Nitrogen Compounds (OCR A Level Chemistry)

Exam Questions

2 hours30 questions
1a1 mark

This question is about amines.

Describe what is meant by a tertiary amine.

1b3 marks

State whether the following amines are classed as either primary, secondary or tertiary amines. 

i)
Propylamine
[1]
ii)
2-aminobutane
[1]
iii)
Phenylamine  

[1]

1c3 marks

Name the amines shown in Figure 1

Figure 1

amines-2

1d2 marks

Complete the equation for the formation of ethylamine.

CH3CH2Br + __________ → __________ + NH4Br

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2a3 marks

This question is about the synthesis and nature of amines.

State the reagents and conditions required for the conversion of 1-bromobutane into butylamine.

2b1 mark

Explain why amines can act as bases.

2c1 mark

Amines can be produced from haloalkanes.

Explain how a mixture of primary, secondary, tertiary and quarternary amines are produced in these reactions.

2d2 marks

Write an equation to show how ethylamine acts as a base when reacted with hydrochloric acid and give the name of the product formed in this reaction.

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3a4 marks

This question is about organic compounds containing nitrogen atoms.

Chloroethane will react with ethylamine to produce a secondary amine. Complete the reaction mechanism in Figure 1 for the formation of the secondary amine. 

 

Figure 1

amine-nucleophilic-substitution

3b1 mark

Give the name of the mechanism outlined in part (a)

3c1 mark

Phenylamine can be prepared from nitrobenzene. State the reagents and conditions required for this reaction.

3d1 mark

What is the structural formula of the functional group in a primary amide?

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4a1 mark

This question is about amino acids.

State the general formula for an α-amino acid.

4b1 mark

The amino acid alanine is shown below in Figure 1.

Figure 1
alanine

Draw the structure of the salt formed when alanine reacts with sodium hydroxide.

4c1 mark

Draw the structure of alanine when it is reacted with excess hydrochloric acid, HCl.

4d1 mark

Draw the structure of the product when alanine reacts with methanol in the presence of sulfuric acid.

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5a2 marks

This question is about amides and amines.

The structure of an amide is shown in Figure 2.

 Figure 2

n-methylpropanamide

i)
Determine whether this is a primary or secondary amide.
[1]
ii)
State the name of this amide.

[1]

5b1 mark

Write an equation for the reaction between trimethylamine (N(CH3)3) and hydrochloric acid.

5c1 mark

Write an equation to show the formation of methylamine from chloromethane.

5d1 mark

Give a condition for the reaction of chloromethane in part c) that would favour the formation of a quaternary ammonium salt.

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1a2 marks

Name the compound drawn below and state the class of compound to which it belongs. 

1-11

1b1 mark

Explain why an excess of ethylamine, CH3CH2NH2, is required for the formation of the compound in part (a).

1c7 marks

Three nitrogen containing molecules NH3, C6H5NH2 and N-methylethylamine, CH3CH2NHCH3, are drawn below:

2-7

i)

State the IUPAC name of CH3CH2NHCH3.

ii)

Explain how these compounds can behave as a Brønsted-Lowry base. 

1d3 marks

Phenylamine, C6H5NH2 shown in part (c) can be produced from nitrobenzene, C6H5NO2

Name the type of reaction and suggest suitable reagents and conditions for this conversion. 

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2a2 marks

Two amino acids, alanine and valine are drawn below.

1-12

i)

Give the IUPAC name for valine.

ii)

Draw the species formed when alanine is in a solution of high pH.

2b2 marks

Name the type of reaction and the structural formula of alanine when it reacts with propanol, CH3CH2CH2OH in the presence of concentrated sulfuric acid, H2SO4

2c2 marks

The isoelectric point of alanine is at pH 6.0.

i)

What is meant by the term isoelectric point

ii)

Draw the structure of alanine at pH 6.0

2d4 marks

Valine exists as a pair of stereoisomers.

Explain the meaning of the term stereoisomers and explain how the stereoisomers of valine can be distinguished from one another. 

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3a3 marks

The compound drawn below is caffeine. Caffeine is a stimulant drug that speeds up the messages travelling between the brain and body. Ingesting too much caffeine may promote headaches and high blood pressure.

12

i)

Give the molecular formula of caffeine. 

ii)
Calculate the percentage by mass of nitrogen in caffeine. Give your answer to 1 decimal place.
3b1 mark

Deduce the total number of peaks in the 13C NMR spectrum of caffeine.

3c3 marks

There are three nitrogen atoms labelled in the caffeine molecule drawn in part (a)

i)

Suggest why the nitrogen atoms labelled a and b are unlikely to be protonated.

ii)

Give the name, including the classification, of the functional group that contains the nitrogen atom labelled c.

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4a4 marks

Two separate solutions of methylamine, CH3NH2 and dimethylamine, (CH3)2NH, were left unlabelled in a laboratory. Suggest how, other than smell, they could be distinguished from one another. Justify your answer.

