Which from following compounds does $\underline{\text { NOT }}$ contain phantom atom?

Which from following compounds does $\underline{\text { NOT }}$ contain phantom atom?
  1. Acetaldehyde
  2. Methyl cyanide
  3. $\mathrm{n}$ - propyl alcohol
  4. Propionic acid

Solution

New rule: Expand out multiple bonds with "Phantom atoms" In order to properly compare, we "expand out" all multiple bonds and treat them as single bonds attached to "phantom atoms" (in blue) Note that the process of assigning "phantom atoms" to the nitrogen involves looking "backwards" towards the chiral center. This is the only case we ever do this!

Asked in: MHT CET 2020 (13 Oct Shift 2)

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