19295-16-0Relevant academic research and scientific papers
Parallelism Between Nucleophilically Solvent-Assisted and Phenyl-Assisted Reactions. Possible Existence of Nucleophilically β-Phenyl-Solvated Ion Pairs
Laureillard, Jeanne,Casadevall, Andre,Casadevall, Eliette
, p. 352 - 360 (1984)
Solvolysis rate constants in MeOH and t-BuOH are compared for β-methyl and β-phenyl derivatives of two cycloalkyl systems.It appears that the β-phenyl derivatives solvolyse at the same rate as the β-methyl ones.The lack of deceleration is attributed to phenyl assistance.It is established by configurational analysis of the reaction products, that those products which necessarily originate from a cationic species are the most abundant ones.It is suggested that these reactions could proceed through ion-pair intermediates, which are nucleophilically solvated by phenyl or by the solvent.A parallel between phenyl assistance and 'SN2 (intermediate)' mechanism, suggested by Bentley and Schleyer, is drawn.
ASSISTANCE D'UN GROUPE VOISIN POUR DES TOSYLATES SECONDAIRES β-SUBSTITUES DIEQUATORIAUX DANS L'HEXAFLUOROISOPROPANOL 97percent
Laureillard, J.,Casadevall, E.
, p. 2117 - 2122 (2007/10/02)
Solvolysis rates in methanol and 97percent hexafluoroisopropanol (HFIP) for four β-methyl and β-phenyl bicyclic tosylates, show that solvent nucleophilic assistance is operating in the former solvent.However, in 97percent HFIP, for three of the mentioned compounds, the mechanism involves ? or ? neighboring group assistance.The factors influencing the occurrence of these processes are discussed.Owing to these possible neighbouring group assistances in non-nucleophilic solvents used to obtain kc reference mechanisms, it is concluded that the ks/kc ratio which was proposed as a quantitative evaluation of solvent nucleophilic assistance must be used with caution.
