Since ancient times, the bark of willow trees has been used for pain relief - VCE - SSCE Chemistry - Question 8 - 2010 - Paper 1
Question 8
Since ancient times, the bark of willow trees has been used for pain relief. In the 19th century, chemists isolated the active compound, salicin, from the bark. This... show full transcript
Worked Solution & Example Answer:Since ancient times, the bark of willow trees has been used for pain relief - VCE - SSCE Chemistry - Question 8 - 2010 - Paper 1
Step 1
What type of linkage is circled in the structure of salicin?
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Answer
The type of linkage circled in the structure of salicin is an ester linkage. This kind of linkage is formed between a hydroxyl group and a carboxylic acid.
Step 2
In step 1, salicylic alcohol and another compound is produced.
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i. The other compound belongs to the group of biomolecules known as carbohydrates.
ii. The atom or group of atoms represented by A in the reaction scheme is a hydroxyl group, -OH.
Step 3
Step 2 involves the conversion of salicylic alcohol into salicylic acid.
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i. The type of reaction occurring in step 2 is an oxidation reaction. This reaction involves the conversion of a primary alcohol into a carboxylic acid.
ii. A suitable reagent to carry out this reaction would be an oxidizing agent such as chromic acid (H₂CrO₄) or potassium dichromate (K₂Cr₂O₇).
Step 4
Step 3 requires sulfuric acid catalyst and another reagent. Name this reagent.
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The other reagent required in step 3 is aspirin which reacts with sulfuric acid to facilitate the esterification process.
Step 5
Draw the structure of product B.
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Product B is the salt formed from aspirin reacting with a strong base. The structure can be represented as:
O
||
CH₃—C—O⁻ + H₂O
/ \
H OH
This reflects the deprotonation of the carboxyl group.
