Tài liệu Cu-based organic frameworks as catalysts for c-c and c-n coupling reactions.

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VIETNAM NATIONAL UNIVERSITY – HO CHI MINH CITY HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY DANG HUYNH GIAO Cu-BASED ORGANIC FRAMEWORKS AS CATALYSTS FOR C–C AND C–N COUPLING REACTIONS Major: Organic Chemical Technology Major code: 62527505 PhD THESIS SUMMARY HO CHI MINH CITY 2015 The thesis was completed in University of Technology –VNU-HCM Advisor 1: Advisor 2: Prof. Dr. Phan Thanh Son Nam Dr. Le Thanh Dung Independent examiner 1: Prof. Dr. Dinh Thi Ngo Independent examiner 2: Assoc. Prof. Dr. Nguyen Thi Phuong Phong Examiner 1: Assoc. Prof. Dr. Nguyen Cuu Khoa Examiner 2: Assoc. Prof. Dr. Nguyen Thai Hoang Examiner 3: Assoc. Prof. Dr. Le Thi Hong Nhan The thesis will be defended before thesis committee at ..................................................................................................................... ..................................................................................................................... On……………………………………………………………………………….. The thesis information can be looked at following libraries: - General Science Library Tp. HCM - Library of University of Technology – VNU-HCM Abstract Four highly porous Copper-based organic frameworks (Cu-MOFs) such as Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY) and Cu(BDC) were synthesized and characterized by X-ray powder diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma mass spectrometry (ICP-MS), hydrogen temperature-programmed reduction (H2 -TPR) and nitrogen physisorption measurements. Three Cu-MOFs including Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY) were used as heterogeneous catalysts for direct CC coupling reactions to synthesize propargylamines. Cu(BDC) was employed as heterogeneous catalyst for CN coupling reaction to synthesize quinoxalines. These catalytic systems offered practical approaches with high yields and selectivity. Additionally, broad functionality was shown to be compatible. The Cu-MOFs catalysts could be recovered and reused several times without significant degradation in catalytic activity. To the best of our knowledge, these transformations using Cu-MOFs catalysts were not previously mentioned in the literature. INTRODUCTION Homogeneous transition metals are often employed as catalysts to promote the transformation of an organic compound in the liquid phase. However, difficulties in removing catalyst impurities in the final products narrow the application of homogeneous catalytic systems, especially in pharmaceutical industry. Metal-organic frameworks (MOFs) have recently attracted significant attention with advantages in replacing homogeneous catalysts in chemical process. Propargylamines and quinoxalines have emerged as important intermediates in the synthesis of numerous nitrogen-containing biologically active compounds as well as a variety of functional organic materials. Many transition-metal catalytic systems, both in homogeneous and heterogeneous catalysis, were applied for the preparation of propargylmines and quinoxalines via the C−C and C−N coupling reations. However, many of those processes suffered from one or more limitations such as harsh reaction conditions, low product yields, tedious work-up procedures, and the use of toxic metal salts as catalysts. Consequently, study for the high-effective, sustainable synthetic routes of proparylamines and quinoxalines is an unquestionable trend in near future. Among several popular MOFs, copper-based organic frameworks (CuMOFs) previously