Peter Panster

Replacing liquid acids in fine chemical synthesis by sulfonated polysiloxanes as solid acids and as supports for precious metal catalysts

The use of solid acid catalysts, consisting of polysiloxanes bearing alkylsulfonic acid groups, is described, in organic synthesis and in technical applications. Although sulfonated polysiloxanes have been reported in the literature and have been found to show excellent activities in comparison to conventional polystyrene based cation exchange resins, no large scale technical use has become known thus far. We now report on the esterification of free fatty acids and phthalic anhydride to obtain the corresponding esters in quantitative yield and high purity (acid number The condensation of phenol with acetone was also extensively studied and a catalyst prepared that gives high conversion and good selectivity to the desired product p-,p-bisphenol-A. The alkylation of phenol was studied with isobutene in the temperature range from 90–130°C and high conversion was found as well as in the alkylation of α-methyl-styrene with 2,3-dimethyl-1-butene. Finally, the catalytic hydrogenolysis of the model substance 1-phenyl-ethanol to ethylbenzene proceeds quantitatively at 30°C without addition of a soluble acid.

Supported iridium catalysts — a novel catalytic system for the synthesis of toluenediamine

Abstract This paper deals with the preparation, characterization, and testing of a new modified iridium catalyst for the selective hydrogenation of dinitrotoluene (DNT) to toluenediamine (TDA) in liquid phase. The new catalyst does thoroughly avoid the formation of ring-hydrogenated and incompletely converted side-products that are frequently observed in the presence of supported palladium catalysts. Moreover, the catalytic hydrogenation of DNT with supported iridium catalysts is also accompanied by an extremely low amount of undesired dimers and oligomers (“tar formation”) in comparison to industrially applied standard Pd/C or Pd-Fe/C catalysts.

Hardening of fats and oils in supercritical CO2

Abstract Selective and complete hardening reactions of fats and oils, free fatty acids and fatty acid esters with hydrogen were carried out continuously in supercritical CO 2 (sc CO 2 ) with DELOXAN ® supported precious metal fixed bed catalysts. Depending on feed and the desired degree of hardening, temperatures between 60 and 160°C, total pressures between 8.0 and 16.0 MPa and space velocities (LHSV) between 5 and 60 h −1 were investigated. We observed up to 6 times higher space time yields in free fatty acid hardening using a DELOXAN ® supported 1 wt. % palladium fixed bed catalyst in comparison to trickle bed hardening with an activated carbon supported 2 wt. % palladium fixed bed catalyst. The formation of undesirable products in edible oil hardening (e. g. trans fatty acids) is significantly decreased with a DELOXAN ® supported 1 wt. % platinum fixed bed catalyst in sc CO 2 .

New catalytic systems for the selective hydrogenation of halogenated aromatic nitro compounds

Abstract For the selective reduction of halogenated aromatic nitro compounds a new modified supported iridium based catalyst system has been developed. These catalysts are characterized by a high activity combined with an extreme low rate of dehalogenation. Moreover, the formation of other undesired side products such as azo- or azoxy- compounds can be widely avoided. The new modified indium system is an interesting alter-native to existing supported platinum and modified platinum catalysts in this application.

94 Influence of hydrogen supply on by-product formation during the hydrogenation of DNT to TDA

Abstract The hydrogenation of dinitrotoluene (DNT) to toluenediamine (TDA) is an important reaction for the polymer industry due to TDAs role as an intermediate in the production of polyurethanes (PU). TDA is converted with phosgene to toluenediisocyanate (TDI) which is mainly used, together with polyether polyols, for the production of PU. How the catalysts are tested for DNT hydrogenation is very important for their development. Apart from catalyst activity, the amount of by-product formation (i.e. “tar formation”; typically a few percent) is crucial for the process. This paper describes how the catalysts need to be tested for DNT hydrogenation and describes what is, apart from the catalyst, also responsible for by-product formation.

The effects of raney alloy structure on the activation process and the properties of the resulting catalyst

Abstract The rate of nitrobenzene hydrogenation over activated base metal catalysts (ABMC) was found to be strongly influenced by the residual Al content of the catalyst, whereas higher Al contents resulted in lower activities. It was also shown that the ability to leach Al from an alloy was dependent on its initial Al content, the percentage of the Ni2Al3 phase, and the size of the Ni2Al3 domains. For alloys with ∼60%Ni2Al3, the larger Ni2Al3 domains leached Al faster than the smaller ones. Additionally, the larger Ni2Al3 domains required longer activation times to reach optimal activity suggesting a restructuring process. In principle, the leaching of alloys with smaller phase domains should produce catalysts with higher surface areas and activities, however it has been demonstrated that one can make equally or more active catalysts from alloys with larger phases by incrasing the activation time.

Stereoselective reductions of aromatic compounds

Mono- and bimetallic Rh catalysts were evaluated for the stereoselective reductive amination of alkylphenols to the corresponding alkylcyclohexylamines. Rhodium catalysts as well as bimetallic catalyst formulations with platinum were found to be the most suitable for this one-step hydrogenation. Both the chemo-and the stereoselectivity of that reaction depend on the amount of base added and other parameters such as kind of solvent and/or support.