Organo-Alkali Compounds

We shall not here discuss the mechanism of metallation reactions which has recently been reviewed (Shatenshtein, 1962). Bryce-Smith (1954) has correctly interpreted these reactions by pointing out that the protophilic reagent (carbanion of the organo-alkali compound) is responsible for the ionization of the hydrogen in the CH bond. In order to emphasize this fact and note the acid-base nature of metallation reactions, Bryce-Smith referred to them as protophilic substitution of hydrogen. 

The importance of the electrophilic character of the cation in organo-alkali compounds has been discussed by Morton (793,194) for a variety of reactions. Roha (195) reviewed the polymerization of diolefins with emphasis on the electrophilic metal component of the catalyst. In essence, this review willattempt to treat coordination polymerization with a wide variety of organometallic catalysts in a similar manner irrespective of the initiation and propagation mechanisms. The discussion will be restricted to the polymerization of olefins, vinyl monomers and diolefins, although it is evident that coordinated anionic and cationic mechanisms apply equally well to alkyl metal catalyzed polymerizations of polar monomers such as aldehydes and ketones. 

The development of organo-alkali-compounds, especially organolithium compounds, led to attempts to form Si-C bonds ... 

In reactions with ClCOOCH3 to avoid further reaction of the organo alkali compound with the ester RCOOCH3. Example Vol. I, p. 145. 

Alkali metals can be intercalated into MPS3 either by chemical or electrochemical techniques. Chemical intercalation takes place when the host is reacted with an organo-alkali metal compound such as n-butyllithium or sodium napthalide. The reaction with n-butyllithium can be represented as ... 

The rate of hydrogen exchange depends on the protolytic properties of both the solvent and the substrate. In fact there is a correspondence between the magnitude of the rate constants for deuterium exchange with ND3 and the conventional ionization constants of hydrocarbons which were used by Conant and Wheland (1932) and by McEwen (1936) to obtain the first quantitative estimates of the acidity of hydrocarbons. To do this, they determined the equilibrium of metallation of hydrocarbons by organo-alkali metal compounds. This reaction was described by Shorygin (1910) and is represented by the equation... 

The alkylation of alkyl-substituted aromatic hydrocarbons by propylene and isobutylene described by Pines and Schaap (1960), and the dimerization of olefins with organo-alkali metal compounds, are also found to proceed most easily when primary carbanions are formed since they are more stable than secondary and particularly tertiary carbanions. 

Gilman s significant observation that triphenylchlorosilane is a catalyst in Wurtz-like reactions forming cyclic silanes appears to be due to intermediate formation of triphenylsilyl lithium (see Chapter 9 Cyclic Silanes). The triphenyl compounds are particularly good catalysts because the corresponding alkali-triphenylsilyl compounds are the most stable among the alkali-organo-silicon compounds. 

From Tellurium and Organo Alkali Metal Compounds... 

If instead of the alkali metals one uses organo-alkali metal compounds, the microstructure of the diene polymers remains very much the same if the polymerization is carried out... 

Still one more class of alkyl derivatives should be mentioned in this part of our study. These are compounds of the alkyl radicals with metals, and are known in general as organo-metallic compounds. A large number of metals form compounds of this kind, and the ease of formation seems to have a definite relation to the position of the metal in the periodic system. Compounds of the alkali metals with organic radicals have not been isolated, but they probably exist as intermediate products and also as double compounds with other metallic alkyl compounds. The two groups of these compounds which we shall briefly consider are those of zinc and magnesium. 

The polymerization of the higher aliphatic aldehydes has many similarities with formaldehyde polymerization. Notable differences are a lower ceilii temperature and the possibility of different steric configurations due to the substituted carbon atom. Especially anionic catalysts such as alkali metal alkoxides, soluble hydrides, and organo metal compounds lead to polymerizations during which crystalline isotactic polymer is produced 96). Little is known about the morphology and the detailed crystallization mechanism of the polyaldehydes. 

The polymerization of N-carboxy-a-amino acid anhydrides (Leuchs anhydrides) has also been achieved by water and by a variety of bases like amines, alkali metal hydroxides, alkali metal oxides, and organo-metallic compounds in bulk, inert solvents, or starting with the solid monomer (705). Despite a great interest in the polypeptides produced in these reactions, little attention has been paid to conditions which yield solid polymer. In case the solid was produced, no physical chemical analysis of the polymer was carried out. Pol5mierization of the crystalline monomer was already observed in 1940 705). 

A further possibility for the conversion of alkali metal alanates into organo-aluminum compounds is the reaction with heptafluoropropyl iodide, from which perfluoropropylalanates are obtained (93). 

Ether Cleavage with Organo-Alkali Metal Compounds and Alkali Metais" Maercker. A. Anaew. Chem. Int. Ed, Engl, 1987, 26, 972. 

Compounds of metals and alkyl or aryl groups are frequently spontaneously ignitible in air, especially the lower members of homologous scries, such as the methyl and ethyl compounds. The metals in the most active compounds are the alkali metals and aluminum, zinc, and arsenic. The nonmetals boron and phosphorus also furnish active members, which conventionally are classed with the metal-organic (sometimes called organo-metallic) compounds. It is noteworthy that the alkyls of silicon do not flame in air. 

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