Mechanisms for this type of reaction are discerned by the parameter m in the Grunwald–Winstein equation. It’s not alkylation, but the presence of sulfur in mustard gas increases the rate of one of these reactions in a classic example of anchimeric (“an-kye-MER-ic”) assistance. (-5[1])Carbocation (“carbo-CAT-eye-on”) intermediates act as Lewis acids in one of these reactions. In one type of this reaction, inversion of configuration (10[1])occurs (10[1])due to a “backside attack.” (10[2])A pentavalent transition state occurs in one type of this reaction whose name indicates that it is bimolecular. (10[1])High temperatures (10[1])or bulky bases cause eliminations to be favored over these reactions. For 10 points, the nucleophilic SN1 and SN2 mechanisms exemplify (10[1])what type of reaction, in which one group of a compound is exchanged (10[1]-5[1])for another? ■END■ (10[1])