Why does Tautomerization occur?
Mechanism of Tautomerization Either acid or base can catalyze proton transfer. Hence, tautomerization occurs by two different mechanisms. In the first step of acid-catalyzed tautomerization of the keto form, hydronium ion protonates the carbonyl oxygen atom. Then, water removes the α-hydrogen atom to give the enol.
What are the conditions for keto-enol tautomerism?
There must be a carbon linked to that electron withdrawing atom and further this carbon is linked to another carbon having a hydrogen atom. This hydrogen is referred to as acidic α−hydrogen. Keto compounds fulfill these conditions and the keto-enol tautomeric pair is one of the most common tautomeric pairs.
What do you mean by Tautomerization?
Tautomers are isomers of a compound which differ only in the position of the protons and electrons. The carbon skeleton of the compound is unchanged. A reaction which involves simple proton transfer in an intramolecular fashion is called a tautomerism.
What is the condition for Tautomerization?
For tautomerism, the condition is that the carbonyl group should have an alpha hydrogen which is attached to the sp3 hybridized carbon atom. Hence, four compounds as shown in above image will exhibit tautomerism.
What is Tautomerization with example?
One of the most common examples of tautomers are the isomers of phenol. One of the tautomers has three double bonds inside the ring system and an alcohol functional group, while the other only contains two double bonds associated with the ring and a ketone (carbon-oxygen double bond) functional group.
How can Tautomerization cause mutation?
Likewise, cytosine and adenine are normally in amino forms, but when in the rare imino forms they can join by two hydrogen bonds with amino forms of adenine or cytosine, respectively. Tautomeric shifts that modify the pairing of nucleotides can result in base substitutions and, as a result, mutations.
What is Tautomerization in DNA?
In DNA bases, tautomerization results in altered base pairing configurations or mispairing due to changes in hydrogen-bonding capabilities. DNA mutations are likely to be caused by such alterations. Cytosine is one of the building pyrimidine nucleobases of RNA.
Why is the keto form more stable than enol form?
In general , keto form is more stable than enol form due to greater bond energy of c=o. than c=c . But, in some cases enol form is more stable than keto . For example, if bulky phenyl groups are present at sp3 alpha carbon then enol is more stable than keto form due greater bond angle.
What is keto enol tautomerism and how does it work?
In Keto Enol Tautomerism, a carbonyl double bond is broken, an alkene double bond is formed, and a hydrogen atom migrates from the alpha carbon to the oxygen atom, forming an alcohol. What is this equilibrium you speak of?
Is there an equilibrium between the keto and enol forms?
There is an equilibrium between the keto and enol form, almost exclusively favoring the keto form. However, the enol form does exist in solution. The ratio of keto to enol forms depends on several factors, which we will discuss further below.
What is the enolization of a ketone?
When we refer to the enolization, we specifically refer to the process that takes you from a ketone or an aldehyde to an enol or an enolate. When we refer to a keto-enol tautomerism, we mean the equilibrium in general.
What is enolization in chemistry?
Enolization or a keto-enol tautomerism is a process of converting a ketone or an aldehyde to a corresponding enol (in acidic conditions) or an enolate (in basic conditions). This process can occur in esters as well.