Question 30.60 - Organic Chemistry

Question

The reaction of urea $\left[\left({\mathrm{NH}}_2\right)C=O\right]$ and formaldehyde $\left({\mathrm{CH}}_2=O\right)$ forms a highly cross-linked polymer used in foams. Suggest a structure for this polymer. [Hint: Examine the structures of Bakelite (Figure 30.7) and Melmac (Problem 30.58).]

Step-by-Step Solution

Answer

Answer

Cross-linked polymer

Step-by-Step Solution Step 1: About urea

The organic compound that contains two   groups with one carbonyl group is called urea. This organic compound is a carbamide and has a very major role in metabolism in animals.

 

This compound is colorless and solid at room temperature having high solubility in water.

Step 2: About the reaction

Urea and formaldehyde combine to form 1-(hydroxymethyl)urea. On rearrangement, it will give rise to a cation known as 1-methyleneuronium. It is again treated with urea which leads to the formation of 1,1'-methylenediurea. The reaction is shown below.

Chemical reaction

Step 3: Formation of cross-linked polymer

The steps are repeated, leading to the formation of the cross-linked polymer. The reaction is shown below.

Formation of cross-linked polymer