OCR A Level Chemistry

Topic Questions

A LevelChemistryOCRTopic Questions6. Organic Chemistry & Analysis (A Level Only)6.8 Organic Synthesis

6.8 Organic Synthesis

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11 mark

CN– ions react with haloalkanes and with carbonyl compounds.

Which row gives the correct mechanisms for the reactions?

  Reaction of CN- with haloalkanes Reaction of CN- with carbonyl compounds 
A Electrophilic substitution  Electrophilic addition
B Electrophilic substitution  Nucleophilic addition
C Nucleophilic substitution  Electrophilic addition
D Nucleophilic substitution  Nucleophilic addition

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21 mark

Phenylamine can be produced in a two-stage synthesis shown below.

imT7nJgb_6-8-q2-phenylamine

What is the correct classification of the steps?

  Step 1 Step 2
A Electrophilic substitution Reduction
B Nucleophilic addition Reduction
C Nitration Oxidation
D Nucleophilic addition Oxidation

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31 mark

Propanal can be converted to propanoyl chloride via a two-stage synthesis route shown below.

propanal  rightwards arrow with Step space 1 on top  propanoic acid  rightwards arrow with Step space 2 on top  propanoyl chloride

What are the correct reagents for steps 1 and 2?

  Step 1 Step 2
A H2O / HCl SOCl2
B NaBH4 / H2O H2O / HCl
C K2Cr2O7 / H+ SOCl2
D K2Cr2O7 / H+ H2O

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41 mark

Many organic products can be synthesised from a few starting compounds using the correct reagents and conditions.

Which skeletal formula is a correct example for the functional groups stated?

  Functional groups Example
A Alcohol and nitrile 6-8-q4-a
B Alcohol and nitrile 6-8-q4-b
C Ester and alkene 6-8-q4-c
D Carbonyl and haloalkane 6-8-q4-d

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51 mark

Which of the following compounds can not be formed directly from an alcohol?

  • Amine

  • Ester

  • Alkene

  • Ketone

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11 mark

Which row contains the correct number of minimum steps to convert an aldehyde into the given compound?

 

Amide

Primary amine

Dihalogenoalkane

A

2 steps

3 steps

4 steps

B

4 steps

2 steps

3 steps

C

3 steps

4 steps

2 steps

D

2 steps

4 steps

3 steps

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21 mark

Propyl 4-aminobenzoate or risocaine is a local anesthetic that can be synthesised from 4-nitrobenzaldehyde via the following three step synthesis.

nwnKtwWD_7-8-h-q1-mcq-aqa-al-chemistry

Which row contains the correct molecular formulae of compounds X and Y?

  Compound X Compound Y
A C7H6NO3 C9H11NO4
B C7H6NO4 C10H11NO3
C C7H5NO4 C10H11NO4
D C7H5NO3 C9H11NO3

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31 mark

Which statement about the purification of an organic solid is not correct?

  • Recrystallisation uses a solvent in which the organic solid dissolves when hot but will crystallise out when cold. 

  • Hot filtration can be used after recrystallisation to remove any solid impurities that remain. 

  • Impurities tend to lower the melting point of organic solids such as aspirin. 

  • A water bath can be used to determine the melting point of the organic solid. 

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41 mark

Below is a sequence of reactions from the starting molecule bromopropane.

l4hQIC9o_ocr-a2-6-8h-mcq-q2-reaction-sequence

Which reagent or type of mechanism is not correct for the indicated step?

  • Step 1 NaCN / Nucleophilic substitution

  • Step 2 H2O/HCl / Hydrolysis

  • Step 3 SOCl2 / Chlorination 

  • Step 4 methylamine / Nucleophilic substitution 

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51 mark

A reaction sequence starting from ethene is shown below.

ocr-a2-6-8h-mcq-q3-reaction-sequence

Which statement(s) is/are correct?

  1. Two of the molecules belong to the same homologous series.
  2. Reaction 4 produces a compound that will conduct electricity in the molten state.
  3. Reactions 1, 2, 3 and 5 require sulfuric acid. 

  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1

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11 mark

The structure of the amino acid phenylalanine is shown below.

phenylalanine

Which functional group(s) is / are in a molecule of phenylalanine?

  1. Amine
  2. Amide
  3. Alcohol

  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1

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21 mark

Which statement about melting point tests is not correct?

  • Impurities can raise or lower the melting point of organic solids

  • The melting point tubes must be heated slowly

  • Organic solids with high melting points can decompose before melting

  • The organic solid must be finely powdered and dry

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31 mark

The synthesis of ethyl butanoate can be carried out using the reaction scheme shown below.

                        C4H9Br   rightwards arrow with Step space 1 on top  C4H9OH  rightwards arrow with Step space 2 on top  C3H7COOH  rightwards arrow with Step space 3 on top  C3H7COOC2H5  

What is the correct classification of the steps?

 

Step 1

Step 2

Step 3

A

Substitution

Oxidation

Condensation

B

Addition

Substitution

Condensation

C

Oxidation

Substitution

Condensation

D

Substitution

Oxidation

Substitution

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41 mark

Propanone can be converted to 2-bromopropane using the three step synthetic scheme shown below. 

Propanone rightwards arrow with Step space 1 on top propan-2-ol rightwards arrow with Step space 2 on toppropene rightwards arrow with Step space 3 on top2-bromopropane

What are the correct reagents for each step?

 

Step 1

Step 2

Step 3

A

K2Cr2O7 / H2SO4

Conc. NaOH

HBr

B

NaBH4

Al2O3

HBr

C

H2O / H2SO4

Al2O3

Br2

D

NaBH4

K2Cr2O7 / H2SO4

HBr

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51 mark

Butylamine can be prepared in two steps from 1-bromopropane

CH3CH2CH2Br → X → CH3CH2CH2CH2NH2

What is the structural formula of X?

  • CH3CH2CH2OH

  • CH3CH=CH2

  • CH3CH2CH2CN

  • CH3CH2CH2CHO

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