CHEMISTRY OF POLYMER-BOUND ORTHO-BENZYNE - FREQUENCY OF ENCOUNTER BETWEEN SUBSTITUENTS ON CROSS-LINKED POLYSTYRENES

o-Benzyne was generated by oxidation of 1-aminobenzotriazole derivatives covalently bound to various polystyrene supports. When lead tetraacetate is employed as the oxidizing agent, in the absence of any other substrates, the intermediate is converted to a mixture of isomeric aryl acetates. This reaction is not observed for monomeric 1-aminobenzotriazoles, where dimerization is the predominant pathway. The results are explained by a low frequency of encounter between the polymerbound intermediates which allow the relatively slow acetate formation to compete with the encounter-controlled dimerization process. Delayed trapping of the intermediate by a diene demonstrated a surprisingly long lifetime for the intermediate. When iodobenzene diacetate was used as oxidizing agent, no acetates were formed, and a rather complex series of reactions eventually resulted in intrapolymeric coupling of the benzyne. From the delayed trapping experiments, conducted under these two different sets of conditions, it can be concluded that the frequency of encounter between the intermediates bound to a 2% cross-linked polystyrene resin must lie between 2.6 X 10-2 and 1.1 X 10-3 s-1. © 1979, American Chemical Society. All rights reserved.