Organic Chemistry Laboratory I - Chem 341

Quiz 11d

1. Why is sodium carbonate (Na₂CO₃) used in the reaction to prepare Nylon-6,10? (1 pt)

Sodium carbonate is a base and it neutralizes the HCl, which is a byproduct of the condensation of the amine and acid chloride groups.

2. Draw the structure of Nylon-4,10. (2 pts)

The first number refers to the number of carbons in the amine monomer and the second number refers to the number of carbons in the dicarboxylic acid or acid chloride monomer.

3. Explain why the addition of sodium tetraborate to polyvinyl alcohol created slime, when both precursors were liquids. (2 pts)

This is due to the borate, which cross-links the polyvinyl alcohol chains. The cross-linked polymer is much less soluble and traps the liquid to form a gel.

4. Consider the energy diagram for the hypothetical reaction below and answer the following questions.

(a) Which is the thermodynamic product? (1 Pt)

Since C is lower in energy than B, C is the thermodynamic product and B is the kinetic product.

(b) Was this an endothermic or exothermic reaction? (1 Pt)

This is an exothermic reaction, since B & C are lower in energy than A. The difference is usually released as heat.

(c) Which product is favored at high temperature? Why? (2 Pts)

C, because it’s a thermodynamic product, at higher temperatures it is possible for B to be converted back to A, but it is unlikely for C to be converted back to A. Therefore all A is eventually converted into C.

(d) Define DH^‡_C. (1 Pt)

DH^‡_C, the activation energy is defined as the minimum amount of energy required for a reaction to occur, in this case for A to get converted to C.