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Department of Chemistry & Biochemistry National Chung Cheng University

ZnO Nanoparticle-Supported NHCs as Recyclable Catalysts for Nucleophilic Substitution and Aldol Condensation Reactions in Aqueous Solutions. 演講者： 呂 晉安 指導教 授 : 于淑君 博士 106/12/04. Department of Chemistry & Biochemistry National Chung Cheng University. Outline. Introduction.

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Department of Chemistry & Biochemistry National Chung Cheng University

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  1. ZnO Nanoparticle-Supported NHCs as Recyclable Catalysts for Nucleophilic Substitution and Aldol Condensation Reactions in Aqueous Solutions 演講者：呂晉安 指導教授: 于淑君 博士 106/12/04 Department of Chemistry & Biochemistry National Chung Cheng University

  2. Outline Introduction • The choice of metal-Zn • The NHC applications • Aldo condensation and nucleophilic substitution Experimental • Synthesis and characterization ofimidazolium salt[HOOCMMIM][PF6] 2 • Synthesis and characterization of Zinc oxide nanoparticle[HOOCMMIM][PF6] 3 Results and Discussion • The activity of [HOOCMMIM][PF6] 2toward aldol condensation and nucleophilic substitution • The catalytic activity ofZnO-[HOOCMMIM][PF6] 3 Conclusions

  3. The Advantage of Zinc Abundance in Earth’s crust (ppm) Price (USD 100 g, Sigma-Adrich) Salient U.S. recycling statistics for Zinc (U.S. Geological Survey - 2014)

  4. The Advantage of Zinc Applications of Zinc (International Zinc Association India) Acute toxicity LD50 Oral - rat

  5. Nanomaterial-Based Catalyst Concept: Higher surface area increasing catalytic activity Can also be easily separated and recycled with more retention of catalytic activity

  6. Applications of ZnO-NPs as Catalysts Mannich reaction Knoevenagel condensation ZnO coumarins 4-amino-5-pyrimidine carbonitrile β-phosphono malonates polyhydroquinoline Synthesis of: 2,3-disubstituted quinalolinones benzimidazole β-acetamido ketones/esters

  7. ZnO as Catalysts for Knoevenagel Condensation Table. Optimization of the ZnO nanoparticles catalyzed model reaction for synthesis of ethyl 2-oxo-2H-chromene-3-carboxylate. aIsolated yield bReactionwas carried out at 120 ◦C cReaction was carried out at MW 300W, 120 ◦C Recyclability of ZnO nano catalyst. Kumar, B. V.; Naik, H. S. B.; Girija, D.; Kumar, B. V., Journal of Chemical Sciences 2011,123 (5), 615-621.

  8. Properties of N-Heterocyclic Carbenes • Diaminocarbenes (NHCs) are strong σ-donors, have reactivities like other classical 2 e - donors: phosphines, amines, ethers • NHCs are easier to make and store than their phosphine counterparts. Arduengo, A. J.; Harlow, R. L.; Kline, M., Journal of the American Chemical Society 1991,113 (1), 361-363.

  9. Applications of N-Heterocyclic Carbenes • Acyl anions: • Benzoin Condensations • Stetter Reactions • Hydrocylations • Azolium Enolates / Acyl Azoliums: • [2+2] Cycloadditions • [4+2] Cycloadditions • [3+2] Cycloadditions • Enolate Chemistry • Homoenolates: • Cyclopentene Synthesis • Spiro Annulations • Lactam / Lactone Synthesis • Conversion of Enals to Saturated Esters

  10. Nucleophilic Substitution Mechanism Vanos, C. M.; Lambert, T. H., AngewandteChemie International Edition 2011,50 (51), 12222-12226.

  11. Aldol Condensation BA: benzaldehyde HA: heptanal JA: jasminaldehyde UiO – 66: Zr6O4(OH)4(O2C–C6H4–CO2)6 11 Frederik V.; Rob A.; Alexandre V.; Christian S.; Dirk D. V. Chem. Commun., 2011, 47, 1521–1523

  12. Aldol Condensation UiO – 66: Zr6O4(OH)4(O2C–C6H4–CO2)6 Mechanism aPretreated under deep vacuum at high temperatures (573 K). bPretreated under deep vacuum at high temperatures (473 K). Frederik V.; Rob A.; Alexandre V.; Christian S.; Dirk D. V. Chem. Commun., 2011, 47, 1521–1523

  13. Motivation Organic Catalyst Molecular • We understood of the advantages of zinc oxide nanoparticles, and hoped to synthesis ZnO nanoparticles supported nanoparticles, which anchored the molecular catalyst with spacing linker, and different solvents proportions could be used to adjust the dispersion of the nanoparticles, • In the case of good dispersibility of ZnO nanoparticles, the structure and the quantitative determination can be performed with spectroscopic analysis in solution because the molecular catalyst was completely exposed to the solvent with spacing linker. • In addition, the catalyst contained insoluble nano-particles, which could be separated and recovered by mechanical ways such as centrifugation, sedimentation, filtration without solvent wasted.

