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Alkali metal naphthalenides

Anionic Alkoxides RO" M (M=alkali metal, complexed or not by crown ether) Carboxylates RCOO" (M=alkali metal) Alkali metal naphthalenides Alkali metal supramolecular complexes Grafitides KC24... [Pg.5]

This activated zinc would be an aggregation of very fine zinc particles dispersed in the DMF solution. The size of these particles is smaller than that obtained in the previous process, which was performed in the absence of naphthalene12. This electrochemical method is comparable to the chemical Rieke procedure in which the activated zinc is prepared by reduction of zinc halide with alkali metal naphthalenide in THF13. [Pg.759]

Treatment of MX5 with alkali metal naphthalenide in DME at —60 °C provides thermally unstable brown intermediates, assumed to be [M(C10H8)2] or [M(l-MeCioH7)2], which react with CO (1 atm) to give [M(CO)6]- in 30-54% yields.718 Carbonylation, using sodium in the presence of cyclooctatetraene in THF under CO (1 atm, 40 °C), has also been reported, although its efficiency is low in the case of Ta (12%).719 Cyclooctatetraene complexes are thought to form as intermediates, but the mild carbonylation conditions compared to those of [Nb(COT)3]- (50 atm, 100 °C) suggest that a compound of different stoichiometry may be involved.720... [Pg.684]

A variety of strong reducing agents, including solutions of alkali metals in liquid ammonia, sodium solubilized by crown ethers or cryptands in tetrahydrofuran (THF), and alkali metal naphthalenides in THF, have been found to reduce M2(CO)10 and/or [M(CO)5] (M = Mn and Re) to the respective [M(CO)4]3- however, [Re(CO)5] has often been observed to be... [Pg.2]

The complex is stable in air for a short time, but is sensitive to hydrolysis it melts at 171 °C without decomposition. From equations 64 and 65 it can be assumed that 82 is reduced by alkali metal naphthalenides, but not by potassium anthracenide, and this assumption was proved in separate experiments182. [Pg.2164]

Of this latter point, we have utilized combined GC/MS to analyze solutions of alkali metal naphthalenide in THF (90 mM metal, 40 mM naphthalene, 25 ml THF) quenched with D2O, so that we may determine the stability of the reactant system itself on a time scale of 100 hours. The predominant product, other than naphthalene itself, for both sodium and potassium naphthalenide quenches was 1-ethyl 1-protio, 4-deutero 4-protio naphthalene (3) (and/or the 1,1 2,2 isomer (4)) rather than the expected 1-deuteFo 1-protio, 4-deutero 4-protio "naphthalene (5). [Pg.84]

The reduction of alkyl halides by solutions of dissolved metals like, e.g. sodium in ammonia or alkali metal naphthalenides in tetrahydrofuran, provides a convenient means of removing halogens to produce hydrocarbons or to prepare alkali metal organic compounds. It is generally accepted that these reductions involve free radical intermediates R pathway A, Scheme 12) . [Pg.741]

The reduction of tertiary cyclopropyl halides with alkali metal naphthalenides leads to a similar situation. After treatment of a 78 22 and a 25 75 mixture, respectively, of r-1-bromo-l-methyl-c-2-methyl-r-2-phenylcyclopropane (110) and its isomer (111) with LiN in THE at 20°C, protonation with methanol led to identical 45 55 mixtures of r-l-phenyl-l,c-2-dimethyl- and r-1-phenyl-l,r-2-dimethylcyclopropanes (112 and 113). [Pg.742]

Free secondary and tertiary cyclopropyl radicals reach their thermodynamic equilibrium before they are trapped by a bimolecular SET reaction from the alkali metal naphthalenides to give a configurationally stable alkali metal species. Net retention is not observed under such conditions (Scheme 13). [Pg.743]

SCHEME 13. Alkali metal naphthalenide reductions of cyclopropyl halides... [Pg.744]

Table 18 summarizes the net retentions of configuration of the cyclopropane 49 observed in the reactions of the optically active cyclopropyl halides 5(1-52 with alkali metal naphthalenides MN as the halide X, the gegenion M and the concentrations are varied. The effect of inverse versus normal addition is demonstrated in Table 19. The influence of the solvent is given in Table 20. Dicyclohexyl-18-crown-6 also affects the. amount of retention of cyclopropane 49 (Table 21). Table 18 summarizes the net retentions of configuration of the cyclopropane 49 observed in the reactions of the optically active cyclopropyl halides 5(1-52 with alkali metal naphthalenides MN as the halide X, the gegenion M and the concentrations are varied. The effect of inverse versus normal addition is demonstrated in Table 19. The influence of the solvent is given in Table 20. Dicyclohexyl-18-crown-6 also affects the. amount of retention of cyclopropane 49 (Table 21).
What is the reason for the alternative pathways in the reactions of the cyclopropyl halides 106,107,110, 111, 114 Hal, 115-Haland 50-1,51-Br, 52-CI, 118-Hal with alkali metal naphthalenides ... [Pg.746]

