Acid-base chemistry proton affinity

Paze, C., Bordiga, S., Lamberti, C., Salvalaggio, M., Zecchina, A., Bellussi, G. (1997). Acidic Properties of H-p Zeolite as Probed by Bases with Proton Affinity in the 118-204 kcal moH Range A FTIR Investigation. Journal of Physical Chemistry B, Vol.101, No.24, (June 1997), pp. 4740-4751, ISSN 1520-6106 Peri, J.B. (1965). A Model for the Surface of y-Alumina. Journal of Physical Chemistry, VoL69, No.l, (January 1965), pp. 220-230, ISSN 0022-3654 Pillo, T., Zimmermann, R., Steiner, P., Hufner, S. (1997). The Electronic Structure of PdO Found by Photoemission (UPS and XPS) and Inverse Photoemission (BIS). Journal of Physics Condensed Matter, Vol.9, No.l9, (May 1997), pp. 3987-3999, ISSN 0953-8984 Rakai, A., Tessier, D., Bozon-Verduraz, F. (1992). Palladium-Alumina Catalysts - a Diffuse Reflectance Study. New Journal of Chemistry, Vol.16, No.8-9, (August-September 1992), pp. 869-875, ISSN 1144-0546... 

Theory helps the experimentalists in many ways this volume is on chemical shift calculations, but the other ways in which theoretical chemistry guides NMR studies of catalysis should not be overlooked. Indeed, further theoretical work on two of the cations discussed above has helped us understand why some carbenium ions persist indefinitely in zeolite solid acids as stable species at 298 K, and others do not (25). The three classes of carbenium ions we were most concerned with, the indanyl cation, the dimethylcyclopentenyl cation, and the pentamethylbenzenium cation (Scheme 1), could all be formally generated by protonation of an olefin. We actually synthesized them in the zeolites by other routes, but we suspected that the simplest parent olefins" of these cations must be very basic hydrocarbons, otherwise the carbenium ions might just transfer protons back to the conjugate base site on the zeolite. Experimental values were not available for any of the parent olefins shown below, so we calculated the proton affinities (enthalpies) by first determining the... 

Proton transfer reactions play very important role in chemistry and biochemistry [1-3]. Considerable attention has been focused on the gas phase reactions in the last decades, since they are free of the solvent pollution thus being related to the intrinsic reactivity [4 6]. In particular, investigations of gas-phase acidities and basicities were some of the major undertakings in the field [7,8]. The proton affinity (PA), on the other hand is an interesting thermodynamic property by itself. It gives useful information on the electronic structure of base in question and serves as an indicator of the electrophilic substitution susceptibility of aromatic compounds [9]. It is the aim of this article to describe some recent advances in theoretical calculations of the proton affinities of substituted aromatics. We shall particularly dwell in more detail on the additivity rules, which enable simple and quick estimates of PAs in heavily substituted benzenes and naphthalenes. Some prospects for future developements will be briefly discussed too. 

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