Catalytic Reactions in Surfactant Systems:Product Isolation and Catalyst Recycling

Abstract

The potential of surfactant based reaction media was studied with different homogeneous catalytic reactions. Micellar systems with the surfactants (p-tert-octylphenoxy) polyethoxyethanol (Triton X-100) and dodecyl sulfate sodium salt were used as reaction media for the enantioselective catalytic hydrogenation of dimethyl itaconate (DMI) with the Rh catalyst complexed with the chiral ligand (2S,4S)-1-tert-butoxycarbonyl-4diphenylphosphino-2-(diphenylphosphinometyl)-pyrrolidine (BPPM) at 30 °C and 1.1 bar, obtaining an enantiomeric excess (ee) of up to 69%. After complete hydrogenation was achieved, micellar enhanced ultrafiltration (MEUF) was used to recycle the catalyst achieving up to 95% retention. A microemulsion system stabilized with the surfactant Triton X-100 was used as alternative reaction media for the hydrogenation of DMI with a Rh catalyst complexed with the water-soluble tris(3-sulfophenyl)phosphine trisodium salt (TPPTS) at 50 °C and 1.1 bar. With the Triton X-100 system, phase separation by temperature induced separation allowed for up to four repetitive batches of DMI hydrogenations, resulting in a TON of 1530. Suzuki coupling for the synthesis of 4′-methyl-2-biphenylcarbonitrile proceeded faster in a narrow range alkylpolyglycol ether (Novel 8 ) Novel 1216CO-8 Ethoxylate) three-phase system than in an dioctyl sulfosuccinate sodium salt (AOT) two-phase system, demonstrating the retarding effect of the salinization on the reaction rate.

Creating and mastering nano-objects to design advanced catalytic materials

“…For meso-cyclohexanones the yields are lower, but enantio-selectivity is higher (ee up to 92%) moving from organic to water-surfactant media. Micellar systems were also used for the enantioselective catalytic hydrogenation (with Rh complexes) not only to improve the performance, but also to facilitate catalyst recovery and recycling [94].…”

Rhodium catalyzed hydrogenation reactions in aqueous micellar systems as green solvents

“…In all integrated processes with step-wise catalyst recycling, the catalyst recovery was high, but the filtration times, in the same order than the reaction time, led to low space-time-yields. 22 Only an integrated process in which the reaction, the filtration, and the feeding of new reactants happen simultaneously, can overcome this problem. An example for the full continuous hydrogenation of DMI in aqueousmicellar TX-100 solution is shown in ref.…”

Experimental strategies for increasing the catalyst turnover number in a continuous Heck coupling reaction

“…In order to test the long term stability a membrane was kept under constant reaction conditions for about 6 days (reactants flow rate of 20 mL.min -1 and temperature of 298 K) and a conversion and selectivity of about 50% and 88% were obtained, respectively (TON data not presented). Another work from Milano-Brusco et al [6], used a different approach based on the potential of surfactant based reaction media in different homogeneous catalytic reactions. The reaction under study was the enantioselective catalytic hydrogenation of dimethyl itaconate (DMI) using two different reaction media.…”