Grignard reagent application

Some of the applications of the Grignard reagent described above may be expressed in general terms thus ... 

The mam synthetic application of Grignard reagents is their reaction with certain carbonyl containing compounds to produce alcohols Carbon-carbon bond formation is rapid and exothermic when a Grignard reagent reacts with an aldehyde or ketone... 

You have already had considerable experience with carbanionic compounds and their applications in synthetic organic chemistry The first was acetyhde ion m Chapter 9 followed m Chapter 14 by organometallic compounds—Grignard reagents for example—that act as sources of negatively polarized carbon In Chapter 18 you learned that enolate ions—reactive intermediates generated from aldehydes and ketones—are nucleophilic and that this property can be used to advantage as a method for carbon-carbon bond formation... 

Next to the formation of Grignard reagents, the most important application of this reaction is the conversion of alkyl and aryl halides to organolithium compounds, but it has also been carried out with many other metals, (e.g., Na, Be, Zn, Hg, As, Sb, and Sn). With sodium, the Wurtz reaction (10-93) is an important side reaction. In some cases, where the reaction between a halide and a metal is too slow, an alloy of the metal with potassium or sodium can be used instead. The most important example is the preparation of tetraethyl lead from ethyl bromide and a Pb—Na alloy. 

For a review of the synthetic applications of metalation hy Grignard reagents at positions other than at triple bonds, see Blagoev, B. Ivanov, D. Synthesis, 1970, 615. 

The report by Luche and coworkers that ultrasonic waves from a common ultrasonic laboratory cleaner aid the formation of organolithium and Grignard reagents and also improve the Barbier reaction spurred much of the current interest in the synthetic applications of ultrasound(lO) ... 

---