When a reaction is accompanied by a change with the speed close to or slower than the reaction rate, a circulating reaction flow can exist among the reaction states in the macroscopic stationary state. If the accompanying change were at equilibrium in the timescale of the relevant reaction, the transition-state theory would hold to eliminate the flow.
Keywords: chemical ratchet; detailed balance; kinetics; rate equation; reaction theory; thermal equilibrium; transition-state theory.