Q33E - Organic Chemistry (Mcmurry)

Question

Epoxy adhesives are cross-linked resins prepared in two steps. The first step involved the SN2 reaction of the disodium salt of bisphenol A with epichlorohydrin to form a low molecular weight prepolymer. This polymer is then cured into a cross-linked resin by treatment with a triamine such as 

1. What is the structure of prepolymer?
2. How does addition of the triamine to prepolymer result in cross-linking?

Step-by-Step Solution

Answer

Part (A)

The structure of the prepolymer is:

Part (B)

Addition of triamine to prepolymer

Step- by- Step solution Step 1: Bisphenol A

Bisphenol A is classified as a chemical compound that is important in manufacturing different types of plastics. It comprises fifteen atoms of carbon, sixteen atoms of hydrogen, and two atoms of oxygen.

Step 2: Epichlorohydrin

Epichlorohydrin is classified as an organochlorine compound. It comprises three atoms of chlorine, five atoms of hydrogen, one atom of chlorine and one atom of oxygen. 

Step 3: Structure of prepolymer

The structure of prepolymer

Step 4: Part (B)

A prepolymer is referred to as the system of monomers that tend to react to form an intermediate molecular mass state.

Step 5: The given reaction

The addition of the triamine to prepolymer that results in cross-linking is shown as:

Addition of triamine to prepolymer