STABLE CARBONIUM IONS .73. 3-ARYL-2,3-DIMETHYL-2-BUTYL CATIONS AND FACTORS CONTROLLING PHENONIUM ION-PHENETHYL CATION-BENZYL CATION EQUILIBRIA

Ionization either of 3-p-X-phenyl-2,3-dimethyl-2-butyl chloride (1) or p-X-pheny-t-butylmethylcarbinyl chloride (2)·(X = H, CH3, OCH3, or CF3) yields the same thermodynamically most stable carbonium ion(s). For X = H, the tetramethylethylenephenonium ion (3-H) is the most stable ion. For X = CH 3, the tetramethylethylene-p-toluonium ion (3-CH3) and the p-tolylmethyl-z-butylcarbonium ion (7-CH3) have comparable stability. For X = OCH3, the p-anisyl-t-butylmethylcarbonium ion (7-OCH3) is the most stable, and for X = CF3, the 3-p-trifluoromethylphenyl-2,3-dimethyl-2-butyl cation (4-CF3) is the most stable ion. The factors controlling these equilibria and the relationship between these ions and other systems where equilibrating ions and/or bridged ions may be important are discussed. © 1969, American Chemical Society. All rights reserved.