exhibited high activity in various organic reactions due to their unsaturated open copper metal sites. Especially, the Cu-MOFs including Cu3 (BTC)2 , Cu(BDC), Cu2 (BDC)2 (DABCO) and Cu2 (BPDC)2 (BPY), which are constructed from copper salts and 1,4-benzenedicarboxylic acid (BDC), 1,3,5benzenetricarboxylic acid (BTC) and 4,4’-biphenyldicarboxylic acid (BPDC), exhibit many advantages for catalytic application. Those organic linkers are commercial and relatively cheap. These Cu-MOFs have surface areas higher than 1000 m2 /g (except for Cu(BDC)) and thermal stability of up to 300 °C or higher. Moreover, the largest pore apertures of Cu2 (BDC)2 (DABCO), Cu3 (BTC)2 and Cu2 (BPDC)2 (BPY) are in the range of 7.5 – 9.0 Å which can allow average size substrates to enter the pores and reach catalytic sites. However, to the best of our knowledge, the direct C–C and C–N coupling reactions for the synthesis of proparylamines and quinoxalines using these CuMOFs were not previously mentioned in the literature. The first purpose of this thesis is to synthesize Cu-MOFs including Cu3 (BTC)2 , Cu(BDC), Cu2 (BDC)2 (DABCO) and Cu2 (BPDC)2 (BPY). The second objective is to study their use as heterogeneous catalysts for the direct C–C and C–N coupling reactions to form proparylamines and quinoxalines. CHAPTER 1 LITERATURE REVIEW: Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY), Cu(BDC) AND C–C, C–N COUPLING REACTIONS 1.1 Introduction to metal-organic frameworks  In comparison with other porous materials, MOFs possess unique structures, in which the metal ions combine with organic linkers to form secondary building units (SBUs), which dictate the final topology of a whole framework. The combination of numerous kinds of linkers and metal ions can lead to considerable diversity of this material.  Many studies reported MOFs containing copper active sites as efficient heterogeneous catalysts.  Among organic linkers that are often used for Cu-MOFs synthesis, 1,4benzenedicarboxylic acid (BDC), 1,3,5-benzenetricarboxylic acid (BTC) and 4,4’-biphenyldicarboxylic acid (BPDC) have advantages that they are commercial and relatively cheap. In another approach, MOFs can be constructed from mixed linkers to provide greater flexibility in terms of surface area, modifiable pore size and chemical environment. Linkers BDC and BPDC could be easily combined with pillar linkers such as 1,4-diazabicyclo [2.2.2]octane (DABCO) or 4,4’bipyridine (BPY) to form rigid Cu-MOFs. Therefore, Cu-MOFs constructed from BDC, BTC or BPDC recently attracted great attention. 1.1 1.2 Cu3 (BTC)2, Cu(BDC), Cu2 (BDC)2(DABCO) and Cu2 (BPDC)2 (BPY)  Cu3 (BTC)2 , Cu(BDC), Cu2 (BDC)2 (DABCO) and Cu2 (BPDC)2 (BPY) constitute Cu-MOFs that contain common SBUs of two 5-coordinate copper cations bridged in a paddle wheel-type configuration (Fig. 1.4). Fig 1.4. Common coordination geometry of paddle wheel building units of Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY), Cu(BDC) and their framework structures (L = Carboxylate linker, P = N-containing bidentate pillar linker and G = Guest molecule).  Cu3 (BTC)2 , Cu(BDC), Cu2 (BDC)2 (DABCO) and Cu2 (BPDC)2 (BPY) are synthesized by solvothermal methods. Their physicochemical properties are presented in Table 1.2: Table 1.2: Physicochemical properties of Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO) and Cu2 (BPDC)2 (BPY) MOFs Decomposition BET surface temperature area (°C) (m2 /g) Cu3 (BTC)2 300 1000-1450 Cu(BDC), Pore aperture (Å2 ) 8.0  9.0 Cu(BDC) 325 545-625 _ Cu2 (BDC)2 (DABCO) 300 1461 7.5  7.5 4.7  3.8 Cu2 (BPDC)2 (BPY) 320 1210 12.3  7.8 8.8  8.0  Cu3 (BTC)2 , Cu(BDC), Cu2 (BDC)2 (DABCO) and Cu2 (BPDC)2 (BPY) can be characterized by various techniques, such as single crystal X-ray diffraction (SC-XRD), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), inductively coupled plasma mass spectrometry (ICP-MS), and gas physisorption measurement, etc. 1.3 C–C coupling reactions  Traditional routes to access propargylamines often suffer from disadvantages such as hard conditions, low yields, and limited reaction scopes.  