Fundamentals of Organic ChemistryChemistryAldehydes and Ketones
Propanal and propanone are isomers with the same molecular formula ( C ₃ H ₆ O ) . Which of the following statements correctly compares their boiling points?
Options
- ABoth have the same boiling point.
- BThe boiling point of propanal is lower than that of propanone.
- CTheir boiling points cannot be compared based on the given information.
- DThe boiling point of propanal is higher than that of propanone.
Correct answer
B. The boiling point of propanal is lower than that of propanone.
Step-by-step solution
Propanal ( CH ₃ CH ₂ CHO ) and propanone ( CH ₃ COCH ₃ ) are functional isomers with the molecular formula C ₃ H ₆ O . The boiling point of a compound depends on the strength of its intermolecular forces. Both propanal and propanone have dipole-dipole interactions due to the polar carbonyl group. In propanone, the carbonyl carbon is attached to two electron-donating methyl groups, which increases the polarity of the C=O bond compared to propanal, where the carbonyl carbon is attached to only one ethyl group. As a r