DP Chemistry (last assessment 2024)
Question 21M.2.hl.TZ1.5e(ii)
| Date | May 2021 | Marks available | [Maximum mark: 2] | Reference code | 21M.2.hl.TZ1.5e(ii) |
| Level | hl | Paper | 2 | Time zone | TZ1 |
| Command term | Explain | Question number | e(ii) | Adapted from | N/A |
e(ii).
[Maximum mark: 2]
21M.2.hl.TZ1.5e(ii)
Ethanol is obtained by the hydration of ethene, C2H4.
Alternative synthetic routes exist to produce alcohols.
(e(ii))
Explain why the major organic product is 2-bromopropane and not 1-bromopropane.
[2]
Markscheme
«2-bromopropane involves» formation of more stable «secondary» carbocation/carbonium ion/intermediate
OR
1-bromopropane involves formation of less stable «primary» carbocation/carbonium ion/intermediate ✔
«increased» positive inductive/electron-releasing effect of extra–R group/–CH3/methyl «increases stability of secondary carbocation» ✔
Award [1] for “more stable due to positive inductive effect”.
Do not award marks for quoting Markovnikov’s rule without any explanation.
