Alkali metals isolation

Potassium was the first alkali metal isolated in its elemental state. Sir Humphrey Davy electrolyzed caustic potash in 1807 applying a powerful battery. He gained metallic globules of a reactive metal collected at the cathode. It was the first time that a metallic element was isolated by means of electrolysis. Davy discovered sodium in the same year. He used caustic soda for the electrolysis. Before Davy s discoveries, these alkalis were not thought to be elements. 

English, potash - pot ashes L.. kalium, Arab qali, alkali) Discovered in 1807 by Davy, who obtained it from caushc potash (KOH) this was the first metal isolated by electrolysis. 

Fluoride ion sources include alkali metal, ammonium, tetraalkylammomum, and silver fluorides. With silver fluoride, the polyfluoroalkylsilver intermediates can be isolated [/, 37] (equation 6)... 

Carbamyl and thiocarbamyl fluorides are obtained from hydrogen fluoride and cyanic acid or alkali metal cyanates or thiocyanates [/, 54] Nitnles give iraidofluoride salts with hydrogen fluoride [7] whereas hydrogen cyanide affords difluoromethylamine, which can be isolated as its hexafluoroarsinate salt [55) (equation II)... 

More general procedures for additions of halogen fluorides to highly fluori-nated olefins involve reactions with a source of nucleophilic fluoride ion, such as an alkali metal fluoride, in the presence of aposttive halogen donor [62 107, lOff, 109, 110, 111] (equations 11 and 12) These processes are likely to occur by the generation and capture of perfluorocarbamonic intermediates Tertiary fluormated carbanions can be isolated as cesium [112], silver [113], or tns(dimethylamino)sul-... 

A particularly imaginative application of this concept has led to the isolation of compounds which contain monatomic alkali metal anions. For example, Na was reacted with cryptand in the presence of EtNHi to give the first example of a sodide salt of... 

Compounds containing M-C bonds are well established for Be and Mg but, as with the alkali metals, reactivity within the group increases with increasing electropositivity, and relatively few OrganometalHc compounds of Ca, Sr or Ba have been isolated. 

Most sulfites (except those of the alkali metals and ammonium) are rather insoluble as indicated above such solutions contain the HSOi ion predominantly, but attempts to isolate M HSOs tend to produce disulfites (p. 720) by dehydration" ... 

Although alkali-metal salts of trisimido organophosphates [R PlNRlj] have not been isolated and structurally characterized compelling evidence for their... 

Sulphonic acids are frequently crystalline solids, readily soluble in water and often hygroscopic. Because of the difficulty of isolation of the free acids, they are usually encountered as the alkali metal salts. 

The reduction of the stannyl radical (t-Bu2MeSi)3Sn with alkali metals produces a variety of structural modifications depending on the solvent used (Scheme 2.55). Thus, in nonpolar heptane, a dimeric stannyllithium species [58c Li ]2 (E = Sn) was formed, whereas in more polar benzene, the monomeric pyramidal structure 58c [Ti -Li (C6H5)] was produced. In the latter compound the Li+ ion was covalently bonded to the anionic Sn atom being at the same time n -coordinated to the benzene ring. A similar monomeric pyramidal CIP 58c [Li (thf)2] was prepared by reduction in polar THE the addition of [2.2.2]cryptand to this compound resulted in the isolation of the free stannyl anion 58c K+([2.2.2]cryptand), in which the ion lacked its bonding to the Sn atom. ... 

Although organosilanes appear to react slowly (if at all) with water alone, in the presence of acids or bases (e.g., alkali metal hydroxides), reactions to give a silanol and H2 are rapid, with bases being particularly powerful catalysts. The evolution of H2 in this type of reaction may be used as both a qualitative and a quantitative test for Si-H bonds, and the mechanism of the acid and the base hydrolysis has been discussed in detail (30,31). This hydrolytic method is not very common for the preparation of silanols that are to be isolated, because both acids and bases catalyze the condensation of silanols to siloxanes, and therefore, only compounds containing large substituents are conveniently made in this way. If an anhydrous alkali metal salt is used, a metal siloxide may be isolated and subsequently hydrolyzed to give the silanol [Eq. (10)] (32). 

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