PROCESS FOR PREPARING CATALYST LOADED POLYPHENYLENE PARTICLES, THE OBTAINED POLYPHENYLENE PARTICLES AND THEIR USE AS CATALYSTS

Abstract

The present invention refers to processes for preparing catalyst loaded polyphenylene particles, the so-obtained polyphenylene particles and their use as catalysts.

Claims

1.-14. (canceled)

15. Catalyst-loaded polyphenylene polymer particles having nanoparticles of catalytically active material dispersed in a polymer network, said nanoparticles having a particle size from 0.25 to 10 nm and the catalytically active material being selected from the group consisting of metals selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Mo, Se, Sn, Pt, Ru, Pd, W, Ir, Os, Rh, Nb, Ta, Pb, Bi, Au, Ag, Sc, Y and alloys thereof, and compounds thereof wherein said compounds are selected from oxides, phosphides, nitrides and sulfides, wherein said polyphenylene polymer particles are obtainable by a Suzuki coupling reaction of di-, tri or tetrahalo-aryl compounds or mixtures thereof with di-, tri- or tetraboronic acid aryl-compounds or mixtures thereof, wherein said nanoparticles are present from 0.25 to 15%-by weight based on the total weight of the polymer.

16. Catalyst-loaded polyphenylene polymer particles particles according to claim 15, wherein the nanoparticles of the catalytically active material dispersed in the polymer network have a particle size from 0.25 to 5 nm.

17. Catalyst-loaded polyphenylene polymer particles according to claim 15, wherein the catalytically active material is a metal is selected from the group consisting of Co, Ni, Pt, Ru, Pd, Ag, Au and alloys thereof.

18. Catalyst-loaded polyphenylene polymer particles according to claim 15, wherein said nanoparticles are present from 2.5 to 10%-by weight based on the total weight of the polymer.

19. Catalyst-loaded polyphenylene polymer particles according to claim 15, wherein the catalyst-loaded polyphenylene polymer particles are obtainable by a Suzuki coupling reaction of a halogen-aryl compound selected from the group consisting of di-, tri and tetrahalo-aryl compounds with a boronic acid-aryl selected from the group consisting of di-, tri and tetraboronic acid-aryl compounds in the presence of a palladium compound and a base, whereby the molar ratio of the halogen-aryl compound to the boronic acid-aryl compound is in the range of 2.5:1.0 to 1.0:2.5 and wherein the metal is Pd.

20. Process for preparing catalyst-loaded polyphenylene polymer particles of claim 19, said process comprising reacting a halogen-aryl compound selected from the group consisting of di-, tri and tetrahalo-aryl compounds or mixtures thereof with a boronic acid-aryl compound selected from the group consisting of di-, tri and tetraboronic acid-aryl compounds or mixtures thereof in the presence of a palladium compound and a base in a temperature range of 130 C. to 250 C. in a Suzuki coupling reaction whereby the molar ratio of the halogen-aryl compound to the boronic acid-aryl compound is in the range of 2.5:1.0 to 1.0:2.5.

21. Process for preparing catalyst-loaded polyphenylene polymer particles according to claim 20, wherein said di-, tri or tetrahalo-aryl-compounds are selected from di-, tri- or tetrahalo-phenyl or -biphenyl compounds or mixtures thereof.

22. Process for preparing catalyst-loaded polyphenylene polymer particles according to any of claim 20, wherein said di-, tri or tetraboronic acid aryl-compounds are selected from di-, tri- or tetraboronic-acid phenyl or -biphenyl compounds or mixtures thereof.

23. Process for preparing catalyst-loaded polyphenylene polymer particles according to any of claim 20, wherein di-, tri or tetrabromophenyl or -biphenyl compounds or mixtures thereof are reacted with di-, tri or tetraboronic phenyl or -biphenyl compounds or mixtures thereof.

24. Catalyst-loaded polyphenylene polymer particles obtainable by a process comprising treating the catalyst-loaded polyphenylene polymer particles obtainable according to the process of claim 20 by an oxidative leaching whereby the Pd metal is removed and the obtained metal-free polyphenylene polymer particles are impregnated with a solution of a metal compound and evaporating the solvent.

25. A process comprising carrying out a chemical reaction in the presence of a catalyst, wherein the catalyst comprises catalyst-loaded polyphenylene polymer particles as claimed in claim 15, wherein the catalytically active material is a metal is selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Mo, Se, Sn, Pt, Ru, Pd, W, Ir, Os, Rh, Nb, Ta, Pb, Bi, Au, Ag, Sc, Y or alloys thereof, or compounds thereof wherein said compounds are selected from oxides, phosphides, nitrides or sulfides.

