ISSN:
0894-3230
Keywords:
Organic Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The reactions of n-butylamine and piperidine with 1-chloro-2, 4-dinitrobenzene and 4-chloro-3-nitrotrifluoromethylbenzene were studied in n-hexane, benzene and mesitylene. The reactions seem to follow a bimolecular SNAr mechanism for both substrates and amines. However, whereas in n-hexane they are base catalysed, in the aromatic solvents only mild acceleration is observed. The different behaviour of these reactions in the aromatic solvents in comparison with hexane is explained by the specific solvent effect exerted by the aromatic compounds, which solvates the aromatic reactant preferentially in view of its electron-donor properties. These conclusions were confirmed by kinetic studies in hexane-aromatic solvent binary mixtures. It can be concluded that the presence of electron-donor solvents may inhibit SNAr reactions when association constant of the solvent with the substrate is greater than the EDA constants between the reactants. These specific solvent effects could also explain why only mild acceleration is observed in aromatic solvents.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/poc.610050902
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