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This question is about 2-bromopropane - AQA - A-Level Chemistry - Question 5 - 2020 - Paper 2
Question 5
This question is about 2-bromopropane. 1. Define the term electronegativity. 2. Explain the polarity of the C–Br bond in 2-bromopropane. Electronegativity Explan... show full transcript
Worked Solution & Example Answer:This question is about 2-bromopropane - AQA - A-Level Chemistry - Question 5 - 2020 - Paper 2
Step 1
Step 2
Explain the polarity of the C–Br bond in 2-bromopropane.
Answer
The C–Br bond in 2-bromopropane is polar due to the difference in electronegativity between carbon and bromine. Bromine is more electronegative than carbon, which means that it will attract the shared pair of electrons more strongly. This results in a partial negative charge ( \delta- ) on the bromine atom and a partial positive charge ( \delta+ ) on the carbon atom, giving the bond its polar character.
Step 3
Outline the mechanism for the reaction of 2-bromopropane with an excess of ammonia.
Answer
The mechanism involves the attack of the nucleophile ammonia ( NH_3 ) on the carbon atom bonded to bromine. A curly arrow is drawn from the bond between the carbon and bromine to the bromine atom, causing the loss of the Br^- ion. An intermediate is formed where the carbon is now bonded to the ammonium ion ( NH_3^+ ). The final step involves the loss of a proton to form the final product.
Step 4
Draw the skeletal formula of the main organic species formed in the reaction between a large excess of 2-bromopropane and ammonia.
Answer
The skeletal formula for the organic product is:
H H
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C--C--C
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H N
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H
- Give a use for the organic product.
The organic product can be used as a hair conditioner or as a surfactant.