A Reliable Route to 1,2-Diamino-4,5-phthalodinitrile

Starting from o-phenylenediamine, we have developed a new and reliable route to 1,2-diamino-4,5-phthalodinitrile that is based on the reductive desulfurisation of 5,6-dicyano-2,1,3-benzothiadiazole with sodium borohydride. The reaction sequence uses only cheap reagents and relies on simple recrystallisations for the purification of all intermediates.