Acetonitrile

Acetonitrile (CH₃CN) is the simplest nitrile and a common polar aprotic solvent. It is termed “aprotic” due to its absence of O-H or N-H bonds, resulting in its inability to act as a hydrogen bond donor with nucleophilic anions such as F(-) and Cl(-). Like DMSO, DMF, and acetone, it has a relatively high dielectric constant (37) and dipole moment (3.92 D). It is an excellent solvent for nucleophilic substitution reactions (S_N2).