26. Process according to claim 25, wherein the chemical reaction is a Suzuki coupling reaction, or an oxidation reaction.

27. Process according to claim 25, wherein said catalyst-loaded polyphenylene polymer particles are recycled from a catalytic process.

Description

FIGURES

[0057] The invention is further illustrated in the attached Figures. In said Figures, there is shown:

[0058] FIG. 1: Scheme for the formation of Pd/PPhen by (Ph.sub.3P).sub.4Pd catalyzed coupling of 1,2,4,5-tetrabromobenzene and benzene-1,4-diboronic acid;

[0059] FIG. 2: Reaction condition of palladium precipitation from Pd(PPh.sub.3).sub.4, and TEM image of palladium nanoparticles;

[0060] FIG. 3: XRD pattern of 2.7 wt %, 5.9 wt % Pd/PPhen and pure PPhen. The diffraction peaks correspond to palladium crystal;

[0061] FIG. 4: Structure of Pd/PPhen solid composite;

[0062] FIG. 5: TEM image of 5.9 wt % Pd/PPhen obtain from 450 mg of Pd(PPh.sub.3).sub.4 in a single batch reaction;

[0063] FIG. 6: Pure PPhen obtained at 100 C. a, TEM at large scale. b, TEM at small scale;

[0064] FIG. 7: PPhen after HCl and H.sub.2O.sub.2 treatment. a, TEM image at large scale. b, TEM image at small scale. 5 mg polymer was dispersed in 3 ml HCl (1 M) and reacted with 0.1 mL H.sub.2O.sub.2;

[0065] FIG. 8: TEM images of [0066] a: Pt/PPhen, b: Co/PPhen, c: Au/PPhen, d: Ru/PPhen, e: Ni/PPhen, f: VO.sub.x/PPhen.

[0067] FIG. 9: Solid-state .sup.31P NMR spectroscopy; [0068] a, Pd/Phen composite. The majority of the phosphor species are Ph.sub.3PO and (PhO).sub.3P, [0069] b, Pure solid Pd(PPh.sub.3).sub.4;

[0070] FIG. 10: Pd/C obtained from Sigma. a, TEM image. b, size distribution;

[0071] FIG. 11: PHAADF-STEM micrographs of a,b) 2.7 wt % Pd/C and d,e) 2.7 wt % Pd/PDVB catalysts prepared via impregnation of Pd(PPh.sub.3).sub.4 on the supports followed by thermal decomposition/reduction in flow of 20% H.sub.2/Ar. Palladium particle size distribution of c) 2.7 wt % Pd/C and f) 2.7 wt % Pd/PDVB.

[0072] The invention is further illustrated in the following Examples.

EXAMPLE 1

Preparation of Metal-Loaded Polyphenylenes

[0073] A. TetraBB-Linked Pd/PPhen (TetraBB-Phenyl)

[0074] For 2.7 wt % Pd/PPhen, 1,2,4,5-tetrabromobenzene (0.765 g, 1.94 mmol) and benzene-1,4-diboronic acid (0.645 g, 3.89 mmol) are added into 60 mL dimethylformamide. The mixture is degassed through three freeze-pump-thaw cycles. K.sub.2CO.sub.3 (2.0 M, 7.5 mL) and Pd(PPh.sub.3).sub.4 (0.225 g, 0.19 mmol) are then added with subsequent three freeze-pump-thaw cycles. The mixture is then purged with Ar and heated to 150 C. for 20 h under stirring. The product precipitates in water, and is washed by water, dichloromethane and methanol. Approximately 600 mg of grey product is obtained in each batch.

[0075] To obtain 2 g polymer at one batch, all the chemical usages are increased 4 times. The amount of Pd(PPh.sub.3).sub.4 is changed to 0.450 mg to obtain 5.9 wt % Pd/PPhen. PVP (M.sub.w=55,000, 100 mg) is added into the synthesis to make the catalysts dispersible in water. They are then used for further aqueous phase cross-coupling reactions.

[0076] 2.7 wt % Pd/PPhen can be obtained from 225 mg of Pd(PPh.sub.3).sub.4 in a single batch reaction. 5.9 wt % Pd/PPhen can be obtained from 450 mg of Pd(PPh.sub.3).sub.4 in a single batch reaction.

