Ullmann Reaction (IMAGE) University of Basel Caption The intermediate product of the Ullmann reaction with the silver catalyst (silver) between the carbon rings (black) and sulfur atoms (yellow) curves like a bridge over the silver surface. Credit University of Basel, Department of Physics Usage Restrictions Give adequate attribution do the original author License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.