A reversal of the configuration of substituents in a chiral molecule brought about in a substitution reaction; a reaction in which this occurs, especially a bimolecular nucleophilic substitution causing a change of configuration from d to l or vice versa.
In a nucleophilic substitution the incoming group enters along the axis of the bond between the central atom and the leaving group, causing the other substituents to move to the opposite side of a plane perpendicular to this axis.
Walden inversion/ˈvald(ə)n ɪnˌvəːʃn/ /ˈwɔːld(ə)n ɪnˌvəːʃn/ /ˈwɒld(ə)n ɪnˌvəːʃn/
Early 20th century. From the name of Paul Walden, Latvian chemist + inversion, after German Walden'sche Umkehrung.