Palladium Nanoparticles Supported on Triphenylphosphine

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Nov 26, 2018 - Triphenylphosphine-Functionalized Porous Polymer as an Active and .... solvents (entries 1–9), such as ethanol, anisole, 1,4-dioxane, toluene, and 1 ... probably due to the low solubility of the reaction solvent (entries 7 and 8).
catalysts Article

Palladium Nanoparticles Supported on Triphenylphosphine-Functionalized Porous Polymer as an Active and Recyclable Catalyst for the Carbonylation of Chloroacetates Yali Wan 1 , Zaifei Chen 2 , Dingfu Liu 1, * and Yizhu Lei 2, * 1 2

*

School of Chemistry and Chemical Engineering, Guizhou University, Guiyang, Guizhou 550025, China; [email protected] School of Chemistry and Materials Engineering, Liupanshui Normal University, Liupanshui, Guizhou 553004, China; [email protected] Correspondence: [email protected] (D.L.); [email protected] (Y.L.); Tel.: +86-085-8860-0172 (Y.L.)

Received: 2 November 2018; Accepted: 22 November 2018; Published: 26 November 2018

 

Abstract: Dialkyl malonates are important organic intermediates that are widely used as building blocks in organic synthesis. Herein, palladium nanoparticles supported on a triphenylphosphinefunctionalized porous polymer were successfully developed as an efficient and recyclable catalyst for the synthesis of dialkyl malonates via the catalytic carbonylation of chloroacetates. The influence of reaction parameters such as solvent, base, and promoter on activity was carefully investigated. With a 1 mol% of palladium usage, excellent yields of dialkyl malonates were obtained. Importantly, the catalyst can be easily separated and reused at least four times, without a significant loss in reactivity. Furthermore, the developed catalyst was also highly active for the alkoxycarbonylation of α-chloro ketones. Keywords: carbonylation; malonate; palladium; porous organic polymer; triphenylphosphine; organic chloride

1. Introduction Carbonylative transformation of organic halides using palladium catalysts represents a versatile method for the synthesis of carboxylic acid and its derivatives [1–4]. Carbon monoxide, an inexpensive and readily available C1 building block, is widely used as a carbonyl source for the palladium-catalyzed carbonylation of aryl halides [5–12]. However, except as a cheap carbonyl source, CO could also act as a strong π-acidic ligand for the palladium metal, thus resulting in a decrease of electron density for the palladium center and making the oxidative addition of aryl halide difficult [13,14]. As such, the carbonylation reaction of organic halides is usually more difficult than corresponding non-carbonylative reactions, especially for those reactions where the oxidative addition of the carbon-halide bond is the rate-determining step. Meanwhile, under a CO atmosphere, the palladium atom is easily aggregated, forming the catalytically inactive species [15,16]. To increase the catalytic activity and stability of palladium catalysts in carbonylation reactions, electron-rich ligands are usually needed [17,18]. Homogeneous palladium complexes usually show high catalytic activity and selectivity [1–4,19–22]; however, they still suffer from some drawbacks, such as problems of catalyst separation and reuse [23]. Heterogeneous switching of a homogeneous palladium complex by immobilizing the complex or nanoparticle onto the solid support has been expected to address these problems [14–25], where traditional polymers and silicas are the most widely used support materials [26]. However, Catalysts 2018, 8, 586; doi:10.3390/catal8120586

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these traditional supports “anchored” palladium catalysts often suffer from poor stability and inhomogeneously distributed active sites [27]. Moreover, under a CO atmosphere, palladium supported on these traditional supports is easily aggregated, forming catalytically inactive species during the reactions and thus lowering their stability and catalytic activities [16]. Therefore, developing a heterogeneous catalytic system, which has high catalytic activity and an excellent stability, is worthy of further study. Porous organic polymers (POPs), which feature a high surface area, excellent stabilities, a designable chemical structure, and a flexible synthetic strategy, have attracted tremendous interest recently because of their potential applications in catalysis, adsorption, separation, gas storage, and other fields [28,29]. In recent years, a series of POPs containing a PPh3 ligand and its derivatives, have been successfully prepared and applied as catalysis supports for immobilizing transition metals [30–34]. Due to the strong interaction between transition metals and phosphine ligands, these catalysts usually exhibit high catalytic activities, long-term reusability, and excellent leaching resistant ability [30–37]. Some of them have even outperformed the activities of their homogeneous analogues [30,35–37]. Although the applications of phosphine functionalized POPs in non-carbonylative cross-coupling reactions of organic halides have been widely investigated in recent years [30,34,36,37], studies of their catalytic applications in the carbonylation of organic halides are relatively unexplored [38]. Dialkyl malonates are important organic intermediates that are widely used as building blocks for the synthesis of vitamins, pharmaceuticals, agrochemicals, and so on [39]. To continue our ongoing efforts for exploring efficient catalysts for the synthesis of dialkyl malonate [40], herein, we reported palladium nanoparticles supported on a triphenylphosphine-functionalized porous polymer (PdNPs@POP-Ph3 P) as an active and recyclable catalyst for the carbonylation of chloroacetates. 2. Results and Discussion 2.1. Characterization of the Catalyst Nitrogen adsorption-desorption analysis of POP-PPh3 showed that the prepared POP-PPh3 has a 1146 m2 ·g−1 BET surface area with a high pore volume (Table 1, entry 1). After immobilization of the palladium metal, the obtained PdNPs@POP-Ph3 P still preserved a high BET surface area of 987 m2 ·g−1 and a high pore volume of 1.92 cm3 /g. The sorption isotherms of the samples (Figure 1) exhibited combined type I and type IV sorption behaviour. The steep increase at a low relative pressure (P/P0 < 0.01) indicates the filling of micropores, the hysteresis loop at the relative pressure of 0.7–1.0 implies the presence of mesopores, and the sharp rise at the relative pressure of 0.8–1.0 indicates the presence of macropores. Correspondingly, the pore size distribution curve (inset) of PdNPs@POP-Ph3 P also indicates its hierarchical pore structure. Table 1. Textural properties of the prepared samples. Entry

Catalysts

SBET (m2 ·g−1 )

Pore Volume (cm3 /g) 1

Average Pore Radius (nm) 2

1 2

POP-PPh3 PdNPs@POP-PPh3

1146 987

2.41 1.92

8.42 6.50

1

Single point adsorption total pore volume of pores at P/Po = 0.99. 2 Adsorption average pore diameter (4V/A by BET).

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Figure 1. Nitrogen adsorption-desorption isotherms of POP-Ph3P (square) and PdNPs@ POP-Ph3P Figure adsorption-desorption isotherms of and Figure 1.and 1. Nitrogen Nitrogen adsorption-desorption isotherms ofPOP-Ph POP-Ph33PP (square) (square) andPdNPs@ PdNPs@POP-Ph POP-Ph33PP 3P. (circle), pore size distribution curves (insert) of PdNPs@POP-Ph (circle), and pore size distribution curves (insert) of PdNPs@POP-Ph P. 3 (circle), and pore size distribution curves (insert) of PdNPs@POP-Ph3P.

The morphology of POP-Ph3P and PdNPs@POP-Ph3P was further characterized by SEM and The morphology ofofPOP-Ph PdNPs@POP-Ph3 P was further characterized by SEM TEM. 3 P3and POP-Ph P and was further by and SEM and TEM.The Themorphology SEM images in Figure 2a,b PdNPs@POP-Ph suggested that 3PPOP-Ph 3P andcharacterized PdNPs@POP-Ph 3P were The SEM images in Figure 2a,b suggested that POP-Ph P and PdNPs@POP-Ph P were comprised 3 POP-Ph3P and PdNPs@POP-Ph 3 TEM. The SEM images in Figure 2a,b suggested that 3 P were comprised of loosely packed and irregular-shape nanoparticles. A representative TEM image (Figure of loosely packed and irregular-shape nanoparticles. A representative TEM image (Figure 2c) of comprised of 3loosely packed and irregular-shape A representative TEM image image (Figure (Figure 2c) of POP-Ph P further confirmed the presence of nanoparticles. mesopores in the polymer. The TEM POP-Ph P further confirmed the presence of mesopores in the polymer. The TEM image (Figure 2d) of 3 2c) of POP-Ph 3P further confirmed theformation presence of in thePd polymer. The TEM image (Figure 2d) PdNPs@POP-Ph 3P showed the ofmesopores well-dispersed nanoparticles with a relatively PdNPs@POP-Ph P showed the formation of well-dispersed Pd nanoparticles with a relatively narrow 3 2d) of PdNPs@POP-Ph 3P As showed the in formation well-dispersed Pd nanoparticles with relatively narrow size distribution. depicted Figure 3,ofthe average diameter of Pd clusters wasa about 2.9 size distribution. As depicted in Figurein3,Figure the average of Pd clusters aboutwas 2.9 about nm. 2.9 narrow size distribution. As depicted 3, the diameter average diameter of Pdwas clusters nm. nm.

Figure of POP-Ph POP-Ph33P PdNPs@ POP-Ph POP-Ph33P Figure 2. 2. SEM SEM images images of P (a) (a) and and PdNPs@ POP-Ph33PP (b); (b); TEM TEM images images of of POP-Ph P (c) (c) and and Figure 2. SEM images of POP-Ph 3P (a) and PdNPs@ POP-Ph3P (b); TEM images of POP-Ph3P (c) and 3 P (d). PdNPs@ POP-Ph PdNPs@ POP-Ph3 P (d). PdNPs@ POP-Ph3P (d).

