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How can an α,β-unsaturated ketone tautomerise?
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Marty Silvia
How can an α,β-unsaturated ketone tautomerise?
If you have an α,β-double bond next to your carbonyl, a γ hydrogen can also take part in tautomerism. Take crotonaldehyde $\ce{H3C-CH=CH-CHO}$:
$$\ce{O=CH-CH=CH-CH3 <<=> HO-CH=CH-CH=CH2}$$
In general, a double bond is able to ‘extend’ the mesomeric properties of a carbonyl compound across two additional atoms. This is known as vinylogous; crotonaldehyde can form a vinylogous enol.
In the specific case of 6,6-dimethylcyclohex-2-en-1-one, these are the two tautomers:
If you have an α,β-double bond next to your carbonyl, a γ hydrogen can also take part in tautomerism. Take crotonaldehyde $\ce{H3C-CH=CH-CHO}$:
$$\ce{O=CH-CH=CH-CH3 <<=> HO-CH=CH-CH=CH2}$$
In general, a double bond is able to ‘extend’ the mesomeric properties of a carbonyl compound across two additional atoms. This is known as vinylogous; crotonaldehyde can form a vinylogous enol.
In the specific case of 6,6-dimethylcyclohex-2-en-1-one, these are the two tautomers:
There should be possibility of an intramolecular acid-base reaction. Acid-base pair are usually Lewis acid-base but there may be others. Such molecules show tautomerism. There are a large number of tautomerisms that can be explained by this way.
Such as keto-enol (your problem too), oxime-nitroso tautomerism and many more.
There should be possibility of an intramolecular acid-base reaction. Acid-base pair are usually Lewis acid-base but there may be others. Such molecules show tautomerism. There are a large number of tautomerisms that can be explained by this way.
Such as keto-enol (your problem too), oxime-nitroso tautomerism and many more.
If you have an α,β-double bond next to your carbonyl, a γ hydrogen can also take part in tautomerism. Take crotonaldehyde $\ce{H3C-CH=CH-CHO}$:
$$\ce{O=CH-CH=CH-CH3 <<=> HO-CH=CH-CH=CH2}$$
In general, a double bond is able to ‘extend’ the mesomeric properties of a carbonyl compound across two additional atoms. This is known as vinylogous; crotonaldehyde can form a vinylogous enol.
In the specific case of 6,6-dimethylcyclohex-2-en-1-one, these are the two tautomers:
If you have an α,β-double bond next to your carbonyl, a γ hydrogen can also take part in tautomerism. Take crotonaldehyde $\ce{H3C-CH=CH-CHO}$:
$$\ce{O=CH-CH=CH-CH3 <<=> HO-CH=CH-CH=CH2}$$
In general, a double bond is able to ‘extend’ the mesomeric properties of a carbonyl compound across two additional atoms. This is known as vinylogous; crotonaldehyde can form a vinylogous enol.
In the specific case of 6,6-dimethylcyclohex-2-en-1-one, these are the two tautomers:
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There should be possibility of an intramolecular acid-base reaction. Acid-base pair are usually Lewis acid-base but there may be others. Such molecules show tautomerism. There are a large number of tautomerisms that can be explained by this way.
Such as keto-enol (your problem too), oxime-nitroso tautomerism and many more.
There should be possibility of an intramolecular acid-base reaction. Acid-base pair are usually Lewis acid-base but there may be others. Such molecules show tautomerism. There are a large number of tautomerisms that can be explained by this way.
Such as keto-enol (your problem too), oxime-nitroso tautomerism and many more.
More
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