... 0002-7863/81/1503-5388$01.25/0 0 1981 American Chemical Society ... 1980, 45, (20) Perst, H. "Oxonium Ions in Organic Chemistry"; Academic Press: London, 197 1. (21) Toyoshima, K ... olefins.29 Given the substituent effects at C, (correlation 3), it remains for us to measure ...