Abstract The rates of solvolysis in various solvents at 25 C were determined for five tertiary alkyl chlorides: 2-chloro-2, 4, 4-trimethylpentane (4), 2-chloro-2, 4-dimethylpentane, 2-chloro- 2-methylpentane, 1-chloro-1, 3, 3-trimethylcyclopentane (7) and 1-chloro-1- methylcyclopentane. The rate data were analysed on the basis of the original and extended Grunwald–Winstein-type equation [log (k/k 0)= mY Cl+ c and log (k/k 0)= lN T+ mY Cl+ c] ...