ABSTRACT
Arran S. Canning, Jonathan J. Gamman, S. David Jackson and Strath Urquart
WestCHEM, Dept. of Chemistry, The University, Glasgow G12 8QQ, Scotland.
sdj@chem.gla.ac.uk
Abstract Four catalyst systems, Pd-KOH/silica, Pd-CsOH/silica, Ni-KOH/silica, and NiCsOH/silica, have been investigated for the conversion of acetone to MIBK. Nickel catalysts were generally less selective, with MIBK being further hydrogenated to MIBC, and isophorone becoming a major product at high temperatures. KOH-based catalysts were found to be less active than their CsOH-based counterparts. The activation energy for MIBK production suggested that the rate determining step was within the base catalyzed part of the reaction sequence and this was supported by the product distributions. Introduction Condensation reactions are an important route to the industrial synthesis of a wide range of compounds including solvents such as methyl isobutyl ketone (MIBK) and Guerbet alcohols for use as lubricants and surfactants. The synthesis of MIBK from acetone proceeds via a base extraction of the α-proton catalyzed by aqueous NaOH and intermolecular attack of the carbonyl group to produce diacetone alcohol. Subsequent acid catalyzed dehydration of diacetone alcohol (DAA) to mesityl oxide (MO) by H2SO4 at 373 K is followed by hydrogenation of MO to MIBK using Cu or Ni catalysts at 288 – 473 K and 310 bar (1). Recently however new one-step technology has been developed and commercialized using palladium on acidic ion-exchange resins (2). The change from the three-step process to a single-step significantly reduces the amount of waste generated at the base catalysis stage and removes the need for concentrated sulphuric acid and its residues. Research in this area is nevertheless continuing with a view to improving the process further (3, 4).
