Arrange the following groups in decreasing order of their leaving group ability: (I) (II) (III) - OMe (IV)

Step-by-step solution

The leaving group ability of an anion is inversely proportional to its basicity. A weaker base is a more stable anion and thus a better leaving group. The basicity of an anion can be compared by looking at the acidic strength of its conjugate acid. A stronger acid will have a weaker, more stable conjugate base. The conjugate acids for the given leaving groups are: (I) p -Toluenesulfonic acid ( p - CH ₃ C ₆ H ₄ SO ₃ H ) (II) Acetic acid ( CH ₃ COOH ) (III) Methanol ( CH ₃ OH ) (IV) Trifluoromethanesulfonic acid ( CF