Abstract: Ionization either of 3-pX-phenyl-2, 3-dimethyl-2-butyl chloride (1) or pX-phenyl-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= CH3, the tetramethylethylenep-toluonium ion (3-CH3) and the p-tolylmethyl-t-butylcarbonium ion (7- ...