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Halogenoalkanes are useful compounds in synthesis - AQA - A-Level Chemistry - Question 2 - 2018 - Paper 2
Question 2
Halogenoalkanes are useful compounds in synthesis. A reaction pathway is shown. CH₃(OH)CH(CH₃)CH₂Br Reaction 1 NaOH → CH₃(OH)CH(CH₃)CH₂OH → Reaction 2 Co... show full transcript
Worked Solution & Example Answer:Halogenoalkanes are useful compounds in synthesis - AQA - A-Level Chemistry - Question 2 - 2018 - Paper 2
Step 1
Step 2
2.1 Reaction 1 occurs via a nucleophilic substitution mechanism. Explain why the halogenoalkane is attacked by the nucleophile in this reaction.
Answer
In the reaction, bromine is more electronegative than carbon, which creates a partial positive charge on the carbon atom bonded to the bromine. This partial positive charge makes the carbon atom susceptible to nucleophilic attack. The nucleophile, which possesses a lone pair of electrons, is attracted to the partially positive carbon atom in the halogenoalkane.
Step 3
3. The infrared spectrum of Compound Y shows a significant absorption in the range 1680-1750 cm⁻¹. Draw the displayed formula of Compound Y.
Answer
The displayed formula of Compound Y (C₂H₄O₂) can be represented as follows:
H O
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H--C--C--OH
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H H
This structure illustrates a carboxylic acid group, indicated by the presence of the C=O and attached -OH.
Step 4
4. Compound Z has the empirical formula C₃H₇NO. Give the structure of Compound Z. Suggest the reagent for Reaction 3.
Answer
The structure of Compound Z (C₃H₇NO) could be constructed as:
H O
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H--C--C--NH₂
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H H
The suggested reagent for Reaction 3 is KCN or HCN, which facilitates the formation of a nitrile.