Addition of H2O across a triple bond Alkyne Reactions: Addition of H2O across a triple bond

Addition of H2O across a triple bond H2O can be added across a triple bond in two ways: By using BH3 followed by H2O2 and NaOH or H2SO4 and HgSO4. Depending on which reagent you use determines where the –OH will end up.

Addition of Water across a triple bond (2 Reactions)

Selectivity As you can see, H2SO4 and HgSO4 attacks the more substituted carbon of the triple bond. Since BH3 actually attacks the less substituted carbon twice, we use a hindered borane, called “(sia)2BH”

Tautomerism The enol (alcohol bonded to ac arbon in an alkene) is less stable than the “keto” (C=O) form. The enol product of hydration of a triple bond tends to tautomerize into it’s keto form.

Examples of Tautomerism: Equilibrium Lies FAR to the right in the tautomerism, with few notable exceptions.

What is the Product? ?

Incorrect

Correct

What is the Product? ?

Incorrect

Correct