Solvolysis of 2-aryl-2-adamantylp-nitrobenzoates and some tertiary benzylicp-nitrobenzoates.YBnOPNB andYxBnOPNB scales

Abstract

Solvolysis rate constants for a number of tertiary benzylic p‐nitrobenzoate esters in a wide range of solvents were measured. New scales of solvent ionizing power for Grunwald–Winstein‐type correlation analyses, YBnOPNB from 2‐phenyl‐2‐adamantyl p‐nitrobenzoate and YxBnOPNB from 2‐(6‐methoxy‐2‐naphthyl)‐2‐ adamantyl p‐nitrobenzoate, were developed for the mechanistic study of solvent effects on the solvolytic reactivity of benzylic p‐nitrobenzoates. The excellent linear log k –YBnOPNB plot for 2‐(4‐methylphenyl)‐2‐propyl p‐nitrobenzoate indicated a limiting SN1 mechanism. The solvolytic transition state for 9‐phenyl‐9‐fluorenyl p‐nitrobenzoate and that for 1,1‐diphenylethyl p‐nitrobenzoate were considered to involve extended positive charge delocalizations from the observation of linear relationships between log k and YxBnOPNB. The ambiguity in the case of 2, 2‐dimethyl‐1‐(4‐methoxyphenyl)‐1‐phenyl‐1‐propyl p‐nitrobenzoate is discussed. Copyright © 2000 John Wiley & Sons, Ltd.

Structures, Lewis Acidities, Electrophilicities, and Protecting Group Abilities of Phenylfluorenylium and Tritylium Ions

“…By using the reported kinetics of solvolysis (see the Supporting Information, part 7),– together with the N f and s f parameters for Br − and Cl − in various solvent mixtures, plots of (log k ion )/ s f against N f were constructed (Figure ) and thus gave access to the electrofugality parameters E f of the five phenylfluorenyls 2(b–f) (Table ).…”

Kinetics of the Solvolyses of Benzhydryl Derivatives: Basis for the Construction of a Comprehensive Nucleofugality Scale

“…Our method of assigning nucleofugality parameters to combinations of leaving groups and solvents is an alternative to previous approaches that employ different Y scales for different leaving groups 3c. 32–34…”