Data response Example 6

laugh Data Response question on paracetamol

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I have made up this question to help prepare students for the data response questions which appear on Section A of Paper 3 for the examinations on the 2014 programme (i.e. for examinations after May 2016). The information given is new to the students but they should be able to use their knowledge and understanding of the chemistry content of the programme to answer the questions. Because I have tried to make the chemistry interesting it may be a little harder than an actual exam question but exposure to questions like this beforehand should make students able to face the data response question in the final examination with considerable confidence. Since some of the answers require a knowledge and understanding of material from the AHL this particular question is only suitable for Higher Level students.

As well as including model answers I have also explained the chemistry fully and given the 'Complete course for students' links to the pages which cover the theory behind each individual question. If you set it as an assigned task using Student Access, students will not be able to see the model answers until after they have submitted their answers to you. If you simply give students access to the page (rather than assigning it as a task) they will be able to access the model answers themselves for review/revision/self-study etc.

If you do not wish to use student access, links to downloadable versions of the questions and, separately the worked answers, can be found at Printable versions of written tasks.

 

Paracetamol, an over the counter pain-killer, can be synthesised from phenol in three separate steps.

(a) (i)  In Step 1 phenol is converted into a mixture of 4-nitrophenol and 2-nitrophenol.
Identify the mechanism of this reaction by stating its name. [1]

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(ii) The two products from Step 1 can easily be separated by a process known as steam distillation.
Suggest why the boiling point of 2-nitrophenol (216 oC) is considerably lower than the boiling point of 4-nitrophenol (279 oC). [2]

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(b) (i) In Step 2 the 4-nitrophenol is converted into 4-aminophenol. Identify the type of chemical reaction that occurs in this step. [1]

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(ii) 4-aminophenol is soluble in aqueous solutions of strong acids.
Deduce the structural formula of the product formed when 4-aminophenol dissolves in dilute hydrochloric acid. [1]

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(c)  The structural formula of ethanoic anhydride is:

(i) Deduce the structural formula of the product, other than paracetamol, formed in Step 3. [1]

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(ii) Other than hydroxyl and phenyl, state the name of a functional group present in paracetamol. [1]

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(iii) 10.00 g of phenol produced 2.47 g of paracetamol. Assuming the percentage yields of Steps 1 and 2 are as listed, calculate the percentage yield for Step 3. [3]

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