Question 19M.2.hl.TZ2.d(ii)
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.2.hl.TZ2.d(ii) |
| Level | hl | Paper | 2 | Time zone | TZ2 |
| Command term | Outline | Question number | d(ii) | Adapted from | N/A |
Phenylethene can be polymerized to form polyphenylethene (polystyrene, PS).
The major product of the reaction with hydrogen bromide is C6H5–CHBr–CH3 and the minor product is C6H5–CH2–CH2Br.
The minor product, C6H5–CH2–CH2Br, can exist in different conformational forms (isomers).
Outline what this means.
[1]
benzene ring «of the C6H5–CH2» and the bromine «on the CH2–Br» can take up different relative positions by rotating about the «C–C, σ–»bond [✔]
Note: Accept “different parts of the molecule can rotate relative to each other”.
Accept “rotation around σ–bond”.
If candidates seemed rather confused in the previous question, they seemed more so in this one. Most simply referred to isomers in general, not seeming to be slightly aware of what conformational isomerism is, even if it is in the curriculum.
