No abstract

No abstract

In trying to understand chemical reactivity, the physical organic chemist has traditionally relied on models or concepts that are qualitative and intuitive. Claude F. Bernasconi was born In Zurich, Switzerland, In 1939. He received his undergraduate degree and Ph.D. (with Heinrich Zollinger) from the Swiss Federal Institute of Technology (ETH), Following a postdoctoral year with Manfred Eigen at the Max Planck Institute for Biophysical Chemistry in Gottingen, he Joined the chemistry faculty at the University of California, Santa Cruz, in 1967, where he has been a Professor of Chemistry since 1977. His research Is focused on kinetics, organic reaction mechanisms, and structure-reactivity problems.Perhaps the best-known physical organic concept is the Hammond postulate3 along with its various extensions(1) This Account is based, in part, on a talk I presented during a symposium honoring Professor Joseph Bunnett on the occasion of his retirement from active service at the University of California at Santa Cruz. The talk was entitled "From Bunnett's Variable Transition State Theory to the Principle of Non-Perfect Synchronization". Except for the introduction, which summarizes the basic features of the principle of nonperfect synchronization (PNS), most of the material is new. Specifically, there is very little overlap with an earlier Account that was entitled "Intrinsic Barriers of Reactions and the Principle of Nonperfect Synchronization".2

No abstract

Three relatively fast kinetic processes can be detected in reactions of 2,4,6-trinitrotoluene (TNT) with lyate ions in methanol, ethanol, and in 50% dioxane-50% water. With the base in excess over TNT, formation of the 2,4,6-trinitrobenzyl anion (TNT-) is the principal process. At high base concentration a second much faster process emerges, which is difficult to identify but could be due to a Meisenheimer complex (MC) coupled to a radical-anion formation. When TNT is in excess over the base, formation of a Janovsky complex (JC) between TNTand a second molecule of TNT is observed, which is identified through its visible spectrum. Rate constants of TNTand JC formation and reversion were measured. Preliminary spectral evidence indicates that in