Why is 1-Naphthalenesulfonic Acid Less Stable than 2-Naphthalenesulfonic Acid? A Case of Application of Computational Chemistry to College Organic Chemistry

The development of computer hardware and computational chemistry software has greatly promoted the widespread application of computational chemistry in chemical research. Moreover, computational chemistry has become an important tool in chemistry teaching. To illustrate the important application of computational chemistry in organic chemistry, comparison of the stability of 1-naphthalenesulfonic acid and 2-naphthalenesulfonic acid and investigation of the reason for their different stability are put forth as an example. In addition, the stability of other isomers formed by −F, −CN, −O^–, −OMe, and −NH₂ groups was also compared. The conclusions are that intramolecular noncovalent interactions including attraction and repulsion occur in both 1-naphthalenesulfonic acid and 2-naphthalenesulfonic acid. Although intramolecular noncovalent interactions of 1-substituted isomers are stronger than those of their corresponding 2-substituted isomers, not all 1-substituted isomers are less stable than their corresponding 2-substituted isomers. This new viewpoint may provide a theoretical basis for organic chemistry teaching. Application computational chemistry to the teaching of organic chemistry has stimulated most students’ interest in learning organic chemistry. The questioning spirit of the students is worth encouraging.