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Figure 3. 3. Particle Particle size size distribution distribution of of palladium palladium nanoparticles POP-Ph333P. nanoparticles on on PdNPs@ PdNPs@ POP-Ph P. Figure nanoparticles on PdNPs@

FT-IR P are are shown in The results revealed that FT-IR spectra spectra of of 3V-PPh 3V-PPh333 and and POP-Ph POP-Ph333P P shown in in Figure Figure 4. 4. The The results revealed revealed that that the the FT-IR spectra of 3V-PPh and POP-Ph are shown Figure 4. results the −1−1) disappeared stretching band of C=C (1627 cm after the polymerization reaction. It indicated thatthat the stretching band of C=C (1627 cm ) disappeared after the polymerization reaction. It indicated −1 stretching band of C=C (1627 cm ) disappeared after the polymerization reaction. It indicated that −1 polymerization of vinyl groups had finished. The characteristic P-Ar stretching vibration (1442 cm the polymerization polymerization of vinyl vinyl groups had finished. finished. The characteristic characteristic P-Ar stretching stretching vibration (1442) the of groups had The P-Ar vibration (1442 −1) also suggested the successful incorporation of the of phosphine ligandligand in the in polymer [41,42].[41,42]. cm−1 also suggested suggested the successful successful incorporation the phosphine phosphine the polymer polymer cm ) also the incorporation of the ligand in the [41,42].

Figure 4. 4. FTIR FTIR spectra spectra of of 3V-Ph 3V-Ph33P P (a) and POP-Ph3P (b). Figure P (b). (b). 3V-Ph 3 (a) and POP-Ph3P

study the the composition composition of of POP-Ph POP-Ph333P P. As XPS analysis analysis was P and and PdNPs@POP-Ph PdNPs@POP-Ph333P. As shown shown XPS was used used to to study study the composition of POP-Ph in Figure 5, P and C elements are present in the two samples. Compared with the POP-Ph 3P polymer, polymer, in Figure 5, P and C elements are present in the two samples. Compared with the POP-Ph33PPpolymer, additional Pd band was observed in the XPS full spectrum of PdNPs@POP-Ph 3P. spectrum The XPS an additional Pd band was observed in the XPS full spectrum of PdNPs@POP-Ph P. The XPS 3 an additional Pd band was observed in the XPS full spectrum of PdNPs@POP-Ph3P. The XPS spectrum of Pd 3d revealed that Pd was present in a zero state. As shown in Figure 6a, the binding of Pd 3d revealed that Pd was present in a zero state. As shown in Figure 6a, the binding energy spectrum of Pd 3d revealed that Pd was present in a zero state. As shown in Figure 6a, the binding 0 (335.4 energy of5/2 Pdwas 3d5/2 5/2 was about about 334.9 eV, which which was about about 0.5 eV lower lower thanof that ofPd free Pd00 (335.4 (335.4 eV) of Pd 3d about 334.9 eV, which was about 0.5 eV0.5 lower than that free eV) [42]. energy of Pd 3d was 334.9 eV, was eV than that of free Pd eV) [42]. Simultaneously, Simultaneously, the Pbinding 2p binding binding energy of PdNPs@POP-Ph PdNPs@POP-Ph P was was about0.3 0.3eV eVhigher higherthan than that Simultaneously, the Pthe 2pP energy of PdNPs@POP-Ph was about 3 P33P [42]. 2p energy of about 0.3 eV higher than that (131.7 eV) POP-Ph 3P (Figure 6b). These results indicated that there was a strong coordination effect (131.7 eV) of POP-Ph (131.7 eV) of POP-Ph33P (Figure 6b). These results indicated that there was a strong coordination effect nanoparticles [30,36,37]. [30,36,37]. between P between P and and Pd Pd nanoparticles nanoparticles [30,36,37].

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Figure 5. XPS full spectra of POP-Ph3P (a) and PdNPs@ POP-Ph3P (b). Figure Figure5.5.XPS XPSfull fullspectra spectraofofPOP-Ph POP-Ph33PP(a) (a)and andPdNPs@ PdNPs@POP-Ph POP-Ph33P P (b). (b).

Figure 6. 6. Pd 3d 3d XPS XPS spectrum spectrum of of PdNPs@POP-Ph PdNPs@POP-Ph33P (a), P 2p XPS XPS spectra spectra of of POP-Ph POP-Ph33P and PdNPs@ PdNPs@ Figure 6. Pd 3d XPS spectrum of PdNPs@POP-Ph3P (a), P 2p XPS spectra of POP-Ph3P and PdNPs@ POP-Ph33P (b). POP-Ph3P (b).

2.2. Alkoxycarbonylation Reactions 2.2. Alkoxycarbonylation Reactions 2.2. Alkoxycarbonylation Reactions With the catalyst in hand, we started our investigation with the carbonylation of ethyl With the catalyst in hand, we started our investigation with the carbonylation of ethyl chloroacetate as a in model reaction. Previous [39,40] showed the solvent and base With the(ECA) catalyst hand, we started our results investigation with thethat carbonylation of ethyl chloroacetate (ECA) as a model reaction. Previous results [39,40] showed that the solvent and base have great impacts activityreaction. and selectivity of results this carbonylation reaction. Hence, the and effect of chloroacetate (ECA)onasthe a model Previous [39,40] showed that the solvent base have great impacts on the activity and selectivity of this carbonylation reaction. Hence, the effect of solvent and impacts base wason first shown inofTable 2, the reaction was carried out with various have great theinvestigated. activity andAs selectivity this carbonylation reaction. Hence, the effect of solvent and base was first investigated. As shown in Table 2, the reaction was carried out with various solvents (entries as ethanol, anisole, 1,4-dioxane, toluene, and 1,2-diethoxyethane (1,2-DEE). solvent and base1–9), was such first investigated. As shown in Table 2, the reaction was carried out with various solvents (entries 1–9), such as ethanol, anisole, 1,4-dioxane, toluene, and 1,2-diethoxyethane (1,2Among 1,2-DEE afforded the highest selectivity of diethyl malonate (97.0%), with a high solventsthem, (entries 1–9), such as ethanol, anisole, 1,4-dioxane, toluene, and 1,2-diethoxyethane (1,2DEE). Among them, 1,2-DEE afforded the highest selectivity of diethyl malonate (97.0%), with a high conversion (83.9%) ethyl chloroacetate (entry selectivity 6). Notably, ethanol and THF gave with the higher DEE). Among them,of 1,2-DEE afforded the highest of diethyl malonate (97.0%), a high conversion (83.9%) of ethyl chloroacetate (entry 6). Notably, ethanol and THF gave the higher conversions; however, the inferior selectivity of diethyl malonate (DEM) was observed (entries 1 conversion (83.9%) of ethyl chloroacetate (entry 6). Notably, ethanol and THF gave the higher conversions; however, the inferior selectivity of diethyl malonate (DEM) was observed (entries 1 and and 9). With 1,2-DEE theinferior solvent,selectivity several bases were malonate screened (entries 10–13). For base screening, conversions; however,asthe of diethyl (DEM) was observed (entries 1 and 9). With 1,2-DEE as the solvent, several bases were screened (entries 10–13). For base screening, Na HPO 1,2-DEE displayed performance (entry were 6). Forscreened comparison, the 10–13). commercial Pd/Cscreening, was also 9). With as the thebest solvent, several bases (entries For base Na22HPO44 displayed the best performance (entry 6). For comparison, the commercial Pd/C was also tested under identical conditions.(entry However, only provided a 21.3% conversion of Na2HPO 4 displayed thereaction best performance 6). ForPd/C comparison, the commercial Pd/C was also tested under identical reaction conditions. However, Pd/C only provided a 21.3% conversion of ethyl ethyl testedchloroacetate. under identical reaction conditions. However, Pd/C only provided a 21.3% conversion of ethyl chloroacetate. Previous research [39,40] suggested that the iodide promoter could extensively enhance the chloroacetate. catalytic activity of 2.this reaction. Therefore, the effect of a effect promoter wasand investigated (Table 3). Table Ethoxycarbonylation of ethyl chloroacetate: of solvent base. 1 1 Table 2. Ethoxycarbonylation of ethyl chloroacetate: effect of solvent and base. Without any promoter, a 16.5% yield of diethyl malonate was gained (entry 1). Replacing Bu4 NI with an equal amount of Bu4 NBr or Bu4 NCl, a low or non-promotion effect was observed (entries 3 and 4). Notably, with the replacement of Bu4 NI with Et4 NI and Me4 NI, much higher conversions were achieved (entries 5 and 6). In contrast to this, the inorganic KI and NaI afforded relatively low yields,

