This question is about the three amines, E, F and G. Amines E, F and G are weak bases. Explain the difference in base strength of the three amines and give the order of increasing base strength. Amine F can be prepared in a three-step synthesis starting from methylbenzene. Suggest the structures of the two intermediate compounds. For each step, give reagents and conditions only. Equations and mechanisms are not required.

A-Level AQA Chemistry Organic Synthesis: This question is about the three

This question is about the three amines, E, F and G - AQA - A-Level Chemistry - Question 11 - 2017 - Paper 2

Question 11

This question is about the three amines, E, F and G. Amines E, F and G are weak bases. Explain the difference in base strength of the three amines and give the ord... show full transcript

Worked Solution & Example Answer:This question is about the three amines, E, F and G - AQA - A-Level Chemistry - Question 11 - 2017 - Paper 2

Step 1

Explain the difference in base strength of the three amines and give the order of increasing base strength.

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Answer

The base strength of amines E, F, and G depends on the availability of the lone pair on the nitrogen atom for bonding with protons (H+).

E is next to an aromatic ring, which can destabilize the lone pair due to resonance, making it less basic.
F is less available to donate its lone pair because of the influence of adjacent groups. It has substituents that can withdraw electron density, which again lowers basicity.
G is the most basic among the three because it has alkyl groups that push electron density towards the nitrogen, making its lone pair more available to accept protons.

Order of increasing base strength: E < F < G.

Step 2

Suggest the structures of the two intermediate compounds.

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Answer

The first intermediate compound can be identified as C6H5CH2NH2 (benzylamine). 2. The second intermediate compound is C6H5CH(CH3)NH2 (isopropylamine).

Step 3

Step 1

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Answer

Reagents/Conditions: C6H5CH3 + Br2 (bromination) with UV light.

Step 4

Step 2

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Answer

Reagents/Conditions: KCN in alcoholic solution.

This question is about the three amines, E, F and G - AQA - A-Level Chemistry - Question 11 - 2017 - Paper 2

Worked Solution & Example Answer:This question is about the three amines, E, F and G - AQA - A-Level Chemistry - Question 11 - 2017 - Paper 2

Explain the difference in base strength of the three amines and give the order of increasing base strength.

Suggest the structures of the two intermediate compounds.

Step 1

Step 2

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