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Quaternization Reaction of Aromatic Heterocyclic Imines in Methanol − A Case of Strong Anti‐Reactivity Selectivity Principle with Isoselective Temperature
Author(s) -
Alfaia António J. I.,
Calado António R. T.,
Reis João Carlos R.
Publication year - 2000
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200011)2000:21<3627::aid-ejoc3627>3.0.co;2-j
Subject(s) - chemistry , selectivity , reactivity (psychology) , enthalpy , methanol , reaction rate , computational chemistry , reaction rate constant , organic chemistry , medicinal chemistry , thermodynamics , kinetics , catalysis , medicine , physics , alternative medicine , pathology , quantum mechanics
Accurate second‐order rate constants were measured at 5 °C intervals in the temperature range 20−60 °C for the Menshutkin reaction of 1‐methylbenzimidazole, 2‐amino‐1‐methylbenzimidazole and N , N ‐dimethylaniline with iodomethane and iodoethane in methanol. In every case a good linearity in the Eyring plots was observed. Values for the activation enthalpy and entropy are reported. Analysis in terms of Exner’s redefinition of the reactivity−selectivity principle (RSP) identified the present reaction series as a case of strong anti‐RSP for selectivity towards the substrate. This case is shown to represent an isoselective relationship with the isoselective temperature lower than the experimental temperatures ( β is = −52 °C). The isokinetic relationship does not hold in the reaction series with a fixed substrate. These findings suggest an early transition state in the Menshutkin reaction of polyfunctional aromatic imines.