Sel. Yield Conv. (mol%) (mol%) 3 (mol%) 2 2.2. Alkoxycarbonylation Reactions 1 PdNPs@POP-Ph3P ethanol Na2HPO4 99.8 40.7 40.6 2 PdNPs@POP-Ph 3 P anisole Na 2 HPO 4 67.5 95.2 With the catalyst in hand, we started our investigation with the carbonylation 64.3 of ethyl 3P 1,4-dioxane Na2HPO 4 82.6 that the 85.6solvent 70.7 3 PdNPs@POP-Ph chloroacetate (ECA) as a model reaction. Previous results [39,40] showed and base PdNPs@POP-Ph3P. 37.9 Na2HPO4 Catalysts 2018, 8, 586 6 of 12 have 4great impacts on the activity and toluene selectivity of this carbonylation reaction.92.4 Hence, the35.0 effect of DGDE Na2HPO4 75.1 95.7 71.9 5 PdNPs@POP-Ph3P solvent and base was first investigated. As shown in Table 2, the reaction was carried out with various 1,2-DEE Na2HPO4 83.9 97.0 81.4 6 PdNPs@POP-Ph3P solvents (entriesthe 1–9), as ethanol, anisole, solvent 1,4-dioxane, toluene, and 1,2-diethoxyethane (1,2probably lowsuch solubility of the1,2-DME reaction 7 and 81.0 8). With an95.4 optimal promotion 7 due toPdNPs@POP-Ph 3P Na(entries 2HPO4 77.3 DEE). them, 1,2-DEE afforded highest selectivity of4 diethyl malonate (97.0%), with a high in hand, the influence of the amount ofthe Me studied (entries 9–11).96.5 The results showed 3P TEOF Na2HPO 82.4 79.5 8Among PdNPs@POP-Ph 4 NI was further conversion (83.9%) of ethyl chloroacetate (entry 6). Notably, ethanol and THF gave the higher 9 PdNPs@POP-Ph 3 P THF Na 2 HPO 4 94.1 85.0 80.0 that a 93.8% conversion of ethyl chloroacetate could be obtained when the molar ratio of Me4 NI was conversions; however, inferior selectivity of diethyl malonate 3P 1,2-DEE 2CO3 Me(DEM) 95.6was observed 88.2 (entries 84.3 1 and 10 PdNPs@POP-Ph increased to 15% (entrythe 10). However, the presence of K excess 4 NI afforded a little lower yield of 3 P 1,2-DEE K 3 PO 4 99.9 90.5 90.4 11 PdNPs@POP-Ph 9). Withmalonate 1,2-DEE(entry as the11). solvent, basestime were (entries 10–13). base screening, diethyl When several the reaction wasscreened further prolonged to 9 h, For a high yield (94.9%) 12 4 displayed PdNPs@POP-Ph 3P 1,2-DEE K2HPO 4 64.7 94.8 Pd/C61.3 Na 2HPO the best performance (entry 6). For comparison, the commercial was also of diethyl malonate was obtained (entry 12), which was a little bit higher than that of a previously 3P 1,2-DEE NaHCO 3 51.4a 21.3%79.1 40.7 13under identical PdNPs@POP-Ph tested reaction conditions. However, Pd/C only provided conversion of ethyl reported homogeneous and colloid catalyst [39,40]. Under the optimal conditions, we tried to lower Pd/C 1,2-DEE Na2HPO4 21.3 96.1 20.5 14 4 chloroacetate. the CO decrease1,2-DEE in yield was observed 15 5 pressure, while Pd(PPha3)slight 2Cl2 Na2HPO4 (entry 13). 91.6 96.7 88.6 Entry

Catalyst

Solvent

Base

Reaction condition: 3P (125 mg, 0.02 mmol Pd), Bu4NI (0.2 mmol), base (4 mmol), ethyl TablePdNPs@POP-Ph 2. Ethoxycarbonylation Ethoxycarbonylation of ethyl ethyl chloroacetate: chloroacetate: effect effect of of solvent solvent and and base base.1 .1 Table 2. of chloroacetate (2 mmol), EtOH (4 mmol), solvent (3 mL), CO (2 MPa), 80 °C, 8 h, stirring speed (800 rpm). 2 (n0 and n1 represent the molar number of the added and remanent ECA before and n 0 -n1 1

Conv. =

n0

× 100%

after the reaction). 3 Yield= nDEM ×100%.4 Pd/C (42 mg, 0.02 mmol Pd). 5 Pd(PPh3)2Cl2 (14 mg, 0.02 mmol). Entry Catalyst n0 Solvent Base Sel. (mol%) Conv. (mol%) 2 Yield (mol%) 3 1

PdNPs@POP-Ph3 P

ethanol

Na2 HPO4

99.8

40.7

40.6

Previous research [39,40] suggested Na that the iodide 67.5 promoter could95.2 extensively enhance the 2 PdNPs@POP-Ph anisole 64.3 2 HPO4 3P 3 PdNPs@POP-Ph P 1,4-dioxane Na2 HPO 85.6 investigated70.7 catalytic activity of this 3reaction. Therefore, the4 effect of82.6 a promoter was (Table 3). 4 any PdNPs@POP-Ph P. toluene Na2 HPO 37.9gained (entry 92.4 4 Without promoter, a 316.5% yield of diethyl malonate was 1). Replacing 35.0 Bu4NI with PdNPs@POP-Ph3 P DGDE Na2 HPO4 75.1 95.7 71.9 5 an equal of Bu4NBr or 1,2-DEE Bu4NCl, a low or non-promotion observed (entries PdNPs@POP-Ph Na2 HPO 83.9 effect was 97.0 81.43 and 4). 6 amount 3P 4 Notably, with the replacement of Bu4NINa with Et Me4NI, much95.4 higher conversions were 7 PdNPs@POP-Ph 1,2-DME 77.3 3P 2 HPO 4 4NI and81.0 8 PdNPs@POP-Ph TEOF to this, Na2the HPOinorganic 82.4and NaI afforded 96.5 relatively 79.5 3 PIn contrast 4 achieved (entries 5 and 6). KI low yields, PdNPs@POP-Ph3 P THF Na2 HPO4 94.1 85.0 80.0 9 probably due to the low solubility of the reaction solvent (entries 7 and 8). With an optimal promotion 10 PdNPs@POP-Ph3 P 1,2-DEE K2 CO3 95.6 88.2 84.3 in hand, influence of the amount NI was further studied (entries90.5 9–11). The results 11 the PdNPs@POP-Ph 1,2-DEEof Me4K 99.9 90.4showed 3P 3 PO4 PdNPs@POP-Ph 1,2-DEE K2 HPO 64.7 when the94.8 that a1293.8% conversion of chloroacetate could be obtained molar ratio of 61.3 Me4NI was 3 Pethyl 4 PdNPs@POP-Ph P 1,2-DEE NaHCO 51.4 79.1 40.7 13 3 3 increased to 15% (entry 10). However, the presence of excess Me4NI afforded a little lower yield of Pd/C 1,2-DEE Na2 HPO4 21.3 96.1 20.5 14 4 diethyl malonate (entry 11). When the reaction time was further to 9 h, a high yield 5 Pd(PPh 1,2-DEE Na2 HPO 91.6 prolonged96.7 88.6 (94.9%) 15 3 )2 Cl2 4 of diethyl malonate was obtained (entry 12), which was a little bit higher than that of a 1 Reaction condition: PdNPs@POP-Ph P (125 mg, 0.02 mmol Pd), Bu NI (0.2 mmol), base (4 previously mmol), 3 4 reported and colloid [39,40]. Under optimal we tried to lower ethylhomogeneous chloroacetate (2 mmol), EtOH (4catalyst mmol), solvent (3 mL), COthe (2 MPa), 80 ◦ C,conditions, 8 h, stirring speed (800 rpm). 2 Conv. = n0 −n1 × 100% (n and n represent the molar number of the added and remanent ECA before and after 0 1 the CO pressure, decrease in yield was observed (entry 13). n0 while a slight the reaction). 3 Yield = nDEM × 100%. 4 Pd/C (42 mg, 0.02 mmol Pd). 5 Pd(PPh3 )2 Cl2 (14 mg, 0.02 mmol). n 0

Table 3. Carbonylation of ethyl chloroacetate: effect of promoters. 1. Table 3. Carbonylation of ethyl chloroacetate: effect of promoters 1 .

Amount Entry Amount (mol%) 2 Conv. Conv. (mol%)3 3 (mol%) EntryPromoter Promoter (mol%) 2 1 17.5 17.5 2 1 Bu4 NI 1083.9 Bu4NI 10 83.9 3 2 Bu4 NBr 10 29.7 4 3 Bu4 NCl 10 14.8 Bu4NBr 10 29.7 5 Et4 NI 10 87.5 4 Bu4NCl 10 14.8 6 Me4 NI 10 89.6 5 Et 4NI 10 87.5 7 NaI 10 47.1 10 89.6 8 6 KIMe4NI 10 50.3 9 7 Me4 NINaI 510 59.2 47.1 10 8 Me4 NIKI 15 93.8 10 50.3 11 Me4 NI 20 94.0 9 Me4NI 5 59.2 Me4 NI 15 97.7 12 5 Me4 NI 15 93.2 13 5,6

Sel.(mol%) (mol%) Sel.

Yield Yield (mol%) 4

94.4 94.4 97.0 97.0 95.9 96.1 95.9 97.1 96.1 97.2 97.1 96.9 97.2 96.9 96.8 96.9 97.2 96.9 96.4 96.8 97.1 96.6

94.9 90.0

(mol%) 4 16.5 16.5 81.4 81.4 28.5 14.2 28.5 85.0 14.2 87.1 85.0 45.6 87.1 48.7 57.3 45.6 91.2 48.7 90.6 57.3

1 Reaction condition: PdNPs@POP-Ph P (125 mg, 0.02 mmol Pd), promoter, Na HPO (4 mmol), ethyl chloroacetate 3 2 4 (2 mmol), EtOH (4 mmol), 1,2-DEE (3 mL), CO (2 MPa), 80 ◦ C, 8 h, stirring speed (800 rpm). 2 Mole ratio (promoter/ethyl chloroacetate). 3 Conv. = n0n−n1 × 100% (n0 and n1 represent the molar number of the added and 0

remanent ECA before and after the reaction). 4 Yield = nDEM × 100%. 5 Reaction time (9 h). 6 CO (1 MPa). n 0

Reaction condition: PdNPs@POP-Ph3P (125 mg, 0.02 mmol Pd), promoter, Na2HPO4 (4 mmol), ethyl chloroacetate (2 mmol), EtOH (4 mmol), 1,2-DEE (3 mL), CO (2 MPa), 80 °C, 8 h, stirring speed (800 n 0 -n1 (n0 and n1 represent the molar rpm). 2 Mole ratio (promoter/ethyl chloroacetate). 3 1

Conv. =

n0

× 100%

number of the added and remanent ECA before and after the reaction).

4

Catalysts 2018, 8, 586

Yield =

n DEM 5 ×100% . 7 of 12 n0

Reaction time (9 h). 6 CO (1 MPa).

