Lithium sodium compounds, organo

The three elements lithium, sodium, and potassium bear little resemblance to copper, silver, and gold in their inorganic derivatives but, with the exception of gold, they show more resemblance in their organo-metallic compounds. 

Commercial products are often unsatisfactory in kinetic studies. Preparation of some commonly used initiators is given elsewhere141. Benzyl sodium is prepared from mercury dibenzyl and metallic sodium123 a similar technique yields barium and strontium salts. Fluorenyl lithium, sodium etc., are conveniently prepared from fluorene and a suitable organo-metallic compound, e.g. 

Schonberg and his co-workers675 obtained sulfides by cleaving disulfides with organo-lithium or -sodium compounds e.g., he obtained phenyl tri-phenylmethyl sulfide from diphenyl disulfide and (triphenylmethyl)sodium. 

Organotin compounds of this type can be further treated with Grignard reagents or organo-lithium or -sodium compounds, thus yielding a variety of mixed organotin derivatives for example, trialkyl- and tri(cyclohexyl)-tin... 

In many syntheses activation is not effected by sonochemical preparation of the metal alone but rather by sonication of a mixture of the metal and an organic reagent(s). The first example was published many years ago by Renaud, who reported the beneficial role of sonication in the preparation of organo-lithium, magnesium, and mercury compounds [86]. For many years, these important findings were not followed up but nowadays this approach is very common in sonochemistry. In another early example an ultrasonic probe (25 kHz) was used to accelerate the preparation of radical anions [87]. Unusually for this synthesis of benzoquinoline sodium species (5) the metal was used in the form of a cube attached to the horn and preparation times in diethyl ether were reduced from 48 h (reflux using sodium wire) to 45 min using ultrasound. 

Also other reaction types have been dealt with in CHEC(1984) and CHEC-II(19%) like reduction to alcohols (e.g., sodium borohydride), Wolff Kishner reduction, nucleophilic addition via reaction with Grignard reagents or organo-lithium compounds, and formation of imine type functional groups (e.g., hydrazones). New examples are the reaction of... 

Wenger, F. Polymerisation of methyl methacrylate with sodium naphthalene and organo lithium compounds in tetrahydrofuran. Chem. and Ind., p. 1094. 

LDA and related, sterically hindered, lithium dialkylamides, first investigated by Levine [1], have completely replaced the more nucleophilic sodium amide, which had been the base of choice for many years [2], Because the reactivity of an organo-metallic compound depends to a large extent on its state of aggregation (i.e. on the solvent and on additives) and on the metal, transmetalation of the lithiated intermediates and the choice of different solvents and additives emerged as powerful strategies for fine-tuning the reactivity of these valuable nucleophiles. 

Lithium telluride, prepared from tellurium and lithium triethylborohydride in tetrahydrofuran2, and sodium telluride, obtained from sodium and tellurium in a dipolar, aprotic solvent or from tellurium2,5 and Rongalite in aqueous sodium hydroxide2, reacted with aliphatic2,3,6 and aromatic5 dihalides to produce polymeric organo tellurium compounds. 

Lithium alkanetellurolates, prepared from tellurium and an alkyl lithium compound or dialkyl ditellurium derivatives and hthium, and sodium arenetellurolates, obtained from diaryl ditellurium compounds and sodium borohydride ", reacted with triorganosilyl, -germyl, -stannyl, and -plumbyl chlorides to produce, for instance, organo triorganosilyl tellurium compounds. 

Like their aryl and alkenyl counterparts, alkynylboronic adds can be made by displacement of magnesium or lithium acetylides with borate esters. For example, Mat-teson and Peacock have described the preparation of dibutyl acetyleneboronate from ethynylmagnesium bromide and trimethyl borate [294]. The C-B hnkage is stable in neutral or acidic hydrolytic solvents but readily hydrolyzes in basic media such as aqueous sodium bicarbonate. Brown and co-workers eventually applied their organo-lithium route to boronic esters to the particular case of alkynylboronic esters, and in this way provided a fairly general access to this class of compounds [295]. 

A notable exception to the emphasis on free-radical polymerization studies was provided by Karl Ziegler and his co-workers who extended the study of the alkali metal polymerization of dienes to include metals other than sodium and various metal alkyls. Of particular interest were the results obtained with the simplest Group I alkali metal, lithium. It was found that when lithium metal was used as a polymerization initiator 1,4- structures predominated over 1,2-polymers. It was also found that polymerization in hydrocarbon solvents further favoured production 1,4- structures whilst polymerization in polar liquids such as ethers and amines often favoured the formation of 1,2- units. It was also found that reaction of lithium with monomer led to the production of an organo-lithium compound which made feasible homogeneous polymerization—a discovery which eventually led to commercial exploitation. 

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