THE RELATIVE STABILITY OF PENTAARYLETHANES. III.¹ THE REVERSIBLE DISSOCIATION OF PENTAARYLETHANES^*

Abstract

4 Schlenk and Marcus, Ber., 47, 1670 (1914). 354* The symbols (0-, 1-, etc.) throughout the paper refer to the positions of the biphenyl groups on the "1" carbon atom (with three aryl groups) and the "2" carbon atom (with two aryl groups) of the pentaarylethane; thus pentaphenylethane is called 0-, penta-p-biphenylethane is 1,1,1,2,2-, etc. * It will be recalled that hexa-p-biphenylethane is completely dissociated in solution as well as in the solid state; Schlbnk, Weickel and Herzenstein, Ann.,

The Persistent Radical Effect: From Mechanistic Curiosity to Synthetic Tool

“…In a 2001 review on this kinetic phenomenon and its applications [6], Fischer goes further in his acknowledgment of previous, independent descriptions of the effect by Bachmann and Wieselogle [7], and Perkins [8].…”

The Persistent Radical Effect in Organic Synthesis

“…Already in 1936, Bachmann and Wiselogle reported on unusual selectivities for the cross‐coupling of persistent with transient radicals . In this pioneering study, it was found that pentaphenylethane ( 1 ) in o ‐dichlorobenzene shows an unexpectedly long lifetime at high temperature.…”

The crystal structure of the molecular complex between triphenylmethyl dimer and ethyl acetate

“…It lies close to the value, 1.582 /~, found for hexamethylethane (Bartell & Boates, 1976) whose thermolysis involves an activation energy of 68.5 kcal mol -~ (Tsang, 1966). Pentaphenylethane (PPE), which can be regarded as a true ethane at room temperature, only splits into radicals above 105 °C (Bachmann & Wiselogle, 1936) with an activation energy of 27.6 kcal mo1-1. Empirical forcefield calculations (EFF) have recently been performed to determine strain energies and geometries of hexaphenylethane (HPE) and similar strained hydrocarbons (Hounshell, Dougherty, Hummel & Mislow, 1977).…”