In addition to catalytic activity, the recovery and reusability of the catalyst are also crucial in In addition to catalytic activity, the recovery and reusability of the catalyst are also crucial in the the evaluation of the economic feasibility of a catalytic process. The reusability and stability of evaluation of the economic feasibility of a catalytic process. The reusability and stability of PdNPs@POP-Ph3 P were evaluated under the optimal conditions. After each run, the catalyst was PdNPs@POP-Ph3P were evaluated under the optimal conditions. After each run, the catalyst was recovered by centrifugation and washed with 1,2-DEE. The obtained liquid was quantitatively analysed recovered by centrifugation and washed with 1,2-DEE. The obtained liquid was quantitatively using GC. As shown in Figure 7, the catalyst could be effectively reused at least four times, with only analysed using GC. As shown in Figure 7, the catalyst could be effectively reused at least four times, slight loss in its activity. Moreover, ICP analysis suggested that the palladium loading of the recycled with only slight loss in its activity. Moreover, ICP analysis suggested that the palladium loading of PdNPs@POP-Ph3 P after being reused four times was 1.61 wt%, indicating that 95% of palladium on the recycled PdNPs@POP-Ph3P after being reused four times was 1.61 wt%, indicating that 95% of PdNPs@POP-Ph3 P was preserved during the recycling. palladium on PdNPs@POP-Ph3P was preserved during the recycling.

Figure Figure 7. 7. Reuse Reuse of ofPdNPs@POP-Ph PdNPs@POP-Ph33P. P. Reaction Reaction condition: condition: PdNPs@POP-Ph PdNPs@POP-Ph33PP(125 (125mg, mg,0.02 0.02mmol mmolPd), Pd), Me44NI NI(0.3 (0.3mmol), mmol), Na Na22HPO HPO44(4(4mmol), mmol),ethyl ethylchloroacetate chloroacetate(2(2mmol), mmol),EtOH EtOH(4 (4mmol), mmol),1,2-DEE 1,2-DEE(3 (3mL), mL), Me ◦ C, 9 h, stirring speed (800 rpm). CO (2 (2 MPa), 80 °C, CO 9 h, stirring speed (800 rpm).

Then, we weturned turnedour ourfocus focusto to general applicability of this catalytic system (Table 4). Then, thethe general applicability of this catalytic system (Table 4). The The carbonylation of methyl chloroacetate with methanol could proceed smoothly under the optimized carbonylation of methyl chloroacetate with methanol could proceed smoothly under the optimized conditions, and and an an excellent excellent yield yield (95.8%) (95.8%) of ofdimethyl dimethylmalonate malonatewas wasachieved achieved(entry (entry1). 1).Interestingly, Interestingly, conditions, some mixed-alkyl malonates were also prepared in excellent yields under the reaction conditions some mixed-alkyl malonates were also prepared in excellent yields under the reaction conditions (entries 2–4), reaction with the the chloroacetate substrate or with (entries 2–4), although althoughaacompeting competingtransesterification transesterification reaction with chloroacetate substrate or the malonate product was possible. Alkoxycarbonylation of α-chloro ketones ketones represents a valuable with the malonate product was possible. Alkoxycarbonylation of α-chloro represents a alternative for the synthesis of the useful β-keto esters [43]. Considering the similar structure of valuable alternative for the synthesis of the useful β-keto esters [43]. Considering the similar structure Catalysts 2018, 8, ketones x8,8,FOR PEER REVIEW of 12 Catalysts 2018, xxFOR PEER REVIEW 88of Catalysts 2018, FOR PEER REVIEW of12 12 α-chloro ketones and chloroacetates, the tested of α-chloro and chloroacetates, thealkoxycarbonylation alkoxycarbonylationof ofα-chloro α-chloro ketones ketones was was also also88tested Catalysts 2018, 8, x8,FOR PEER REVIEW of812 Catalysts 2018, x FOR PEER REVIEW of 12 Catalysts 2018, x FOR PEER REVIEW of 12 Catalysts 2018, 8, x8,FOR PEER REVIEW 8 of812 under the optimal catalytic system. To our delight, both α-chloroacetone and α-chlorobenzophenone under the optimal catalytic system. To our delight, both α-chloroacetone and α-chlorobenzophenone reacted readily, readily, affording reacted affording corresponding corresponding β-keto β-keto esters esters in in high high yields yields within within 44 hh (entries (entries 5–8). 5–8). 1. 1 1.1. Table 4. 4. Alkoxycarbonylation ofof chloroacetates and α-chloro ketones. Table 4. Alkoxycarbonylation of chloroacetates and α-chloro ketones. Table 4.Alkoxycarbonylation Alkoxycarbonylation ofchloroacetates chloroacetates and α-chloro ketones. Table and α-chloro ketones 1. . 1. Table 4. Alkoxycarbonylation of chloroacetates and α-chloro ketones. Table 4. Alkoxycarbonylation of chloroacetates and α-chloro ketones. 1. 1. Table 4. Alkoxycarbonylation of chloroacetates α-chloro ketones. Table 4. Alkoxycarbonylation of chloroacetates andand α-chloro ketones.

999 999 9 9

Con. Con. Con. Con.2 Con. Con. (mol%) 2 22 Con. Con. (mol%) (mol%) (mol%) 2 2 (mol%) (mol%) 2 2 (mol%) (mol%) 98.5 98.5 98.5 98.5 98.5 98.5 98.598.5

Sel. Sel. Sel. Sel. Sel.Sel. (mol%) Sel. Sel. (mol%) (mol%) (mol%) (mol%) (mol%) (mol%) (mol%) 97.3 97.3 97.3 97.3 97.3 97.3 97.397.3

Yield Yield Yield Yield 3 Yield Yield (mol%) 3 33 Yield Yield (mol%) (mol%) (mol%) 3 3 (mol%) (mol%) 3 3 (mol%) (mol%) 95.8 95.8 95.8 95.8 95.895.8 95.895.8

MeOH MeOH MeOH MeOH MeOH MeOH MeOH MeOH

9 99 999 99

98.2 98.2 98.2 98.2 98.2 98.2 98.2 98.2

95.3 95.3 95.3 95.395.3 95.395.3

93.6 93.6 93.6 93.693.6 93.6 93.693.6

3 33 3 3 3 3

EtOH EtOH EtOH EtOH EtOH EtOH EtOH EtOH

9 99 9 9 99 9

97.6 97.6 97.6 97.697.6 97.6 97.6 97.6

94.8 94.8 94.8 94.894.8 94.8 94.8 94.8

92.5 92.5 92.5 92.592.5 92.592.5

4 44 4 4 4 4

i-PrOH i-PrOH i-PrOH i-PrOH i-PrOH i-PrOH i-PrOH

1212 12 12 12 12 12

97.0 97.0 97.0 97.097.0 97.097.0

96.0 96.0 96.0 96.096.0 96.096.0

93.1 93.1 93.1 93.193.1 93.193.1

5 55 5 5 5 5

MeOH MeOH MeOH MeOH MeOH MeOH MeOH

2 22 2 2 2 2

99.5 99.5 99.5 99.599.5 99.599.5

99.0 99.0 99.0 99.099.0 99.099.0

98.5 98.5 98.5 98.598.5 98.598.5

6 66 6 6 6 6

EtOH EtOH EtOH EtOH EtOH EtOH EtOH

2 22 2 2 2 2

99.2 99.2 99.2 99.299.2 99.299.2

99.2 99.2 99.2 99.299.2 99.299.2

98.4 98.4 98.4 98.498.4 98.498.4

Entry Entry Entry Entry Entry Entry Entry Entry

Organic Organic Organic Organic Organic Organic Chloride Organic Organic Chloride Chloride Chloride Chloride Chloride Chloride Chloride

ROH ROH ROH ROH ROH ROH ROH ROH

tt (h) (h) tt(h) (h) t (h) t (h) t (h) t (h)

MeOH MeOH MeOH MeOH MeOH MeOH MeOH MeOH

2 22 2 2 2 2

1 111 1 1 1 1

Product Product Product Product Product Product Product Product

1. 1. Table 4. Alkoxycarbonylation chloroacetates and α-chloro ketones. Table 4. Alkoxycarbonylation of of chloroacetates and α-chloro ketones. 1. 1. Table 4. Alkoxycarbonylation of chloroacetates and α-chloro ketones. Table 4. Alkoxycarbonylation of chloroacetates and α-chloro ketones. 1. 1. Table 4. Alkoxycarbonylation of chloroacetates and α-chloro ketones. Table 4. Alkoxycarbonylation of chloroacetates and α-chloro ketones. 1. 1. Table 4. Alkoxycarbonylation of chloroacetates andand α-chloro ketones. Table 4. Alkoxycarbonylation Alkoxycarbonylation of chloroacetates chloroacetates α-chloro ketones. 1. 1. Table 4. of α-chloro ketones. Table 4. Alkoxycarbonylation of chloroacetates andand α-chloro ketones.