4b2 marks

Ethanoyl chloride, CH3COCl and methylamine, CH3NHreact to form an N-substituted amide. Name and draw the structure of the amide that is formed.

4c3 marks

4-methylphenylamine is a useful compound in the manufacture of azo dyes. It can be manufactured from methylbenzene in two stages.

i)

Draw the structure of the intermediate required to manufacture 4-methylphenylamine

ii)

State the reagents and conditions required to manufacture the intermediate 

4d2 marks

The final stage for the preparation of 4-methylphenylamine involves the intermediate being heated under reflux in the presence of concentrated hydrochloric acid and a tin catalyst. Explain why sodium hydroxide is also required in this step.

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5a4 marks

The reaction scheme below shows some reactions of Compound A to produce three different products. 

8-2

Explain how the reactions and the conditions of reaction 2 and reaction 3 are different from one another. 

5b4 marks

Compound B drawn in part (a) is a primary amine.

Give the IUPAC name of Compound B and state the conditions required for reaction 1. 

5c1 mark

Draw an isomer of Compound B from part (a) that would display optical isomerism.

5d7 marks

An alternative method of producing Compound B in part (a) is from 1-bromopropane, CH3CH2CH2Br in two steps. 

i)

State the reagents and conditions required for both steps of this reaction and give the name of the intermediate compound formed. 

ii)
Suggest one advantage and one disadvantage for this method.

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1a1 mark

Compound Q is an organic nitrogen compound containing C, H and N, that reacts with dilute sulfuric acid in a 1:1 ratio. 

Suggest a general formula for compound Q.

1b
Sme Calculator
4 marks

The elemental analysis by mass of compound Q is: C: 61.22% ; 10.20%, the rest being nitrogen. Determine the empirical and molecular formula of Q.

1c1 mark

The 13C NMR spectrum of Q shows four peaks. Draw a structure for Q consistent with this information.

1d1 mark

Write an equation for the reaction of Q with sulfuric acid.

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2a2 marks

Bromocyclopentane is an alkyl halide that is a precursor in the synthesis of ketamine. Ketamine is a drug used to induce anaesthesia and treat depression. The structure of ketamine is shown below.

6-4_q2a-ocr-a-as--a-level-hard-sq

Identify the functional groups in ketamine.

2b3 marks

In the boxes draw the organic products for the reactions of bromocyclopentane.

6-4_q2b-ocr-a-as--a-level-hard-sq
2c3 marks

Name all the organic products of the reactions in part b).

2d1 mark

Name the inorganic product(s) of the reaction in b).

2e1 mark

State the IUPAC name of the following molecule:

6-4_q2e-ocr-a-as--a-level-hard-sq

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3a3 marks

2,4,6-triaminotoluene is a useful precursor in the synthesis of aromatic compounds and has the structure shown below:

6-4-q3a

13C spectroscopy can be used to distinguish between isomers in complex organic molecules.



i)
State how many positional isomers are possible in 2,4,6-triaminotoluene. 

[1]

ii)
Explain how the 13C NMR spectrum would enable a student to distinguish between positional isomers of 2,4,6-triaminotoluene.
[2]

3b1 mark

In the box, draw the starting material for the reaction shown below:

6-4_q3b-ocr-a-as--a-level-hard-sq
3c1 mark

A derivative of 2,4,6-triaminotoluene called 2,4,6-tri(aminomethyl)toluene is shown below. Complete the structure of the reactant in the box.

ocr-6-4h-3c
3d2 marks

A student was preparing 2,4,6-tri(aminomethyl)toluene using the reaction in part c). To check their success they made an IR spectrum of the starting material and the product, but unfortunately the student mixed the two unlabelled spectra. One the two spectra is shown below.

6-4_q3d-ocr-a-as--a-level-hard-sq

State which substance the spectrum belongs to and explain your reasoning.

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4a1 mark

Tryptophan is a naturally occurring α-amino acid. Its structure is shown below.

ocr-6-4h-4a

Draw a circle around the R group in this amino acid

4b2 marks

Deduce the molecular formula for tryptophan and write a balanced equation for the reaction of tryptophan with dilute nitric acid.

4c3 marks

Draw the structures for the organic product of the reaction of tryptophan and the following substances:

i)
NaOH (aq)
[1]
ii)
C2H5OH and concentrated sulfuric acid.
[2]
4d2 marks
Two more naturally occurring amino acids are leucine and isoleucine shown below:
ocr-6-4h-4d

State how many optical isomers there are for leucine and isoleucine.

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5a1 mark

The amino acid alanine is shown below:

6-4_q5a-ocr-a-as--a-level-hard-sq 

Alanine will react with excess chloromethane. Draw the structure of the product formed in this reaction. 

5b2 marks

Alanine can also react with serine to produce two different dipeptides. The structure of serine is shown below.

6-4_q5b-ocr-a-as--a-level-hard-sq

Draw both dipeptide formed in this reaction.

5c3 marks

Explain the conditions in which alanine exists as a solid and draw the structure of the amino acid in these conditions. 

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