Organolithium reagents from alkyl halides

Metal-halogen interconversions are primarily used to prepare organolithium compounds from alkyl and aryl hahdes. Particular Grignard reagents can be prepared from this methodology. They often give better yields than reactions between halides and magnesium... 

Because organolithium and Grignard reagents are themselves prepared from alkyl halides, a two-step method converts an alkyl halide into an alkane (or another hydrocarbon). 

Organocuprates can be prepared from organolithium reagents and cuprous halides. Organocuprates react with alkyl halides to form a new C-C bond in the product 24,25, 32, 33, 42. 

Organolithium compounds are sometimes prepared in hydrocarbon solvents such as pentane and hexane, but nonnally diethyl ether is used. It is especially important that the solvent be anhydrous. Even trace amounts of water or alcohols react with lithium to form insoluble lithium hydroxide or lithium alkoxides that coat the surface of the metal and prevent it from reacting with the alkyl halide. Furthennore, organolithium reagents are strong bases and react rapidly with even weak proton sources to fonn hydrocarbons. We shall discuss this property of organolithium reagents in Section 14.5. 

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