Bimolecular reactions with one charged reactant

The TS for anionic SN2 reactions involves loose ion pairs as in a charge delocalized (soft) anion. On the another hand, the GS could involve a neutral electrophile and either tight or loose ion pairs depending on the anion structure (hard or soft) (Eq. 32). 

1 Anionic Sn2 Reactions Involving Charge-localized Anions 

In this case, the anion being hard and with a high charge density, the reactions are concerned with tight-ion-pairs. During the course of the reaction, ionic dissociation is increased and, hence, polarity is enhanced from the GS towards the TS. Specific microwave effects should be expected. 

Selective dealkylation of aromatic alkoxylated compounds Selective de-ethylation of 2-ethoxyanisole is achieved by use of KO Bu as the reagent in the presence of 18-crown-6 as the phase-transfer agent (PTA). With addition of ethylene glycol (E.G.), the selectivity is reversed and demethylation occurs (Eq. (61), Table 4.18). Although involvement of microwaves is favorable in both examples, the second reaction was shown to be more strongly accelerated than the first [147]. 

The microwave-specific effect is more apparent in the demethylation (Sn2). Microwave acceleration clearly is more pronounced with the difficulty of the reaction, 

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