Organosodium compounds with ethers

Organosodium compounds are prepared from sodium and other organometaUic compounds or active methylene compounds by reaction with organic haUdes, cleavage of ethers, or addition to unsaturated compounds. Some aromatic vinyl compounds and aHyUc compounds also give sodium derivatives. 

Another very important ring substitution reaction of ferrocene is its ability to undergo metalation with organolithium and organosodium compounds. Metalation with n-butyllithium in ethyl ether, first reported by Nesmeyanov and coworkers (63) and independently by Benkeser, Goggin, and Schroll (3),"leads to rather low yields of ferrocenyllithium (XXXI, M = Li) and l,l -ferrocenylenedi-lithium (XXXII, M = Li). It was subsequently shown by Mayo, Shaw, and... 

In contrast with the low reactivity observed with n-butyllithium solutions in hydrocarbons (5) or ether (6), the n-butyllithium-amine adducts rapidly metalate unsaturated hydrocarbons including even simple olefins. In this respect they surpass even organosodium compounds and will probably prove to be of considerable synthetic value. Addition of a hexane solution containing equimolar amounts of n-butyllithium and an amine to excess toluene at ordinary temperatures results in rapid formation of a benzyllithium-amine complex that in some cases separates as a yellow crystalline solid. 

Aryl ethers can be cleaved by metallic sodium with the formation of the sodium salt of a phenol. A number of such reactions have been studied qualitatively, but the nature of the other products of these reactions has not been established in a sufficient number of cases to demonstrate the mechanism of the reaction (28). In some cases, the isolation of coupling products has suggested that the displaced group is a free radical in other cases it appears that an organosodium compound was at least a transitory intermediate. 

The other system is the polymerization carried out in polar ethereal media at temperatures lower than -40 °C to avoid the undesirable side reaction of media with anionic initiators and chain-end anions. The condition in tetrahydrofuran (THF) at -78 °C is among the most employed system. In polar media, not only RLi but also organosodium and organopotas-sium compounds can be used as initiators. Furthermore, radical anion complexes formed by aromatic hydrocarbons and alkali metals are often used as difrmctional initiators. In the propagating chain-end anion in polar media, there is equilibrium among several ion pairs and a free ion, each of which can participate in the propagation reaction. 

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