Aldehydes and ketones are similar in properties, neutral but polar.
Like ethers, they are good solvents for organic compounds; but unlike
ethers, they are good solvents for organic compounds; but unlike
ethers, they are at least partially miscible in water.
They resemble ethers in being low-boiling and volatile because of
the absence of hydrogen bonds in the liquid, but differ form ethers
in being chemically reactive.
The polar and exposed -C(O)-H and -C(O)- groups have a slightly
negative oxygen and a slightly positive carbon connected by a double
bond and, as mentioned in Chapter 19, are wide open to attack either
by electrophiles or nucleophiles (right). Aldehydes and ketones
are the starting materials for many organic syntheses.