Organic Chemistry
7 marks · EasyThe compound propyl ethanoate is formed by the reaction of an alcohol with a carboxylic acid.
Draw the displayed formula of propyl ethanoate.
Name the alcohol and carboxylic acid you would react to make propyl ethanoate.
The polymer poly(propene) is used for making ropes and crates. Below is a section of the polymer chain:
Draw the structure of the monomer that is used to make poly(propene).
Deduce the number of carbon atoms in the repeat unit of poly(propene) and explain your reasoning.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) — · must show Correct carbon chain: CH3CH2CH2COOCH2CH3 or equivalent displayed formula, Correct ester linkage (–COO–) shown between correct groups
(b) propan-1-ol and ethanoic acid · must show Both names correct: propan-1-ol and ethanoic acid
(c) — · must show Displayed or structural formula of propene: CH2=CHCH3 or drawn structure
(d) There are three carbon atoms in the repeat unit of poly(propene)—two from the backbone joined together and one methyl group attached to one of these carbons. · must show States correct number: 3, Explains based on structure/backbone
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Marking points
M1 (a) · 1 mark · Correct backbone and correct number of carbon atoms in propyl ethanoate.
A1 (a) · 1 mark · Correct ester linkage (–COO–) between appropriate carbon atoms.
B1 (b) · 1 mark · Both starting materials (propan-1-ol and ethanoic acid) correct.
M2 (c) · 1 mark · Draws correct structure of monomer: propene (CH2=CHCH3).
A2 (c) · 1 mark · Double bond present and methyl group in correct position on propene.
B2 (d) · 1 mark · Correctly states number of carbon atoms in repeat unit (3).
E1 (d) · 1 mark · Explains reasoning: two backbone carbons and one methyl side group.
Worked solution
a) The displayed formula of propyl ethanoate can be shown as:
or fully displayed:
b) The alcohol is propan-1-ol, and the carboxylic acid is ethanoic acid.
c) The monomer used to make poly(propene) is propene. Its structure is:
d) The repeat unit of poly(propene) has 3 carbon atoms: two in the backbone, and one as the methyl group side chain, all originating from the propene monomer.