Intermediate step?

[Lilac12]

For the reaction of 2-butyne with water, is there an intermediate unstable step of 2-buten-2-ol before it becomes a stable form of butanone?

Because I know that there is an unstable intermediate step for the combination of ethyne and water, but I wasn’t sure if it was the same rule for all alkynes.

Also, if there isn’t an intermediate step, is there a rule I can use for future questions or is it just you need to know depending on what substance it is?

Thanks!

[Chester Malone]

Yes, there is an intermediate unstable step in the reaction of 2-butyne with water, and it involves the formation of an enol.  
Protonation of the alkyne: A proton from the acid catalyst adds to one of the carbon atoms of the triple bond, forming a carbocation intermediate.  
Nucleophilic attack by water: A water molecule attacks the carbocation, forming an oxonium ion. Deprotonation: A base, such as water, removes a proton from the oxonium ion, forming an enol.  
Tautomerization: The enol tautomerizes into the more stable ketone form, which is butanone in this case.  

So, the intermediate unstable step is the enol, 2-buten-2-ol.

This mechanism is common for the acid-catalyzed hydration of alkynes. However, the specific products and reaction conditions can vary depending on the structure of the alkyne and the reaction conditions used.

[laurennjames10]

Yes, 2-butyne hydration typically forms an enol intermediate (2-buten-2-ol), which then tautomerizes to the more stable keto form, butanone. This keto-enol tautomerization is common in alkyne hydration reactions, especially for terminal alkynes and some internal alkynes. In general, alkynes undergoing hydration follow this pathway where an enol intermediate briefly forms before stabilizing as a ketone or aldehyde.

[matthewmiles]

Yes, in the hydration of 2-butyne, an intermediate step of 2-buten-2-ol (enol) forms first, which is unstable and quickly tautomerizes to the more stable ketone form, butanone. This is typical in alkyne hydration reactions where the enol intermediate is present, especially in terminal or symmetrical alkynes. For future questions, remember that most alkyne hydrations initially form an enol intermediate, which typically rearranges to a ketone or aldehyde, depending on the structure of the starting alkyne.