Oct., 1933 STEREOCHEMISTRY OF DIPHENYLS. XXXII 4225 ... Copper Bronze.-Ordinary copper bronze sometimes gave very satisfactory and sometimes very poor results in the Ullmann condensation. A simple treatment of the commercial copper bronze made possible more uniform results and frequently made possible a more rapid reaction at a lower temperature. The copper bronze was treated with a 2% solution of iodine in acetone for about five to ten minutes. ...