Rate constants for the overall rearrangement of the 2, 2-dimethyl-3-buten-1-yl radical to the 1, 1-dimethyl-3-buten-1-yl radical, k C= C, have been measured from-145° C to-101° C by kinetic epr spectroscopy and at 40° C by spin trapping with 1-methyl-4-nitroso-3, 5- diphenylpyrazole. The temperature dependence can be represented by where θ= 2.3 RT kcal mol-1. This rearrangement, which must proceed via a 2, 2- ...