Organoalkali compounds

Typical initiators for living anionic polymerization of siloxanes include conventional organoalkali compounds and lithium siloxanolates22). Initiators containing lithium counterions are preferable to sodium or potassium counterions due to the lower catalytic activity of lithium in siloxane redistribution reactions. Living anionic polymeriza-... 

Kinetics in Polar Media. These polymerizations, initiated by organoalkali compounds mainly in ether solvents, have... 

All unsaturated hydrocarbons that possess removable allylic hydrogens or activated double bonds readily undergo oligomerization in the presence of basic reagents.30,31 Alkali metals, organoalkali compounds, and alkali alcoholates are most frequently applied. 

Base catalysis is most effective with alkali metals dispersed on solid supports or in the homogeneous form as aldoxides, amides, and so on. Small amounts of promoters may be added to form organoalkali compounds that really have the catalytic power. Basic ion exchange resins also are useful. Some base-catalyzed processes are isomerization and oligomerization of olefins, reaction of olefins with aromatics, and hydrogenation of polynuclear aromatics. 

This represented the discovery of the first addition of an organometallic (organoalkali) compound to a C=C double bond. The organopotassium compound used had at that time been known for only 4 years. It was found by the author and Schnell (46) as the result of a systematic search for the simplest ether to be split by an alkali metal according to the equation... 

The Si—H bond as well as the Si-halogen bond reacts with organoalkali compounds and this fact can be used formation of new derivatives ... 

Dover BT, Kamienski CW, Morrison RC, Currin RT, Schwindeman JA. Organoalkali compounds and their preparation. US Patent, 5976403, 1999. 

T. Cohen, M. Bhupathy, Organoalkali Compounds by Radical Anion Induced Reductive Metalation of Phenyl Thioethers, Acc. Chem. Res. 1989, 22, 152-161. 

Most of the progress concerning organoalkali reagents in chemistry have been made using superbases. The following sections deal with the preparation and use of organoalkali compounds of vinyl, aryl, and benzyl type. 

Conductivity studies show that organoalkali compounds, such as ethyllithium, C2H5—Li, are good conductors when dissolved in diethyl-zinc. Ionization apparently occurs, and, since the formation of ethide ions, C2H7, is unlikely, the reaction may be best represented as a sbl-volysis by the acidic zinc compound ... 

The dimerization of propene at about 210° in the presence of potassium or cesium yielded 4-methyl-l-pentene as the predominant dimer (8). The dimerization proceeds through an initial formation of an organoalkali compound, followed by metalation of the propene. 

This is an excellent reaction for the conversion of most halides to acids containing one additional carbon atom. Carbonation of Grignard reagents and organoalkali compounds gives acids in yields of 50-85%. Ether solutions of the organometallic compounds formerly were treated with carbon dioxide gas at 10° to -10°. A more recent technique involves pouring the solution onto excess crushed Dry Ice. Carbon dioxide... 

The preparation of adducts of conjugated hydrocarbons by reaction with alkali metals demands absence of Oj, HjO or solvent impurities that can combine with the organometallic product or the alkali metal. The T must be below the decomposition point of the organoalkali compound in the particular solvent. Adequate contact between the alkali metal and the hydrocarbon must be established. In small-scale preparations the alkali metal is deposited as a mirror on the walls of the reaction vessel, where it can come in contact with solvent. In larger scale or synthetic preparations the alkali metal is in the form of a sand or dispersion (see 5.5.3.2.1), and good stirring may be helpful. 

Functional End-Group Polymers. The formation of various functional groups on the "living" ends of anionic polymer chains is based on the well-known reaction of organometallic compounds with various reagents. Thus, organoalkali compounds can react as illustrated in the following typical reactions ... 

Normally strongly basic organoalkali compounds react at much lower temperatures with Me3SiCl. The relatively low reactivity of 3-quinolinyllithium is probably due to its slight solubility. 

Further, organoalkali compounds may add to the C=C bond of unsymmetrical olefins. 

It was Ziegler and Colonius who first showed that the primary products in a Wurtz synthesis are organoalkali compounds which, under suitable conditions, do not react further and can be obtained as the main product of the reaction.34... 

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