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Alkyne Hydration quiz

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  • What is the initial product formed when water is added to a triple bond (alkyne)?
    The initial product is a vinyl alcohol, also known as an enol, which is an alcohol attached directly to a double bond.
  • What unique reaction do vinyl alcohols (enols) undergo after their formation?
    Vinyl alcohols undergo tautomerization, a process where a hydrogen and a pi bond swap positions, converting the enol into a more stable carbonyl compound.
  • What is the more stable form that enols rapidly convert into during alkyne hydration?
    Enols rapidly tautomerize into the keto form, which is usually a ketone or an aldehyde, because the keto form is much more stable.
  • What is tautomerization in the context of alkyne hydration?
    Tautomerization is the reversible process where a hydrogen atom and a pi bond switch places, converting an enol into a ketone or aldehyde.
  • What is the intermediate called when an alcohol is attached to a double bond during alkyne hydration?
    The intermediate is called an enol, which stands for an alcohol (ol) on an alkene (ene).
  • Why is the keto form favored over the enol form in tautomerization?
    The keto form is favored because it is much more stable than the enol form, so the equilibrium lies heavily toward the keto side.
  • What is the final product when a terminal alkyne undergoes Markovnikov hydration?
    The final product is a ketone, formed after the enol intermediate tautomerizes.
  • Which two methods can be used to hydrate alkynes to form ketones via Markovnikov addition?
    Oxymercuration and acid-catalyzed hydration can both be used, and both favor Markovnikov addition of the alcohol.
  • Where does the alcohol group add during Markovnikov hydration of an alkyne?
    The alcohol group adds to the more substituted carbon of the triple bond.
  • What should you label the second step of alkyne hydration if you are not required to show the full mechanism?
    You should label the second step as 'tautomerization' and then draw the final product.
  • What functional group is formed after tautomerization of a vinyl alcohol produced from alkyne hydration?
    A carbonyl group (either a ketone or an aldehyde) is formed after tautomerization.
  • What is the main difference in the product of hydration between alkenes and alkynes?
    Hydration of alkenes gives an alcohol, while hydration of alkynes gives a ketone or aldehyde after tautomerization.
  • Why are enols considered unstable compared to their keto counterparts?
    Enols are unstable because the keto form is much more thermodynamically favored, leading to rapid tautomerization.
  • What does the term 'enol' mean in organic chemistry nomenclature?
    'Enol' refers to a molecule with an alcohol group directly attached to a carbon-carbon double bond (alkene).
  • What is the significance of the equilibrium arrows in the tautomerization process?
    The equilibrium arrows are uneven because the conversion strongly favors the keto form over the enol form.