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MO14 Ester hydrolysis

Mer Scott 9 questions

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Questions in this quiz (9)

  1. 1An ester is hydrolysed to give:
    1. AA ketone and an anime
    2. BA carboxylic acid and a ketone
    3. CA carboxylic acid and an alcohol
  2. 2Under acidic conditions it is possible for a carboxylic acid and alcohol
    to form an ester.
    1. ATrue
    2. BFalse
  3. 3What will move the equilibrium of acid catalysed ester hydrolysis to the RHS/product side? (Select all correct)
    1. ARemoval of products
    2. BRemoval of reactants
    3. CExcess of water
    4. DReduction of water
  4. 4Step one of acid-catalysed ester hydrolysis is [blank_start]protonation[blank_end] of the carbonyl oxygen, ie the lone pair of electrons on the carbonyl [blank_start]oxygen[blank_end] attacks a proton. This increases the electron withdrawing properties of oxygen, making the carbonyl carbon [blank_start]more electrophilic(δ++)[blank_end].
    Step two is the nucleophilic attack by water. The lone pair of electrons on water’s oxygen is the [blank_start]nucleophile[blank_end] that attacks the carbonyl [blank_start]carbon[blank_end] of the ester.
    Thirdly, proton [blank_start]transfer[blank_end] occurs that sets up the [blank_start]C-O ester[blank_end] bond to break.
    Finally, [blank_start]R-OH+[blank_end] is a good leaving group, and transfer of [blank_start]electrons[blank_end] to R-OH+ is
    favourable, which produces a neutral alcohol.
    1. Aprotonation
    2. Boxygen
    3. Cmore electrophilic(δ++)
    4. Dless electrophilic(δ--)
    5. Enucleophile
    6. Fcarbon
    7. Gtransfer
    8. HC-O ester
    9. IR-OH+
    10. Jelectrons
  5. 5Step one of base-catalysed ester hydrolysis is attack by a [blank_start]hydroxide ion[blank_end]. The hydroxide ion (base) attacks the carbonyl [blank_start]oxygen[blank_end], and an [blank_start]alcohol[blank_end] group is added to the ester. The carbonyl oxygen becomes [blank_start]negatively[blank_end] charged.
    Then, the C-O bond breaks and an [blank_start]alkoxide[blank_end] (negatively charged alcohol) is produced. However, the proton from the carboxylic acid is [blank_start]quickly[blank_end] transferred to the alcohol, to make a [blank_start]neutral[blank_end] alcohol and a [blank_start]carboxylate[blank_end].
    1. Ahydroxide ion
    2. Boxygen
    3. Calcohol
    4. Dnegatively
    5. Epositively
    6. Falkoxide
    7. Gquickly
    8. Hneutral
    9. Icarboxylate
  6. 6Choose the incorrect statement.
    1. AThe rate of acid catalysed hydrolysis has been shown to be independent of pH in the approx. 4 – 7 pH range in some cases
    2. BIn the stomach at pH 1.5 – 3 the rate of acid-catalysed ester hydrolysis is comparatively faster.
    3. CGenerally from pH 8 and above the more basic the slower the rate of hydrolysis
    4. DThe rate of ester hydrolysis is slower at neutral pH.
  7. 7Lactones (cyclic esters) are actually often more chemically stable to ester hydrolysis than the corresponding acyclic ester.
    1. ATrue
    2. BFalse
  8. 8Choose the correct statement.
    1. ANearby steric bulk slows the chemical ester hydrolysis reaction
    2. BAn electron donating substituent would speed up the rate of ester hydrolysis
  9. 9Ester hydrolysis could activate a prodrug or inactive an active drug.
    1. ATrue
    2. BFalse

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Description
PHCY211 (Molecules) Quiz on MO14 Ester hydrolysis, created by Mer Scott on 12/04/2018.
Author
Mer Scott
Language
English
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