two large opposing contributions, viz., the ion–solvent energy and the solvent reorganization energy, does not differ much for the three solvents. In all...

Functionalization of polymeric organolithium compounds. Carbonation

Abstract: The carbonation reactions of polymeric organolithium compounds with high purity, gaseous carbon dioxide have been investigated in benzene and benzene/tetrahydrofuran (75/25) solutions. The polymers investigated were poly(styryl)lithium, poly(isoprenyl)lithium, and poly(styrene-b-isoprenyl)lithium. In Benzene solution the products are a mixture of the carboxylic acid and the ketone (dimer). No tertiary alcohol product (trimer) was observed. In benzene/tetrahydrofuran solution, the quantitative carboxylation of chain ends was observed.

Stripping compositions and methods of stripping resists

Abstract: Stripping compositions for removing resist materials from substrates comprise compositions of a 2-pyrrolidinone compound and tetrahydrofuran compound. Either or both of polyethylene glycol and a diethylene glycol monoalkyl ether may be added to provide even more effective stripping compositions.

Specular Lithium Deposits from Lithium Hexafluoroarsenate/Diethyl Ether Electrolytes

Abstract: : A new class of aprotic organic electrolytes in which to cycle the lithium electrode has been developed. Blends of diethyl ether (DEE) and tetrahydrofuran (THF) incorporating LiAsF6 have been found to afford Li electrode cycling efficiencies in excess of 98%. In addition, specular deposits of up to 10 C per sq cm may be plated from these systems. The kinetic stability of these blended electrolytes toward Li is thought to be due to the formation of a protective lithium ethoxide film. (Author)

SYNTHESIS OF METHYL-t-BUTYL ETHER FROM METHANOL AND ISOBUTENE USING A CLAY CATALYST

Abstract: The acid-catalyzed reaction between methanol and isobutene to give methyl-t-butyl ether may be carried out using a cation-exchanged smectite as the catalyst. In 1,4-dioxan solvent at 60°C smectites exchanged with Al3+, Fe3+, or Cr3+ give yields of ∼60% after 4 hr, whereas smectites exchanged with Cu2+, Pb2+, Ni2+, Co2+, Ca2+, and Na+ give less than ∼8% yield. The reaction is efficient only when certain solvents are used, e.g., with Al3+-smectite the yield is ∼5% when using 1,2-dimethoxyethane, diethyleneglycol diethylether, n-pentane, tetrahydropyran, N-methylmorpholine, or tetrahydrofuran solvents compared with ∼60% using 1,4-dioxan solvent (4 hr). Moreover, the effective solvents depend somewhat on the clay interlayer cation. The use of tetrahydrofuran and tetrahydropyran gives ∼35% yields at 60°C (4 hr) with Fe3+- or Cr3+-smectites but ∼4% yield with Al3+-smectite.

Water and oil repellent for glass surface

Abstract: PURPOSE: To provide the titled water and oil repellent capable of imprating a glass surface with water-repellency, oil-repellency and stain resistance for a long period, by mixing water glass to a silane compound containing polyfluoroalkyl group. CONSTITUTION: The objective water and oil repellent is prepared in the form of a solvent solution, etc. by mixing (A) a compound having polyfluoroalkyl group (hereinafter called as Rf group) and represented by the formula (Rf is 4W16C perfluoroalkyl containing one or more ether bonds; Q is bivalent orgnaic group; Z is 1W4C lower alkyl; Y is halogen, alkoxy or RCOO-), e.g. RfCH 2 CH 2 SiCl 3 , or the partial hydrolytic condensate of said compound, and (B) water glass (e.g. sodium metasilicate) with (C) an organic solvent (e.g. tetrahydrofuran). The weight ratios of the Rf group-containing silane compound to water glass is preferably 1:0.1W5. USE: Treatment of glass plate, mirror, etc. COPYRIGHT: (C)1983,JPO&Japio

Diastereoselektive Synthese von β‐Methyl‐homoallylalkoholen durch lk‐Addition von (2‐Butenyl)triphenoxytitan an Aldehyde

Abstract: Diastereoselective Synthesis of β-Methyl-homoallylic Alcohols by lk-Addition of (2-Butenyl)triphenoxytitanium to Aldehydes (2-Butenyl)triphenoxytitanium, prepared in situ from (2-butenyl)magnesium halogenide and chlorotriphenoxytitanium in tetrahydrofuran solution, adds to aldehydes with like (Re,Re/Si,SiRe*,Re*) relative topicity in diastereoselectivities of 80–99%.

