MC test: Opiates

Multiple choice test on D.3 Opiates

Use the following 'quiz' to test your knowledge and understanding of this sub-topic. As this relates to a sub-topic on the options you may need access to the IB data booklet.

If you get an answer wrong, read through the explanation carefully to learn from your mistakes.

How does the structure of codeine differ to that of morphine?

Both codeine and morphine contain a cyclic ether. The hydroxyl group -OH in morphine is replaced by the methoxy group -OCH3 in codeine so codeine contains two ether groups.

 

Which are natural opiates?

I. morphine

II. diamorphine

III. codeine

Diamorphine (heroin) is semi-synthetic as it can be prepared from morphine.

 

Which terms describe the type of reaction that takes place during the preparation of diamorphine from morphine?

I. condensation

II. methylation

III. diesterification

Methylation is the addition of a methyl group or the substitution of a hydrogen atom or alkyl group by a methyl group. When morphine is converted into diamorphine two -CO-CH3 groups replace the hydrogen atoms of the two hydroxyl groups (this is known as acetylation or acylation) so diesterification occurs - this is also a condensation reaction.

 

Which are possessed by all opiates?

I. a hydroxyl group

II. a phenyl group

III. a tertiary amine group

Diamorphine (heroin) is an example of an opiate that does not possess a hydroxyl group.

 

Which method can be used to make opiates more soluble in aqueous solution?

The tertiary amine present in all opiates can be converted into a substituted ammonium ion by reacting with a strong acid to produce a soluble salt.

 

Which describes how opiates function as an analgesic?

Opiates bind to the μ-opiate receptors in the brain blocking the transmission of pain impulses.

 

Which are withdrawal symptoms experienced by addicts when they stop taking diamorphine? 

I. cold sweats

II. diarrhoea

III. muscular cramps

All three are likely to be experienced together with nausea, vomiting, hot sweats, anxiety and a craving for diamorphine.

 

Methadone can be used to wean addicts off heroin. Which functional group is present in methadone that is absent in morphine, codeine and diamorphine?

Methadone is the only one that contains a carbonyl functional group (it is actually a ketone). This is according to the IB (Topic 10.1) which does not class the C=O bond in diamorphine as a carbonyl group, instead it classes R-CO-OR as the ester functional group although other sources do include esters as containing a carbonyl group.

 

Which reagent can be used to make diamorphine from morphine in the presence of sulfuric acid?

Diamorphine is a diester so ethanoic acid is required to react with the hydroxyl groups on morphine to form the diester and water.

 

Which is a common side-effect when morphine is used as an analgesic?

Morphine tends to cause constipation and is sometimes taken (as kaolin and morphine mixture) to treat diarrhoea.

 

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