Lab Quiz on Experiment 2

Tuesday Form

1. In the multi-step synthesis of Para Red, explain why acetanilide is converted to p-nitroaniline in two steps instead of converting aniline directly to p-nitroaniline in one step.

Aniline has a very reactive amino group (-NH₂) which would be protonated (-NH₃⁺) during the acidic conditions of nitration. When protonated, it deactivates the ring and leads to other reactions, such as oxidation or meta-nitration.

2. In the first step of the synthesis, why is the nitrating mixture of concentrated acids added slowly to acetanilide at cold temperatures?

The nitrating mixture is extremely reactive. We add slowly in order to keep the nitronium ion concentration low and avoid polynitration of the ring. Cold temperatures slow down the reaction rate and also help avoid over-nitration.

3. The correct product is

4. In project 9.2, what would happen if the solution of p-nitroaniline, sodium nitrite, and acid is allowed to warm to room temperature?

At warmer temperatures, water replaces the diazonium -N₂⁺ group and a phenol is formed.

5. c

6. a

7. b

Thursday Form

1. In the first step of the synthesis, why is the nitrating mixture of concentrated acids added slowly to acetanilide at cold temperatures?

The nitrating mixture is extremely reactive. We add slowly in order to keep the nitronium ion concentration low and avoid polynitration of the ring. Cold temperatures slow down the reaction rate and also help avoid over-nitration.

2. The correct reactants are

3. In project 9.2, what would happen if the solution of p-nitroaniline, sodium nitrite, and acid is allowed to warm to room temperature?

At warmer temperatures, water replaces the diazonium -N₂⁺ group and a phenol is formed.

4. In the multi-step synthesis of Para Red, explain why acetanilide is converted to p-nitroaniline in two steps instead of converting aniline directly to p-nitroaniline in one step.

Aniline has a very reactive amino group (-NH₂) which would be protonated (-NH₃⁺) during the acidic conditions of nitration. When protonated, it deactivates the ring and leads to other reactions, such as oxidation or meta-nitration.

5. d

6. a

7. b