Polyethers, their preparation, and their use as lubricants

Abstract: Polyethers obtainable by polymerisation of ethylene oxide and/or propylene oxide or butylene oxide, an alpha -alkylene oxide, tetrahydrofuran and in the presence of a bifunctional compound, can be used as lubricants.

Chemistry of o-xylidene–metal complexes. Part 1. o-Xylidene-magnesium reagents as metallocyclic precursors and synthesis of [Pt(CH2C6H4CH2-o)(cod)](cod = cyclo-octa-1,5-diene); the X-ray crystal structure of the macrometallocycle [{Mg(CH2C6H4CH2-o)(C4H8O)2}3]

Abstract: A high-yield synthesis of a tetrahydrofuran (thf) solution of the di-Grignard reagent (A) derived from o-bis(chloromethyl)benzene is described, as well as that of an analogue obtained from 1,2-bis(chloromethyl)-4,5-dimethylbenzene. Cooling (A) to ca. –40 °C yields the colourless chloride-free Mg(CH2C6H4CH2-o)(thf) of unknown structure, whereas at ambient temperature a concentrated solution (> ca. 0.1 mol dm–3) slowly (days) deposits colourless needles of [{Mg(CH2C6H4CH2-o)(thf)2}3]. A single-crystal X-ray structure determination of the latter (R= 0.054 for 1 117 ‘observed’ reflections at 295 K) shows it to be a trimer. Crystals are orthorhombic, space group F2dd. with a= 24.706(8), b= 8.948(3), c= 44.315(9)A, and Z= 8; the trimeric unit lies on a crystallographic two-fold axis. Each of the three magnesiums is bridged to the other two by a –CH2C6H4CH2–-o ligand, the pseudo-tetrahedral co-ordination about each magnesium atom being completed by a pair of thf molecules. The utility of the di-Grignard reagent as a general metallocycle precursor is illustrated by the synthesis of [graphic omitted] (cod = cycle-octa-1,5-diene) from [Ptl2(cod)]. In contrast [PtCl2(dppe)] with [{o-C6H4(CHSiMe3)2}{Li(tmen)}2](dppe = Ph2PCH2CH2PPh2, tmen = Me2NCH2CH2NMe2) affords [Pt(dppe)2].

The mechanism of the Mitsunobu reaction. A 31P N.M.R. study

Abstract: 31P n.m.r. studies indicate that in the Mitsunobu reaction, alcohols react with diethyl azodicarboxylate and triphenylphosphine in tetrahydrofuran to produce phosphorane intermediates. Diethyl azodicarboxylate and tributylphosphine, however, result in the formation of oxyphosphonium salt intermediates.

Reinvestigation of the reaction of tert-butyllithium with uranium tetrachloride: formation of catalytically active uranium(III) hydride complexes

