교과서 질문
Propose a mechanism for the following reactions:
a.
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13. Alcohols and Carbonyl Compounds
Nucleophilic Addition
객관식
Which of the following best describes the movement of electrons (curved arrows) during the nucleophilic addition that converts an to its form?
A
The lone pair on the carbon attacks the carbonyl carbon, forming a new carbon-carbon bond and generating a cyclic intermediate.
B
A lone pair on the enolate oxygen forms a double bond with the adjacent carbon, and the electrons from the carbon-carbon double bond move to capture a proton, resulting in the form.
C
The electrons of the carbon-carbon double bond move to form a new bond with a proton, while the lone pair on the oxygen remains unchanged.
D
A lone pair on the enolate oxygen forms a double bond with the adjacent carbon, while the carbon-carbon double bond electrons move to the carbon to form a carbanion.
검증된 단계별 안내1
Understand the structure of the enolate ion: it has a negatively charged oxygen atom and a carbon-carbon double bond between the α-carbon and the carbonyl carbon.
Recall that the keto form is the neutral, carbonyl-containing form, where the double bond is between carbon and oxygen, and the α-carbon is fully saturated (no double bond).
Identify the electron movement during tautomerization: the lone pair on the enolate oxygen forms a double bond with the adjacent carbon, restoring the carbonyl group (C=O).
Simultaneously, the π electrons from the carbon-carbon double bond move to the α-carbon, which then captures a proton (H⁺), converting the double bond into a single bond and neutralizing the charge.
Summarize the curved arrow movement: from the lone pair on oxygen to form the C=O double bond, and from the C=C π bond to the α-carbon to accept a proton, resulting in the keto form.
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