Grignard reagents, reaction with oxygen

Indeed, it is endothermic by over 130 kJmoU This documents that the polar/ionic bond between magnesium and oxygen is exceptionally strong, a fact we already surmised by the vigor of the reaction of Grignard reagents with air and water. 

The emphasis of this chapter will be on the mechanistic aspects of the ( normal ) addition reaction of Grignard reagents to the carbon-oxygen double bond, as is found for ketones. However, it will become clear that for reactions with other substrates, the general mechanistic aspects of these carbonyl addition reactions are also applicable. 

The driving force for the reaction of Grignard reagents with a carbonyl compound is, as previously mentioned, the formation of the strong bond between magnesium and oxygen. As illustrated in Scheme l.l. this bond is formed in both the concerted and the stepwise reaction mechanisms. 

Newer developments in the study of the reactions of benzophenone with Grignard reagents have been the use of radical probes. If the alkyl of the reagent has the ability to undergo isomerization as, for example, cyclization or cia-inms isomerization, while it exists as a free radical, it is possible to get information about the nitc of recombination of alkyl and kclyl in the formation of the various reaction products.. S-Hexenylmagnesium bromide has been used in the study of the free radical type mechanism by its reactions with oxygen and the rate of cyclization of the, S-hexenyi radical was known to he 10 s. ... 

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