Quantifying Electrophilicity and Nucleophilicity

Herbert Mayr ,  Florian Seeliger ,  Stefan Berger 

LMU München, Department Chemie und Biochemie, Butenandtstrasse 5-13, München 81377, Germany


Reactions of donor stabilized carbocations with electron-rich π-systems and reactions of acceptor substituted carbanions with electron-poor π-systems are often treated as representatives of different classes of reactions - carbocation chemistry on one side, and carbanion chemistry on the other side.

We now demonstrate that the nucleophilicity parameters N and s, as defined by eq. 1 and previously derived from reactions of carbanions with benzhydrylium ions and quinone methides [1], can also be employed for describing the reactions of carbanions with various other types of Michael acceptors (Figure). In this way, carbocations and electron-deficient ethylenes can be located on a common electrophilicity scale while carbanions and electron-rich ethylenes can be located on a common nucleophilicity scale.

Figure. Plot of (log k)/s for the reactions of carbanions with electrophiles in DMSO at 20 °C versus the nucleophilicity parameters N of the carbanions. a) C6H4X = julolidyl

Figure shows that the slopes of (log k)/s plots versus the nucleophilicity parameters N of carbanions deviate from the slope of 1, indicating that eq. 1 does not properly describe these reactions, as previously reported for SN2 type reactions [2].

[1] H. Mayr, A. R. Ofial, Pure Appl. Chem. 2005, 77, 1807-1821.

[2] T. B. Phan, M. Breugst, H. Mayr, Angew. Chem. Int. Ed. 2006, 45, 3869-3874.

Legal notice
  • Legal notice:

    Copyright (c) Pielaszek Research, all rights reserved.
    The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
    In every case, proper references including Author(s) name(s) and URL of this webpage: http://science24.com/paper/8302 must be provided.


Related papers
  1. Electrophilicities of Benzylidenebarbituric Acids
  2. Nucleophilicities of Triflinate-Stabilized Carbanions
  3. Nucleophilicities of Amines and Amino Acids
  4. Towards a General Scale of Nucleophilicity?

Presentation: oral at 18th Conference on Physical Organic Chemistry, Symposium 1, by Herbert Mayr
See On-line Journal of 18th Conference on Physical Organic Chemistry

Submitted: 2006-05-31 17:38
Revised:   2009-06-07 00:44
Web science24.com
© 1998-2021 pielaszek research, all rights reserved Powered by the Conference Engine