Question

. 10 pts. Which of the folowing wld be uptically active a) A pare sample of A yu b) A sample ot E (d) An misturm of A and B Be 6. 20 pts. Draw the coupleto mecbanism for the following polse reaction. Identify the nucleophie and the dlectrophile in the rvuctants Use the eprseet arrows to show she electroa placement Ci

Answer 1

Answers for 5:

Br H Br H Br H Br H3C CH Нас CH (2R,3R)-2,3-dibromobutane (2S,3S)-2,3-dibromobutane НН Br H Br CH3 H2C CH (2R,3S)-2,3-dibromobutane (2R,3S)-2,3-dibromobutane

5a: Pure sample of A: Yes. It's optically active

5b: Pure sample of B: Yes. It's optically active

5c: Pure sample of C: No. It's optically inactive

5d: Equimolar mixture of A and B: No. It's optically inactive

Explanation:

Compounds A and B are enantiomers as their mirror images are not superposable and they are optically active. Compounds C and D are mesomers as their mirror images are superposable and these compounds have internal plane of symmetry. Equimolar mixture of A and B will be optically inactive as this mixture of enatiomers cancel rotation of polarized light each other since they rotate it in opposite directions.

Answer for 6:

Mechanism of given reaction is shown below:

Electrophile: H⁺

CI

^​​Nucleophile: Cl^-

^​​The mechanism is known as electrophilic addition of HCl across a double bond. Addition of 'H' takes place such that it generates a more stable tertiary carbonium ion leading to the final product of tertiary chloro derivative.