Mixed zincate metalation

The difficulty of the problem is enhanced because it is now known that the bonds between atoms in compounds and in crystals can be partly ionic and partly covalent in character, and not simply one or the other. This applies in particular to many mixed oxides so that aluminates, titanates, zincates, etc., can be regarded as built up entirely from metal and oxygen ions, though to some extent negative aluminate, titanate, etc., ions seem to be present. 

Reactions of the amphoteric metals zinc and aluminum with dilute aqueous alkali, to form zincates or aluminates, are also a convenient source of hydrogen. Electrolysis of dilute mineral acids may be used to obtain hydrogen but care must be taken to avoid mixing with the oxygen released at the anode as this leads to explosive mixtures. Industrially, hydrogen is obtained as a by-product of the electrolytic cells used in the production of sodium hydroxide (reaction of the Na/Hg amalgam with water), or by the water-gas route in which steam is decomposed by hot coke. 

In 1999, our group designed and synthesized a new category of 2,2,6,6-tetramethyl-piperidino-zincate, LiZn(TMP) Bu2, simply by mixing Zn Bua and LiTMP (Eq. 7) [28]. Several analogs such as diisopropylamino-zincates LiZn(DA) Bu2 and LiZn (DA)Me2 were obtained later similarly [29]. These V-zincates possess excellent reactivity for directed orf/io-metalation (DoM) of arenes [9]... 

Five research groups with expertise in the field summarize recent fascinating developments, including l,4-dUithio-1,3-butadienes and their transmetallated organo-di-metallic compounds, mixed dimers of lithium amide/alkyllithium, gem-diorganometallic compounds, alkali-metal mixed-metal ate compounds, and lithium zincates. 

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