Gauging the Stability of Molecules with the Inductive Effect

The inductive effect, also known as the I Effect, is a phenomenon that depends on the distance. In this effect, the charge of a chemical bond influences the orientation of adjacent bonds in a molecule, resulting in a permanent state of polarisation. This article has gauged the Stability of Molecules with the Inductive Effect (Solved Example). It also elaborates gauging the stability of molecules with the inductive effect (solved example) meaning and gauging the Stability of Molecules with the Inductive Effect (Solved Example) importance.  

How I Effect Works?

When molecules from two or more elements engage in a bond, the electron density of the bond is not uniform. Electron clouds in a bond tend to gravitate toward the bond’s more electronegative atom. 

In water molecules, an inductive effect occurs. A water molecule’s chemical bonds are more positively charged near the hydrogen atoms and much more negatively charged towards the oxygen atoms. Water molecules, as a result, are polar. However, because the induced charge is small and the inductive effect is only effective over short distances, it can be quickly overcome by other factors.

 Types Of Inductive Effects

+I Effect

The +I effect happens when an atom or group contributes electrons to a bond and gains a partial positive charge, it is referred to as a +I group, and the effect is known as the positive Inductive Effect or the +I effect. 

The +I effect takes place in the following groups: – O –, – COO –, –CR3, –CHR2, –CH2R, –CH3, –D

-I Effect

You can say the -I effect takes place when an atom or group attracts bonding electrons onto itself and develops a slight negative charge. It is referred to as a -I group, and the corresponding effect is referred to as the electron-withdrawing inductive effect or the -I effect.

The -I effect takes place in the following groups: –NO2, – SO2R, –CN, –SO2Ar, –COOH, –F, – Cl, – Br, – I, –OAr, –COOR, –OR, –COR, –SH, –SR, –OH, –Ar, – CH = CR2

Gauging the Stability of Molecules with the Inductive Effect (Solved Example)

Question 1

 Explain the stability using the inductive effect of the mentioned figure. 

Solution: 

The order of stability can be given as:

Tertiary > Secondary> Primary

The positive charge is shared by three alkyl groups surrounding the carbon in the tertiary carbocation. These groups, through their collective Inductive effect (+I), neutralise the positive charge to some extent, thus trying to stabilise it. The secondary has two alkyl groups, and the primary has one (or none), which accounts for their decreasing stability.

 Question 2  

Which of the following shows positive(+) inductive effect?

1. NO2 

2. –OCH3 

3.  –COOH 

 –CH3  

Solution: 

-CH3  shows a positive inductive effect. 

 Question 3

 Determine whether the following statements are true or false. 

1.  The –I effect is present in all alkyl groups.

2. The capacity of an atom or a group of atoms to cause polarisation of charge density along with a covalent bond causes the atom with higher electronegativity to become electron deficient.

3. The –OH group has no inductive effect.

Solution:

1. True. The +I effect is present in all alkyl groups. The electron density of an alkyl group is pushed away from itself and towards the carbon to which it is attached.

2. False. Inductive effect is the tendency of a particle or several atoms to cause polarisation of charge density along with a covalent bond, but the atom with higher electronegativity obtains slightly higher electron density and then becomes ö-.

3. False. When an OH group is bonded to an sp2 carbon, it can exhibit a mesomeric effect through lone pair donation, whereas oxygen can exhibit an inductive effect due to its higher electronegativity. However, when it is present, the mesomeric effect is dominant.

4. True. The dipole moment is defined as the charge multiplied by the distance between the charges. Because the inductive effect causes charge separation, the dipole moment exists. However, there are examples of molecules with charge separation in a bond but a net-zero dipole moment due to symmetry induced cancellation.

Question 4

Carbocation stability is determined by the electron-releasing inductive effect of groups adjoining to positive charge atoms, as well as the participation of adjoining groups in hyperconjugation and resonance. Which of the mentioned ions has the highest stability?

Solution: 

Carbocation (A) is a more stable compound than carbocation (B) (B). Because carbocation (A) is more planar, it is stabilised by resonance, whereas carbocation (B) is non-planar and thus does not undergo resonance. Furthermore, double bonds are more stable inside the ring than outside the ring. 

Question 5 

Which compound has a more inductive effect, -OH or -OR?

Solution

-OR has more -I effect than -OH. The main cause of the -I effect is the electronegativity difference. 

Conclusion 

This article gives you about gauging the Stability of Molecules with the Inductive Effect (Solved Example). The inductive affects the stability as well as acidity or basicity of a chemical species. Molecules with negative inductive effects reduce the electron density, making it more electron-deficient and acidic.