Amides of alkali metals

High inhibitive efficiency relative to thermal destruction of n-alkanes is displayed by hydrides and amides of alkali metals [33-35]. 

Solutions of alkali metals in liquid ammonia are valuable as powerful and selective reducing agents. The solutions are themselves unstable with respect to amide formation ... 

Considering the importance of alkali metal phosphanides it is not surprising that numerous review articles have dealt with this subject [34-36]. The solid state and solution structures vary from dimers with central M2 P2 cycles to larger rings and from chain to ladder structures as described for the lithium amides (see Sections 3.6.1 and 3.6.2). Cage compounds in the field of lithium phosphanides are unusual... 

Ruthenium(III) catalyses the oxidative decarboxylation of butanoic and 2-methylpropanoic acid in aqueous sulfuric acid. ° Studies of alkaline earth (Ba, Sr) metal alkoxides in amide ethanolysis and of alkali metal alkoxide clusters as highly effective transesterification catalysts were covered earlier. Kinetic studies of the ethanolysis of 5-nitroquinol-8-yl benzoate (228) in the presence of lithium, sodium, or potassium ethoxide revealed that the highest catalytic activity is observed with Na+.iio... 

Pedersen used reactions of nucleophilic substitution to synthesize most of the crown ethers he has obtained. On the other hand, Lehn and his coworkers [17] (Fig. 7.1.4) carried out cyclization reactions involving amide formation under high dilution conditions in their quest for cryptands such as 54. Pedersen analysis of the selective inclusion of alkali metal cations into the crown ethers cavity... 

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. 

A variety of alkali metal and metallocene-containing magnesium amides are known. Thus, attempted metallation of ferrocene using potassium tris(amido)magnesiate KMg N-(SiMe3)2 3 unexpectedly led to n-coordination of neutral ferrocene moieties to a pota-... 

Experimental evidence in support of this explanation is the fact that lithium added to a solution of lithium iodide in ethylenediamine dissolves without imparting a blue color to the solution—i.e., reacts immediately to give the amide. By contrast, lithium added to a solution of lithium chloride in ethylenediamine dissolves and imparts a deep blue color to the solution. The catalytic effect of iodide anion may be related to the effect of iodide anion on the electron spin resonance (ESR) absorption of solutions of alkali metals in liquid ammonia. Catterall and Symons (2) observed a drastic change in the presence of alkali iodides but very little change in the presence of alkali bromides or chlorides. They attributed this change to interaction of the solvated electron with the 6 p level of the iodide anion. 

The very dilute solutions of alkali metals in ammonia thus come close io presenting the chemist with the hypothetical ultimate base, the free electron (Chapter 9). As might be expected, such solutions are metaslable, and when catalyzed, the electron is leveled to the amide ion ... 

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. 

Amides with electron-withdrawing substituents can be sufficiently labile towards nucleophilic attack to enable their use as protective groups. This is the case, for example, with trifluoro- [102,290] and trichloroacetamides [163], which are readily hydrolyzed under mild conditions (Figure 10.13). Suitable nucleophiles are hydrazine [291], aliphatic amines, and hydroxide, but if a hydrophobic support has been chosen, it must be borne in mind that the reactivity of alkali metal hydroxides will be reduced because of poor diffusion into the support. Amides of electron-poor amines (e.g. anilides) can also be readily cleaved by nucleophiles [292],... 

Bismuth is an important element in many of the new high-temperature, oxide superconductors and in a variety of heterogeneous mixed oxide catalysts. Some of the methods employed in the preparation of these materials, namely sol-gel and chemical vapor deposition processes, require bismuth alkoxides as precursors and a number of papers on these compounds have recently been published.1 One synthetic route to bismuth alkoxides, which avoids the more commonly used trihalide starting materials and the often troublesome separation of alkali metal halides, involves the reaction between a bismuth amide and an alcohol according to the following equation ... 

The amides of alkali and alkaline-earth metals catalyse hydrogen exchange in hydrocarbons even in the absence of liquid ammonia. For example, the heterogeneous deuterium exchange of benzene and 2-methylbutene-l occurs with a considerable velocity on solid KND2 and Ca(ND2)2 at 70°. This gives rise to the isomerization of 2-methyl-butene-1 to 2-methylbutene-2 (Shatenshtein et al., 1958a). 

This conclusion is supported by observations of the isomerization of unsaturated hydrocarbons catalysed by potassium amide not only in ammonia solution (Shatenshtein and Vasil eva, 1954 Shatenshtein et al., 1954) but also by solid amides of alkali and alkaline-earth metals (Shatenshtein et al., 1958a). For example, diallyl rearranges to dipropenyl, pentene-1 to pentene-2, and 2-methylbutene-l to 2-methyl-butene-2. Subsequently, a further number of examples of isomerization... 

The use of alkali-metal amides instead of the amine itself has the advantages of avoiding polyaddition reactions and the need of using an excess of amines (see above). This process has been applied to the synthesis of SMA. A chloromethylsilane was condensed with an amide preformed from an acidic amine function. In general, good yields were obtained.17 81 88 91... 

The Tschitschibabin reaction285,266 of alkali metal amides with pyridine bases has been the subject of much recent discussion. While there is yet no agreement concerning the detailed mechanism (due to the lack of experimental information) there is no doubt that the overall reaction proceeds by an SN2 type addition-elimination pathway. 

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... 

On addition of alkali metal amides S3N" and SJ" are believed to form.6... 

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