| Date | November 2016 | Marks available | 2 | Reference code | 16N.3.hl.TZ0.26 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Outline | Question number | 26 | Adapted from | N/A |
Question
Excess stomach acid leads to medical conditions that affect many people worldwide. These conditions can be treated with several types of medical drugs.
Omeprazole exists as a racemic mixture whereas esomeprazole is a single enantiomer. Outline how, starting from a non-chiral molecule, esomeprazole but not omeprazole, could be synthesized. Details of chemicals and conditions are not required.
Markscheme
Any two of:
chiral molecule/auxiliary/optically active species is used/added/connected «to the starting molecule to force reaction to follow a certain path»
chiral intermediate forms «only» one enantiomer
OR
auxiliary creates stereochemical condition «necessary to follow a certain pathway» / stereochemical induction
OR
existing chiral centre affects configuration of new chiral centres
«after new chiral centre created» chiral auxiliary removed «to obtain desired product»