Abstract: The reaction of UCl/sub 4/ with t-C/sub 4/H/sub 9/Li in alkane solvents has been reinvestigated in detail by quantitative collection and identification of gaseous products and by spectral, analytical, and chemical characterization of the solid uranium products. Treatment of UCl/sub 4/ with 4 equiv of t-C/sub 4/H/sub 9/Li generates 1.5 to 1.8 equiv of 2-methylpropane and 2-methylpropene in a 2.5-3 to 1 ratio and a solid U(III) hydride product which readily dissolves in tetrahydrofuran (THF). As much as 1.7 equiv of the starting alkyllithium reagent can be recovered unreacted in this reaction, and hence the primary features of the reaction can be reproduced by using only 2 equiv of t-C/sub 4/H/sub 9/Li. Reaction of 1 equiv of t-C/sub 4/H/sub 9/Li with UCl/sub 4/ forms a U(III) product free of hydride. The reaction of n-C/sub 4/H/sub 9/Li with UCl/sub 4/ is similar. Detailed analysis of alkane/alkene ratios of gaseous products suggests that these systems abstract hydrogen from the alkane solvent possibly through a low-valent uranium center. The U(III) hydride product of these reactions is catalytically active in alkyne and alkane hydrogenation reactions conducted under mild conditions.

Photocatalytic hydrogen evolution from water using zinc sulfide and sacrificial electron donors.

Abstract: Irradiation(λ≥290 nm) of an aqueous suspension of ZnS prepared in situ from Na2S and ZnCl2 or ZnSO4 leads to the photocatalytic H2 evolution in the presence of sacrificial electron donors such as tetrahydrofuran, methanol, and ethanol.

Preparation, structural characterization, and reactivity of bis(triethylphosphine)carbonylrhodiumtetracarbonylcobalt ((PEt3)2(CO)Rh-Co(CO)4). A quantitative study of the reversible heterolytic cleavage of the polar rhodium-cobalt bond

Abstract: The reversibility of the reaction has allowed a quantitative assessment of the kinetic lability of the cobalt-rhodium bond through detailed variable temperature NMR studies. (PEt/sub 3/)/sub 2/(CO)Rh-Co(CO)/sub 4/ was prepared by the dropwise addition of a THF solution of K(Co(CO)/sub 4/) to a THF solution of RhCl(CO)(PEt/sub 3/)/sub 2/, under a nitrogen atmosphere. After stirring the mixture at 50/sup 0/C for 24h, the THF was removed and the residue extracted with petroleum ether. Cooling the extract to -65/sup 0/C produced a 77% yield of the complex. The solid state structure is illustrated; values for relative bond angles and bond lengths are given. Structural data indicate that the complex is coordinately unsaturated and is best formulated as possessing a polar-metal Rh(I) and Co(-I) center. The (Co(CO)/sub 4/)/sup -/ group behaves as a pseudohalide, the Rh-Co interaction is relatively weak, easily displaced by acetonitrile and THF. The rate of metal bond cleavage is extremely fast. 2 figures.

Addition of phenyl areneselenosulphonates to acetylenes:a route to acetylenic sulphones

Abstract: Treatment of phenyl areneselenosulplonates (1) with terminal acetylenes resulted in the formation of β-(phenylseleno)vinyl sulphones (2), which on treatment with excess of hydrogen peroxide in tetrahydrofuran at room temperature gave acetylenic sulphones (3) in good yields.

The preparation and reactions of azidobis[1,2-bis(diphenylphosphino)-ethane]nitridotungsten(IV)

Abstract: The complex [W(N2)2(Ph2PCH2CH2PPh2)2] and trimethylsilyl azide in toluene or tetrahydrofuran yield [W-N(N3)(Ph2PCH2CH2PPh2)2] in a reaction which probably involves free radicals. The nitrido-group in [WN(N3)-(Ph2PCH2CH2PPh2)2] is readily attacked by electrophiles to give imido-, alkylimido-, or thionitrosyl complexes.

Synthesis of AB and BAB poly(styrene‐b‐4‐vinylpyridine) and solution properties of their quaternized compounds

Abstract: Well-definded AB and BAB poly(styrene(S)-b-4-vinylpyridine(4VP))s were prepared by anionic polymerization in tetrahydrofuran (THF) at −78°C. Quaternization of these block copolymers was carried out with methyl iodide and P4VP blocks were completely quaternized. The emulsifying effect, viscosity behavior, and binding of methyl orange to the quaternized compounds are discussed in detail from a view-point of sequential arrangements.