above references particularly miller et al and sharp et al another component of the invention is a bromoiodobenzene by 34 bromoiodobenzene 34 is meant an aromatic ring having both a bromine atom and an iodine atom directly on the ring other substituants may be on the ring so long as the substitution does not sterically hinder the coupling reaction and does not excessively react with the other component protective groups may be used to avoid reaction with the other component in general suitable bromoiodobenzenes include such compounds as unsubstituted bromoiodobenzenes nitro substituted bromoiodobenzenes and bromoiodotoluenes specific examples include o bromoiodobenzene m bromoiodobenzene p bromoiodobenzene 2 nitro 4 iodobromobenzene and 3 nitro 4 iodobromobenzene the unsubstituted bromoiodobenzenes are the preferred bromoiodobenzenes although some negligible reaction may occur in the absence of a catalyst a catalyst is necessary for a commercially acceptable reaction rate suitable catalysts include those having palladium in a zero valence state examples of suitable palladium catalysts include finely divided precipitated palladium on an inert support such as carbon and tetrakis triphenylphosphine palladium pd pph 3 4 other forms of palladium such as pdcl 2 where the palladium is present as pd are less effective as a catalyst the catalyst should be present in a catalytically effective amount that is an amount sufficient to significantly increase the rate of reaction generally the catalyst will be present at 0 05 to 40 desirably 0 1 to 30 and.