JN Bronsted

In the simple formalism proposed independently by Bronsted and Lowry in 1923, an acid was defined as a proton donor and a base was defined as a proton acceptor. In the simple acid-base reaction shown below, H3O+ is termed a Bronsted Acid, and HO- a Bronsted Base. In writing organic reaction mechanisms, the flow of electrons is often shown using "curved arrows" and in the example shown, the arrows are designed to show that an …

…For example, diethyl ether reacts with boron trifluoride to form diethyloxonium fluoroborate (shown below). In this reaction, the Lewis acid (the electron acceptor) is BF3 and the Lewis base (the electron donor) is CH3CH2-O-CH2CH3. Many reactions in organic chemistry involve pre-equilibrium steps which include Lewis acid-base chemistry; an understanding of the Lewis concept will greatly aid in the ability to view these reactions logically and to predict likely reaction pathways and products.