Supporting Information. Copyright Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2008

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1 Supporting Information Copyright Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2008

2 1 Supporting Information Palladium(0) Nanoparticles on glass-polymer composite materials as recyclable catalysts: A comparison study on their use in and continuous flow processes Klaas Mennecke, a Raul Cecilia, b Toma N. Glasnov, c Susanne Gruhl, d Carla Vogt, d Armin Feldhoff, e M. A. Larrubia Vargas, f C. Oliver Kappe, c * Ulrich Kunz, b * Andreas Kirschning a * a Center of Biomolecular Drug Research (BMWZ) and Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 1B, D Hannover (Germany). andreas.kirschning@oci.uni-hannover.de b Institute of Chemical Process Engineering (ICVT), Clausthal University of Technology, Leibnizstr. 17 D Clausthal-Zellerfeld (Germany). kunz@icvt.tu-clausthal.de c Christian Doppler Laboratory for Microwave Chemistry and Institute of Chemistry, Karl Franzens University, Heinrichstraβe 28, A-8010 Graz (Austria). oliver.kappe@uni-graz.at d Institute of Inorganic Chemistry, Leibniz University Hannover, Callinstraße 9, D Hannover, Germany e Institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover, Callinstraße 3-3A, D Hannover, Germany f Chemical Engineering Department, University of Malaga, Campus de Teatinos, E Malaga (Spain). 1. Ion exchange Several aspects of generating Pd(0) species inside the PASSflow reactor still require closer investigation. This species is formed by pumping an aqueous solution of sodium tetrachloropalladate (Na 2 PdCl 4 ) through the PASSflow TM reactor loaded with anion exchange resin 1 (chloride form). This process leads to instantaneous ion exchange (Scheme 1, main text). However, the stoichiometry of this process is unknown as three possible species 2a-c can be considered. EPMA (Electron Probe Microanalysis) and EDXS (Energy-Dispersive X- ray spectroscopy) scanning profiles allowed to determine both the palladium as well as

3 2 chlorine profiles inside the polymer/glass composite material (Figure 1). In addition, the same analytical techniques allowed us to detect the Pd content along the direction of the flow. When ion exchange conditions in a recycle mode that theoretically should lead to 2c (ion exchange sites / palladate ions= 2:1 molar ratio) where employed, we determined a uniform distribution of chlorine throughout the sample, but encountered a Pd gradient in the flow direction through the sample during the loading procedure (Figure 1a). Obviously, the outer surface area of the polymer phase traps most of the palladate anions. This observation supports the fact that the aforementioned theoretical ion exchange equation with a 2:1 ratio is not valid. When the ion exchange experiments were conducted with the same sample but employing a different initial molar ratio of palladate to ion exchange sites, it became evident that the loading ratio is in fact close to 1:1 (Figure 2). Figure S1. a) EPMA picture of a Raschig ring profile of 2 (VBC, 5.3 wt% DVB); enlargement of one of the pores and Cl and Pd EDXS (Energy-Dispersive X-ray) scanning profile inside a carrier pore. The black arrow marks the direction of the flow during the Pdloading procedure inside the reactor. b) representation of the outer (OS) and inner surface (IS) in a real ring. Figure S2. Palladate ion exchange conversion for different Cl - / [PdCl 4 ] 2- ratios under flowthrough conditions (polymer phase: VBC, 5.3% cross linking DVB) and EPMA pictures of a polymer / glass pore depicting Cl, Pd and Na EDXS scanning.

4 3 In order to exclude additional sorption of palladium on the polymeric phase, the solutions used for loading as well for washing during the catalyst preparation method were analyzed with respect to the Pd content by Atomic Absorption Spectroscopy (AAS). The Pd content obtained by AAS strongly indicates that sorption is a neglectable process (Table 1 and explanation). A 1:1 ratio of ion exchange sites and palladate-species is consistent with species 2a or 2b (Scheme 1). [1,2] In order to discern about both possibilities a sample obtained after ion exchange was analyzed by EDXS (Figure 2). The results obtained clearly reveal a large amount of Cl compared to Pd and the absence of sodium (except for the glass carrier material), which is consistent with the proposed ionic species 2a. Table S1. % DVB Cl : [Pd 2 Cl 4 ] 2 washing time MI (mol/) M AAS (mol/) M Abs (mol/) abs. (%) 5.3 1:1 1h h :1 1h h :1 1h h :1 1h h In Table 1 results are listed regarding the amount of palladium charged on the polymer phase per, calculated a) from the amount of palladate left in solution after the ion exchange equilibrium is reached (M I ), b) from the amount of palladate in solution recovered after ion exchange and washing with two different washing times (M AAS ), as well as c) the amount of

5 4 palladate anchored by absorption as a difference between M I and M AAS (M Abs ). The absorption percentage is calculated using the following equation: Abs= [(M AAS - M I )/M I ]*100. All measurements show larger values of M AAS than M I which results in negative values for M Abs. After washing, the amount of palladium recovered should be at least equal or larger than the palladium measured in the ion-exchange equilibrium (M AAS M I ). Therefore, this experimental fact could only be explained in terms of possible systematic small palladium losses during the recovery of the palladate solution during the washing step. The palladate lost is not present in solution as judged by AAS and as a result is supposed to be in the polymer phase. These small differences (between M AAS and M I and abs.% is less than 5% in all cases) indicate that the absorption processes are neglectable. 2. Governing factors for Pd nanoparticle size Figure S3: TEM bright-field micrograph of the Pd-doped polymer 5.3% DVB (0:1) prepared under a pure kinetic regime. Figure S4: Ion exchange initial rate versus flow.

