SUBSTITUENT EFFECTS IN THE BIRCH REDUCTION REACTION OF SUBSTITUTED BENZENES

The substituent effects in the Birch reduction reaction of substituted benzenes are discussed. A nonplanar^boat-form conformation is suggested for the benzene radical union formed by the transfer of an electron to a substituted benzene-molecule. In this conformation the 1,4 -dienyl radical union has two double bonds isolated,the negative charge is localized on po-sion 6 and the. single electron is on position 3.the farthest position from the negative charge, when the substituent is electron-withdrawing. Both alkyl and alkoxy groups are considered to be electron-withdrawing. These sub-stituents should be activating groups for their inductive effect. The reaction rate decreasing of alkyl benzenes may be caused by reasons other than electronic effect. The reduction of benzole acid and. benzamide, in which 1,4-dihydro benzenes are obtained,is considered to be an exceptional example,in which an extra stabilized Y-aromatic radical union may be involved.

SUBSTITUENT EFFECTS IN THE BIRCH REDUCTION REACTION OF SUBSTITUTED BENZENES

The substituent effects in the Birch reduction reaction of substituted benzenes are discussed. Anonplanar, boat-form conformation is suggested for the benzene radical anion formed by the transfer of an electron to a substituted benzene molecule. In this conformation ,the 1,4-dienyl radical anion has two double bonds isolated, the negative charge is localized on posion 6 and the single electron is on position 3, the farthest position from the negative chareg, when the substituent is electron-withdrawing. Both alkyl and alkoxy groups are considered to be electron-withdrawing. These substituents should be activating groups for their inductive effect. The reaction rate decreasing of alkyl benzenes may be cansed by reasons other than electronic effect. The reduction of benzoic acid and benzamide, in which 1,4-dihydro benzenes are obtained, is considered to be an exceptional example, in which an extra stabilized Y-aromatic radical anion may be invilved.