Lithium naphthalene electron transfer reaction

The presence of organolithium compounds in etheric solvents at temperatures above 0°C may lead to extensive decomposition of the solvent and solute a slow electron transfer side reaction of lithium naphthalene or sodium naphthalene with the THE solvent (equation 5) has been reported . The three isomeric forms of BuLi were shown to induce extensive decomposition of THE. The main path for this process is metallation at position 2 of THE, leading to ring opening and elimination of ethylene. An alternative path is proton abstraction at position 3, followed by ring opening. The presence of additives such as (—)-sparteine (24), DMPU (25), TMEDA and especially HMPA does not prevent decomposition but strongly affects the reaction path. ... 

The study of the photochemistry of aryl carbanions has been restricted to aryllithiums with only a limited number of studies available. Hence, a general picture of their photochemistry is not available at this time. Photolysis of phenyllithium in the presence of aromatic hydrocarbons such as naphthalene, biphenyl, phenylene, etc. in diethyl ether results in electron transfer from the phenyllithium to the aromatic hydrocarbon, with production of the corresponding hydrocarbon radical anion, as observed by ESR spectroscopy [6-8] (Eq. 1). Photolysis of phenyllithium or 2-naphthyllithium alone gave the corresponding biaryl products and metallic lithium [9-10]. For this reaction, it is possible to write a mechanism which does not require electron transfer from the anion [9,10],... 

An alternative method of initiation is through the use of the radical anion produced from the reaction of sodium (or lithium) with naphthalene. Such radical anions react with styrene by electron transfer to form styrene radical anions these dimerize to produce a dianion, which initiates polymerization as outlined in Scheme 14. One particular feature of this method is that polymerization proceeds outwards from the centre. Subsequent reaction of the living chains ends with another suitable monomer system produces a triblock copolymer. This is the principle by which styrene-butadiene-styrene triblock copolymers (formed when butadiene is polymerized in the same way. and styrene is added as second monomer) are produced commercially. This material behaves as a thermoplastic elastomer, since the rigid styrene blocks form cross-links at room temperature on heating these rigid styrene portions soften, allowins the material to be remoulded. ... 

Additionally, it was found that the double reductive alkylation of the 2,5-diester 66 could be achieved under Birch conditions (Li/NH3) to produce the 3-pyrroline 67. On the basis of a mechanistic postulate that such reductions do not involve transfer of a proton from ammonia, the authors discovered that the same reduction could be performed in THF (no ammonia) with lithium metal and catalytic amounts of naphthalene as an electron shuttle, thereby making this reaction more practicable on a large scale <00TL1327>. 

The lithium reduction of zinc (II) cyanide using naphthalene or biphenyl as a catalytic electron carrier yields a more reactive form of Rieke zinc. This new form of Rieke zinc is able to undergo direct oxidative addition to alkyl chlorides under mild conditions and tolerates the presence of nitriles and bulky tertiary amides [17]. Table 3.5 shows representative reactions of alkyl zinc chloride reagents with benzoyl chloride. The activation of the zinc surfeice could originate by the adsorption of the Lewis base cyanide ion on the metal surface. The adsorbed cyanide ion can affect the metal s reactivity in two possible ways. One possible mode of activation would be the reduction of the metal s work function in the vicinity of the adsorbed cyanide ion, and the second could be that the cyanide ion is acting as a conduction path for the transfer of the metal s electrons to the alkyl chloride. One or both processes could account for the observed enhanced chemical reactivity. 

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