Alkali metal amides lithium

Synthetically important alkali—metal amides Lithium, sodium, and potassium hexamethyldisilazides, diisopropylamides, and tetramethylpiper-idides 13AG(E)11470. 

Reactions of amines with alkenes have been reviewed298,299. Alkali metal amides are active homogeneous catalysts for the amination of olefins. Thus diethylamine and ethylene yield triethylamine when heated at 70-90 °C at 6-10 atm in the presence of lithium diethylamide and /V./V./V. /V -tetrarncthylcthylcncdiaminc. Solutions of caesium amide promote the addition of ammonia to ethylene at 100 °C and 110 atm to give mixtures of mono-, di- and triethylamines300. The iridium(I)-catalysed addition of aniline to norbomene affords the anilinonorbomane 274301. Treatment of norbomene with aniline... 

The intervening years have seen huge growth in the number of well-characterized compounds, the vast majority of which are lithium, sodium or potassium salts. Their strucuiral chemistry has proven to be especially rich and the number of structures of alkali metal amides currently available exceeds 200. These involve a wide selection of structural motifs that were mostly unknown in 1980. 

There have been several reviews on alkali metal amide structural chemistry. Most of these deal with lithium amides but there is also significant coverage of the heavier elements and other topics such as derivatives of primary amides and hydrazides. " Two comprehensive reviews for lithium amides and related salts published in 1991 and 1995 include extensive tables of structural data. There have also been reviews of the of lithium amides as well as of the extensive use of alkah metal... 

Lithium amides are the most important of the alkali metal amides. This is mainly due to the facility with which they can be prepared in solution by the simple reaction of the amine with commercially available LiBu". An analogous reaction with heavier metal alkyls is much more difficult due to the high reactivity of heavier alkali metal alkyls which attack many solvents. Another advantage of lithium amides is that they tend to be more soluble in hydrocarbons than their heavier element congeners. This is due to the small size (and hence greater polarizing power) of the lithium ion, which induces greater covalent character. 

Iminoboranes have been suggested as intermediates in the formation of compounds derived from the pyrolysis of azidoboranes (77). The intermediate is presumed to be a boryl-substituted nitrene, RR BN, which then rearranges to the amino iminoborane, neither of which has been isolated (78). Another approach to the synthesis of amino iminoboranes involves the dehydrohalogenation of mono- and bis(amino)haloboranes as shown in equation 21. Bulky alkali-metal amides, MXA, have been utilized successfully as the strong base, D, in such a reaction scheme. Use of lithium-teti-hutyl(trimethylsilyl)amide... 

The only new compound produced in these studies was LiAlF4 however, this work is significant because control was achieved even with the highly exothermic reactions of lithium aluminum hydride, alkali metal borohydrides, and alkali metal hexahydroaluminated with elemental fluorine. The reactions of alkali metal amides with fluorine have also been successfully controlled. These reactions provide extremely clean routes to the fluoride analogues. 

Although the first bis(iminophosphorano)methanides were reported by Elsevier,15 the first structurally characterised examples were reported by Cavell.16 Solvent-free 1 and 2 were prepared from the reaction between the parent methane and lithium or sodium bis(trimethylsilyl)amides in aromatic solvents. By avoiding Lewis base solvents such as ethers, dimeric complexes were isolated. Treatment with excess quantities of alkali metal amide did not effect a second deprotonation, even under reflux conditions over days, which was attributed to the less basic nature of amides compared to alkyls (see section 3.2 below). In addition to the expected methanide-alkali metal bonds, methine C H — Li interactions were observed in 1 in the solid state but the analogous C-H — Na interactions appeared to be weak in 2. 

The carbonylation of alkali metal amides was described in 196785 the reaction of lithium tert-butylamide (80) with CO at 50 °C was reported in 1971 to give apparently an orange solution of ferf-butylcarbamoyllithium (81), which was trapped with trimethylelement chlorides derived from silicon, germanium and tin86. When this reaction was performed at — 75 °C it was found that carbamoyllithium equilibrated to the... 

Introduction. Potassium f-butoxide is intermediate in power among the bases which are commonly employed in modem organic synthesis. It is a stronger base than the alkali metal hydroxides and primary and secondary alkali metal alkoxides, but it is a weaker base than the alkali metal amides and their alkyl derivatives, e.g. the versatile strong base Lithium Diisopropylamide. ... 

However, the most common route to metal-imido compounds is some type of fv-elimination. For example, imido complexes have been prepared by the addition of amine or alkali metal amides to a metal halide (Equations 13.54 and 13.55). This reaction most likely occurs through an a-elimination from an amido halide intermediate. In addition, the first low-valent, late-transition-metal-imido complex was prepared by the simple reaction of [Cp rCyj with hindered lithium amides (Equation 13.56). - ... 

The use of metal alkoxides, especially those of Ti and Mg, as active components of multicomponent Ziegler-Natta type catalysts has an established place in industry. Many patent applications have been filed over the years but they read rather like cookery recipes and will not be documented here. Anionic polymerization of styrene, butadiene, and isoprene has also received much investigation. The addition of alkali metal alkoxides MOR to alkali metal amides MNH2 gives rise to a range of complex base initiators whose properties may be modulated by the nature of the metal, alkoxide group, and solvent. Similarly the effect of lithium alkoxides on the rate of polymerization of styrene initiated by -butyl lithium has also been reported. " ... 

Ring Additions Catalyzed by Alkali Metals. The addition of tributyltin chloride and olefins such as styrene, isoprene, or butadiene to sulfolane is cataly2ed by alkah metals, including sodium and lithium, and by sodium amide (10—13). The addition of tributyltin chloride to sulfolane in the... 

A number of compounds of the types RBiY2 or R2BiY, where Y is an anionic group other than halogen, have been prepared by the reaction of a dihalo- or halobismuthine with a lithium, sodium, potassium, ammonium, silver, or lead alkoxide (120,121), amide (122,123), a2ide (124,125), carboxylate (121,126), cyanide (125,127), dithiocarbamate (128,129), mercaptide (130,131), nitrate (108), phenoxide (120), selenocyanate (125), silanolate (132), thiocyanate (125,127), or xanthate (133). Dialkyl- and diaryUialobismuthines can also be readily converted to secondary bismuthides by treatment with an alkali metal (50,105,134) ... 

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