There are only four types of reaction ("Skeletal chemistry" 9 of 9)

"There is really only one type of reaction, but for convenience we think of all chemical change as one of four processes: [1] the transfer of a proton (acid-base reactions); [2] the transfer of an electron (redox reactions); [3] the sharing of electrons (radical reactions); and [4] the sharing of electron pairs (Lewis acid-base reactions). When you think about it, all four types of change are manifestations of a single process in which an electron falls into a hole. That is easily seen to be the case with redox and radical reactions: in Lewis acid-base reactions there are two electrons falling into a double hole, and Brønsted acid-base reactions are just special cases of Lewis reactions."