Making diazonium chemistry safer

As a rule, it's generally advisable to tread carefully with things that can explode in the laboratory. But it can be difficult to avoid dangerous compounds when the explosive substance is a key player in a number of useful organic transformations —as diazonium salts are. A new approach to taming aryldiazonium chemistry, published in Science by Tobias Ritter and his group at the Max Planck Institute for Kohlenforschung, may help scientists reap the synthetic benefits with less risk ( Science 2024, DOI: 10.1126/science .adn7006 ). Their take on the Sandmeyer reaction, a halogenation method that starts with a diazonium salt, takes advantage of kinetic insights to moderate the buildup of reactive intermediates. "Everybody knows that they're dangerous," says Ritter. "We no longer have to accumulate them." Aryldiazonium salts are made from the reaction of an aniline derivative with nitrosonium (NO + ). Since the 1800s, the status quo has been