Physical and Chemical Properties

What are two physical properties of aldehydes and ketones?

1. The carbonyl confers polarity and allows for hydrogen bonding with water.
   • Smaller aldehydes and ketones are very soluble in water, while larger aldehydes/ ketones (including aromatic aldehydes/ketones) are insoluble in water
   • 1,3-dicarbonyls allow for internal hydrogen bonding
2. Boiling point:
   • Higher than similarly sized alkanes and alkenes
   • Lower than corresponding alcohols

What is the infrared absorption of the aldehyde C-H and the ketone carbonyl bonds?

Table 47.1: Infrared absorption of the aldehyde C-H and the ketone carbonyl bonds

Bond Frequency	($cm^{-1}$)
(O)C-H	$\sim$2800
C$=$O	$\sim$1700