Organic Synthesis (Edexcel International A Level Chemistry)

Exam Questions

11 mark

The melting temperature is determined for impure crystals of an organic compound.

When compared with a data book value for the pure compound, the measured melting temperature

  • will be the same as the true value

  • will be higher than the true value

  • will be lower than the true value

  • could be higher or lower than the true value

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11 mark

But-2-ene-1,4-diol may be converted into 2-oxobutanedioic acid in a two-step synthesis through an intermediate compound W.

HOCH2CHequalsCHCH2OH   rightwards arrow from Step space 1 to steam space and space straight H subscript 2 SO subscript 4 of W  rightwards arrow for Step space 2 of  HO2CCOCH2CO2H
          but-2-ene-1,4-diol                                                         2-oxobutanedioic acid

Identify the intermediate compound W and the reagent for Step 2.

      Compound W Reagent for Step 2
  A HOCH2CH(OH)CH2CH2OH LiAlH4 in dry ether
  B HOOCH2CHequalsCHCOOH LiAlH4 in dry ether
  C OHCCH(OH)CH2CHO hot acidified K2Cr2O7
  D HOCH2CH(OH)CH2CH2OH hot acidified K2Cr2O7

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    21 mark

    Grignard reagents react with

    • water giving primary alcohols

    • all aldehydes giving secondary alcohols

    • ketones giving secondary or tertiary alcohols

    • carbon dioxide giving carboxylic acids

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    31 mark

    The structure of a hydrocarbon is shown.

    q16-paper-5-jan-2021-edexcel-ial-chemistry

    How many peaks will there be in the 13C NMR spectrum of this compound?

    • four

    • five

    • seven

    • eight

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    4
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    1 mark

    When a sample of a hydrocarbon is burned completely in oxygen, 2.64 g of carbon dioxide and 0.81 g of water are formed.

    Which of these could be the molecular formula of the hydrocarbon?

    • C2H3

    • C4H3

    • C4H6

    • C12H9

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    1
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    1 mark

    Benzenecarboxylic acid may be produced from benzene in a two-step synthesis.

    q18-paper-5-jan-2021-edexcel-ial-chemistry

    8.24 g of benzenecarboxylic acid was formed in this synthesis.

    What mass of benzene was used?

    • 3.48 g

    • 5.27 g

    • 19.51 g

    • 30.52 g

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