Sodium/ions naphthalenide

Sodium naphthalenide behaves similarly when the solvent is changed from tetrahydrofuran to 1,2-dimethoxyethane. The formation of solvent-separated from contact ion pairs is shown by a dramatic simplification of the ESR spectrum the 100-line spectrum of the contact ion pair, due to the spin-spin coupling of the unpaired electron with the four equal hydrogen nuclei in the a- and y9-positions, together with the sodium nucleus (/ = 3/2), collapses to a 25-line spectrum as the interaction with the sodium ion is disrupted [169, 170]. 

Tri-(l-naphthyl)phosphine is cleaved by alkali metals in THF solution. " Reaction with sodium gives the naphthalene radical-ion, with lithium the perylene radical-ion, and with potassium the radical-ion (22). Hydrocarbon radical-ion formation was thought to occur via naphthalene derived from the metal naphthalenide. E.s.r. spectra of further examples of phosphorus-substituted picrylhydrazyl radicals have been reported. ... 

Esr spectra are subject to exchange effects in the same way as nmr spectra. A specific example is provided by electron exchange between sodium naphthalenide and naphthalene. Naphthalene has a set of ten 77-molecular orbitals, similar to the six 7r-molecular orbitals of benzene (Figure 21-5). The ten naphthalene it electrons fill the lower five of these orbitals. In a solvent such as 1,2-dimethoxyethane, which solvates small metal ions well, naphthalene accepts an electron from a sodium atom and forms sodium naphthalenide, a radical anion ... 

Na <=4 —0 + Na) in the radical anion in the absence of excess diphenylmethanone Why [Notice that there is no 23Na splitting of the electron resonance of sodium naphthalenide in 1,2-dimethoxyethane, but such splittings are observed in oxacyclopentane (tetrahydrofuran) see Sections 8-7F and 15-11E for discussion of possible differences between solvents in their ion-solvating powers.]... 

From a synthetic objective it is unfortunate that attempts to produce the dianion of OFCOT by various reduction procedures have not resulted in a stable dianion. Although the organic decomposition products resulting from reduction by alkali metals or sodium naphthalenide are unknown, fluoride ion is produced (126). However, the nine-7t-electron radical anion has been produced at low temperatures by y irradiation of OFCOT, and electron spin resonance (ESR) spectroscopy indicates that it possesses the anticipated planar delocalized D8b structure 55 (127). The unavailability of the dianion... 

This observation, as well as other facts, led to the conclusion that ion pairs may exist in various forms which could differ greatly in their reactivities. The nature of ion pairs is revealed by various studies (34), and the ESR technique applied to paramagnetic ion pairs provides probably the most penetrating and powerful tool for such investigations. Indeed, the very first direct evidence for the existence of ion pairs as independent molecular species was furnished by Weissman s ESR studies of sodium naphthalenide (I, 2). In the following years the ESR method revealed many interesting phenomena which acquaint us with the thermo-... 

Hirota (1966) has studied in detail the ion-pairs formed by the alkali-metal salts of aromatic hydrocarbons and ketyls in various solvents. The observation of two superimposed spectra, with different Na-splittings, for sodium naphthalenide in diethyl ether at — 100°C indicates the presence of both tight (i.e. contact) and loose (i.e. solvent-separated) ion-pairs (a ,= l-05 and 0-058 G, respectively). In other cases, where only one ion-pair spectrum is observed, the temperature-dependence of the sodium-splitting and the line-widths indicates a rapid equilibrium between the two types of ion-pair. Distinctions can be made between these ion-pairs and the free solvated ions (see also Hirota and Kreilick, 1966). 

In his paper dealing with the separation of radical and anion cyclizations Garst also comments on the apparent halogen effects on product distributions in both sodium naphthalenide and sodium mirror reactions 96 While there are other possible explanations, the possibility that alkyl halide radical anions could be intermediates that undergo reactions other than fragmentation to alkyl radicals and halide ions should be kept in mind. ... 

Surface modification and metallization of poly(tetrafluoroethylene) (PTFE) has attracted a considerable attention from viewpoints of fundamental science and applied technology. PTFE has a low surface free energy while it shows excellent thermal and chemical stability. Therefore, the chemical and physical inertness of PTFE makes metallization an extremely difficult process. At present a chemical treatment using a sodium naphthalenide solution (1-4), a radio frequency plasma process (5-8), and electron/ion beam irradiation (9-//) have been employed for the modification of PTFE surface. 

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