  14. Synthesis of ImidazoliumSalts [HOOCMMIM][Br] (1) 48.88 % Sharma, H.; Singh, N.; Jang, D. O., Tetrahedron Letters 2014,55 (49), 6623-6626. [HOOCMMIM][Br] (1) [HOOCMMIM][PF6] (2) 93.27 % Ma, C.; Li, J.; Peng, J.; Bai, Y.; Zhang, G.; Xiao, W.; Lai, G., Journal of Organometallic Chemistry 2013,727, 28-36.

  15. Characterization with NMR

  16. Range of Td for Some imidazoliumILs Td = decomposition temperature ILs composed of BF4- , PF6- , NTf2- , are thermally more stable than corresponding halides. The relative anion stability follows the order: PF6 > BF4 > AsF6 >> I, Br, Cl. Sowmiah, S.; Srinivasadesikan, V.; Tseng, M.-C.; Chu, Y.-H., Molecules 2009,14 (9), 3780-3813.

  17. Synthesis of ZnO Nanoparticles [HOOCMMIM][PF6] (2) = 100 mg ZnO-[HOOCMMIM][PF6] (3) Zn(NO3)2 = 57 mg 71 mg Sharma, H.; Singh, N.; Jang, D. O., Tetrahedron Letters 2014,55 (49), 6623-6626.

  18. Characterization with NMR

  19. TEM Image of ZnO-[HOOCMMIM][PF6] (3) Particle Size=8.61~29.30nm, solvent = THF Compare to another TEM image in CH3CN

  20. Control Experiments ofNucleophilic Substitution

  21. Application on Nucleophilic Substitution Reaction conditions : 0.02 mmol reactant, 0.06 mmolKI and 50 mol% [HOOCMMIM][PF6] (2) are in 1 mL acetonitrile at 120 ℃ for 6 hours.

  22. Application on Nucleophilic Substitution Reaction conditions : 0.02 mmol reactant, 0.06 mmolKI and 50 mol% [HOOCMMIM][PF6] (2) are in 1 mL acetonitrile at 120 ℃ for 6 hours.

  23. Dipole Moments of Benzyl Bromide with Substituents 31∘ 72∘ 28∘ • Equilibrium Geometry at Ground state in Gas with Density Functional B3LYP (method) 6-31+G(d,p) (basis set). • Dipole moments: (13a) 1.88 debye, (13b) 3.53 debye, (13c) 4.27 debye

  24. Application on Nucleophilic Substitution Reaction conditions : 0.02 mmol reactant, 0.06 mmolKI and 50 mol% [HOOCMMIM][PF6] (2) in molecu;ar or NPsare in 1 mL acetonitrile at 120 ℃ for 6 hours.

  25. Reactivity of ZnO-NPs-Supported Catalysts Reaction conditions : 0.02 mmol reactant, 0.06 mmolKI and 50 mol% [HOOCMMIM][PF6] (2) in molecu;ar or NPsare in 1 mL acetonitrile at 120 ℃ for 6 hours.

  26. Reactivity of ZnO-NPs-Supported Catalysts

  27. Recyclibilityof 3 on Nucleophilic Substitution

  28. Recyclibilityof 3 on Nucleophilic Substitution

  29. Proposed Mechanism of (2) on Nucleophilic Substitution An, J.; Denton, R. M.; Lambert, T. H.; Nacsa, E. D., Organic & Biomolecular Chemistry 2014,12 (19), 2993-3003.

  30. Aldol Condensation in Aqueous Solution

  31. Aldol Condensation in Aqueous Solution

  32. Reactivity of ZnO-NPs-Supported Catalysts Reaction conditions : 1 mmol reactant and 1 mol% [HOOCMMIM][PF6] (2) are in 1 mL tetrahydrofuran at reflux, than put 0.5 mL 50 % NaOH(aq) and reflux 6 hours.

  33. Proposed Mechanism of (2) on Aldol Condensation Nair, V.; Menon, R. S.; Biju, A. T.; Sinu, C. R.; Paul, R. R.; Jose, A.; Sreekumar, V., Chemical Society Reviews 2011,40 (11), 5336-5346.

  34. Conclusions • The NHCs catalysts [HOOCMMIM][PF6] was synthesized and the structurally characterized. • We have successfully synthesized the ZnOnanoparticle-supported NHC catalyst. This hydrid catalyst exhibits excellent dispersity in most organic solvents which allows more applicable spectroscopic analysis in solution for molecular resolution. • Both the molecular and the ZnO-supported NHC catalysts were demonstrated to exhibit excellent catalysts for nucleophilic substitution and aldol condensation reactions. And the molecular NHC catalysis did not lose its reactivity upon anchoring (or stepwise heterogenization) processes. • Both catalytic reactions can be efficiently performed in aqueous solution. • The ZnO-supported NHC catalysts can be easily recovered by simple centrifugation, precipitation and decantation without using the traditional multistep organic solvent extraction method. • The ZnO-supported NHC catalysts can be effectively recycled for 12 times to still give 85% catalytic activity.

