# Two reactions which speed each other up [closed]

Recently I have started looking for two reactions that would speed each other up. That means that the products of the first reaction accelerate the second one, and in turn, the products formed in the second reaction accelerate the first one. Do you know any examples of such reactions?

\begin{align} \ce{H^. + Br2 &-> HBr + Br^.} \\ \ce{Br^. +H2 &-> HBr + H^.} \end{align}