Question 19M.3.hl.TZ2.25
| Date | May 2019 | Marks available | [Maximum mark: 4] | Reference code | 19M.3.hl.TZ2.25 |
| Level | hl | Paper | 3 | Time zone | TZ2 |
| Command term | Examine, Outline | Question number | 25 | Adapted from | N/A |
Taxol is a drug that was once obtained from yew trees and is now produced using chiral auxiliaries.
Examine the synthesis of taxol in terms of green chemistry criteria.
[2]
Any two of:
produced by genetically engineered/modified bacteria/E. coli
OR
sustainable because synthesized and not obtained from yew trees [✔]
chiral auxiliaries «isolated and» reused [✔]
one enantiomer produced [✔]
toxicity/recycling of solvents/materials used [✔]
overall yield/atom economy/waste generated [✔]
The synthesis of taxol in terms of green chemistry criteria invited varied responses. While some candidates were precise in their answers but others lost focus and wrote something about green chemistry.
Outline the operation of a polarimeter used to distinguish between enantiomers.
[2]
Any two of:
«plane-» polarized light
OR
light passes through polarizer/polarizing filter [✔]
enantiomers rotate plane of «plane-» polarized light «by equal angles» in opposite directions [✔]
measure angle/direction of rotation [✔]
The operation of a polarimeter to distinguish between enantiomers was generally well handled by the candidates while some missed stating to measure the angle/direction of rotation.