Steric Effects on Reaction Rates. IV. Evaluation of the Ketone Model for the Solvolysis Transition State of Secondary p-Toluenesulfonates

✍ Scribed by Paul Müller; Jacky Blanc; Jean-Claude Pcrlberger

• Publisher: John Wiley and Sons
• Year: 1982
• Tongue: German
• Weight: 430 KB
• Volume: 65
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19820650514

✦ Synopsis

Abstract

The rates of solvolysis of secondary p‐toluenesulfonates in acetic acid or 97% trifluoroethanol are interpreted in terms of strain changes between substrate and the corresponding ketone. Such strain changes are obtained from force‐field calculations (Δ__E__~st~) and from equilibration of alcohols and ketones (Δ__G__~ox~). This simple model reproduces the behaviour of substrates reacting by __k__c‐pathways to afford unstrained carbenium ions. Anchimeric assistance and leaving group hindrance in the transition state are recognized in clear‐cut cases by deviations from the expected reactivity. However, the model breaks down when highly strained carbenium ions of the cyclobutyl or 7‐norbornyl type are involved.