Chirality and optical isomerism
- Created by: Anon
- Created on: 10-03-15 15:13
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- Chirality and optical isomerism
- Optical isomerism
- Optical isomerism occurs if a molecule has a chiral centre
- A chiral centre had 4 different groups/ atoms attached to the same atom
- Optical isomers are non-superimposable mirror images
- Chiral centres are often represented by *
- Optical isomerism is a type of stereoisomerism
- The isomers have the same structural formula, but a different arrangement in space
- Another type of isomerism is E/Z
- For E/Z isomerism you need a C=C, because a double bond lacks rotation
- An E/Z isomer must also have at least 2 different groups on each carbon atom
- When representing optical isomers in the exam, they should be mirror images of each other
- Optical isomerism occurs if a molecule has a chiral centre
- Optical isomerism in phamaceutica-ls
- Drugs are usually reasonably large molecules, so it follows that the chance of them having a chiral centre is high, which can cause problems
- Problems of optical isomerism
- One isomer may be biologically inactive and so a double dose is needed
- One isomer may have harmful side effects
- Optical isomers are very, very expensive to separate
- Solutions for optical isomerism
- Chiral pool synthesis. Meaning you have an optically pure starting material
- A naturally occuring enzyme could be used to synthesise the drug (if there is one)
- As a last resort you could separate the isomers by chromatography
- But this is very expensive
- It is quite difficult to separate isomers that are so chemically similar
- Optical isomerism
- Solutions for optical isomerism
- Chiral pool synthesis. Meaning you have an optically pure starting material
- A naturally occuring enzyme could be used to synthesise the drug (if there is one)
- As a last resort you could separate the isomers by chromatography
- But this is very expensive
- It is quite difficult to separate isomers that are so chemically similar
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