Q.2-2-10P - Organic Chemistry (Mcmurry)

Question

Draw the indicated number of resonance forms for each of the following

species:

(a) The methyl phosphate anion, CHOPO₃^2-(3)

(b) The nitrate anion,NO₃ (3)

(c) The allylcation,H₂CPCHOCH₂⁺(2)

(d) The benzoate anion (4)

Step-by-Step Solution

Answer

(a)

(b)

(c)

Step 1: Resonance

Resonance is a method of describing delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be expressed by one single Lewis structure. A molecule or ion with such delocalized electron is represented by several contributing structure called resonance structure.

Step 2: Draw indicated number of resonance forms in the given speciesa and b

The three-atom grouping contains a multiple bond next to an atom with a p-orbital. Exchange the positions of the bond and electrons in the p-orbital to draw resonance form for each grouping.

(a) Methyl phosphate anion has three-atom groupings and thus has three resonance forms.

(b) Nitrate anion has three resonance forms

Step 3: Draw indicated number of resonance forms in the given species c and d

(c) The allylcation has two resonance forms.

(d) Benzoate anion shows four resonant forms.