Insertion lithiated carbons

During electrochemical reduction (charge) of the carbon host, lithium cations from the electrolyte penetrate into the carbon and form a lithiated carbon Li rCn. The corresponding negative charges are accepted by the carbon host lattice. As for any other electrochemical insertion process, the prerequisite for the formation of lithiated carbons is a host material that exhibits mixed (electronic and ionic) conductance. 

Insertion into Carbon-Carbon o-Bonds. First examples of this concept were reported with anionic nucleophiles in the context of the addition of a-lithioalkyl and a-lithioarylacetonitriles to arynes. In 1984, Meyers and Pansegrau proposed a cyclization rearrangement mechanism to account for the formation of products 77 in the reaction of a-lithioacetonitriles to 3-oxazolylbenzyne. Initial attack of the nucleophile takes place at C-2 probably due to chelation of the lithium atom from the lithiated nitrile to the oxazoline moiety (Scheme 12.40) [67]. 

In case of an inerease in operating temperature with a strong current or because of poorly-eontrolled or uncontrolled environmental conditions, the phenomenon leading to thermal runaway is linked primarily to the deeomposition of the SEI of the lithiated carbon electrode, leaving exposed the electrode, whieh deeomposes by reaction between the inserted lithium and the eleetrolyte. Gas formation occurs, once again leading to an increase in the internal pressure of the element. 

There have been three reports of cr-bond insertion reactions developed for use as tools for synthesis. In general these involve carbenoids rather than carbenes, but they are included here because of their interest as selective reagents. In the first a lithiated gem-dihalide (68) effectively inserted into carbon-zirconium bonds, for example (69), to give ultimately the corresponding carbocycles (70) in moderate-to-good yields. This process is arguably stepwise involving a carbenoid species rather than a carbene. ... 

It should be noted that the study of noble metal electrodes in nonaqueous Li salt solutions is even more relevant to the understanding of the behavior of lithiated carbon anodes because, in the latter case, the carbon electrodes that are initially nearly surface film-free, are also polarized from OCV ( 3 V ra. IA/lU, see also Figure 2) to low potentials in the course of Li intercalation, and surface films are gradually formed on the carbon electrode as it reaches lower potentials. Hence, the order of surface reactions may be similar to that described in Figure 2, except for the Li under potential deposition and stripping processes, which are irrelevant to carbon electrodes (into which lithium is inserted at potentials higher than that of Li deposition). 

Benzofurans. A method for the preparation of benzofurans from o-hydroxy phenones involves conversion to the alkynes (deoxygenation with one-carbon insertion) by reaction with lithiated trimethylsilyldiazomethane, and treatment of the products with TBAF. 

In fact, the ability of layer-structured carbon to insert various species was well known by the latter half of the 1800s. The ability of graphite to intercalate anions promoted exploration into the use of a graphite cathode for rechargeable batteries. Juza and Wehle described carbon lithiation studies in the middle of last century. ... 

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