The compound below is fexofenadine and the only chirality center, as identified by the textbook is, the one circled in red.
I don't understand why the carbonyl carbon is not a chiral center too. Isn't it attached to a tert-butyl group? So isn't it attached to four different substituent groups? Or is it that the hydroxide group is attached to the carbon by the oxygen, thereby making a 'duplicate' substituent group of the carbon already double bonded to the oxygen?