Grignard reagents benzophenone

In an alternative method of preparation, benzophenone is used. Prepare the Grignard reagent from 13 -5 g. of magnesium turnings as above, cool in cold water, and add a solution of 91 g. of benzophenone (Section IV,139) in 200 ml. of dry benzene at such a rate that the mixture refluxes gently. Reflux the mixture for 60 minutes, and isolate the triphenylcarbinol in the manner described above. The yield is of the same order. 

Amination of aryl Grignard reagents without a Cu(I) catalyst could succeed using 3,3, 5,5 -tetrakis(triflnoromethyl)benzophenone 0-tosyloxime 6j as an amination reagent in tolnene (Scheme 64). ... 

Narasaka reviewed the synthesis of arylamines by amination of Grignard reagents with 4,4 -bis(trifluoromethyl)benzophenone O-p-tosyloxime 6i and 3,3, 5,5 -tetrakis(triflnoro-methyl)benzophenone O-tosyloxime... 

The SET mechanism is known to be operative for reactions of Grignard reagents and aromatic ketones such as benzophenone ". In reactions of Grignard reagents and aliphatic ketones and aldehydes, the polar mechanism seems to be major . The reactions of aliphatic ketones and aldehydes are more widely ntilized in organic syntheses. Thns, at first, the polar addition mechanism was examined. 

The Grignard reagent is prepared from 6 gms. (2 mols.) of dry magnesium, and 39 gms. (2 mols.) of ethyl iodide (redistilled), as described in Preparation 19, 120 c.cs. of anhydrous ether being used. 23 gms. (1 mol.) of dry, finely divided benzophenone are added, the flask being cooled if the reaction becomes too vigorous. The mixture is then heated 6 hours on a water bath, treated with dilute acid, extracted with ether, the ether removed on a water bath, and the residue fractionated under reduced pressure, the fraction 169°—170° at 18 mms. being separately collected and recrystallised from petroleum ether. 

A concerted electron transfer mechanism, with formation of an alkyl radical and quinone radical anion, has been proposed to account for the products of reaction of benzophenone with alkyllithium or Grignard reagents 92 the ratio of addition to reduction products is dependent on the alkyl group and not on the metal. 

Reaction of benzaldehyde with the Grignard reagent of bromobenzene followed by oxidation of the resulting secondary alcohol gives benzophenone. 

When [1-14C]phenylalanine was tested as a precursor, the entire activity of decinine and decodine was unequally divided between C-ll and C-3. The carbonyl carbon at C-ll [isolated as benzophenone oxime as a result of phenylation with the Grignard reagent, dehydration, and chromic acid... 

A particularly stable ketyl radical is derived from benzophenone (cf. Figure 17.52). This is why additions of the Grignard reagents R2Mg2Hal2 to this substrate proceed more frequently via radicals as intermediates than others. An example in which the occurrence of such a radical intermediate is documented by the typical radical cyclization 5-hexenyl —> cyclopentyl-carbinyl (cf. Section 1.10.2) is the following ... 

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