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Carboxylic acids and derivatives (A-level only)

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Question 6

This question is about esters, including those that find applications as biofuel components.

a.

An ester is formed by the reaction of propanoic anhydride with butan-1-ol.

  1. Complete the equation for this reaction. In your answer, show clearly the structure of the ester formed and write its IUPAC name.
Propanoic anhydride+CH3CH2CH2CH2OH→… \text{Propanoic anhydride} + \text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{OH} \rightarrow \dots Propanoic anhydride+CH3​CH2​CH2​CH2​OH→…
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b.

In a transesterification reaction to produce biodiesel, one mole of a vegetable oil (triglyceride) reacts with an excess of ethanol to form two moles of an ethyl ester with molecular formula C18H34O2\text{C}_{18}\text{H}_{34}\text{O}_2C18​H34​O2​ and one mole of an ethyl ester with molecular formula C20H40O2\text{C}_{20}\text{H}_{40}\text{O}_2C20​H40​O2​.

  1. Draw the structure of the vegetable oil showing clearly the ester links. You should represent the hydrocarbon chains in the form CxHy\text{C}_x\text{H}_yCx​Hy​ where xxx and yyy are the actual numbers of carbon and hydrogen atoms in each chain.
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c.
  1. Write a balanced chemical equation for the complete combustion of the ethyl ester C18H34O2\text{C}_{18}\text{H}_{34}\text{O}_2C18​H34​O2​.
[1]
Markscheme

Carboxylic acids and derivatives (A-level only) Questions

  1. A Level
  2. /Chemistry
  3. /Carboxylic acids and derivatives (A-level only)

22 exam-style questions on AQA A Level Chemistry Carboxylic acids and derivatives (A-level only), covering Carboxylic acids and esters (A-level only) and Acylation (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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