If the substrate under nucleophilic attack is chiral , this can lead , although not necessarily , to an inversion of stereochemistry called a Walden inversion ( the nucleophile attacks the electrophilic carbon center , inverting the tetrahedron , much like an umbrella turning inside out in the wind ) .
If the substrate under nucleophilic attack is chiral , this can lead , although not necessarily , to an inversion of stereochemistry , called the Walden inversion .