Rank the following isomers from the one with the lowest boiling point to the one with the highest boiling point. Explain your answer.

• A. (lowest boiling point) (vinyloxy)methanol < methyl acetate < propionic acid (highest boiling point)
  
  (Vinyloxy)methanol has the weakest intermolecular forces (dipole-dipole interactions), so it has the lowest boiling point.
  Both methyl acetate and propionic acid can form hydrogen bonds. However, propionic acid can form two hydrogen bonds and boils as the dimers. As a result of this, propionic acid has a higher boiling point than methyl acetate.
• B. (lowest boiling point) (vinyloxy) methanol < propionic acid < methyl acetate (highest boiling point)
  
  (Vinyloxy)methanol has the weakest intermolecular forces (dipole-dipole interactions), so it has the lowest boiling point.
  Both methyl acetate and propionic acid can form hydrogen bonds. However, methyl acetate can form two hydrogen bonds and boils as the dimers. As a result of this, methyl acetate has a higher boiling point than propionic acid.
• C. (lowest boiling point) methyl acetate < (vinyloxy)methanol < propionic acid (highest boiling point)
  
  Methyl acetate has the weakest intermolecular forces (dipole-dipole interactions), so it has the lowest boiling point.
  Both (vinyloxy)methanol and propionic acid can form hydrogen bonds. However, propionic acid can form two hydrogen bonds and boils as the dimers. As a result of this, propionic acid has a higher boiling point than (vinyloxy)methanol.
• D. (lowest boiling point) methyl acetate < propionic acid < (vinyloxy)methanol (highest boiling point)
  
  Methyl acetate has the weakest intermolecular forces (dipole-dipole interactions), so it has the lowest boiling point.
  Both (vinyloxy)methanol and propionic acid can form hydrogen bonds. However, (vinyloxy)methanol can form two hydrogen bonds and boils as the dimers. As a result of this, (vinyloxy)methanol has a higher boiling point than propionic acid.

Answer: (C)