Ethanol reacts with potassium cyanide, followed by dilute acid, to form 2-hydroxypropanenitrile - AQA - A-Level Chemistry - Question 4 - 2019 - Paper 3
Question 4
Ethanol reacts with potassium cyanide, followed by dilute acid, to form 2-hydroxypropanenitrile.
1. Name the mechanism for the reaction between potassium cyanide an... show full transcript
Worked Solution & Example Answer:Ethanol reacts with potassium cyanide, followed by dilute acid, to form 2-hydroxypropanenitrile - AQA - A-Level Chemistry - Question 4 - 2019 - Paper 3
Step 1
Name the mechanism for the reaction between potassium cyanide and ethanol.
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Answer
The mechanism is known as 'nucleophilic addition'.
Step 2
State the name of this type of mixture.
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Answer
The name of this type of mixture is 'racemic mixture'.
Step 3
Explain how the structure of ethanol leads to the formation of two isomers.
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Answer
Ethanol has a chiral center due to its hydroxyl (-OH) group, allowing for equal chance of attack from either side of the carbon atom to which the hydroxyl group is attached. This results in two distinct isomers of 2-hydroxypropanenitrile.
Step 4
Draw 3D representations of the two isomers to show the relationship between them.
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Answer
The 3D representations of the two isomers can be shown diagrammatically as follows:
Isomer A:
H OH
\ |
C--C≡N
/
H
Isomer B:
OH H
| /
C--C≡N
\
H
Step 5
Suggest a suitable reagent and conditions for the conversion of 2-hydroxypropanenitrile into acryloitrile.
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Answer
A suitable reagent for this conversion is conc. H2SO4 and the conditions should involve heating at approximately 170°C.
Step 6
Draw a section of the polymer polyacrylonitrile, showing three repeating units.
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Answer
The structure of polyacrylonitrile with three repeating units is represented as:
-[CH2-CH(CN)]-
-[CH2-CH(CN)]-
-[CH2-CH(CN)]-
This illustrates three repeating units of the polymer chain.