Catalysts 2018, 8, x FOR PEER REVIEW Catalysts 2018, 8, 586

Entry Entry Entry Entry Entry Entry Entry Entry Entry Entry 1 1 1 11 11 11 1 2 2 22 22 2 22 2Entry Entry 3 3 33 33 3 33 3 4 144 44 44 4 44 4 5 25 55 55 5 55 5 6 36 66 66 6 66 6 7 7 77 477 7 77 7

Sel. Organic Con. Sel. Organic Con. Sel. Organic Con. ROH t (h) t (h) Product Sel. Organic Con. ROH Product Sel. Organic Con. 2 2 (mol%) Sel. Organic Con. ROH t (h) Product (mol%) Chloride (mol%) ROH t (h) Product Chloride (mol%) Sel. Organic Con. 2 Sel. Organic Con. 2 ROH t (h) Product ROH t (h) Product (mol%) Chloride (mol%) 1. Chloride Sel. Organic Con. Sel. Organic Con. 2 (mol%) 2 ketones. Table 4. Alkoxycarbonylation of chloroacetates α-chloro ROH Product ROH tt (h) t (h) (h)Table Product and(mol%) (mol%) Chloride (mol%) (mol%) Chloride (mol%) 4. Cont. 2 2 ROH t Product ROH (h) Product (mol%) Chloride (mol%) (mol%) Chloride (mol%) 2 2 (mol%) Chloride (mol%) (mol%) Chloride (mol%) MeOH 98.5 97.3 MeOH 9 9 98.5 97.3 MeOH 98.5 97.3 MeOH 99 99 98.5 97.3 MeOH 98.5 97.3 MeOH 98.5 97.3 MeOH 9 98.5 97.3 MeOH 9 98.5 97.3 MeOH MeOH 9 9 98.598.5 97.397.3 MeOH 98.2 95.3 MeOH 9 9 98.2 95.3 MeOH 98.2 95.3 MeOH 9 99 98.2 95.3 MeOH 98.2 95.3 MeOH 98.2 95.3 MeOH 99 99 98.2 95.3 MeOH 98.2 95.3 Con. Sel. Organic MeOH 98.2 95.3 MeOH 9 98.2 95.3 Sel. Organic Con. ROH t (h) Product 2 EtOH 9 97.6 94.8 ROH t (h) Product EtOH 9 97.6 94.8 (mol%) Chloride EtOH 97.6 2 (mol%) 94.8 EtOH 99 99 97.6 94.8 (mol%) Chloride (mol%) EtOH 97.6 94.8 EtOH 97.6 94.8 EtOH 9 97.6 94.8 EtOH 9 97.6 94.8 EtOH EtOH 9 9 97.697.6 94.894.8 MeOH 9 98.5 97.3 i-PrOH 12 97.0 96.0 i-PrOH 12 97.0 96.0 i-PrOH 97.0 i-PrOH 12 12 97.0 96.0 i-PrOH 97.0 96.0 i-PrOH 12 97.0 96.0 i-PrOH 12 12 97.0 96.0 i-PrOH 12 97.0 96.0 i-PrOH 12 97.0 96.0 i-PrOH 12 12 i-PrOH 97.097.0 96.096.0 MeOH 98.2 95.3 MeOH 99.5 99.0 MeOH 2 92 99.5 99.0 MeOH 22 2 99.5 99.0 MeOH 99.5 99.0 MeOH 99.5 MeOH 2 99.5 99.0 MeOH 99.5 99.0 MeOH 22 22 99.5 99.0 MeOH 99.5 99.0 MeOH MeOH 2 99.599.5 99.099.0 EtOH 99.2 99.2 EtOH 2 92 99.2 99.2 EtOH 97.6 94.8 EtOH 99.2 EtOH 2 2 99.2 99.299.2 EtOH 99.2 99.2 EtOH 99.2 EtOH 222 22 99.2 99.2 EtOH 99.2 99.2 EtOH 99.2 99.2 EtOH EtOH 2 2 99.299.2 99.299.2 i-PrOH 2 93.8 97.8 i-PrOH 212 93.8 97.8 i-PrOH 97.0 96.0 i-PrOH 93.8 97.8 i-PrOH 22 22 93.8 97.8 i-PrOH 93.8 97.8 i-PrOH 93.8 97.8 i-PrOH 93.8 97.8 i-PrOH 222 22 93.8 97.8 i-PrOH 93.8 97.8 i-PrOH 93.8 97.8 i-PrOH 93.8 97.8

8 of 12 8 of 12

Yield Yield Yield Yield Yield 3 3 Yield (mol%) (mol%) Yield 3 Yield 3 (mol%) (mol%) Yield Yield 3 3 (mol%) (mol%) 3 3 (mol%) (mol%) 3 (mol%) (mol%) 95.8 3 95.8 95.8 95.8 95.8 95.8 95.8 95.8 95.895.8 93.6 93.6 93.6 93.6 93.6 93.6 93.6 93.6 Yield 93.6 93.6 Yield 92.5 92.5 3 3 (mol%) 92.5 92.5 (mol%) 92.5 92.5 92.5 92.5 92.592.5 95.8 93.1 93.1 93.193.1 93.1 93.1 93.1 93.1 93.1 93.193.1 93.6 98.5 98.5 98.5 98.5 98.5 98.5 98.5 98.5 98.5 98.598.5 98.4 98.4 92.5 98.4 98.4 98.4 98.4 98.4 98.4 98.4 98.498.4 91.7 91.7 93.1 91.7 91.7 91.7 91.7 91.7 91.7 91.791.7

MeOH 99.5 99.0 98.5 EtOH 99.4 93.6 93.0 8 58 EtOH 4 24 99.4 93.6 93.0 EtOH 99.4 93.6 93.0 88 88 EtOH 44 44 99.4 93.6 93.0 EtOH 99.4 93.6 93.0 EtOH 99.4 93.6 93.0 8 88 EtOH 4 44 99.499.4 93.693.6 93.093.0 EtOH 99.4 93.6 93.0 EtOH 86 EtOH 4 99.4 93.6 93.0 EtOH 4 99.4 93.0 EtOH 2 99.2 99.2 98.4 1 Reaction condition: PdNPs@POP-Ph3P (125 mg, 0.02 mmol Pd), Me4NI (0.3 mmol), Na2HPO4 (4 1 Reaction condition: PdNPs@POP-Ph 3 P (125 mg, 0.02 mmol Pd), Me 4 NI (0.3 mmol), Na 2 HPO 4 (4 1 Reaction condition: PdNPs@POP-Ph3P (125 mg, 0.02 mmol Pd), Me4NI (0.3 mmol), Na2HPO 1 Reaction condition: PdNPs@POP-Ph 3P (125 mg, 0.02 mmol Pd), Me4NI (0.3 mmol), Na2HPO4 (44 (4 1 Reaction 1 Reaction condition: PdNPs@POP-Ph P (125 mg, 0.02 mmol Pd), Me 4NI (0.3 mmol), Na 2HPO 4 (4 condition: PdNPs@POP-Ph 3P 3(125 mg, 0.02 mmol Pd), Me 4NI (0.3 mmol), Na 2HPO 4 (4 1mmol), 1 mmol), chloroacetate or α-chloro ketones (2 mmol), ROH (4 mmol), 1,2-DEE (3 mL), CO (2 MPa), chloroacetate or α-chloro ketones mmol), ROH (4mmol mmol), 1,2-DEE (3(0.3 mL), CONa (22Na MPa), condition: PdNPs@POP-Ph 3P (125 mg, 0.02 mmol Me 4NI4NI (0.3 mmol), HPO 4 80 (444 80 Reaction condition: PdNPs@POP-Ph 3(2 P mmol), (125 mg, 0.02 Pd), Me mmol), 2HPO (4 1 Reaction 1 Reaction mmol), chloroacetate or α-chloro ketones (2 mmol), ROH (4 Pd), mmol), 1,2-DEE (3 mL), CO (2 condition: PdNPs@POP-Ph 3(125 P (125 mg, 0.02 mmol Pd), Me (0.3 mmol), Na 2MPa), HPO (4 1Reaction mmol), chloroacetate or α-chloro ketones (2 ROH (4 mmol), 1,2-DEE (3 mL), CO (2 80 condition: PdNPs@POP-Ph 3P 2 mg, 0.02 mmol Pd), Me 493.8 NI4NI (0.3 mmol), Na 2MPa), HPO 491.7 (4 80 i-PrOH 97.8 7Reaction condition: PdNPs@POP-Ph P (125 mg, 0.02 mmol Pd), Me NI (0.3 mmol), Na HPO (4 mmol), 2 mmol), chloroacetate or α-chloro ketones (2 mmol), ROH (4 mmol), 1,2-DEE (3 mL), CO (2 MPa), 80 2 mmol), chloroacetate or α-chloro ketones (2 mmol), ROH (4 mmol), 1,2-DEE (3 mL), CO (2 MPa), 80 3 4 2 4 n -n 0(4and nrepresent 1 represent the molar number of the stirring speed (800 rpm). n 0(2 -n01mmol), (n 0(n and n 1mmol), the molar number of the °C,°C, stirring speed (800 rpm). 1mmol), mmol), chloroacetate or α-chloro ketones ROH mmol), 1,2-DEE (3 mL), CO (2 MPa), 80 2 mmol), chloroacetate or α-chloro ketones (2 ROH (4 1,2-DEE (3 mL), CO (2 MPa), 80 ◦ 2 n10mmol), -n Conv. × mmol), 100% (n 0(4and n 1 mL), represent the number of °C, stirring speed (800 rpm). Conv. = n=0ROH × 100% -n (n and n1 mmol), represent molar number the °C, stirring speed (800 rpm). chloroacetate or α-chloro ketones mmol), 1,2-DEE (3 CO the (2 (3 MPa), 80CO C,CO stirring 1(4 mmol), chloroacetate or α-chloro ketones mmol), (4 1,2-DEE (3molar mL), (2 of MPa), 80 mmol), chloroacetate or α-chloro (2 ROH mmol), 1,2-DEE mL), (2 MPa), 80the 2ketones 2 (2 nn(2 -n -n 0 and n 1 represent the molar number of the °C, stirring speed (800 rpm). (n00ROH 0(n and represent the molar number of speed the °C, stirring speed (800 rpm). == nn= ××100% 1 × 100% 2 Conv. 2 Conv. n0rpm). −n1rpm). 0 n10 0-n 2speed (n and nn11 number represent the molar number of the °C, stirring (800 (n 0molar and n11 represent represent the molar number of the °C, stirring speed (800 =n0n0-n Conv. 100% n0 × 11 2 Conv. 1 × 100% 2 Conv. Conv. (800 rpm). = (800 × 100% (n n the of the added and remanent ECA 0represent 0 =and n -n n= -n (n 0 and n the molar number of the °C, stirring speed (n 0 and n 1 represent the molar number of the °C, stirring speed (800 rpm). 100% 0 Conv. × 100% n0 rpm). 1 10 0 n 0× 100% Conv. =n40nafter ×reaction). 100% 3 3 Conv. =nafter n t n99.4 nthe = mole number added and remanent ECA .n0.n=n0 mole number ofofof added remanent ECA before and 3 before t × 8 and EtOH 93.6 93.0 0100%. 0 the 3 Yield ntt100% before and after the reaction). Yieldand =and n0 reaction). = mole number of mole number ×chloride, 100% 3 Yield n= = added nafter 1==mole number of added and remanent ECA before and reaction). nafter .n 0 .n ==00mole number of added and remanent ECA before the reaction). 0 the 0 n 3 0 3 n100% n=tt ×n× Yield Yield = = mole number added and remanent ECA before and after the reaction). t × 100% .n 0.n mole number of of added and remanent ECA before and after the reaction). 3 3 n n 0 0 Yield = × 100% Yield = × 100% target product. .n 0 .n = number of added and remanent ECA before and after the reaction). t nt 0mole = mole number of added and remanent ECA before and after the reaction). 3 3 n 0t × 100% = n= × 100% Yield = mole number added remanent ECA before after reaction).Yield .n0 .n = 0mole number of of added andand remanent ECA before andand after thethe reaction). Yield Yield = n=0t0 ×nn100% 0 × 100% = mole number target product. chloride, = 1mole number of of target product. added chloride, n1 n 1 added 0 n4 0NI (0.3 mmol), Na2HPO4 (4 Reaction condition: PdNPs@POP-Ph 3 P (125 mg, 0.02 mmol Pd), Me n 1 = mole number of target product. added chloride, number of target product. added chloride, n1 =n 0 0 = mole number of target product. added chloride, n1mole mole number of target target product. added chloride, mole of product. added chloride, nn11 ==n 1 = mole number of target target product.ROH (4 mmol), 1,2-DEE (3 mL), CO (2 MPa), 80 added chloride, 3. Materials and Methods mmol), chloroacetate or number α-chloro (2 mmol), = mole number of product. added chloride, number ofketones target product. added chloride, n1 =n1mole 3. and Methods 3. Materials and Methods n 0 -n1 (n0 and n1 represent the molar number of the °C, stirring speed (800 rpm). 2 3. Materials Materials and Methods 3. Materials and Methods

