Chemistry Fundamental Principles of Organic Chemistry UHS 2023
PMDC Verified Question 18 of 83
What is vinyl alcohol and acetaldehyde?
A
Position isomers
B
Chain isomers
C
Metamers
D
Tautomers
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Tautomers
Concept:

Tautomerism involves the rapid equilibrium shift of a proton and a pi bond within a molecule. The most common form is keto-enol tautomerism.

Solution:

  • Vinyl alcohol is an enol (alkene + alcohol): \( \text{CH}_2=\text{CH--OH} \).


  • Acetaldehyde is an aldehyde: \( \text{CH}_3\text{--CHO} \).


  • In aqueous solution, the proton from the \( \text{-OH} \) of vinyl alcohol shifts to the adjacent carbon, and the double bond shifts to form a carbonyl \( \text{C}=\text{O} \).


  • This dynamic interconversion makes them tautomers.


Why other options are incorrect:

They are not positional or chain isomers. Metamerism requires polyvalent functional groups varying in alkyl chains.

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