A LevelChemistryOCRExam Questions6. Organic Chemistry & Analysis (A Level Only)6.5 Optical Isomerism

Optical Isomerism (OCR A Level Chemistry)

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6.5 Optical Isomerism

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6.5 Optical Isomerism

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11 mark

Which statement is the most correct for an optical isomer?

  • Four different atoms or groups of atoms around a carbon atom cause optical isomerism

  • Optical isomerism occurs as a result of restricted rotation about a carbon–carbon double bond

  • Optical isomers are superimposable mirror images of each other called enantiomers

  • Optical isomers are molecules that have the same structural formula but have the atoms arranged differently in space

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21 mark

Which carbon atom is the chiral centre in the following molecule?

1-1

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    31 mark

    Which compound contains a chiral carbon?

    • Butanone

    • Butan-2-ol

    • Cyclopentanol

    • Propanal

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    41 mark

    Which compound does not contain a chiral carbon?

    2-5

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      51 mark

      Transition metal complexes can show optical isomerism.

      Which of the following combinations will not exhibit optical isomerism?

      1. Octahedral complex with six identical monodentate ligands.
      2. Octahedral complex with three identical bidentate ligands.
      3. Tetrahedral complex with four different monodentate ligands.

      • 1, 2 and 3

      • Only 1 and 2

      • Only 2 and 3

      • Only 1

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      11 mark

      Which statement about optical isomerism is correct?

      • Optical isomers have a different arrangement of carbon atoms in the skeleton of the molecule

      • Optical isomers have a different boiling point

      • Optical isomers have the same structural formula

      • Optical isomers have four different atoms attached to the chiral carbon

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      21 mark

      Which statement about 2,3-dihydroxybutanedioic acid, shown below, is correct?

      23-dihydroxybutanedioic-acid

      • There are four asymmetric carbon atoms

      • The structure shown rotates plane polarised light to the right

      • 2,3-dihydroxybutanedioic acid is a racemate

      • The molecule has two chiral centres

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      31 mark

      Which of the following compounds will produce optical isomers when it undergoes reduction?

      • CH3COCH3

      • CH3CH=CH2

      • CH3CH2COCH3

      • CH3CH2COOH

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      41 mark

      What is the number of chiral centres in the molecule below?

      ibuprofen

      • 1

      • 2

      • 3

      • 4

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      51 mark

      Ethanal reacts with hydrogen cyanide followed by hydrochloric acid to make 2-hydroxypropanoic acid in the two-step reaction sequence below.

      ethanal-two-step-rxn-optical-isomers

      Which description of the reactants and products is correct?

        Reactant Product of step 1 Product of step 2
      A Optically active Optically active Optically active
      B Optically inactive Mixture of optical isomers Mixture of optical isomers
      C Optically active Optically inactive Optically active
      D Optically active Mixture of optical isomers Mixture of optical isomers

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        11 mark

        Which compound forms a reduction product capable of exhibiting optical isomerism?

        • CH3CH2CH2COCH3 

        • CH(CH3)2CH2CHO

        • C(CH3)3CHO

        • CH3CH2COCH2CH3 

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        21 mark

        Arthrinin-F is a relatively novel compound isolated from fungus.

        Arthrinin-F IB 20.3 MCQs H

        How many chiral centres does Arthrinin-F have in its structure?

        • 14

        • 11

        • 6

        • 4

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        31 mark

        Which statement about but-1-en-3-ol, CH2CHCHOHCH3, is not true?

        • It has stereoisomers

        • It will turn an acidified potassium dichromate(VI) solution green

        • It contains a peak at 1650 cm−1 on its IR spectrum

        • It has optical isomers

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        41 mark

        N,N-Dimethyl-2-hydroxy-3-methylbutanamide can exist as a pair of optical isomers.

        Which is the correct structure for an N,N-dimethyl-2-hydroxy-3-methylbutanamide enantiomer?

        • nn-dimethyl-2-hydroxy-3-methylbutanamide-option-a 

        • nn-dimethyl-2-hydroxy-3-methylbutanamide-option-b 

        • nn-dimethyl-2-hydroxy-3-methylbutanamide-option-c 

        • nn-dimethyl-2-hydroxy-3-methylbutanamide-option-d 

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        51 mark

        Which compound forms a stereoisomeric product when reduced?

        • CH3CH2CH2=CHCH3

        • CH3CH2CH2CH2CHO

        • CH3CH2C(CH3)=CHCH3

        • CH3CH2CH2COCH3

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