Which of the following functional groups is present in carboxylic acids?

Many naturally occurring compounds contain more than one functional group. Identify the functional groups in the ­following compounds:

d. Thyroxine is the principal thyroid hormone.

There are eight different five-carbon alkyl groups.

c. In each case, label the degree of substitution (primary, secondary, or tertiary) of the head carbon atom bonded to the main chain.

When we begin studying functional groups, the designation of substitution will be especially important. Label the following bromoalkanes as 1° , 2°, 3°, or 4° based on the carbon to which the bromine is attached.

(b)

Which functional group is responsible for the characteristic smell of $\mathrm{esters}$?

Which of the following functional groups is characterized by a carbon atom double-bonded to an oxygen atom ($C=O$)?

Which of the following is a characteristic functional group found in alcohols?

Which of the following functional groups is present in all amino acids?