A Study on the Synthesis of p-phenylenediamine (PPD) Using Copper Catalyst

− p-Phenylenediamine (PPD) was synthesized by aromatic amination of p-diiodobenzene (PDIB) using liquid ammonia and Cu-catalysts. The effects of the catalyst, reductant, ammonia quantity and reaction temperature on PPD production were investigated. Cu(I) compounds and Cu powder were selected as catalyst due to a higher selectivity than Cu(II) compounds. As the catalyst quantity increased, rate of PPD production as well as side reaction of aniline decreased with increasing the quantity of ammonia. Reductants such as ascorbic acid, hydrazine and dihydroxyfumaric acid were tested to lower the catalyst loading. The use of reductants resulted in increasing the reaction rate but also increased the amount of aniline The rate of reaction using ascorbic acid or dihydroxyfumaric acid was faster than that using hydrazine. The lowest side reaction of aniline was found in dihydroxyfumaric acid of reductants investigated.