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Draw the enol tautomers for each of the following compounds. If the compound has more than one enol tautomer, indicate which one is more stable.
(a)
Interpretation:
The enol tautomer of the given compound has to be drawn and more stable structure has to be identified.
Concept Introduction:
Tautomerism is the ability of a molecule to exist in more than one chemical form.
Tautomers are formed by the migration of a hydrogen atom, accompanied by the switching of a single and neighboring double bond.
The only difference in keto-enol tautomers is the location of hydrogen and double bond.
Enol tautomer is much less stable than the keto tautomer.
Enol tautomer is more stable when enol tautomer is aromatic or when the double bonds are conjugated.
Resonance is an electron displacement effect for stabilizing a molecule through delocalization of bonding electrons in the pi orbital.
Delocalized electrons stabilize a compound. The extra stability gains from having delocalized electrons are called resonance stabilization or resonance energy.
Explanation of Solution
Given keto tautomer is,
The only difference in keto-enol tautomer is the location of hydrogen and double bond.
Enol tautomer 1 is more stable than enol tautomer 2.
Enol tautomer 1 can undergo delocalization and are more stable.
Thus enol tautomer 1 is more stable since it has more resonance structures and also possess intramolecular hydrogen bonding.
(b)
Interpretation:
The enol tautomer of the given compound has to be drawn and more stable structure has to be identified.
Concept Introduction:
Tautomerism is the ability of a molecule to exist in more than one chemical form.
Tautomers are formed by the migration of a hydrogen atom, accompanied by the switching of a single and neighboring double bond.
The only difference in keto-enol tautomers is the location of hydrogen and double bond.
Enol tautomer is much less stable than the keto tautomer.
Enol tautomer is more stable when enol tautomer is aromatic or when the double bonds are conjugated.
Resonance is an electron displacement effect for stabilizing a molecule through delocalization of bonding electrons in the pi orbital.
Delocalized electrons stabilize a compound. The extra stability gains from having delocalized electrons are called resonance stabilization or resonance energy.
Explanation of Solution
Given keto tautomer is,
The only difference in keto-enol tautomers is the location of hydrogen and double bond.
These tautomers undergo resonance and are shown below,
Enol tautomer 1 can undergo delocalization. Enol tautomer 1 is more stable than enol tautomer 2.
The enol tautomer 1 is more stable because there is a conjugation between the double bond and benzene ring. No such conjugation is possible in the enol tautomer 2.
(c)
Interpretation:
The enol tautomer of the given compound has to be drawn and more stable structure has to be identified.
Concept Introduction:
Tautomerism is the ability of a molecule to exist in more than one chemical form.
Tautomers are formed by the migration of a hydrogen atom, accompanied by the switching of a single and neighboring double bond.
The only difference in keto-enol tautomers is the location of hydrogen and double bond.
Enol tautomer is much less stable than the keto tautomer.
Enol tautomer is more stable when enol tautomer is aromatic or when the double bonds are conjugated.
Explanation of Solution
Given keto tautomer is,
The only difference in keto-enol tautomers is the location of hydrogen and double bond.
The alkene double bond formed by tautomer 1 is tetra-substituted which is stable than tautomer 2.
Hence, enol tautomer 1 is more stable.
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Chapter 13 Solutions
Essential Organic Chemistry (3rd Edition)
- Give the organic products: (benzyne) Br ? CH3 + K* :NH, liq NH3 HINT: Two products are formed. Each is a substituted aniline; they are isomers of each other. NH2 II I H₂N. CH3 CH3 III Select one: ○ A. I and II ○ B. I and III O C. I and IV O D. II and III O E. III and IV H₂N CH3 IV CH₂-NH2arrow_forwardPredict the major products of this organic reaction: HBr (1 equiv) cold ? Some important notes: • Draw the major product, or products, of this reaction in the drawing area below. • You can draw the products in any arrangement you like. • Pay careful attention to the reaction conditions, and only include the major products. • Be sure to use wedge and dash bonds when necessary, for example to distinguish between major products that are enantiomers. • Note that there is only 1 equivalent of HBr reactant, so you need not consider the case of multiple additions. Erase something Explanation Check 2025 McGraw Hill LLC. All Rights Reserved. Terarrow_forwardQ14. Fill this chart: (please refer to ppt notes/browser to answer these questions) What alcohol is also called wood alcohol? What is the common name of ethanol? Draw the structure of phenol and thiophene? Are bigger chain alcohol like heptanol and octanol are soluble or insoluble in water and explain it ? Are ethers soluble or insoluble in water? What suffix and prefix are used for alcohol while naming alcohol and ether? What the process called when we add water to any alkene to make alcohol? Q16. Draw the diagram of following aromatic compound (practice from previous module) Aniline Phenol Benzoic acid Methyl benzoate Q17. a. Write the oxidation reactions for the 2 propanol. b. Write the oxidation reaction of the ethanol.arrow_forward
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Organic Chemistry: A Guided InquiryChemistryISBN:9780618974122Author:Andrei StraumanisPublisher:Cengage Learning