Difficults in removing catalysts contaminated in final products narrow the application of homogeneous catalytic systems, especially in pharmaceutical industry.  Recently, the most attractive synthetic route is the use of Manich-type reaction, a three component procedure of terminal alkynes, formaldehyde, and secondary amines. However, the aldehyde-free, oxidative Manich reactions have not been previously reported under any catalysis. 1.4 C–N coupling reactions  Traditionally, quinoxalines have been prepared by the acid-catalyzed condensation of 1,2-aryldiamines with 1,2-diketone or 1,2-diketone alternatives, such as epoxides, α-bromoketones, and α-hydroxyketones.  Although the contamination of the desired products with transition metals or other solids would be minimized under heterogeneous catalysts conditions, developing an efficient heterogeneous catalyst system for the quinoxaline synthesis still remains to be explored. 1.2 1.5 Aim and objectives  Propargylamines and quinoxalines are frequently found as the versatile intermediates for the synthesis of many nitrogen-containing biologically active compounds.  Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY) and Cu(BDC) have many advantages for suitable catalytic applications.  To the best of our knowledge, the direct C–C and C–N coupling reactions for synthesizing proparylamines and quinoxalines using these Cu-MOFs were not previously mentioned in the literature.  The main aim of this dissertation is using Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY) and Cu(BDC) as catalysts for the synthesis of proparylamines and quinoxalines: i) Synthesis and characterization of the Cu-MOFs including Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY) and Cu(BDC); ii)Catalytic studies of Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY) on C–C coupling reactions between amine compounds and terminal alkynes, catalytic studies of Cu(BDC) on C–N coupling reaction between α-hydroxyacetophenone and ophenylenediamine. CHAPTER 2 SYNTHESIS AND CHARACTERIZATION OF Cu3 (BTC)2 , Cu2 (BDC)2(DABCO), Cu2 (BPDC)2 (BPY), Cu(BDC) 2.1 Introduction In this chapter, the synthesis, characterization methods, physicochemical properties of Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY) and Cu(BDC) were studied. 2.2 Experimental  Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY) and Cu(BDC) were synthesized by solvothermal methods.  They were charactized by different techniques such as PXRD, FT-IR, SEM, TEM, TGA, ICP-MS and nitrogen physisorption measurement. 2.3 Results and discussions 2.3.1 Synthesis and characterization of Cu3 (BTC)2  The synthesis yield was approximately 85% based on H3 BTC.  The copper content in the Cu3 (BTC)2 was 29% (ICP-MS).  The BET surface areas of Cu3 (BTC)2 were achieved approximately 1799 m2 /g, the Langmuir surface areas were achieved approximately 2007 m2 /g.  The thermal stability of Cu3 (BTC)2 is over 300 o C (TGA).  The PXRD pattern of the synthesized Cu3(BTC)2 was similar to the simulated pattern previously reported in the literature (Figure 2.2).  