| Date | May 2019 | Marks available | 2 | Reference code | 19M.3.hl.TZ2.25 |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | Examine | Question number | 25 | Adapted from | N/A |
Question
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.
Outline the operation of a polarimeter used to distinguish between enantiomers.
Markscheme
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 [✔]
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 [✔]
Examiners report
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.
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.
Syllabus sections
-
17N.3.hl.TZ0.21c:
Explain the low environmental impact of most medical nuclear waste.
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17M.3.sl.TZ2.19a:
Suggest one problem associated with chlorinated organic solvents as chemical waste.
- 16N.3.sl.TZ0.17c: The synthesis of oseltamivir is dependent on a supply of the precursor shikimic acid, which...
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17N.3.sl.TZ0.16:
Radioisotopes are used to diagnose and treat various diseases. Explain the low environmental impact of most medical nuclear waste.
- 16N.3.hl.TZ0.28d: Outline the nature of the radioactive waste that is generated by the use of technetium-99m in...
- 18N.3.sl.TZ0.12c: Outline one effect of over-prescription of penicillin.
- 19N.3.sl.TZ0.19a: Outline the impact of antibiotic waste on the environment.
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18N.3.sl.TZ0.16:
Suggest two reasons why chlorinated solvents should neither be released into the atmosphere nor incinerated (burnt).
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19M.3.sl.TZ2.15e:
Outline two factors which must be considered to assess the greenness of any chemical process.
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17M.3.sl.TZ1.21c:
Suggest why the administration of antibiotics to humans and animals can affect the environment.
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18M.3.sl.TZ2.20:
Drug synthesis often involves solvents.
Identify a common hazardous solvent and a Green solvent that could replace it.
- 19N.3.hl.TZ0.25c: Suggest a concern about the disposal of solvents from drug manufacturing.
- 19N.3.hl.TZ0.25b: Outline the impact of antibiotic waste on the environment.
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17M.3.sl.TZ1.19e:
The pharmaceutical industry is one of the largest producers of waste solvents.
State a green solution to the problem of organic solvent waste.
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19M.3.sl.TZ1.19b:
Outline the disposal of LLW.
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19M.3.sl.TZ1.19a:
Outline what is meant by low-level waste.
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17M.3.sl.TZ2.19b:
Suggest how the principles of green chemistry can be used to solve the environmental problems caused by organic solvents.
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18M.3.sl.TZ1.13c.iii:
Outline two consequences of prescribing antibiotics such as penicillin unnecessarily.
- 19N.3.sl.TZ0.19b: Suggest a concern about the disposal of solvents from drug manufacturing.
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17M.3.hl.TZ1.25e:
The pharmaceutical industry is one of the largest producers of waste solvents.
State a green solution to the problem of organic solvent waste.
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18M.3.sl.TZ1.15b:
Shikimic acid, the precursor for oseltamivir (Tamiflu), was originally extracted from star anise, and is now produced using genetically modified E. coli bacteria.
Suggest one difficulty associated with synthesizing oseltamivir (Tamiflu) from star anise.
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17M.3.sl.TZ1.21b:
Oseltamivir was commercially produced from shikimic acid, a precursor which is a metabolite in micro-organisms and plants.
Outline how green chemistry was used to develop the precursor for oseltamivir in order to overcome a shortage of the drug during the flu season.
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20N.3.sl.TZ0.13b:
Outline a green chemistry solution for problems generated by the use of organic solvents.
- 20N.3.sl.TZ0.13a: Describe the proper disposal of low-level radioactive waste in hospitals.
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20N.3.hl.TZ0.17c:
Describe the proper disposal of low-level radioactive waste in hospitals.
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19M.3.hl.TZ1.24b(i):
Outline what is meant by low-level waste.
