The first-order rate constants, the products, and the activation parameters for the acetolysis of 2, a-dimethylcyclooctyl p-nephthalenesulfonate and several medium-sized-ring spiran esters have been determined. The spiro compounds studied were 1 with m= 8 and n= 5, 6, and 7; 1 with m= 6 and n= 7; and 1 with m= 9 and n= 8. The 2, 2-dimethylcyclooctylp- naphthalenesulfonate yielded products arising exclusively from ring contraction. For the ...