In what way is the functional group of an ester different from that of a carboxylic acid?

Question

Santiago Alfonso · Accepted Answer

The existence of OH # - CO-OH# is carboxylic acid functional group.
# -COO-# is ester functional group.  The presence of Hydrogen in #-OH# form makes the carboxylic acids behave like inorganic acids. Esters on the other hand are less reactive compounds than Carboxylic acids. Carboxylic acids are acids like #HCl, H_2SO_4# etc. They react with bases to form salt and they turn blue litmus paper to red  and have other properties of acids. They are more weaker than inorganic acids. (i.e.)These acids are weak in terms of corrosive ability and this is due to the fact that they are compounds with covalent bond and dissociate with a reaction which is reversible in NTP.
#R-COOH rightleftharpoons R-COO^(- )+ H^+# Thus, the mixture of carboxylic acids and their salts with bases forms a solution that is of constant pH and is referred to as buffer solution. Examples of such a solution are acetic acid and sodium acetate. This indicates that the above reaction is subject to the Lee-Chatlier Principle and the Common Ion Effect. The esters on the other hand are products of carboxylic acids and alcohols. They are of general formula #R - COO- R'#, They are neutral compounds. Animal fat and vegetable oils are esters of carboxylic acids and glycerol. Even butter is butyric acid ester. They hydrolyse to form the original acid and the alcohol components.  This process, known as the saponification reaction, is what makes soap: potassium salts of the carboxylic acids are formed by hydrolyzing the oils with potassium hydroxide; the glycerol is separated and used for other purposes, such as the production of moisturizing creams, etc. The potassium salts are soaps that are subsequently formed into solid masses.

Elias Aguila · Answer

undefined The functional group of an ester consists of a carbonyl group bonded to an oxygen and an alkyl group. In contrast, a carboxylic acid has a carbonyl group bonded to both an oxygen and a hydroxyl group.