Conv. = × 100% 3. and Methods 3.3.1. Materials and Methods Materials n0 3. and Methods 3. Materials Materials and Methods 3. Materials and Methods 3. Materials Materials and Methods Materials 3.1.3.1. Materials = mole and number of added and remanent ECA before and after2,2’-azobis(2-methylpropionitrile) the reaction). 3 Yield = n t × 100% .n0(AIBN), 3.1. Materials 3.1. Materials 4-Bromostyrene, phosphorus trichloride, palladium 3.1. Materials 3.1. Materials n0 3.1. Materials 3.1. Materials 3.1. Materials 3.1. Materials 4-Bromostyrene, phosphorus trichloride, 2,2’-azobis(2-methylpropionitrile) (AIBN), and 4-Bromostyrene, phosphorus trichloride, 2,2’-azobis(2-methylpropionitrile) (AIBN), and acetate (99%) were obtained from Energy Chemical Co. Ltd. (Shanghai, China). (AIBN), Chloroacetates, 4-Bromostyrene, phosphorus trichloride, 2,2’-azobis(2-methylpropionitrile) (AIBN), and 4-Bromostyrene, phosphorus trichloride, 2,2’-azobis(2-methylpropionitrile) and =phosphorus mole number of target product. added chloride, n1(99%) 4-Bromostyrene, phosphorus trichloride, 2,2’-azobis(2-methylpropionitrile) (AIBN), and 4-Bromostyrene, trichloride, 2,2’-azobis(2-methylpropionitrile) (AIBN), and palladium acetate were obtained from Energy Chemical Co. Ltd. (Shanghai, China). palladium acetate (99%) were obtained from Energy Chemical Co. Ltd. (Shanghai, China). 4-Bromostyrene, phosphorus trichloride, 2,2’-azobis(2-methylpropionitrile) (AIBN), and 4-Bromostyrene, phosphorus trichloride, 2,2’-azobis(2-methylpropionitrile) (AIBN), and chloroacetones, methanol, ethanol, 1,2-dimethoxyethane (1,2-DME), 1,2-diethoxyethane (1,2-DEE), palladium acetate (99%) were obtained from Energy Chemical Co. Ltd. (Shanghai, China). 4-Bromostyrene, phosphorus trichloride, 2,2’-azobis(2-methylpropionitrile) (AIBN), and 4-Bromostyrene, phosphorus trichloride, 2,2’-azobis(2-methylpropionitrile) (AIBN), and palladium acetate (99%) were obtained from Energy Chemical Co. Ltd. (Shanghai, China). palladium acetate (99%) were obtained from Energy Chemical Ltd. (Shanghai, China). palladium acetate (99%) were obtained from Energy Chemical Co.Co. Ltd. (Shanghai, China). Chloroacetates, chloroacetones, methanol, ethanol, 1,2-dimethoxyethane (1,2-DME), 1,2Chloroacetates, chloroacetones, methanol, ethanol, 1,2-dimethoxyethane (1,2-DME), 1,2palladium acetate (99%) were obtained from Energy Chemical Co. Ltd. (Shanghai, China). palladium acetate (99%) were obtained from Energy Chemical Co. Ltd. (Shanghai, China). diethylene glycol dimethyl ether (DGDE), triethyl orthoformate (TEOF), isopropanol, and bases chloroacetones, methanol, ethanol, 1,2-dimethoxyethane (1,2-DME), 1,2palladium acetate (99%)were wereobtained obtained from EnergyChemical Chemical Ltd.(Shanghai, (Shanghai, China). palladium acetate (99%) from Energy Co.Co.Ltd. China). Chloroacetates, chloroacetones, methanol, ethanol, 1,2-dimethoxyethane (1,2-DME), 1,23.Chloroacetates, Materials and Methods Chloroacetates, chloroacetones, methanol, ethanol, 1,2-dimethoxyethane (1,2-DME), 1,2Chloroacetates, chloroacetones, methanol, ethanol, 1,2-dimethoxyethane (1,2-DME), 1,2diethoxyethane (1,2-DEE), diethylene glycol dimethyl ether (DGDE), triethyl orthoformate (TEOF), diethoxyethane (1,2-DEE), diethylene glycol dimethyl ether (DGDE), triethyl orthoformate (TEOF), Chloroacetates, chloroacetones, methanol, ethanol, 1,2-dimethoxyethane (1,2-DME), 1,2Chloroacetates, chloroacetones, methanol, ethanol, 1,2-dimethoxyethane (1,2-DME), 1,2were of analytical grade and used as received. CO and Ar with the purity of 99.99% were obtained diethoxyethane (1,2-DEE), diethylene glycol dimethyl ether (DGDE), triethyl orthoformate (TEOF), Chloroacetates, chloroacetones, methanol, ethanol, 1,2-dimethoxyethane (1,2-DME), 1,2Chloroacetates, chloroacetones, methanol, ethanol, 1,2-dimethoxyethane (1,2-DME), 1,2diethoxyethane (1,2-DEE), diethylene glycol dimethyl ether (DGDE), triethyl orthoformate (TEOF), diethoxyethane (1,2-DEE), diethylene glycol dimethyl ether (DGDE), triethyl orthoformate (TEOF), diethoxyethane (1,2-DEE), diethylene glycol dimethyl ether (DGDE), triethyl orthoformate (TEOF), isopropanol, and bases were of analytical grade and used as received. CO and Ar with the purity of isopropanol, and bases were of analytical grade and used as received. CO and Ar with the purity of diethoxyethane (1,2-DEE), diethylene glycol dimethyl ether (DGDE), triethyl orthoformate (TEOF), diethoxyethane (1,2-DEE), diethylene glycol dimethyl ether (DGDE), triethyl orthoformate (TEOF), from a localand manufacturer. Pd/C (palladium content, 5ether wt%) was supplied byorthoformate Shaanxi Rock New isopropanol, and bases were of analytical grade and used as received. CO and Ar with the purity of diethoxyethane (1,2-DEE), diethylene glycol dimethyl (DGDE), triethyl (TEOF), diethoxyethane (1,2-DEE), diethylene glycol dimethyl ether (DGDE), triethyl orthoformate (TEOF), isopropanol, bases were of analytical grade and used as received. CO and Ar with the purity of 3.1. Materials isopropanol, and bases were of analytical grade and used as received. CO and Ar with the purity of isopropanol, and bases were of analytical grade and used as received. CO and Ar with the purity of 99.99% were obtained from aaTris(4-vinylphenyl)phosphane local manufacturer. Pd/C (palladium content, 55prepared wt%) was supplied by 99.99% were obtained from aof local manufacturer. Pd/C (palladium content, 5and wt%) was supplied by isopropanol, and bases were analytical grade and used as received. CO and Ar with the purity of isopropanol, and bases were of analytical grade and used as received. CO Ar with the purity of Materials Co. Ltd. (China). (3V-PPh was according to 3 )CO 99.99% were obtained from local manufacturer. Pd/C (palladium content, wt%) was supplied by isopropanol, and bases were of analytical grade and used as received. and Ar with the purity of isopropanol, and bases were of analytical grade and used as received. CO and Ar with the purity of 99.99% were obtained from a local manufacturer. Pd/C (palladium content, 5 wt%) was supplied by 99.99% were obtained from a local manufacturer. Pd/C (palladium content, 5 wt%) was supplied by 99.99% were obtained from a local manufacturer. Pd/C (palladium content, 5 wt%) was supplied by 1 4-Bromostyrene, phosphorus trichloride, 2,2’-azobis(2-methylpropionitrile) (AIBN), and Shaanxi Rock New Materials Co. Ltd. (China). Tris(4-vinylphenyl)phosphane (3V-PPh 3 ) was Shaanxi Rock New Materials Co. Ltd. (China). Tris(4-vinylphenyl)phosphane (3V-PPh 3 ) was 99.99% were obtained from a local manufacturer. Pd/C (palladium content, 5 wt%) was supplied by 99.99% were obtained from a local manufacturer. Pd/C (palladium content, 5 wt%) was supplied by the procedures reported ina the literature [35]. Tris(4-vinylphenyl)phosphane, Hwas NMR (400 MHz, Shaanxi Rock New Materials Co. Ltd. (China). Tris(4-vinylphenyl)phosphane (3V-PPh )) by was 99.99% were obtained from a local manufacturer. Pd/C (palladium content, 5 wt%) was supplied by 99.99% were obtained from local manufacturer. Pd/C (palladium content, 5 wt%) supplied Shaanxi Rock New Materials Co. Ltd. (China). Tris(4-vinylphenyl)phosphane (3V-PPh 3) 3was Shaanxi Rock New Materials Co. Ltd. (China). Tris(4-vinylphenyl)phosphane (3V-PPh was Shaanxi Rock New Materials Co. Ltd. (China). Tris(4-vinylphenyl)phosphane (3V-PPh 3) 3was palladium acetate (99%) were obtained from Energy Chemical Co. Ltd. (Shanghai, prepared according to the procedures reported in the literature [35]. Tris(4-vinylphenyl)phosphane, prepared according to the procedures reported in the literature [35]. Tris(4-vinylphenyl)phosphane, Shaanxi Rock New Materials Co. Ltd. (China). Tris(4-vinylphenyl)phosphane (3V-PPh 3)China). Shaanxi Rock New Materials Co. Ltd. (China). Tris(4-vinylphenyl)phosphane (3V-PPh 3was ) was DMSO-d ): δ = 7.59–7.41 (6 H, m), 7.31–7.14 (6 H, m), 6.74 (3 H, dd, J = 17.8, 11.0 Hz), 5.87 (3 H, dd, 6 prepared according to the procedures reported in the literature [35]. Tris(4-vinylphenyl)phosphane, ShaanxiRock Rock New Materials Ltd. (China). Tris(4-vinylphenyl)phosphane (3V-PPh ) was Shaanxi New Materials Co.Co.Ltd. (China). Tris(4-vinylphenyl)phosphane (3V-PPh 3) 3was prepared according to the procedures reported in the literature [35]. Tris(4-vinylphenyl)phosphane, according to the procedures reported in the literature Tris(4-vinylphenyl)phosphane, according to the procedures reported in the literature [35]. Tris(4-vinylphenyl)phosphane, 1prepared 1prepared 13 chloroacetones, ethanol, 1,2-dimethoxyethane (1,2-DME), 1,2H NMR MHz, DMSO-d ): == methanol, 7.59–7.41 H, m), 7.31–7.14 (6 H, m), 6.74 JJ17.8, == 17.8, 11.0 H NMR (400 MHz, DMSO-d 6): 6Jδ 7.59–7.41 (6 (6 H, m), 7.31–7.14 (6 [35]. H,MHz, m), 6.74 (3 (3 H,H, J =137.7, 11.0 prepared according to the procedures reported in the literature [35]. Tris(4-vinylphenyl)phosphane, prepared according to the procedures reported in the literature [35]. Tris(4-vinylphenyl)phosphane, JChloroacetates, =NMR 17.7, 1.0(400 Hz), 5.31 (3 