Organic Chemistry

Keto-enol tautomerism

Figure 182 The reaction mechanism of ozonolysis.

86.3.4 Hydration of alkynes

Water is added to an alkyne in a strong acid. The strong acid used is sulfuric acid and
mercuric acid.

86.4 Keto-enol tautomerism.

In the presence of an acid (H+) or a base (OH-), the aldehyde or ketone will form an
equilibrium with enols, in which the double bond of the carbonyl group migrates to form
double bond between the carbonyl and the alpha (α) carbon.

In the presence of an acid, protonation of the oxygen group will occur, and water will
abstract an alpha (α) hydrogen.

In the presence of a base, deprotonation of the alpha hydrogen will occur, and a hydrogen
from water will be abstracted by the carbonyl oxygen.

This is an important feature of ketone and aldehydes, and is known as theketo-enolic
tautomeryorketo-enol tautomerism, i.e. the equilibrium of carbonyl compounds between
two forms.