[0077] B. DiBB-Linked Pd/PPhen (DiBB-Phenyl)

[0078] For Pd/PPhen (100% DBB), 1,4-dibromobenzene (0.458 g, 1.94 mmol) and benzene-1,4-diboronic acid (0.332 g, 1.94 mmol) are added into 30 mL dimethylformamide. The mixture is degassed through three freeze-pump-thaw cycles. K.sub.2CO.sub.3 (2.0 M, 3.75 mL) and Pd(PPh.sub.3).sub.4 (0.112 g, 0.1 mmol) are then added with subsequent three freeze-pump-thaw cycles. The mixture is then purged with Ar and heated to 150 C. for 20 h under stirring. The product precipitates in water, and is washed by water, dichloromethane and methanol. Approximately 300 mg of grey product is obtained in each batch.

##STR00005##

[0079] C. DiBB-TetraBB-Linked Pd/PPhen (DiBB/TetraBB-Phenyl)

[0080] For Pd/PPhen with 75%, 50%, 25% DiBB, a mixture of 1,2,4,5-tetrabromobenzenen and 1,4-dibromobenzene are added into 30 mL dimethylformamide together with benzene-1,4-diboronic acid (0.645 g, 3.89 mmol). The molar ratio between 1,2,4,5-tetrabromobenzenen and 1,4-dibromobenzene are 1:3, 2:2 and 3:1 for Pd/PPhen (75%, 50%, 25% DBB) respectively. The mixture is degassed through three freeze-pump-thaw cycles. K.sub.2CO.sub.3 (2.0 M, 7.5 mL) and Pd(PPh.sub.3).sub.4 (0.225 g, 0.2 mmol) are then added with subsequent three freeze-pump-thaw cycles. The mixture is then purged with Ar and heated to 150 C. for 20 h under stirring. The product precipitates in water, and is washed by water, dichloromethane and methanol. Approximately 600 mg of grey product is obtained in each batch.

[0081] D. TriBB-Linked Pd/PPhen (TriBB-Phenyl)

[0082] For Pd/PPhen (TriBB), 1,3,5-tribromobenzene (0.816 g, 2.59 mmol) and benzene-1,4-diboronic acid (0.332 g, 1.94 mmol) are added into 30 mL dimethylformamide. The mixture is degassed through three freeze-pump-thaw cycles. K.sub.2CO.sub.3 (2.0 M, 3.75 mL) and Pd(PPh.sub.3).sub.4 (0.112 g, 0.1 mmol) are then added with subsequent three freeze-pump-thaw cycles. The mixture is then purged with Ar and heated to 150 C. for 20 h under stirring. The product precipitates in water, and is washed by water, dichloromethane and methanol. Approximately 600 mg of grey product is obtained in each batch.

##STR00006##

[0083] E. TriBB-Linked Pd/PPhen (TriBB-Biphenyl)

[0084] For Pd/PPhen (TriBB+Biphenyl), 1,3,5-tribromobenzene (0.079 g, 0.25 mmol) and 4,4-biphenyldiboronic acid benzene-1,4-diboronic acid (0.091 g, 0.375 mmol) are added into 8 mL dimethylformamide. The mixture is degassed through three freeze-pump-thaw cycles. K.sub.2CO.sub.3 (2.0 M, 0.75 mL) and Pd(PPh.sub.3).sub.4 (0.025 g, 0.02 mmol) are then added with subsequent three freeze-pump-thaw cycles. The mixture is then purged with Ar and heated to 150 C. for 20 h under stirring. The product precipitates in water, and is washed by water, dichloromethane and methanol. Approximately 50 mg of grey product is obtained in each batch.

##STR00007##

EXAMPLE 2

Preparation of Metal-Free PPhen

[0085] Method 1: First, 1,2,4,5-tetrabromobenzene (0.765 g, 1.94 mmol) and benzene-1,4-diboronic acid (0.645 g, 3.89 mmol) are added into 60 mL dimethylformamide. The mixture is degassed through three freeze-pump-thaw cycles. K.sub.2CO.sub.3 (2.0 M, 7.5 mL) and Pd(PPh.sub.3).sub.4 (0.112 g, 0.10 mmol) are then added with subsequent three freeze-pump-thaw cycles. The mixture is then purged with Ar and heated to 100 C. for 12 h under stirring. The product precipitates in water, and is washed by water, dichloromethane and methanol. Approximately 600 mg of a slight yellow product is obtained in each batch.