H, dd, ===δδ10.9, 1.0 Hz) ppm; Cliterature NMR (100 DMSO-d ) δdd, = 136.2, 1prepared 6dd, 1prepared H NMR (400 MHz, DMSO-d 6 ): 7.59–7.41 (6 H, m), 7.31–7.14 (6 H, m), 6.74 (3 H, dd, 17.8, 11.0 according to the procedures reported in the [35]. Tris(4-vinylphenyl)phosphane, according to the procedures reported in the literature [35]. Tris(4-vinylphenyl)phosphane, H (400 MHz, DMSO-d 6 ): δ 7.59–7.41 (6 H, m), 7.31–7.14 (6 H, m), 6.74 (3 H, dd, J = 17.8, 11.0 1H1H NMR (400 MHz, DMSO-d ): δ = 7.59–7.41 (6 H, m), 7.31–7.14 (6 H, m), 6.74 (3 H, dd, J = 17.8, 11.0 NMR (400 MHz, DMSO-d 6): 6δ = 7.59–7.41 (6 H, m), 7.31–7.14 (6 H, m), 6.74 (3 H, dd, J = 17.8, 11.0 13NMR 13 1Hz), 1 diethoxyethane (1,2-DEE), diethylene glycol dimethyl ether (DGDE), triethyl orthoformate (TEOF), Hz), 5.87 (3 H, dd, J = 17.7, 1.0 Hz), 5.31 (3 H, dd, J = 10.9, 1.0 Hz) ppm; C NMR (100 MHz, DMSO5.87 (3 H, dd, J = 17.7, 1.0 Hz), 5.31 (3 H, dd, J = 10.9, 1.0 Hz) ppm; C (100 MHz, DMSOH NMR (400 MHz, DMSO-d 6 ): δ = 7.59–7.41 (6 H, m), 7.31–7.14 (6 H, m), 6.74 (3 H, dd, J = 17.8, 11.0 H NMR (400 MHz, DMSO-d 6115.4 ): δ = 7.59–7.41 (6 H, m), 7.31–7.14 (6 H, m), 6.74 (3 H, dd, J = 17.8, 11.0 136.0, 133.4, 133.4, 126.5, 126.4, ppm. 13 1NMR 1H 13 Hz), 5.87 (3 H, dd, J = 17.7, 1.0 Hz), 5.31 (3 H, dd, J = 10.9, 1.0 Hz) ppm; C NMR (100 MHz, DMSOH NMR (400 MHz, DMSO-d 6δ):=δ7.59–7.41 = 7.59–7.41 (6 H, m), 7.31–7.14 (6 H, m), 6.74 (3 H, dd, J = 17.8, 11.0 (400 MHz, DMSO-d 6): (6 H, m), 7.31–7.14 (6 H, m), 6.74 (3 H, dd, J = 17.8, 11.0 Hz), 5.87 (3 H, dd, J = 17.7, 1.0 Hz), 5.31 (3 H, dd, J = 10.9, 1.0 Hz) ppm; C NMR (100 MHz, DMSO13 13 Hz), 5.87 (3 H, dd, == 17.7, 1.0 Hz), 5.31 (3 H, dd, ==used 10.9, 1.0 Hz) ppm; C NMR (100 MHz, DMSOHz), 5.87 (3 H, H, dd, Jbases =JJ136.0, 17.7, 1.0 Hz), 5.31 (3 H, H, dd, Jand =JJ10.9, 10.9, 1.0 Hz) ppm; C13NMR NMR (100 MHz, DMSO13CO and were of analytical grade as received. and Ar with the DMSOpurity of 6)5.87 δ = 137.7, 136.2, 133.4, 133.4, 126.5, 126.4, 115.4 ppm. d 6isopropanol, )d δ = 137.7, 136.2, 136.0, 133.4, 133.4, 126.5, 126.4, 115.4 ppm. Hz), (3 dd, J = 17.7, 1.0 Hz), 5.31 (3 dd, J = 1.0 Hz) ppm; C (100 MHz, Hz), 5.87 (3 H, dd, 17.7, 1.0 Hz), 5.31 (3 H, dd, 10.9, 1.0 Hz) ppm; C NMR (100 MHz, DMSO13 13 = 137.7, 136.2, 133.4, 133.4, 126.5, 126.4, 115.4 ppm. Hz), 5.87 (3136.2, H, dd, = 17.7, 1.0 Hz), 5.31 (3126.4, H, dd, = 10.9, 1.0 Hz) ppm;C NMR C NMR (100 MHz, DMSOHz), (3 H, dd, J136.0, = J136.0, 17.7, 1.0 Hz), 5.31 (3 H, dd, J115.4 = J10.9, 1.0 Hz) ppm; (100 MHz, DMSOd 6)d δδ66))5.87 ==δ 137.7, 133.4, 133.4, 126.5, ppm. d δ = 137.7, 136.2, 136.0, 133.4, 133.4, 126.5, 126.4, 115.4 ppm. d 699.99% ) 137.7, 136.2, 136.0, 133.4, 133.4, 126.5, 126.4, 115.4 ppm. 3.2. Preparation of the Porous Polymer (POP-Ph P) were obtained from a local manufacturer. Pd/C (palladium content, 5 wt%) was supplied by 3126.4, d 136.2, 136.0, 133.4, 133.4, 126.5, 126.4, 115.4 ppm. dδδ66))==δδ137.7, 137.7, 136.2, 136.0, 133.4, 133.4, 126.5, 115.4 ppm. == 137.7, 136.2, 136.0, 133.4, 133.4, 126.5, 126.4, 115.4 ppm. d66))d 137.7, 136.2, 136.0, 133.4, 133.4, 126.5, 126.4, 115.4 ppm. 3.2. Preparation of the Porous Polymer (POP-Ph 3P) Shaanxi Rock New Materials Co. Ltd. Tris(4-vinylphenyl)phosphane (3V-PPh3) was 3.2. Preparation of the Porous Polymer (POP-Ph 3(China). P) 3.2. Preparation of the Porous Polymer (POP-Ph 3P) POP-Ph P was obtained according to 33the synthetic procedures reported by the literature [31], 3.2. Preparation the Porous Polymer (POP-Ph P) 3 of 3.2. Preparation of the Porous Polymer (POP-Ph 3P) 3.2. Preparation of the Porous Polymer (POP-Ph P) prepared according to the procedures reported in the literature [35]. Tris(4-vinylphenyl)phosphane, 3.2. Preparation of the Porous Polymer (POP-Ph 3P)3P) 3.2. Preparation ofobtained the Porous Polymer (POP-Ph with slight modifications. The polymerization reaction was carried out in stainless-steel autoclave 3.2. Preparation of the Porous Polymer 3P) 3.2. Preparation ofobtained the Porous Polymer (POP-Ph 3P) POP-Ph P was according to synthetic procedures reported the literature [31], with POP-Ph 3P 3was according to(POP-Ph thethe synthetic procedures reported byaby the literature [31], with 3was P was obtained according to the synthetic procedures by the literature [31], with 1HPOP-Ph POP-Ph obtained according the synthetic procedures by the literature with NMR33PP(400 MHz, DMSO-d 6): δ = to 7.59–7.41 (6 H, m), 7.31–7.14reported (6reported H, m), 6.74 (3 H, dd, J [31], = 17.8, 11.0 POP-Ph 3 P was obtained according to the synthetic procedures reported by the literature [31], with POP-Ph was obtained according to the synthetic procedures reported by the literature [31], with (Teflon-lined). Generally, tris(4-vinylphenyl)phosphane (3V-PPh , 2.0 g) and AIBN (50 mg) were slight modifications. The polymerization reaction was carried out in a stainless-steel autoclave slight modifications. The polymerization reaction was carried out in a stainless-steel autoclave POP-Ph 3 P was obtained according to the synthetic procedures reported by the literature [31], with 3 POP-Ph 3P was obtained according to the synthetic procedures reported by the literature [31], with slight modifications. The polymerization reaction was carried out in a stainless-steel autoclave 13 POP-Ph 3was P was obtained according to the synthetic procedures reported by the literature [31], with POP-Ph 3P(3 obtained according to the synthetic procedures reported by the literature [31], with slight modifications. The polymerization reaction was carried out in a stainless-steel autoclave Hz), 5.87 H, dd, J = 17.7, 1.0 Hz), 5.31 (3 H, dd, J = 10.9, 1.0 Hz) ppm; C NMR (100 MHz, DMSOslight modifications. The polymerization reaction was carried out in aathe stainless-steel autoclave slight modifications. The polymerization reaction was carried out in ain stainless-steel autoclave dissolved in THF (20The mL) intris(4-vinylphenyl)phosphane a 100 mL Teflon lining. After replacing air Teflon lining with Ar (Teflon-lined). Generally, (3V-PPh 3out , 2.0 g) and AIBN (50 mg) were (Teflon-lined). Generally, tris(4-vinylphenyl)phosphane (3V-PPh 3, 2.0 g) and AIBN (50 mg) were slight modifications. polymerization reaction was carried out in a stainless-steel autoclave slight modifications. The polymerization reaction was carried in stainless-steel autoclave Generally, tris(4-vinylphenyl)phosphane (3V-PPh 3out ,, in 2.0 AIBN (50 mg) were slight modifications. The polymerization reaction was carried in a and stainless-steel autoclave slight The polymerization reaction was carried ag) stainless-steel autoclave (Teflon-lined). Generally, tris(4-vinylphenyl)phosphane (3V-PPh 3out ,, 2.0 g) and AIBN (50 mg) were d(Teflon-lined). 6) δ modifications. = 137.7, 136.2, 136.0, 133.4, 133.4, 126.5, 126.4, 115.4 ppm. (Teflon-lined). Generally, tris(4-vinylphenyl)phosphane (3V-PPh 3 2.0 g) and AIBN (50 mg) were (Teflon-lined). Generally, tris(4-vinylphenyl)phosphane (3V-PPh 3 2.0 g) and AIBN (50 mg) were for 5 minin(1in L/min), the Teflon lining was transferred into an autoclave, and heated in anwith oven at dissolved THF mL) in aa 100 Teflon lining. After replacing air in the Teflon lining with Ar dissolved THF (20(20 mL) in atris(4-vinylphenyl)phosphane 100 mLmL Teflon lining. After replacing in g) the Teflon lining Ar (Teflon-lined). Generally, tris(4-vinylphenyl)phosphane (3V-PPh 3, 2.0 g) and AIBN (50 mg) were (Teflon-lined). Generally, (3V-PPh 3air , 2.0 2.0 and AIBN (50 mg) were dissolved in THF (20 mL) in 100 mL Teflon lining. After replacing air in the Teflon with Ar (Teflon-lined). Generally, (3V-PPh 3air ,air g) and AIBN (50 mg) were (Teflon-lined). Generally, tris(4-vinylphenyl)phosphane (3V-PPh 3, 2.0 g) and AIBN (50lining mg) were dissolved in THF (20 mL) in atris(4-vinylphenyl)phosphane 100 mL Teflon lining. After replacing in the Teflon lining with Ar ◦ C for dissolved in THF (20 mL) in a 100 mL Teflon lining. After replacing air in the Teflon lining with Ar dissolved in THF (20 mL) in a 100 mL Teflon lining. After replacing in the Teflon lining with Ar 100 24 h. After the polymerization reaction, the obtained white solid monolith was washed with dissolved in THF (20 mL) in a 100 mL Teflon lining. After replacing air in the Teflon lining with Ar dissolved in THF (20 mL) in a 100 mL Teflon lining. After replacing air in the Teflon lining with Ar dissolved THF (20 mL) a 100 Teflon After replacing air in the Teflon lining with Ar dissolved in in THF mL) in in aPolymer 100 mLmL Teflon lining. After replacing air in the Teflon lining with Ar 3.2. Preparation of(20 the Porous (POP-Ph 3P)lining. ethanol five times, and then dried under vacuum (60 ◦ C). POP-Ph3P was obtained according to the synthetic procedures reported by the literature [31], with slight modifications. The polymerization reaction was carried out in a stainless-steel autoclave (Teflon-lined). Generally, tris(4-vinylphenyl)phosphane (3V-PPh3, 2.0 g) and AIBN (50 mg) were dissolved in THF (20 mL) in a 100 mL Teflon lining. After replacing air in the Teflon lining with Ar

