Is there another parameter that can replace the sigma Hammett constant?
The question is so brief will you please write in more details . If you want tabulation there is one good reference: chem. Rev.1991, 91, pages 165-195( C. Hansch, A. Leo and R.W. Taft).
It depends whether you want single parameter model ( Hammett type) or Multiple substituent parameters model. In each case there are so many substituent parameters . Also, the type of the studied property influence the choice of the type of substituent parameter.
Note that use of σ- and σ+ parameters can increase the quality of your Hammett correlations. Use them instead of the standard σ values when either a large negative or a large positive charge builds up in the transition state.
See for example: Hansch et al.: Comprehensive Medicinal Chemistry, Vol 4., p. 196. *Pergamon Press, 1990). However, be prepared for terrible bad correlations.
I have just found one good book: Handbook of Molecular Descriptors
by Roberto Todeschini and Viviana Connsonni : Methods and Principles in medicinal Chemistry Vol 11 (Wiley-VCH) ISBN: 3-52-29913-0 (2000)
These values can be found in: C. Hansch, A. Leo, R.W. Taft, A Survey of Hammett Substituent Constants and Resonance and Field Parameters, Chem. Rev. 1BBl. 97, 165-195.
- Badges
- Science topic
- Similar topics
- Chemistry
- Organic Chemistry