SCHEME 15. Alternative pathway for the alkali metal naphthalenide reduction of the cyclopropyl halides 50-52 and 118-HaE ... [Pg.748]

Cyclopropyl anions have a high synthetic potential, see Section IV.D. Their direct preparation from cyclopropyl halides with metals, by halogen-metal exchange as well as by alkali metal naphthalenide has been discussed in Section III. [Pg.767]

The reductive alkylation of coal, involving reduction by alkali metal naphthalenide followed by alkylation by alkyl halide, involves chemistry that is more complex than that of the reductive alkylation of simple aromatic compounds. [Pg.225]

The volatile side product hexamethyldisilane was detected by a GC comparison with an authentic sample and unambiguously identified by GC-MS. This molecule corresponds to the H2 formed upon reactions of alkali metals with water. Alkali metal naphthalenides showed the same reaction behavior. [Pg.162]

Synthesis of cyantrimethylsilylamides from elemental alkali metal naphthalenides. Small pieces of lithium or sodium were added to a stirred solution of 5 g naphthalene in 120 mL THF, generating a dark green suspension. This alkali metal naphthalenide reagent was slowly added to a stirred mkture of 10 mL BTSC and 10 mL n-hexane at -40 °C. Isolation and purification were performed as described above after complete separation of the naphthalene. [Pg.164]

Low-valent group 4 metal derivatives might be prepared from mono-Cp titanium(iv) derivatives by mild reductive conditions. The tetracarbonyltitanates(O) [Cp Ti(CO)4] (Cp = Cp, Cp ) are prepared as Et4N+ salts in 40-50% yield by reduction of Cp TiCL with alkali metal naphthalenides at low temperature, followed by carbonylation at atmospheric pressure. Increased yields of up to 70% have been obtained when reduction is done in the presence of excess CioH8.429 The reduction of CpTiCl3 with zinc and subsequent treatment with 3 equiv. of potassium... [Pg.399]

Garst and coworkers have used the reactions of l-methyl-5-hexenyl halides 136, (X = Hal) with alkali metals or alkali metal naphthalenides such as sodium naphthal-enide Na+N", as a mechanistic probe over the years95 . A 1984 publication96 discloses the possibility of differentiating between the radical 134 and anion 138 cyclization. [Pg.28]

Neutral Ti(CO)6 is an extremely unstable compound which decomposed even below -220 °C, as shown by matrix isolation spectroscopy [165]. The much more stable phosphine derivatives Ti(CO)3(dmpe)2, Ti(CO)5(dmpe), Ti(CO)5(PMe3)2, Ti(CO)4(PMe3)3 have been isolated [166-168]. In contrast, the dianionic salt [Ti(CO)6] (53) is thermally much more stable and decomposes only above 200 C. Complex 53 was obtained by reductive carbonylation of Ti(CO)3(dmpe)2 by alkali metal naphthalenides in the presence of cryptand [169]. Carbonylation of 79 also produces 53 [170]. The naph-thalenide-assisted reductive carbonylation of the zirconium tetrachloride afforded the zirconium analog [Zr(CO)6] (54) [171], which was also derived by carbonylation of the tris(diene) dianion 45 [150]. One anion [R3Sn] effectively stabilizes Ti(CO)e as an air stable monoanionic salt, [R3SnTi(CO)J [172]. [Pg.85]

Naphthalene complexes CioH8Ln(THE) (Ln - Eu, Yb x - 2,3), obtained by reaction of Lnl2 with alkali metals naphthalenides, like the products of ytterbium and alkynes cocondensation, readily react with cyclopentadiene at room temperature to give Cp2Ln in a high yield [50]. [Pg.138]

Fluoropolymers. There are no known adhesives for fluoropolymers that give bonds of adequate strength without pretreatment. Simple, low-quality bonds can be obtained with contact adhesives. After chemical pretreatment, for example, with a solution of an alkali metal naphthalenide in THF, polyfluorocarbons can be bonded with high strength by using epoxy and polyurethane adhesives. [Pg.66]

Since alkali metal naphthalenides have been claimed not to polymerize P-lactones at room temperature [43], the polymerization of P-lactones from those... [Pg.236]

Scheme 9.13 Ring-opening mechanism of P-butyrolactone using complexed alkali metal naphthalenide [44],... Scheme 9.13 Ring-opening mechanism of P-butyrolactone using complexed alkali metal naphthalenide [44],...

See other pages where Alkali metal naphthalenides is mentioned: [Pg.3]    [Pg.4]    [Pg.10]    [Pg.12]    [Pg.288]    [Pg.4913]    [Pg.702]    [Pg.742]    [Pg.229]    [Pg.700]    [Pg.463]    [Pg.4912]    [Pg.2523]    [Pg.91]    [Pg.81]    [Pg.114]    [Pg.163]    [Pg.163]    [Pg.600]    [Pg.605]    [Pg.160]   
See also in sourсe #XX -- [ Pg.741 , Pg.742 , Pg.743 , Pg.744 , Pg.745 , Pg.746 , Pg.747 , Pg.748 ]




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Complexes alkali metal naphthalenide

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