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Potassium in THF

Zheng et al. treated potassium [l,2,4]diazaphospholides, obtained from the reaction of 3,5-disubstituted-[l,2,4]diazaphospholes with metallic potassium in THF, with [Cp RuCl]4 to afford [(T75-dp)RuCp ] type pseudoruthenocene complex (106) (Scheme 33). Sandwich structure with almost eclipsed orientation of two n-bonded ligands has been confirmed by X-ray crystal structure determination [110], Catalytic application of [(rf-dp)RuCp ] complexes in the Heck reaction has also been investigated [111]. [Pg.199]

Radical anions have also been obtained recently from the tin equivalents of the alkynes, the distannynes (see Section 3.14.24.6). Reduction of 2,6-di(2,4,6-triisopropylphenyl)phenyltin(ll) chloride (ArSnCl) with potassium in THF gave [ArSnSnAr] K+, which showed g= 2.0069, (117Sn) = 0.83 mT, (119Sn) = 0.85 mT, and in the crystal, the radical anion adopts a tram-bent structure. The 2,6-di(2,6-diisopropylphenyl)phenyltin analog behaves similarly.533 534... [Pg.865]

For example, a 4.5 1 mixture of CgHg + CgHg forms the 2 1 mixture of ( CgHg) -F ( CgHg) on reduction at 100°C by the half-stoichiometric amount of potassium in THF. Therefore, the heavier anion-radical amount is less than the amount of the heavier parental substrate in the initial mixture. The ESR data were reproduced by means of nuclear magnetic resonance (NMR) and mass-spectral methods after transformation of anion-radical mixtures into mixtures of corresponding neutral compounds and removal of the solvent. [Pg.120]

The red azocinyl dianions can be generated by means of dissolving potassium in THF or ammonia, and give NMR spectra showing downfield shifts of 0.8 p.p.m. for the protons on methyl substituents, evidence for a considerable diamagnetic ring current (71JA168). [Pg.664]

Naphthalene-terminated polyvinyl aromatics and polyisoprene were obtained successfully. These functional polymers were metalated by potassium in THF at 25°C. The formation of a stable dinegative ion is observed unless the naphthalene is directly attached to the end of the polyvinyl aromatics, in which case a few isoprene units can be advantageously inserted between the naphthalene end group and the polyvinyl aromatics. The polymeric and stable dinegative ion polymerizes oxirane by both anionic sites and forms three-branched starshaped block copolymers. [Pg.211]

Naphthalene is known to form a stable lithium dianion at -80°C in tetrahydrofuran (THP) at concentrations lower than 0.5 mol.I-1 (9-12). Unfortunately organolithium compounds are unable to polymerize oxirane (13). Naphthalene can also be metalation by sodium and potassium in THF but no experimental evidence for a dianion of naphthalene sodium or potassium is to be found. Although naphthalene metalation by sodium is thoroughly described ( , lU, 15), very few results about potassium are published (l6, "nT As the reducing power of the alkali metals decreases from lithium (Li/Li+ = 3 02v) to potassium (K/K+ -2.92v) and finally to sodium (Na/Na+ = 2.71v) (l8), it is attractive to study in more detail the naphthalene metalation by in the THF. [Pg.212]

Naphthalene Metalation hy Potassium in THF at Room Temperature Naphthalene Carbanions ... [Pg.215]

Metalation of Naphthalene Ended Polyvinyl Aromatic Chains by Potassium in THF At RT... [Pg.218]

To verify these estimations experimentally, an analysis of electron spin resonance (ESR) spectra resulting from an incomplete reduction of the precisely measured amounts of benzene isotopomers with potassium in THF was conducted (G.R. Stevenson, Espe, Reiter 1986). That approach had been outlined by Chang and Coombe in 1971. The superimposed spectra were analyzed to find the intensity ratio of the signals belonging to the iso-topomeric anion radicals. That ratio produced the concentration ratio of the anion radicals under consideration. [Pg.127]

The preparation of the potassium alcoholate requires much care. Metalation of the alcohol is carried out to completion without attack of the double bond by means of diphenylmethyl potassium in THF solution. Excess alcohol present in the subsequent polymerization system would act as a transfer agent. [Pg.8]

Pyrrole derivatives are of little use as substrates for making pyrazines. However, treatment of 2,3,4,5-tetraphenylpyrrole (74) with potassium in THF for 6 h gave, among other products, 2,3,5,6-tetraphenylpyrazine (75) in 7% yield 564 3-amino-... [Pg.58]

Synthesis of 9,10-disilaanthracene 109 was performed by the treatment of a cisjtrans-mixture of 108 with 2 equiv of Li in THF containing TMEDA at room temperature for 48 h. The structure of dimer 109 was confirmed by MS, and H, 13C, and 29Si NMR spectroscopy as well as X-ray crystallographic analysis. Upon reduction of 109 with an excess of lithium or potassium in THF solution, the dianions 110 were formed (Scheme 22). Subsequent reaction of 110 with a,u -dichloropolysilane or dichlorodimethylsilane led to the formation of corresponding cyclic 111-113 <19950M3625>. [Pg.994]

Reduction of the diborylated naphthalene derivative (52) was studied by Gabbai, who found a reversible reduction wave at — 1.81 V (vs. SCE) by cychc voltammetry. Moreover, treatment of (52) with potassium in THF in the presence of 18-crown-6 led to formation of a dark purple EPR-active solution, the spectrum of which suggested coupling of the electron spin of the free radical with two boron centers (equation 39). The presence of an intramolecular one-electron a-bond in (153) leads to a significant shortening of the boron boron distance as suggested by DFT calculations. ... [Pg.503]

The Riecke zinc, obtained by reduction of a zinc halide with sodium or potassium in THF, is commonly used for the... [Pg.5202]

The 32-electron dititanium compound 21 reacts with two equivalents of potassium in THF to give a green solution with one single line in the H-NMR spectrum (43). However, the published data are insufficient to convince one that the structure assigned to the dianion, 22, is correct. [Pg.96]

The reduction of bis(bicyclooctatetraenyl)diuranium (= biurano-cenylene 427 ) by potassium in THF has been investigated using NMR. The results for the partly reduced system suggest a fast electron exchange, on the NMR time scale, between the remaining biurano-cenylene and the reduction product. The reduced product appears to be a mixed valence compound with one U(IV) and one U(III) atom in the molecule 428). [Pg.126]


See other pages where Potassium in THF is mentioned: [Pg.26]    [Pg.11]    [Pg.60]    [Pg.99]    [Pg.120]    [Pg.124]    [Pg.183]    [Pg.214]    [Pg.296]    [Pg.139]    [Pg.93]    [Pg.132]    [Pg.35]    [Pg.688]    [Pg.556]    [Pg.961]    [Pg.299]    [Pg.961]    [Pg.40]    [Pg.4409]    [Pg.188]    [Pg.224]    [Pg.64]    [Pg.65]    [Pg.191]    [Pg.197]    [Pg.32]    [Pg.116]    [Pg.280]   
See also in sourсe #XX -- [ Pg.199 ]




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