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The formation of grignard compounds—III

1975; Elsevier BV; Volume: 31; Issue: 8 Linguagem: Inglês

10.1016/0040-4020(75)80126-8

1464-5416

H. W. Bodewitz, C. Blomberg, F. Matthias Bickelhaupt,

Oxidative Organic Chemistry Reactions

The reaction of 6-bromo-1-hexene with Mg was studied in order to obtain information on the role of the solvent during the formation of Grignard reagents. The 5-hexenyl radical (Rnc.) is known to cyclize rapidly and irreversibly to the cyclopentylmethyl radical (Rc.). Changes in yields of the cyclized and non-cyclized Grignard compounds have been found on varying the solvent. Information on the radical pairs involved is obtained from the yields of the three possible coupling products (RncRnc, RncRc and RcRc). Results are correlated to the intensity of the CIDNP spectra of the Grignard compounds. It is found that basicity and viscosity of the solvents influence the reactions at the site of single electron transfer. Formation of Grignard compounds via radical pairs increases: (a) with decreasing basicity of the solvent, (b) with decreasing viscosity of the solvent, and (c) on dilution of THF with benzene. It is proposed that interaction between the radical and the π-electron rich solvent benzene plays a role in reactions run in Bz/THF mixtures.