[0086] Method 2: First, a Pd/PPhen is synthesized via the process described in Example 1. Then, pure metal free PPhen can be obtained via H.sub.2O.sub.2 and HCl treatments of the 2.7 wt % Pd/PPhen composite in liquid solutions.

EXAMPLE 3

Preparation of Pd/PPhen from PPhen

[0087] To synthesize 5 wt % Pd/PPhen, 250 mg Pd(PPh.sub.3).sub.4 or 72 mg Pd acetylacetonate (Pd(acac).sub.2) is disolved in to 12.5 g of CH.sub.2Cl.sub.2. The solution is impregnated into 500 mg of PPhen, with subsequent calcination under 5% H.sub.2/Ar at 400 C. for 3 h. The resulted solid in brown. To synthesize Pd/PPhen at other loading, the amount of Pd(PPh.sub.3).sub.4 or Pd(acac).sub.2 is varied.

EXAMPLE 4

Preparation of Other Me/PPhen from PPhen

[0088] To synthesize Pt/PPhen, Au/PPhen, Ru/PPhen, Cu/PPhen, Ni/PPhen, Co/PPhen, Fe/PPhen and VO.sub.x/PPhen, Pt(acac).sub.2, HAuCl.sub.4, Ru(acac).sub.3, Cu(acac).sub.2, Ni(acac).sub.2, Co(acac).sub.2, Fe(acac).sub.3 and VO(acac).sub.2 are used instead of Pd(acac).sub.2 in the procedure of Example 3.

EXAMPLE 5

Suzuki Coupling Reaction Catalyzed by Pd/PPhen

[0089] Typically, phenylboronic acid (91.5 mg, 0.75 mmol), sodium methoxide (81.0 mg, 1.5 mmol), 2.7 wt % Pd/PPhen (15.7 mg, 4 mol) and PVP (M.sub.w=55,000, 0.5 mg) are added into 5 mL water. The solution is treated with ultrasound for 0.5 h, and 4-chlorotoluene (63.3 mg, 0.50 mmol) and dodecane (35.0 mg, 0.21 mmol) are added. Dodecane acts as the internal standard. The mixture is degassed through three freeze-pump-thaw cycles, purged with Ar, and stirred at 80 C. for 3 h. Toluene is added into the solution to extract the products.

[0090] The products are analyzed by gas chromatography (GC) equipped with flame ionization detector (FID) for quantification. For other Suzuki coupling reactions, the same molar amounts of aryl chloride or arylboronic acid are added instead of 4-chlorotoluene or phenylboronic acid. For the Suzuki coupling reaction with other catalysts, catalysts with the same molar amount of palladium are added instead of Pd/PPhen. For recycling, the catalysts are filtered off, washed with ethanol, dried and weighed, and added into a new reaction mixture with a fixed Pd/4-chlorotoluene ratio of 0.8 mol %.

EXAMPLE 6

Suzuki Coupling Reactions Catalyzed by Pd/PPhen

[0091] Similarly, Suzuki coupling reactions catalyzed by the inventive Pd/PPhen as in Example 5 are carried out with other reagents as indicated in Table 3, including a Pd/Phen catalyst material prepared according to U.S. Pat. No. 3,974,095.