6 5 The flow conditions of the reduction are included in the experimental section of the paper 3. Preparation of polymeric samples Table S2. Mass and molar ratios of the different monomers in polymerization mixtures and capacity of the different samples used in this study. Sample %wt %wt %wt %mol %mol %mol capacity DVB VBC styrene DVB VBC styrene (mmol/g) 5.3 (0:1) a 5.3 (1:1) a 5.3 (10:1) b 10 (0:1) a 20 (0:1) a 30 (0:1) a 30 (1:1) b a Capacity measured using the regular titration method b These samples have a higher hydrophobicity, being therefore not completely wetted in the titration method. Accurate titration determinations were not possible, therefore values are calculated based on the monomer content. 4. Reactor set up for microwave / flow Figure S5. Graphical Representation of Flow Microwave Reactor (CEM Voyager)

7 6 1. Reservoir/Receiver for the reaction mixture (closed loop) 2. HPLC-pump 3. Flow reactor with mounted fiber optic probe 4. MW-Cavity with flow reactor inside 5. Back-pressure regulator (17 bar) 5. Effect of the cationic centres dilution Figure S6. TEM images used for the calculation of the Pd particle size distribution shown in figure 5 of the paper.

8 7 6. Swelling properties of polymer samples Table S3: Swelling of polymer samples in the two solvent systems ethanol/cyclohexene and toluene/cyclohexene. EtOH/Cy toluene/cy 30% DVB (1/1) 2% 11% 30% DVB (10/1) 10% 18% 30% DVB (30/1) 4% 18% 5.3% DVB (1/1) 13% 20% 5.3% DVB (10/1) 29% 39% 5.3% DVB (30/1) 22% 26% An NMR tube was filled with dry polymer and the solvent was added. The samples was swollen for 24 h and the increase of volume was measured. The determination was repeated once. 7. Catalytic transfer hydrogenations

9 8 Figure 6. TEM micrographs after 1 st run ( mode; EtOH/cyclohexene). Figures S7a-d. Kinetic studies. a) Batch mode; conventional heating in EtOH: conversion [%] % diffusive 5.3% convective 5.3% (1/1) 5.3% (10/1) 5.3% (30/1) 30% (1/1) time [h] b) Batch mode; conventional heating in toluene:

10 % diffusive 5.3% convective 5.3% (1/1) 5.3% (10/1) 5.3% (30/1) 30% (1/1) conversion [ time [h] c) Flow mode; conventional heating in EtOH: conversion [%] % diffusive 5.3% convective 5.3% (1/1) 5.3% (10/1) 5.3% (30/1) 30% (1/1) time [h] d) Flow mode; conventional heating in toluene:

11 10 conversion [% time [h] 5.3% diffusive 5.3% convective 5.3% (1/1) 5.3% (10/1) 5.3% (30/1) 30% (1/1) 8. Pd content of the different composites Figure S8. Pd weight percentage content of the different samples. wt% Palladium 0,045 0,04 0,035 0,03 0,025 0,02 0,015 0,01 0, (0:1) 5.3 (1:1) 5.3 (10:1) 5.3 (30:1) 30 (1:1) The palladium content on the support after being reduced was measured by dissolving the Pd(0) with aqua regia and determining the content of Pd in solution by Atomic Absorption Spectroscopy (AAS). 9. Leaching Analytical determination of Pd concentrations: All samples were digested with 4mL subboiled HNO 3 and 1 ml H 2 O 2 (p.a., Merck) and afterwards diluted with water. The Pd determination was carried out with an inductively

12 11 coupled plasma mass spectrometer (ICP-MS) Thermo X7 ICP-MS (Thermo Electron GmbH, Dreieich, Germany, This quadrupol instrument had a power of 1200 W throughout the measurement. The gas flow rates were 1.0 ml/min (Nebuliser), 1.2 ml/min (Auxiliary) and 13 ml/min (Cool) argon 4.8, respectively. 105 Pd, 106 Pd, 108 Pd and 110 Pd were the isotopes monitored. Quantification was performed with liquid Pd standards from µg/l averaging the concentrations obtained for all 4 isotopes. For drift corrections during the measurements the standard with the concentration of 1 µg/l was interspaced after every second sample measurement. Under the conditions used the limit of detection for palladium was 1 ng/l. Table S4. Leaching of Pd in ppm. conventional heating MW irradiation EtOH PASSflow EtOH toluene PASSflow toluene EtOH toluene 5.3% (0/1) diff % (0/1) conv % (1/1) % (10/1) % (30/1) % (1/1) Leaching in % conventional heation MW irradiation EtOH PASSflow EtOH toluene PASSflow toluene EtOH toluene 5.3% (0/1) diff % (0/1) conv % (1/1) % (10/1) % (30/1) % (1/1) w Pd per ring [mg] 5.3% (0/1) diff % (0/1) conv % (1/1) % (10/1) % (30/1) % (1/1) References [1] a) F. Helfferich; Ion Exchange, Mc-Graw Hill b) N. Toshima, T. Teranishi, Y. Saito; Macromol. Chem. Macrom. Symp. 1992, 59, [2] Gmelin Handbook of Inorganic Chemistry, Pd supplement volume B2. Springer Verlag 1989.

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