Lopsided Benzene’s Big Moment

Abstract

Chemists have made a new set of hexasubstituted benzenes in which electron-withdrawing cyano groups on one side of the ring and electron-donating amino groups on the other combine to pull and push the molecule’s electron density in the same direction. These compounds are remarkable for being the most polar neutral molecules now known to exist (Angew. Chem. Int. Ed. 2016, DOI: 10.1002/anie.201508249). Organic molecules with large dipole moments are desirable for their ability to enhance the efficiency of polymer films in electronic devices such as lasers, microchips for smart cards, and solar cells. Multisubstituted benzenes have long been synthetic targets, but chemists have been limited in their ability to prepare them using standard electrophilic substitutions. A research team led by Klaus Müllen of the Max Planck Institute for Polymer Research has now devised a new synthesis of hexasubstituted benzenes and dialkyldihydrobenzimidazoles via a new dibromo intermediate they prepared. The most