The SEM micrograph indicated Cu3(BTC)2 exhibited a cubic octahedral morphology (Fig. 2.4). Figure 2.2 X-ray powder diffractograms of the simulated Cu3 (BTC)2 (a) and the synthesized Cu3 (BTC)2 (b) 2.3.2 Figure 2.4 SEM micrograph of the Cu3 (BTC)2 Synthesis and characterization of Cu2 (BDC)2 (DABCO)  The synthesis yield was approximately 66% based on H2 BDC.  The copper content in the Cu2 (BDC)2 (DABCO) was 21.5% (ICP-MS).  Langmuir surface areas of Cu2 (BDC)2 (DABCO) were achieved approximately 1174 m2 /g.  The Cu2 (BDC)2 (DABCO) was stable up over 300 °C. Figure 2.8 X-ray powder diffractograms of the simulated Cu2 (BDC)2 (DABCO) (a) and the synthesized Cu2 (BDC)2 (DABCO) (b)  Figure 2.9 SEM micrograph of the Cu2 (BDC)2 (DABCO) The PXRD pattern of the synthesized Cu2 (BDC)2 (DABCO) was in good accordance with the simulated pattern of the optimized plausible structure by using Cerius 2 (Fig. 2.8).  Figure 2.9 showed that SEM micrograph of Cu2 (BDC)2 (DABCO) revealed that well-shaped, high- quality cubic crystals were formed. 2.3.3 Synthesis and characterization of Cu 2 (BPDC)2 (BPY)  The synthesis yield was approximately 66% based on H2 BPDC.  The copper component in Cu2 (BPDC)2 (BPY) was 18% (ICP-MS).  Langmuir surface areas of 1519 m2 /g were achieved for the Cu2 (BPDC)2 (BPY), BET surface areas were achieved 1082 m2 /g.  TGA result indicated that the Cu2 (BPDC)2 (BPY) was stable up to over 300 °C.  PXRD pattern of the Cu2 (BPDC)2 (BPY) (Fig. 2. 14) showed the presence of a sharp peak at 2θ = 6°, being consistent with the simulated pattern of single-crystal previously reported by James and co-workers.  The SEM micrograph of the Cu2 (BPDC)2 (BPY) revealed that the formed crystals were well-shaped cubic (Fig 2.16). Figure 2.14 X-ray powder diffractograms of the simulated Cu2 (BPDC)2 (BPY) (a) and the synthesized Cu2 (BPDC)2 (BPY) (b) Figure 2.16 SEM micrograph of the Cu2 (BPDC)2 (BPY) 2.3.4 Synthesis and characterization of Cu(BDC)  The synthesis yield was approximately 66% based on H2 BDC.  The copper content in the Cu(BDC) was 29% (ICP-MS).  Langmuir surface areas of 616 m2 /g were achieved for the material.  TGA result indicated that the Cu(BDC) was stable up to over 300 °C.  The PXRD pattern of the Cu(BDC) was also similar to the simulated pattern previously reported in the literature (Fig. 2.20).  The SEM micrograph indicated the formation of the cubic microcrystals of the Cu(BDC). 1.3 Figure 2.20 X-ray powder diffractograms of the simulated Cu(BDC) (a) and the synthesized Cu(BDC) (b) Figure 2.22 SEM micrograph of the Cu(BDC) 2.4 Conclusion The four Cu-MOFs such as Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY) and Cu(BDC) were successfully synthesized and characterized by PXRD, FT-IR, TGA, H2 TPR, ICP-MS and nitrogen physisorption measurements. CHAPTER 3 CATALYTIC STUDIES OF Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY), Cu(BDC) ON C–C AND C–N COUPLING REACTIONS 3.1 Introduction  Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY) and Cu(BDC) exhibited high activity for many reactions due to their unsaturated open metal sites.  In this chapter, the catalytic performance of Cu3 (BTC)2 , Cu2 (BDC)2 (DABCO), Cu2 (BPDC)2 (BPY) and Cu(BDC) on the C–C, C–N coupling reactions will be discussed (Scheme 3. 