Q22-1P - Organic Chemistry (Mcmurry)

Question

Draw structures for the enol tautomers of the following compounds: 

(a) Cyclopentanone 

(b) Methyl thioacetate 

(c) Ethyl acetate 

(d) Propanal 

(e) Acetic acid 

(f) Phenylacetone

 

Step-by-Step Solution

Answer

1. You need to draw the enol tautomers of Cyclopentanone.
2. You need to draw the enol tautomers of Methyl thioacetate.
3. You need to draw the enol tautomers of Ethyl acetate.
4. You need to draw the enol tautomers of Propanal.
5. You need to draw the enol tautomers of Acetic acid.
6. You need to draw the enol tautomers of Phenylacetone.

Step 1: Structure of Cyclopentanone

The structure of Cyclopentanone is 

This is the keto form.

Step 2: Structure of enol form

You can draw the keto-enol tautomers like this;

Step 3: Explanation of the keto enol tautomers

You can form the enol form from the keto form. You just need to remove the hydrogen from the carbon of the adjacent carbonyl carbon atom. Removing of the hydrogen atom forms a double bond between these two carbons atom (carbonyl carbon and its adjacent carbon) and the carbonyl carbon becomes enolic.

Step 4: Conclusion

Hence, the enol tautomer of Cyclopentanone is drawn.

Step 5: Structure of Methyl thioacetate

The structure of Methyl thioacetate is 

This is the keto form.

Step 6: Structure of enol form

You can draw the keto enol tautomers like this;

Step 7: Explanation of the keto enol tautomers

You can form the enol form from the keto form. You just need to remove the hydrogen from the carbon of the adjacent carbonyl carbon atom. Removing of the hydrogen atom forms a double bond between these two carbons atom (carbonyl carbon and its adjacent carbon) and the carbonyl carbon becomes enolic.

Step 8: Conclusion

Hence, the enol tautomer of Methyl thioacetate is drawn.

Step 9: Structure of Ethyl acetate

The structure of Ethyl acetate is 

This is the keto form.

Step 10: Structure of enol form

You can draw the keto enol tautomers like this;

Step 11: Explanation of the keto enol tautomers

You can form the enol form from the keto form. You just need to remove the hydrogen from the carbon of the adjacent carbonyl carbon atom. Removing of the hydrogen atom forms a double bond between these two carbons atom (carbonyl carbon and its adjacent carbon) and the carbonyl carbon becomes enolic.

Step 12: Conclusion

Hence, the enol tautomer of Ethyl acetate is drawn.

Step 13: Structure of Propanal

The structure of Propanal is 

This is the keto form.

Step 14: Structure of enol form

You can draw the keto enol tautomers like this;

Step 15: Explanation of the keto enol tautomers

You can form the enol form from the keto form. You just need to remove the hydrogen from the carbon of the adjacent carbonyl carbon atom. Removing of the hydrogen atom forms a double bond between these two carbons atom (carbonyl carbon and its adjacent carbon) and the carbonyl carbon becomes enolic.

Step 16: Conclusion

Hence, the enol tautomer of Propanal is drawn.

Step 17: Structure of Acetic acid

The structure of Acetic acid is

 

Step 18: Structure of enol form

You can draw the keto enol tautomers like this;

Step 19: Explanation of the keto enol tautomers

You can form the enol form from the keto form. You just need to remove the hydrogen from the carbon of the adjacent carbonyl carbon atom. Removing of the hydrogen atom forms a double bond between these two carbons atom (carbonyl carbon and its adjacent carbon) and the carbonyl carbon becomes enolic.

Step 20: Conclusion

Hence, the enol tautomer of Acetic acid is drawn.

Step 21: Structure of Phenylacetone

The structure of Phenylacetone is 

This is the keto form.

Step 22: Structure of enol form

You can draw the keto enol tautomers like this;

Step 23: Explanation of the keto enol tautomers

You can form the enol form from the keto form. You just need to remove the hydrogen from the carbon of the adjacent carbonyl carbon atom. Removing of the hydrogen atom forms a double bond between these two carbons atom (carbonyl carbon and its adjacent carbon) and the carbonyl carbon becomes enolic.

 

Step 24: Conclusion

Hence, the enol tautomer of Phenylacetone is drawn.