The development of new pharmaceutical drugs depends heavily on organic synthesis. Molecular finetuni — Organic Chemistry Chemistry Question
Synthesis of a local anaesthetic
The development of new pharmaceutical drugs depends heavily on organic synthesis. Molecular finetuning is often required to obtain the desired properties. Here the synthesis of the local anaesthetic proparacaine (also called proxymetabaine) which is used in treatment of eye problems, is considered. It may be assumed that all products are properly isolated.
Complete the synthetic scheme by drawing the structures A, B, C, D, and E.
[VISUAL]
Model Answer
The structures of A, B, C, D, and E are as follows:
- A: 4-hydroxy-3-nitrobenzoic acid
- B: 3-nitro-4-propoxybenzoic acid
- C: 3-nitro-4-propoxybenzoyl chloride
- D: 2-(diethylamino)ethyl 3-nitro-4-propoxybenzoate
- E: 2-(diethylamino)ethyl 3-amino-4-propoxybenzoate (proparacaine)
Which nitration product(s) will be obtained when meta-hydroxybenzoic acid is taken as starting material? Draw the structure(s).
Model Answer
Nitration of meta-hydroxybenzoic acid yields two main isomeric products:
- 3-hydroxy-4-nitrobenzoic acid
- 3-hydroxy-2-nitrobenzoic acid
When tert-C4H9Cl is used in the second step istead of n-C3H7Cl, this will lead to:
- a similar product as B. If it is so, give its structure.
- no reaction at all.
- a decomposition of the tert-C4H9Cl.
- an aromatic substitution reaction.
Mark the correct answer.
Model Answer
Decomposition of the tert-C4H9Cl.