Document type
Journal articles
Document subtype
Full paper
Title
Solvation Effects in the Heterolyses of 3-X-3- Methylpentanes (X=Cl, Br, I)
Participants in the publication
F. Martins (Author)
Dep. Química e Bioquímica
CQB
R. E. Leitão (Author)
L. Moreira. (Author)
Summary
A comparative study of the heterolysis reactions of 3?X?3?methylpentanes (X = Cl, Br, I) in a set of protic and aprotic solvents was performed at 25.00°C. Rate constant values were correlated with solvent descriptors using the TAKA multiparametric equation. Our results point towards a decrease in both hydrogen bond donor acidity (electrophilicity) and hydrogen bond acceptor basicity (nucleophilicity) contributions, and towards an increase in the dipolarity/polarizability term on going from the chloride substrate to iodide. These features suggest the formation of an increasingly early transition state, in contrast to the classical Hughes–Ingold rationale, but in agreement with the Hammond postulate. Furthermore, there seems to be no evidence for a shift in solvation from an electrophilic (or anionic) mode in the chloride substrate to a nucleophilic (or cationic) mode in the iodide, as claimed by some authors. Copyright © 2004 John Wiley & Sons, Ltd.
Date of Submisson/Request
2003-09-03
Date of Acceptance
2004-02-29
Date of Publication
2004-07
Institution
FACULDADE DE CIÊNCIAS DA UNIVERSIDADE DE LISBOA
Where published
JOURNAL OF PHYSICAL ORGANIC CHEMISTRY
Publication Identifiers
ISSN - 0894-3230
Publisher
John Wiley & Sons, Ltd.
Number of pages
6
Starting page
1061
Last page
1066
Document Identifiers
DOI -
https://doi.org/10.1002/poc.816
Rankings
SCIMAGO Q3 (2004) - 0.608 - Physical and Theoretical Chemistry
Web Of Science Q3 (2006) - 1.211 - Chemistry, Physical
Keywords
Reaction kinetics
3-Halo-3-methylpentane
Solute–solvent interactions
Linear solvation energy relationships