Gold-Catalyzed Synthesis of Aromatic Azo Compounds from Anilines and Nitroaromatics
Abdessamad Grirrane,
Avelino Corma,*
Hermenegildo García*
The selective formation of aromatic azo compounds at preparative
or industrial levels requires stoichiometric amounts of environmentally
unfriendly transition metals or nitrites. Here, we show that
gold nanoparticles supported on titanium dioxide (TiO
2) and
nanoparticulated cerium dioxide (CeO
2) catalyze the aerobic
oxidation of aromatic anilines to aromatic azo compounds with
yields above 98% under mild reaction conditions. Gold on TiO
2 can also act as a reductive catalyst to access the compound
directly from nitroaromatics through a two-step, one-pot reaction.
The catalytic process shows promise for efficient synthesis
of symmetric aromatic azo compounds, and even a range of asymmetric
aromatic azo compounds.
* To whom correspondence should be addressed. E-mail: acorma{at}itq.upv.es (A.C.); hgarcia{at}qim.upv.es (H.G.)
