SOLVENTS OF LOW NUCLEOPHILICITY .12. TRIPLE-BOND PARTICIPATION IN ACETOLYSIS, FORMOLYSIS, AND TRIFLUOROACETOLYSIS OF 6-HEPTYN-2-YL TOSYLATE AND 6-OCTYN-2-YL TOSYLATE

6-Heptyn-2-yl tosylate and 6-octyn-2-yl tosylate were prepared and solvolyzed. Analysis of the reaction rates and of the products agreed in showing that triple-bond participation occurred in competition with normal solvolysis, and that the proportion of reaction occurring via a participation path increased as the solvent was varied in the sequence acetic acid, formic acid, and trifluoroacetic acid. 6-Octyn-2-yl tosylate did not exhibit an extremely strong tendency to solvolyze via a linear vinyl cationic transition state or intermediate (in which the cationic carbon is exocyclic to a five-membered ring) in competition with reaction via a bent cation (in which the cationic carbon is part of a six-membered ring). Accordingly the transition state for solvolysis does not resemble a vinyl cation but instead may resemble a bridged ion. The results of the trifluoroacetolysis of 6-hepten-2-yl tosylate indicated that triple-bond participation occurred somewhat more readily than double-bond participation. © 1969, American Chemical Society. All rights reserved.