A sequence of chemical reactions, starting with 2-methylprop-1-ene, is shown in the flow chart - HSC - SSCE Chemistry - Question 26 - 2021 - Paper 1
Question 26
A sequence of chemical reactions, starting with 2-methylprop-1-ene, is shown in the flow chart.
Complete the flow chart by drawing structural formulae for compounds... show full transcript
Worked Solution & Example Answer:A sequence of chemical reactions, starting with 2-methylprop-1-ene, is shown in the flow chart - HSC - SSCE Chemistry - Question 26 - 2021 - Paper 1
Step 1
Complete the flow chart for compound A
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Answer
Compound A is formed through hydration of 2-methylprop-1-ene. The structural formula for compound A is:
HO
|
H3C-C-CH3
|
H
This represents the addition of water across the double bond.
Step 2
Complete the flow chart for compound B
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Answer
Compound B is generated from the oxidation of compound A using acidified KMnO4. The structural formula for compound B is:
OH
|
H2C-C-CH3
|
CH3
This product retains the alcohol from compound A but is oxidized.
Step 3
Complete the flow chart for compound C
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Answer
In the substitution reaction with concentrated HCl and ZnCl2, compound B forms compound C. The structural formula for compound C is:
Cl
|
H3C-C-CH2
|
H
Here, chlorine replaces the hydroxyl group.
Step 4
Complete the flow chart for compound D
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Answer
Compound D is produced from compound C through reflux with methanol and concentrated H2SO4. The structural formula for compound D is:
O
||
H3C-C-CH3
/ \
O H
This structure shows the esterification process, resulting in methyl 2-methylpropanoate.
Step 5
Provide TWO reasons for using this technique
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Answer
Reflux allows the reaction mixture to be heated continuously, thus speeding up the reaction without losing any reactants or products due to evaporation.
The condenser retains volatile substances, ensuring that they can be reused in the reaction, thereby improving yield and efficiency.
