Naphthalene, reaction with sodium amide

Ziegler-Thorpe cycHzation. A recent paper of Newman et al. outlines several useful modifications of this reaction. Sodium N-methylanilide was prepared by the reaction of sodium sand with N-methylaniline in dry ether with isoprene rather than styrene or naphthalene as assistant. Potassium N-methylanilide (prepared from KH and N-methylaniline without isoprene) was also used, but did not prove more convenient. Sodium bis(trimethylsilyl)amide, [(0113)3Si] 2 NNa, was used to a limited extent. The paper also describes a simplified apparatus for carrying out reactions at high dilution. 

Alkali Metals. The well-known reaction of PH3 with solutions of alkali metals in liquid NH3 leads to the formation of pure, crystalline dihydrogen phosphides, MPH2, where M = Li, Na [70 to 72], K [70], Rb [70, 73], and Cs [70]. An excess of PH3 is recommended to obtain phosphides which are free of alkali amides [70]. Sodium in diethyl ether/anthracene mixtures or potassium in THF/naphthalene mixtures also give high yields of the corresponding dihydrogen phosphides [74]. Additional details concerning the syntheses of solutions of PHg and the isolation of solid phosphides under various experimental conditions are described in Section 1.2.4.1, p. 102. Earlier reactions of PH3 with Na are described in Natrium Erg.-Bd. 4, 1967, pp. 1541/2. 

Anionic polymerization of o-divinylbenzene was examined by Aso et al. [294]. The authors used n-BuLi, phenyllithium, and naphthalene/alkali metal in THF, ether, dioxane, and toluene at temperatures between —78 and 20 °C. Generally, it was found that as with radical and cationic initiators, a competition between cyclopolymerization and conventional 1,2-polymerization occurs, with the tendency for cyclization to be lower than with the other mechanisms. The polymerization initiated with the lithium organic compounds resulted in polymers with up to 92% double bonds per monomer unit (THF, 20 °C). Polymerization with lithium, potassium, and sodium naphthalene also showed a rather weak tendency for cyclization. In THF at 0°C and 20 °C the cyclization tendency increased with decreasing ionic radii of the counter cation, while in dioxane the reverse effect was observed, and in ether still another dependence was found (K > Li > Na). Nitadori and Tsuruta [299] used lithium diisopropyl amide in THF at 20 °C to polymerize m- and p-divinylbenzene. The authors obtained soluble products with molecular weight up to 100 000 g/mol (GPC) and showed the polymers to contain pendant double bonds by IR and NMR spectra. It seemed to be important that a rather large excess of free amine (the initiator was formed by reaction of -BuLi with excess diisopropylamine) was present in the polymerization mixture. In later studies [300,301] a closer view was taken on polymerization kinetics and the steric course of the polymerization reaction. 

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