1 and Scheme 3.2). Scheme 3.1. The synthesis of propargylamines Scheme 3.2. The synthesis of quinoxaline 1.4 3.2 Experimental Catalytic studies of Cu3 (BTC)2 on C–C coupling reaction from N,Ndimethylanilines and terminal alkynes (reaction 1); Catalytic studies of Cu2 (BDC)2 (DABCO) on C–C coupling reaction from N-methylanilines and terminal alkynes (reaction 2); Catalytic studies of Cu2 (BPDC)2 (BPY) on C–C coupling reaction from Tetrahydroisoquinoline, benzaldehydes and terminal alkynes (reaction 3); Catalytic studies of Cu(BDC) on C–N coupling reaction from α-hydroxyacetophenone and phenylenediamine (reaction 4). The reaction conversions were monitored by withdrawing aliquots from the reaction mixture at different time intervals, quenching with water (1 ml), drying over anhydrous Na 2 SO4 , analyzing by Gas chromatographic (GC) with reference to inernal standard. All major products from four reactions were confirmed by 1 H NMR and 13 C NMR. 3.3 Results and discussions 3.3.1 Catalytic studies of Cu3 (BTC)2 on C–C coupling reaction (1) Scheme 3.3. The direct oxidative C-C coupling reaction between N,Ndimethylaniline and phenylacetylene using Cu3 (BTC)2 as catalyst.  All optimized synthetic conditions of reaction 1 between N,Ndimethylaniline and phenylacetylene are summaried in Table 3.2. Reaction conditions Temperature Results (Reaction conversion (%)) RT (0), 100 °C (56), 110 °C (76), 120 °C (96) Molar ratio of Phenylacetylene : 1:1 (85), 1: 2 (96), 1:3 (93) N,N-dimethylaniline Catalyst amount (%) Oxidant 0 % (12), 1 % (65), 3 % (83), 5 % (96), 7 %(87) TBHP (96), TBHP in decane (100), DTBP (44), CHP (96, by product), K2 S2 O8 and H2 O (no product) 1 (54), 1.5 (76), 2 (82), 3 (96) DMA (96), Clorobenzene (45), o-xylene (40), DMF, DEF, NMP (99, 95, 100, byproduct) Similar to Cu3 (BTC)2 No product appeared Oxidant concentration (equiv) Solvent Other Cu-MOFs, Cu salts Other MOFs leaching test 100 80 80 Conversion (%) Conversion (%) 5 mol% 100 60 40 60 40 20 20 0 0 0 25 50 75 100 Time (min) 125 1 150 Figure 3.9. Leaching test indicated no contribution from homogeneous catalysis of active species leaching into reaction solution 2 3 4 5 6 Run 7 8 9 10 Figure 3.12. Catalytic recycling studies  Leaching test indicated no contribution from homogeneous catalysis of active species leaching into reaction solution (Fig. 3.9).  The Cu3 (BTC)2 catalyst could be recovered and reused ten times in the direct C-C coupling reaction between N,N-dimethylaniline and phenylacetylene without a significant degradation in catalytic activity. Indeed, a conversion of 95% was still obtained after 150 min for the transformation in the ten run (Fig. 3.12).  XRD result confirmed that the reused Cu3 (BTC)2 was still highly crystalline. Moreover, FT-IR analysis of the reused Cu3 (BTC)2 exhibited a similar absorption as compared to that of the fresh CuMOF.  With various coupling starting materials of N,N-dimethylanilines and terminal alkynes, all the products were characterized by 1 H NMR. The yields were isolated yields. The results showed that the isolated yields were achieved from 55% to 81%. 3.3.2 Catalytic studies of Cu2 (BDC)2 (DABCO) on C–C coupling reaction (2) Scheme 3.4. The direct C-C coupling reaction via methylation and C-H functionalization of N-methylaniline and phenylacetylene.  All optimized synthetic conditions of reaction 2 between Nmethylaniline and phenylacetylene are summaried in Table 3.4. Reaction conditions Temperature Results (Reaction conversion (%)) RT (3), 100 °C (37), 110 °C (67), 120 °C (96) Molar ratio of Phenylacetylene : 1:1 (79), 1: 2 (96), 1:3 (96) N-methylaniline Catalyst amount (%) Oxidant Oxidant concentration (equiv) Solvent 0 % (11), 1 % (83), 3 % (89), 5 % (96), 7 %(96) TBHP (96), TBHP in decane (100), DTBP (44), K2 S2 O8 and Dilauroyl peroxide (no product) 1 (54), 1.5 (76), 2 (83), 3 (96) DMA (96), DMF (82), NMP (97, byproduct), DEF (56), Clorobenzene (57), Diclorobenzene (73), o-xylene (54), Other Cu-MOFs, Cu salts Other MOFs Leaching test Mesitylene (45) Similar to Cu2 (BDC)2 (DABCO) No product appeared 5 mol% 100 100 80 Conversion (%) Conversion (%) 80 60 40 40 20 20 0 0 0 30 60 90 120 Time (min) 150 Figure 3.22. Leaching test indicated no contribution from homogeneous catalysis of active species leaching into reaction solution  60 180 1 2 3 4 5 6 Run 7 8 9 10 Figure 3.24. Catalytic recycling studies. Leaching test indicated no contribution from homogeneous catalysis of active species leaching into reaction solution (Fig. 3.22).  