What is the catalyst used for hydration of alkynes?
As with alkenes, hydration (addition of water) to alkynes requires a strong acid, usually sulfuric acid with a mercuric sulfate catalyst as shown below.
Which compound likely came from acid catalyzed hydration of a terminal alkyne?
Therefore, the hydration of a terminal alkyne produces a ketone through a keto-enol tautomerization of the more substituted enol. In summary, acid-catalyzed hydration of internal alkynes can produce one or two ketones depending if the alkyne is symmetrical or not.
What does HgSO4 do to an alkyne?
Reagent: HgSO4/H2SO4/H2O • You need a Hg catalyst for terminal alkyne hydration. This reaction adds an OH with Markovnikov regioselectivity to form an enol. The enol product then tautomerizes to form a ketone.
What is a terminal alkyne?
Terminal alkyne: An alkyne in which the carbon-carbon triple bond is at the end of the carbon chain.
What does LDA do to alkynes?
– Terminal alkynes react with sodium amide to form alkyne anions. – Terminal alkynes can also be converted to alkyne anions by reaction with sodium hydride or lithium diisopropylamide (LDA).
Do alkynes react with sulfuric acid?
Alkynes readily combine with water in the presence of acid (usually sulfuric acid) and mercury(II) salts (usually the sulfate is used) to form carbonyl compounds, in a process known as Kucherov’s reaction. In the case of acetylene (ethyne) the product is acetaldehyde (ethanal), while other alkynes form ketones.
What type of reaction does alkynes undergo?
addition reactions
Alkynes undergo addition reactions due to the presence of loosely held pi-electrons. Due to the presence of a triple bond in alkynes, halogens, water etc.
Do terminal alkynes undergo acid-catalyzed hydration?
Terminal alkynes also undergo acid-catalyzed hydration. However, they are less reactive toward the addition of water and HgSO4 is used as a catalyst to increase the rate of the reaction:
What is the mechanism of addition of water to alkynes by Mercury?
Mercury(II)-catalyzed addition of water to alkynes. The first mechanistic steps of the reaction are the same as in the oxymercuration of alkenes. But the hydroxy mercury compound intermediately formed is an alkenyl mercury and not an alkyl mercury compound.
How do you hydrate an alkyne?
Let’s look at the hydration of alkynes. So we’re going to start with a terminal alkyne over here. You can see there’s a hydrogen on one side of our alkyne. And on the other side of our alkyne, let’s say it’s an alkyl group, bonded to this carbon on the right. So we’re going to add water, sulfuric acid, and mercury (II) sulfate to our alkyne.
How many ketones can be produced by acid-catalyzed hydration of alkynes?
In summary, acid-catalyzed hydration of internal alkynes can produce one or two ketones depending if the alkyne is symmetrical or not. And terminal alkynes produce only one ketone following the Markovnikov’s rule.