Inductive Effect Questions

Exercise and Answers

Explain the comparative stability of primary, secondary and tertiary carbocations using Inductive effect.

Ans: The order of stability of carbocation is : Tertiary > secondary > primary

The tertiary carbocation has three alkyl groups around the carbon with the positive charge. These groups through their collective Inductive effect( +I) neutralize the positive charge to a certain extent thus stabilising it. The secondary has two alkyl groups and the primary one (or none), which is responsible for their decreasing stability.

State whether the following statements or True or False? Explain your choice.

i) Inductive effect is the ability of an atom or a group of atoms to cause polarization of electron density along the covalent bond so that the atom of higher electronegativity becomes electron difficient.

Ans: False. Inductive effect is the ability of an atom or a group of atoms to cause polarization of electron density along the covalent bond, but the atom of higher electronegativity acquires slightly higher electron density and becomes ö^-.

ii) The –OH group cannot exhibit Inductive effect.

Ans: False. –OH group can exhibit mesomeric effect through donation of the lone pair when it is bonded to a sp2 carbon, at the same time the oxygen through its higher electronegativity can show Inductive effect. But the mesomeric effect when it is prevalent is predominating.

iii) Inductive effect can be responsible for the dipole moment in a molecule.

Ans: True. Dipole moment is charge times the distance separating the charge, Inductive effect causes charge separation hence will have dipole moment. There are however examples of molecules which have charge separation in a bond but the molecule has net zero dipole moment due to symmetry induced cancellation.

iv) All alkyl groups exhibit –I effect.

Ans: False. All alkyl groups exhibit +I effect. An alkyl group pushes electron density away from itself towards the carbon to which it is attached.