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3.3. Preparation of Catalysts In a typical synthesis, POP-Ph3 P (1.0 g) was added to 30 mL methanol containing 43 mg of palladium acetate (99%). After stirring at room temperature for 12 h, 10 mL of methanol solution containing 290 mg of NaBH4 was added into the above solution. The resulting mixture was vigorously stirred for 6 h. PdNPs@POP-Ph3 P was obtained after filtration and washed with methanol. ICP analysis suggested that the prepared PdNPs@POP-Ph3 P has a 1.70 wt% palladium loading. 3.4. Alkoxycarbonylation of Chloroacetates and Chloracetone In a 50 mL Teflon-lined stainless-steel autoclave, PdNPs@POP-Ph3 P (0.02 mmol Pd), Bu4 NI (0.3 mmol), Na2 HPO4 (4 mmol), 1,2-DEE (3 mL), organic chloride (2 mmol), and alcohol (4.0 mmol) were added into the reactor. After purging four times with CO, the autoclave was pressurized with CO to 2.0 MPa. Then, the reaction was reacted at 80 ◦ C for a definite time. After that, the autoclave was cooled to room temperature and carefully depressurized. The catalyst was separated by centrifugation at 8000 rpm for 10 min and washed with 1,2-DEE. The liquid mixture was collected and analyzed qualitatively by GC and GC-MS as reported in the literature [39,40]. All the prepared esters are known products, which we have reported previously [40]. 3.5. Characterization Nitrogen physisorption measurements were carried out at 77 K on a Micrometrics ASAP 2020 system (Norcross, USA), and the samples were treated under vacuum at 90 ◦ C for 10 h before the measurements. The surface area and pore size distribution were calculated by the Brunauer-Emmett-Teller (BET) and nonlocal density functional theory (NLDFT) methods, respectively. Fourier transform infrared (FTIR) spectra were recorded on a Bruker Equinox 55 FTIR spectrophotometer (Karlsruhe, Germany). The morphology of the sample was observed with a TESCAN MIRA3 field emission scanning electron microscope (FE-SEM, Brno, Czech) and a FEI Tecnai G2 F30 transmission electron microscope (TEM, Hillsboro, USA). X-ray photoelectron spectroscopy (XPS) experiments were carried out over a VG multilab 2000 spectrometer (Massachusetts, USA) fitted with a Mg-AlKa X-ray source. The amount of palladium loading and leaching was determined by inductively coupled plasma atomic emission spectroscopy (ICP, PerkinElmer Optima 8000, Massachusetts, USA). Gas chromatography (GC) was performed on a Scientific™ TRACE™ 1310 (Massachusetts, USA) equipped with a TRACE TR-WAX capillary column (Massachusetts, USA) and an FID. 4. Conclusions In conclusion, we have developed an active and recyclable catalyst for the synthesis of malonates via the carbonylation of chloroacetates. Under the optimal condition, the solid catalyst displayed high catalytic activity, affording corresponding dialkyl malonates and mixed-alkyl malonates in high yields. Importantly, the catalyst was quite robust, and could be reused four times with only an appreciable leaching of palladium species. Furthermore, the developed catalyst also showed high catalytic activities for the alkoxycarbonylation of α-chloro ketones. Thus, this protocol not only provides an active heterogeneous catalyst for the alkoxycarbonylation of chloroacetates and α-chloro ketones, but also provides some clues to develop efficient heterogeneous catalysts for other carbonylation reactions. Author Contributions: D.L., Y.L. and Y.W. designed the experiments; Y.W. and Z.C. performed the experiments and analyzed the data; Y.W., D.L. and Y.L. wrote the paper. Funding: This work is financial supported by the National Natural Science Foundation of China (No. 21763017), the Youth Talent Growth Project of Educational Department of Guizhou Province (qian jiao he KY [2016]264), the Natural Science Foundation of Guizhou Province (qian ke he ji chu [2018]1414 and [2016]1133), the Liupanshui Key Laboratory of High Performance Fibers and Advanced Porous Materials (52020-2017-02-02 and 52020-2018-03-02), and the Funds of Liupanshui Normal University (LPSSYKJTD201501 and LPSSYZDXK201602).

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Conflicts of Interest: The authors declare no conflict of interest.

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