Acids and Bases

Organic chemistry is the study of compounds of the element carbon. Organic chemistry uses the ideas of acids and bases in two ways. The more general way is that the concept of Lewis acids and bases is used to classify organic chemical reactions as acid/base reactions because the donation of electron pairs is quite common.

The second way that organic chemistry uses the concepts of acids and bases is in the definition of certain groupings of atoms within an organic molecule called functional groups as acidic or basic. An organic base is, in the true Lewis base style, any molecule with electron pairs that can be donated. The most common organic base involves a nitrogen atom, N, bonded to carbon-containing groups. One important class of such compounds is known as amines. In these compounds, the nitrogen atom has an unbonded electron pair that it can donate as it reacts as a Lewis base. Several of these compounds are gases and have a somewhat putrid, fish-like odor. These compounds are relatively simple molecules; there are larger organic molecules, including many of natural origin, that contain a nitrogen atom and so have certain base-like properties. These compounds are called alkaloids. Examples include quinine, caffeine, strychnine, nicotine, morphine, and cocaine.

Organic chemistry uses the acid concept not only in the definition of the Lewis acid but also by defining a particular collection of atoms as an acid functional group. Any organic molecule containing a carboxyl group, -COOH, is called a carboxylic acid. (Non-organic acids are sometimes called mineral acids). Examples include formic acid, which has the formula HCOOH and is produced by some ants and causes their bites to sting. Another example is acetic acid, CH₃COOH, which is the acid in vinegar.