TABLE-US-00003 TABLE 3 Suzuki coupling reactions using different Pd catalysts, aryl chlorides and arylboronic acids. [00008] Time Yield Entry Aryl chloride Arylboronic acid Catalyst (h) (%) 1 [00009] [00010] Pd/PPhen 2.7 wt % in C.sub.2H.sub.5OH/water 3 82 2 [00011] [00012] Pd/PPhen 2.7 wt % 3 82 3 [00013] [00014] Pd/PPhen 5.9 wt % 3 27 4 [00015] [00016] Pd(PPh.sub.3).sub.4.sup. 3 n.d. 5 [00017] [00018] Na.sub.2PdCl.sub.4.sup. 3 n.d. 6 [00019] [00020] Pd/C from Sigma Aldrich 3 n.d. 7 [00021] [00022] Pd/C.sup. 3 n.d. 8 [00023] [00024] Pd/PDVB.sup. 3 n.d. 9 [00025] [00026] Pd/PPhen 2.7 wt % 3 55 10 [00027] [00028] Pd/PPhen 2.7 wt % 3 20 11 [00029] [00030] Pd/PPhen 2.7 wt % 20 80 12 [00031] [00032] Pd/PPhen 2.7 wt % 3 51 13 [00033] [00034] Pd/PPhen 2.7 wt % 20 87 14 [00035] [00036] Pd/PPhen (25% DiBB) 2.7 wt % 3 32 15 [00037] [00038] Pd/PPhen (50% DiBB) 2.7 wt % 3 43 16 [00039] [00040] Pd/PPhen (75% DiBB) 2.7 wt % 3 24 17 [00041] [00042] Pd/PPhen (10% DiBB) 2.7 wt % 3 13 18 [00043] [00044] Pd/PPhen according to U.S. Pat. No. 3,974,095 (Pd 2.7 wt %) 3 5 *Reaction conditions unless otherwise indicated: aryl chloride 0.5 mmol, arylboronic acid 0.75 mmol, NaOCH.sub.3 1.5 mmol, catalyst (0.8 mol % Pd to aryl chloride), PVP 0.5 mg, water 5 mL, 80 C., under argon. .sup.Tetrabutylammonium bromide (TBAB) 0.3 mmol is added as phase transfer catalyst. .sup.Pd/C and Pd/PDVB here are prepared by impregnation using active carbon or PDVB and P(PPh.sub.3).sub.4 with subsequent calcination under H.sub.2/Ar at 250 C. for 3 h. n.d.: not detectable.

[0092] These results of Table 3 show the superiority of the Pd/PPhen catalyst over all other systems studied. In homogeneous catalysis, Pd(PPh.sub.3).sub.4 is reactive enough for activated (hetero)aryl chlorides in nonaqueous solution. However, more effective ligands, such as N-heterocyclic carbenes, P(tBu).sub.3 or the phosphine family developed by Buchwald and co-workers, are required for palladium complexes to catalyze Suzuki coupling reactions involving unactivated aryl chlorides, such as chlorotoluene, 2-chloro-1,3-dimethylbenzene or 4-chloroanisole owing to their low intrinsic reactivity, which relates to steric effects of the substituents and the electron donating effect for oxidative addition. These substrates are known to pose an even greater challenge to heterogeneous catalysis. Interestingly, similar to Buchwald ligands, polyphenylene also contains biaryl substructures, which provide a similar environment for the catalytic Pd species in the Pd/PPhen solid composite. Indeed, under relevant reaction conditions, the application of Pd/PPhen as catalyst in the Suzuki coupling reaction of 2-chloro-1,3-dimethylbenzene with arylboronic acid results in a reaction yield above 50% after only three hours (Table 3, entry 9). Reaction yields exceeding 80% are obtained for different unactivated substrates after 20 h (Table 3, entry 11, 13). The results indicate that PPhen may act as a ligand to stabilize the transition state of the oxidative addition and/or reductive elimination. Transformation from Pd(PPh.sub.3).sub.4 to Pd/PPhen enables reactions that are impossible for Pd(PPh.sub.3).sub.4 itself. This discovery suggests that careful support engineering allows for catalytic reactions that have previously been inaccessible for solid catalysts.

EXAMPLE 7

Solvent-Free Benzyl Alcohol Oxidation in a Batch Setup

[0093] Typically, benzyl alcohol (10.4 g, 0.096 mol) and Pd/PPhen (10 mg, 2.5 mol) or Pd/C are added into a glass inset inside a stainless steel autoclave reactor. The reactor is purged with O.sub.2 and kept under 5 bar O.sub.2. The product is analyzed by GC-FID using dodecane as standard.

EXAMPLE 8

Benzyl Alcohol Oxidation in a Plug Flow Reaction

[0094] Pd/PPhen (20 mg) is mixed with quartz sand (200 mg), and packed into a tube reactor (6 mm160 mm). An evaporator for benzyl alcohol is connected to the top of the tube reactor. The temperatures of evaporator and reactor are controlled by individual tube ovens. Benzyl alcohol (0.1 ml.Math.h.sup.1) is injected through a syringe pump into the evaporator and carried by O.sub.2 (50 mL.Math.min.sup.1) into the reactor. The partial pressure of benzyl alcohol is controlled to be lower than its vapor pressure. The products are collected in a dry-ice cooled tetrahydrofuran solution with a gas outlet to atmosphere. The solutions are analyzed by GC-FID in one hour intervals with dodecane as standard. The results are shown in Table 4.