  35. Nucleophilic Substitution Vanos, C. M.; Lambert, T. H., AngewandteChemie International Edition 2011,50 (51), 12222-12226.

  36. Aldol Condensation UiO – 66: Zr6O4(OH)4(O2C–C6H4–CO2)6 Frederik V.; Rob A.; Alexandre V.; Christian S.; Dirk D. V. Chem. Commun., 2011, 47, 1521–1523

  37. Quantitative Analysis of ZnO-[HOOCMMIM][PF6] (3)

  38. Quantitative Analysis of ZnO-[HOOCMMIM][PF6] (3) 重量百分比分析 均四甲苯1H-NMR 積分：0.3333, 12H  1H 積分為 0.0278 奈米粒子分子表層觸媒1H-NMR 積分：0.3602, 2H  1H 積分為 0.1801 均四甲苯mol : 分子表層觸媒mol = 0.0278 : 0.1801  0.7 mg 均四甲苯為 5  10-3mmol 分子表層觸媒mmol= 5  10-3 / 0.0278  0.1801 = 0.034 氧化鋅奈米粒子分子表層觸媒之重量 = 0.034 mmol  286.11 g/mol = 9.73 mg 表層分子和氧化鋅奈米粒子的比例 = 9.73 mg / 48 mg = 20.27 %

  39. Quantitative Analysis of ZnO-[HOOCMMIM] [PF6] (3) 氧化鋅分子半徑：0.214 nm，氧化鋅奈米粒子半徑：26.060 nm 單顆氧化鋅奈米粒子表面積：r = r0 n1/3, 26.06 = 0.214  n1/3 n = 1.81  106 (個) S = 4  π  (r0 n1/3)2 = 4  π  [0.214  (1.81  106)1/3]2 = 8547.19 (nm2) 單顆奈米原子團表面原子數：ns = 4  n 2/3 = 59408 (個) 表面原子數與總原子數之百分比：59408 / (1.81  106) =3.3 % 每 1 mg 氧化鋅奈米粒子中有 0.203 mg [HOOCMMIM][PF6] (2)，氧化鋅重量 = 1 - 0.203 = 0.797 (mg) 氧化鋅奈米粒子總數： 0.797 / 81380  (6.02  1023) / (1.81  106) = 3.275  1012 (particles) [HOOCMMIM][PF6] (2) 總數： 0.203 / 286.11  (6.02  1023) = 4.227  1017 (個分子) 單顆氧化鋅奈米粒子包含分子式觸媒數： (4.227  1017) / (3.275  1012) = 1.29 105 (個分子)

  40. Quantitative Analysis of ZnO-[HOOCMMIM][PF6] (3)

  41. Quantitative Analysis of ZnO-[HOOCMMIM][PF6] (3) 重量百分比分析 均四甲苯1H-NMR 積分：2.039, 12H  1H 積分為0.170 奈米粒子分子表層觸媒1H-NMR 積分：2.009, 2H  1H 積分為1.005 均四甲苯mol : 分子表層觸媒mol = 0.170 : 1.005 0.8 mg 均四甲苯為6  10-3mmol 分子表層觸媒mmol= 6 10-3 / 0.170 1.005 = 0.036 氧化鋅奈米粒子分子表層觸媒之重量 = 0.036 mmol  286.11 g/mol = 10.30 mg 表層分子和氧化鋅奈米粒子的比例 = 10.30 mg / 50 mg = 20.60 %

  42. Synthesis of ImidazoliumSalts 1-mesityl-1H-imidazole (4) 45.23 % 11-bromoundec-1-ene (5) 52.29 % 11-bromoundecyl ethanethioate(6) 79.85 %

  43. Synthesis of ImidazoliumSalts 11-bromoundecane-1-thiol (7) 89 % (Mesbim)(CH2)11SH (8) 87.89 %

  44. Synthesis of Au Nanoparticles

  45. Charactorization of Au Nanoparticles

  46. Charactorization of Au Nanoparticles

  47. TEM Image of ZnO-[HOOCMMIM][PF6] (3) In THF In CH3CN

  48. TEM Image of ZnO-[HOOCMMIM][PF6] (3) In THF Sharma, H.; Singh, N.; Jang, D. O., Tetrahedron Letters 2014,55 (49), 6623-6626.

  49. Applications of N-Heterocyclic Carbenes Stetter Reactions https://zh.wikipedia.org/wiki/Stetter%E5%8F%8D%E5%BA%94 Spiro Annulations Duguet, N.; Donaldson, A.; Leckie, S. M.; Douglas, J.; Shapland, P.; Brown, T. B.; Churchill, G.; Slawin, A. M. Z.; Smith, A. D., Tetrahedron: Asymmetry 2010,21 (5), 582-600. Lactam Synthesis Kotha, S.; Deb, A. C.; Kumar, R. V., Bioorganic & Medicinal Chemistry Letters 2005,15 (4), 1039-1043.

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