Question 19M.2.hl.TZ1.c(ii)
| Date | May 2019 | Marks available | [Maximum mark: 4] | Reference code | 19M.2.hl.TZ1.c(ii) |
| Level | hl | Paper | 2 | Time zone | TZ1 |
| Command term | Explain | Question number | c(ii) | Adapted from | N/A |
Xylene is a derivative of benzene. One isomer is 1,4-dimethylbenzene.
Xylene, like benzene, can be nitrated.
Explain the mechanism for the nitration of benzene, using curly arrows to indicate the movement of electron pairs.
[4]
curly arrow going from benzene ring to N «of +NO2/NO2+» [✔]
carbocation with correct formula and positive charge on ring [✔]
curly arrow going from C–H bond to benzene ring of cation [✔]
formation of organic product nitrobenzene AND H+ [✔]
Note: Accept mechanism with corresponding Kekulé structures.
Do not accept a circle in M2 or M3.
Accept first arrow starting either inside the circle or on the circle.
If Kekulé structure used, first arrow must start on the double bond.
M2 may be awarded from correct diagram for M3.
M4: Accept “C6H5NO2 + H2SO4” if HSO4− used in M3.
Performance was fairly good by schools covering the topic while others had no idea. There were many careless steps, such as omission or misplacement of + sign.
