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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 is polar due to the difference in electronegativity between carbon (C) and bromine (Br). Since Br is more electronegative than C, it attracts the shared electron pair closer to itself, creating a dipole with a partial negative charge (δ-) on Br and a partial positive charge (δ+) on C.
Step 3
Outline the mechanism for the reaction of 2-bromopropane with an excess of ammonia.
Answer
The reaction mechanism begins with the nucleophilic attack of ammonia (NH₃) on the carbon bonded to bromine in 2-bromopropane. A curly arrow shows the movement of the lone pair from nitrogen to the carbon, forming an intermediate where Br- is displaced. Following this, a curly arrow represents the loss of H+ from the intermediate, resulting in 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 shows the organic product following the reaction, which generally appears as a primary amine the alkyl chain linked to nitrogen.
The use of the organic product can include applications in hair conditioners or as surfactants.