Tandem Hydrogenation-dehydration Reactions for the Synthesis of Olefins from Aromatic Ketones

NICOLÁS M. BERTERO; CARLOS R. APESTEGUÍA; ALBERTO J. MARCHI

Detroit, Estados Unidos

Congreso; 22nd NAM Catalysis Meeting; 2011

North American Catalysis Society

The synthesis of fine chemicals usually involves several consecutive-parallel reaction steps that often employ as many batch reactors as chemical transformations are needed in the global synthesis. This methodology frequently allows the successful selective synthesis of the desired product, but involves high operative costs. Besides, the multi-step batch processes require large volumes of solvents, salts and acid or basic liquids thereby generating significant amount of wastes that need to be either recycled or removed. Thus, it is of environmental and economic interest to develop novel integrated methodologies allowing one-pot synthesis processes via the catalytic promotion of tandem reactions. The two-steps conversion of aromatic ketones to aromatic olefins that involves consecutive hydrogenation-dehydration reactions has been studied using homogeneous catalysis for obtaining valuable products such as 2,6-dimethylnaphtalene and indenes. Here, we investigated the use of solid catalysts for the one-pot synthesis of aromatic olefins from aromatic ketones via tandem hydrogenation-dehydration reactions. Definitions of “tandem” process are not unanimous in the literature. We used the concept of tandem consecutive reactions, wherein the first step is necessary but not sufficient for the tandem process, and changes in reaction conditions are also required to facilitate propagation. The conversion of acetophenone (AP) to styrene (STY) was used as model reaction. The AP hydrogenation and 1-phenylethanol (PHE) dehydration reactions were first studied separately in order to select the best catalysts for achieving high conversions and selectivities. Then, the selected catalysts were employed for investigating the one-pot synthesis of STY from AP.