The Cu2 (BDC)2 (DABCO) catalyst could be recovered and reused ten times in the direct C-C coupling reaction between N-methylaniline and phenylacetylene without a significant degradation in catalytic activity. Indeed, a conversion of 96% was still obtained after 180 min for the transformation in the ten run (Fig. 3.24).  With various coupling starting materials of N-methylanilines and terminal alkynes, all the products were characterized by 1 H NMR. The yields were isolated yields. The results showed that the isolated yields were achieved from 58% to 77%.  FT-IR analysis of the reused Cu2 (BDC)2 (DABCO) exhibited a slightly different absorption as compared to that of the fresh Cu-MOF. The crystallinity of the reused Cu-MOF was found to be slightly different to that of the fresh catalyst. However, XRD result indicated that the reused Cu2 (BDC)2 (DABCO) was still highly crystalline. 3.3.3. Catalytic studies of Cu2 (BPDC)2 (BPY) on C–C coupling reaction (3) Scheme 3.5. The A3 reaction of tetrahydroisoquinoline, benzaldehyde, and phenylacetylene using Cu2 (BPDC)2 (BPY) catalyst.  All optimized synthetic conditions of reaction 3 from Tetrahydroisoquinoline, benzaldehyde and phenylacetylene are summaried in Table 3.5. Reaction conditions Temperature Molar ratio of Phenylacetylene : Benaldehyde: Tetrahydroisoquinoline Catalyst amount (%) Solvent Pyridine (equiv) Adding product Other Cu-MOFs, Cu salts Results (Reaction conversion (%)) RT (10), 60 °C (20), 70 °C (46), 80 °C (95), 90 (96) 1:1:1 (88), 1:1.1: 1.1 (95), 1:1.2: 1.2 (96), 1:1.5: 1.5 (96) 0 % (10), 1 % (32), 3 % (66), 5 % (95) Toluene (95), p-xylene (52), metylsilene (36), NMP (31), DMA (80), 1,4-dioxane (39) As a catalyst poison with copper sites Product adsorbed on the copper sites of Cu2 (BPDC)2 (BPY) Higher than other Cu-MOFs, similar to Cu salts Other MOFs  No product appeared Interestingly, the Cu2 (BPDC)2 (BPY)-catalyzed C1-alkynylation reaction of tetrahydroisoquinoline offered high regioselectivity to the endo-yne-product. Indeed, more than 99% of (A) was achieved, leaving less than 1% of (B) in the product mixture. 5 mol% Leaching test 80 80 % Selectivity 100 Conversion (%) 100 60 40 60 40 20 20 0 0 0 30 60 90 120 150 180 1 2 3 4 Run 5 6 7 Time (min) Figure 3.35. Leaching test indicated no contribution from homogeneous catalysis of active species leaching into reaction solution  Figure 3.36. Catalyst recycling studies Fig. 3.35 indicated that no contribution from homogeneous catalysis of active species leaching into reaction solution after Cu2 (BPDC)2 (BPY) catalyst was removed.  The Cu2 (BPDC)2 (BPY) catalyst could be recovered and reused several times for the copper-catalyzed A3 reaction of tetrahydroisoquinoline, benzaldehyde, and phenylacetylene without a significant degradation in catalytic activity. Indeed, a conversion of more than 95% was still achieved in the 7th run (Fig. 3.36).  As compared to the FT-IR result of the fresh Cu2 (BPDC)2 (BPY), the spectra of reused Cu-MOF exhibited a similar absorption. Moreover, the XRD result of the recovered Cu2 (BPDC)2 (BPY) indicated that the
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