Selective Hydrogenation
- Selective hydrogenation of α,β-unsaturated aldehydes and ketones to the corresponding allyl alcohols is of great importance in Fine Chemistry because the reaction products are widely used as flavors and perfumes, as well as intermediates for the synthesis of valuable organic molecules. The reaction is also important from a fundamental point of view because involves an interesting problem of regioselectivity. In fact, a,b-unsaturated aldehydes and ketones may be transformed to unsaturated alcohols via the selective hydrogenation of C=O bonds or to saturated aldehydes/ketones by exclusively hydrogenating C=C groups. Both types of products are then consecutively hydrogenated to yield the corresponding saturated alcohols.
Reactions
- Selective hydrogenation of a,b-unsaturated
aldehydes:
We study the use of novel catalysts based on non-noble metals
for selectively hydrogenating α,β-unsaturated
aldehydes. Specifically, the catalysts contain a metallic
component (Cu, Ni or Co), which is highly interdispersed into a
matrix of ZnAl2O4 spinel-like structure.
The reactions under study are the liquid-phase hydrogenations of
cinnamaldehyde, citral and crotonaldehyde. The objective is to
explore the possibility of dramatically improving the intrinsic
catalytic properties of Cu (Co, Ni) to hydrogenate the C=O group
by generating a high density of dual Cu(Co,Ni)-M2+
active sites.
- Selective hydrogenation of α,β-unsaturated ketones: Unsaturated secondary alcohols derived from the selective hydrogenation of allylic ketones are valuable products used in polymer industry. Hydrogen transfer reduction (HTR) reactions using an alcohol as a hydrogen source instead of molecular hydrogen may provide a successful route for selectively reducing the C=O bond of a,b-unsaturated ketones. We study the gas-phase HTR of several a,b-unsaturated ketones such as mesityl oxide and cyclohexenone toward the corresponding allylic alcohol on acid-base catalysts. The goal is to ascertain the nature of the surface intermediates and active sites that promote the reaction pathways leading to the allylic alcohol.
- Selective hydrogenation of aromatic ketones : The selective hydrogenation of the C=O bond of acetophenone leading to 1-phenylethanol (PhE) has been investigated on different metals because PhE is widely employed in pharmaceutical and fragrance industries. We study this reaction on noble (Pt, Pd, Ir) and non-noble (Ni, Cu, Co) metals supported on silica. In particular, we investigate the reaction conditions (including the solvent nature) that improve the PhE yield at the expense of the formation of cyclohexylmethylketone that occurs by hydrogenation of the phenyl group of acetophenone.
- Synthesis of menthols : Menthols, in particular (-)-menthol, are used extensively in pharmaceuticals, cosmetics, toothpastes, chewing gum, and other toilet goods as well as in cigarettes. We study the liquid-phase synthesis of menthols from citral. The process includes three consecutive reactions steps: i) selective hydrogenation of citral to citronellal, ii) citronellal isomerization to isopulegol, iii) isopulegol hydrogenation to menthols. Bimetallic metal/acid catalysts are investigated for efficiently achieving in a one-step process the three consecutive reactions of hydrogenation-isomerization-hydrogenation involved in the reaction mechanism leading from citral to menthols.
Recent Publications:
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Kinetic modelling of the liquid-phase hydrogenation of cinnamaldehyde on copper-based catalysts, A.J. Marchi, J.F. Paris, N. M. Bertero, C.R. Apesteguía, Ind. Eng. Chem. Res., 46, 7657-7666, (2007).
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Design of catalyst systems for the one-pot synthesis of menthols from citral, A.F. Trasarti, A.J. Marchi, C.R. Apesteguía, J. Catal., 247, 155-165 (2007).
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Catalytic and kinetic study of the liquid-phase hydrogenation of acetophenone over Cu/SiO2 catalyst, N.M. Bertero, C.R. Apesteguía, A.J. Marchi, Appl. Catal. A: General, 349, 100–109 (2008).
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Selective liquid-phase hydrogenation of citral over supported bimetallic Pt-Co catalysts, N.M. Bertero, A.F. Trasarti, B. Moraweck, A. Borgna, A.J. Marchi, Applied Catalysis A General, (2009).