Classification of Solvents
There are two types of solvents
(i) Protonic (protic) and (ii) Aprotic
(i) Protonic or Protic Solvents
(i) They are characterized by the presence of a transferable hydrogen and the formation of "Onium" ions Autoionisation taking place in them.
Ex.A)H2O + H2O \(
\rightleftharpoons
\) H3O+ + OH–
B)NH3 + NH3 \(
\rightleftharpoons
\) NH4+ + NH2–
C)3HX \(
\rightleftharpoons
\) H2X + HX2–
D)2H2SO4 \(
\rightleftharpoons
\) H3SO4+ + HSO4–
(ii) Protonic solvents may be
A)Acidic (Anhydrous sulphuric acid, liquid HF, Glacial acetic acid etc.)
B)Basic (liquid NHC)
C)Amphiprotic (H2O, proton containing anions)
(ii)Aprotic Solvents
Such solvents do not have replaceable hydrogen in them. These can be classified into three categories
A)Non polar or very weakly polar, nondissociated liquids, which do not solvate strongly.
Ex.CCl4, hydrocarbons, C6H6, C6H12 etc.
B)Non-ionised but strongly solvating, generally polar solvents.
Ex.Acetonitrile CH3CN, DMF, DMSO (dimethyl sulfoxide), THF and SO2.
C)Highly polar, autoionising solvents.
Ex.Inter halogen compounds (BrF3, IF5 and trichloro phosphine)
A)2BrF3 \(
\rightleftharpoons
\) BrF2+ + BrF4–
B)2 IF5 \(
\rightleftharpoons
\) IF4+ + IF6–
C)2Cl3PO \(
\rightleftharpoons
\) Cl2PO+ + Cl4PO–