fragmentation reaction Grob fragmentation RXNO RXNO:0000111 The fragmentation of a molecule that takes place when an electron-donating fragment (X) and an electron-accepting fragment (X') are situated at positions 1 and 3 on an aliphatic chain, to give a cationic fragment, a neutral fragment (e.g. an alkene) and an anionic fragment. https://www.wikidata.org/wiki/Q5609896