Effect of size of copper nanoparticles on its catalytic behaviour in Ullman

Abstract. The condensation of iodobenzene to biphenyl is an industrially important reaction due to its sig-nificant role in organic synthesis as drug intermediates. The reaction takes place in the presence of copper powder as catalyst. We have shown in this paper that the size of the copper nanoparticles as well as its ex-posed surface area is responsible for the yield of chemical reaction. The uncapped copper powder showed a 43 % conversion of iodobenzene to biphenyl in 5 h under our experimental conditions. Same amount of copper nanoparticles (size, ~ 66 nm diameter) prepared by citrate capping showed 88 % conversion of iodobenzene to biphenyl, which increased to about 95 % when 8 nm diameter capped copper nanoparticles are used. Surpris-ingly, 5 nm size copper nanoparticles showed no change in the yield of about 95%