Q2-59E - Organic Chemistry (Mcmurry)

Question

We’ll see in the next chapter that organic molecules can be classified according to the functional groups they contain, where a functional group is a collection of atoms with a characteristic chemical reactivity. Use the electronegativity values given in Figure 2-2 on page 29 to predict the direction of polarization of the following functional groups.

Step-by-Step Solution

Answer

a.  In ketone the direction of polarization from carbon to oxygen.

b.  Direction of polarization from carbon to oxygen in Carbon-Oxygen bond.

     Direction of Polarization from hydrogen to oxygen in Oxygen-hydrogen bond.

c.  Direction of polarization from $\text{C}\to \text{O}$ in Carbon-Oxygen bond.

    Direction of Polarization from $\text{C}\to \text{N}$ in Carbon-Nitrogen bond.

d.  In ketone the direction of polarization $\text{C}\to \text{N}$  from carbon to nitrogen.

Step 1: Definition of Direction of Polarization

At which atom maximum amount of electron density is shifting in a specified bond is represented by direction of polarisation.

Direction of polarisation is always from less electronegative atom to more electronegative atom.

Step 2: (a) Try to find which is having more electronegativity

In carbonyl bond more electronegative atom is oxygen and less electronegative atom is Carbon.

Direction of polarisation is from $\text{C}\to \text{O}$

Step 3: (b) Try to find which is having more electronegativity

In carbonyl bond more electronegative atom is oxygen and less electronegative atom is Carbon.

Direction of polarisation is from $\text{C}\to \text{O}$ and  $\text{O}\to \text{H}$

Step 4: (c) Try to find which is having more electronegativity

In carbonyl bond, more electronegative atom is oxygen and less electronegative atom is Carbon. 

In carbon nitrogen bond, more electronegative is nitrogen and less electronegative atom is carbon.

Direction of polarisation is from $\text{C}\to \text{O}$

Direction of Polarization from $\text{C}\to \text{N}$

Step 5: (d) Try to find which is having more electronegativity

In carbonyl bond more electronegative atom is oxygen and less electronegative atom is Nitrogen.

Direction of polarisation is from $\text{C}\to \text{N}$