Solution 1:
Acids and Bases : Conjugate Acids and Bases
Discussion: Proton transfers are key features of many organic and biochemical reactions. If a reactant accepts a proton (a Bronsted-Lowry base), the product is termed the conjugate acid of that base. An electron pair from the Bronsted-Lowry base is shared with the proton to make a new bond. If a reactant donates a proton (a Bronsted-Lowry acid), the product is the conjugate base of that acid. The electron pair that was the bond to the transferred proton is left behind as part of the conjugate base. As a fundamental skill necessary to master proton transfer reactions, you will need to be able to draw the conjugates of an acid or base.
Example 1: Provide the products of the following proton transfer reaction. The proton that is transferred is circled. Label all reactants and products as Bronsted-Lowry or conjugate acids and bases.
Solution 1:
Example 2: A small portion of the molecules in liquid water have reacted by proton transfer. This process is termed autoionization. Write an equation for the autoionization of water that clearly illustrates this proton transfer. Name all the products. Label all reactants and products as Bronsted-Lowry or conjugate acids and bases.
Solution 2:
Note that some compounds, such as water in this example, can function
as either an acid or base. Such compounds are termed amphoteric.
Whether a compound is an acid or base is not determined solely by molecular
structure, but rather by the molecule's role in the reaction.
Exercises:
Provide the products of each proton transfer reactions shown below. In each case, the proton that is transferred is circled. Label all reactants and products as Bronsted-Lowry or conjugate acids and bases.
e. The following proton transfer involves two steps. Can you figure out the structure of intermediates A and B?