TABLE-US-00004 TABLE 4 Plug flow benzyl alcohol oxidation. Temperature Benzaldehyde Conversion Selectivity Catalysts ( C.) yields (%) (%) (%) Pd/PPhen 190 25 84 29 Pd/PPhen 160 33 80 43 Pd/PPhen 120 47 59 79 Pd/C 120 12 23 46 Reaction conditions: Benzyl alcohol rate 0.1 mL .Math. h.sup.1, O.sub.2 flow rate 50 mL .Math. min.sup.1, Pd/PPhen 2.7 wt % catalyst 20 mg, Pd/C 5 wt % 4 mg, the products are collected between 3rd and 4th hour on-stream.

[0095] Analysis Methods

[0096] TEM and HAADF-STEM imaging were carried out on an FEI Titan 80-300ST field-emission-gun (FEG) TEM operated at 30 kV. Electron tomography was performed by collecting tilt-series of HAADF-STEM images over a tilt range of 70 to +75 with a tilt increment of 2. Alignment of the tilt series was performed using a collection of palladium nanoparticles (2-3.5 nm), indigenous to the Pd/PPhen composite, as fiducial markers. Tomogram reconstruction was carried out using a weighted back-projection algorithm in IMOD. Segmentation and 3D visualization of the different phases in the reconstructed volume was performed in Avizo (FEI, The Netherlands). SEM imaging was performed on a Hitachi S-5500 FEG SEM. XRD measurement was performed on a Stoe STADI P Bragg-Brentano diffractometer with Cu K.sub.1,2 radiation, using a secondary graphite monochromator. N.sub.2 adsorption isotherm was measured on Micromeritics ASAP 2010 adsorption analyzer at 77 k after activation in vacuum at 250 C. for 24 h. XPS analyses were performed on a Kratos HSi spectrometer with a hemispherical analyzer. The monochromatized Al K X-ray source (E=1486.6 eV) was operated at 15 kV and 15 mA. An analyzer pass energy of 40 eV was applied for the narrow scans. The hybrid mode was used as lens mode. The base pressure during the experiment in the analysis chamber was 4510.sup.7 Pa. All spectra were charge corrected referred to the C1 s photopeak at 284.5 eV. TG measurements were performed on a Netzsch STA 449C thermal analyzer with a heating rate of 10 C. min.sup.1. The solid-state NMR spectra were recorded on a Bruker Avance 500WB spectrometer using a double-bearing standard MAS probe (DVT BL4) at resonance frequencies of 125.8 MHz and 202.5 MHz for 13C and 31P, respectively. High-power proton decoupling (CW) and spinning rates between 10 and 12 kHz were applied for all spectra. Density of PPhen was measured on Micromeritics Accupyc 1330 gas pycnometer.

SUMMARY

[0097] As shown above, the catalysts of the present invention show excellent activity in the coupling of 1,3-dimethyl-2-chlorobenzene with 2-tolylboronic acid, a reaction which represents a serious challenge even for molecular catalysts under homogeneous reaction conditions. The catalysts also show high selectivity in both liquid and gas phase aerobic oxidation. Thus, the polyphenylene support shows the huge potential as an organic catalysis platform to perform organic reactions that are currently inaccessible with heterogeneous catalysis.

[0098] A polyphenylene based solid catalyst platform has been developed for metal catalyzed reactions which are typically performed in homogeneous phase. The Pd/PPhen catalyst, synthesized through the rational coupling of the CC coupling reaction and the decomposition of Pd(PPh.sub.3).sub.4, shows exceptional catalytic activities in aqueous phase Suzuki coupling reactions using unactivated substrates, such as 1,3-dimethyl-2-chlorobenzene and 4-chloroanisole.

[0099] The PPhen support, consisting of aromatic rings, can serve as a solid organic solvent and provides the local organic reaction environment. The PPhen support also shows a synergistic effect for Suzuki coupling reactions, as confirmed by the control experiments using conventional catalysts, such as carbon and PDVB supported palladium nanoparticle, which have the same size ranges with that of Pd/PPhen.

[0100] The Pd/PPhen catalysts show a remarkable capacity to retain the catalytic palladium species, enabling good recyclability. In addition, high selectivity from benzyl alcohol to benzaldehyde was obtained using Pd/PPhen at both liquid and gas phase. PPhen shows its potential as an organic catalysis platform to enable various organic reactions that are currently inaccessible by heterogeneous catalysis.