chapter 2 palladium catalysts in suzuki cross- coupling reaction

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4.5. Leaching Test After the reaction, catalyst was removed from reaction medium by filtration. The filtrate was concentrated by evaporating organic solvent. The filtrate was digested in the presence of H2O2 (Merck, 99%) and HNO3 (conc.). The filtrate was diluted to (1/50) and analyzed by The Inductively Coupled Plasma Mass Spectrometry (ICP-MS). (Standard solutions were prepared as 1, 2, 4, 8, 10, 20 ppb from standard stock solution). 52
CHAPTER 5 RESULTS AND DISCUSSIONS In this thesis, activity of Pd(NH3)4 2+ -loaded NaY was investigated for Suzuki reactions at low Pd concentrations. The Pd(NH3)4 2+ -loaded NaY type zeolite showed high activity in the Suzuki cross-coupling reactions of less expensive aryl chlorides and bromides at low palladium concentrations in air and within very short reaction time. Turnover frequencies (TOF) and turnover number (TON) limits of the catalyst were also investigated. 5.1. The Suzuki Reactions of Aryl Chlorides 5.1.1. Pd-NaY Catalyzed Suzuki Reaction of 4-Chloroacetophenone with Phenylboronic Acid At the beginning of our study, optimization was performed for Suzuki reaction of 4-chloroacetophenone with phenylboronic acid over Pd(NH3)4 +2 modified zeolite containing 0.68% Pd (0.064 mmol Pd/g NaY zeolite) under an inert atmosphere. The zeolite content of the reaction medium was brought to 1 g upon addition of NaY zeolite in an as-received form. In the course of optimization, the effect of tetrabutylammonium bromide (TBAB) additive and temperature was first investigated using Na2CO3 as a base in N,Ndimethylacetamide (DMA). Product formation was increased from 36% to 46% by addition of 0.5 equivalent Bu4NBr into reaction medium at 140 o C under inert atmosphere (Table 5.1, entry1-2). Under this condition, it was observed that increasing the water content (DMA: water ratio of 9:1) lowered the yield to 14 % (entry 3). No activity was observed when the ratio was 1:1. A higher yield (57%) and conversions were obtained at 160 °C in the presence of Bu4NBr (Table 5.1, entry 4). 53
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SHORT-TIME SUZUKI REACTIONS OF ARYL
Page 3 and 4:
ACKNOWLEDGEMENTS Firstly, I’d lik
Page 5 and 6:
ÖZET ARİL HALOJENÜRLERİN HAVA A
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3.2.2. Catalysts Anchored to Inorga
Page 9 and 10:
LIST OF FIGURES Figure Page Figure
Page 11 and 12:
Figure A.27. 13 C NMR of 4-cyanobip
Page 13 and 14: CHAPTER 1 INTRODUCTION The palladiu
Page 15 and 16: CHAPTER 2 PALLADIUM CATALYSTS IN SU
Page 17 and 18: 2.1.2. The Coordination Geometry of
Page 19 and 20: R 1 R 1 4. Sonogashira Reaction: H
Page 21 and 22: 2.2.1. Mechanism of Suzuki Coupling
Page 23 and 24: As a result, organic group or hydri
Page 25 and 26: 2.2.2.2. Halogen Effect Nearly all
Page 27 and 28: found to be excellent complexes for
Page 29 and 30: R Table 2.2. Examples from literatu
Page 31 and 32: L R Pd X R Pd L OR'' X L L + OR' R'
Page 33 and 34: omides and iodides is performed eff
Page 35 and 36: times for the transformation of a l
Page 37 and 38: R Br + (HO) 2B R' 5% Pd(OAc) 2 15%
Page 39 and 40: of insoluble solids are among the m
Page 41 and 42: could be reused multiple times. The
Page 43 and 44: 3.2.2. Catalysts Anchored to Inorga
Page 45 and 46: SO 2NH N Pd SO 2 N SO 2 NH NH H O1.
Page 47 and 48: utilized them in Heck and Suzuki co
Page 49 and 50: Smith et al introduced the use of P
Page 51 and 52: • Complexes immobilized in zeolit
Page 53 and 54: 3.3.3. Preparation of Zeolite-Suppo
Page 55 and 56: CHAPTER 4 EXPERIMENTAL STUDY 4.1. P
Page 57 and 58: temperature, the catalyst was recov
Page 59 and 60: amount of both reactant and product
Page 61 and 62: 4-Methoxybiphenyl: 1 H NMR (400 MHz
Page 63: 51 Table 4.1. Purification of coupl
Page 67 and 68: Table 5.2. The effect of base on Pd
Page 69 and 70: Table 5.4. The Optimization of Pd-N
Page 71 and 72: H 3COC Table 5.5. Effect of zeolite
Page 73 and 74: Table 5.6. Pd(NH3)4 2+ -loaded NaY
Page 75 and 76: The type of other organic co-solven
Page 77 and 78: yield was very low (Table 5.8, entr
Page 79 and 80: evealed excellent reactivity toward
Page 81 and 82: CHAPTER 6 CONCLUSIONS In this thesi
Page 83 and 84: REFERENCES Albisson, D.A., Bedford,
Page 85 and 86: Choudary, B.M., Madhi, S., Chowdari
Page 87 and 88: Heiden, M. Plenio, H. 2004. ‘‘H
Page 89 and 90: Coupling Reactions of Aryl Chloride
Page 91 and 92: Phan, N.T.S., Brown, D.H., Styring,
Page 93 and 94: Wolfe, J.P., Singer, R.A., Yang, B.
Page 95 and 96: Figure A.1. 13 C NMR of 1-phenylnap
Page 97 and 98: Figure A.3. 13 C NMR of 2-acetylbip
Page 99 and 100: Figure A.5 . 13 C NMR of 2-methoxyb
Page 101 and 102: Figure A.7. 13 C NMR of 2-methylbip
Page 103 and 104: Figure A.9. 13 C NMR of 2-phenylnap
Page 105 and 106: Figure A.11. 13 C NMR of 3-acetylbi
Page 107 and 108: Figure A.13. 13 C NMR of 3-methoxyb
Page 109 and 110: Figure A.15. 13 C NMR of 3-phenylpy
Page 111 and 112: Figure A.17. 13 C NMR of 4-acetyl-4
Page 113 and 114: Figure A.19. 13 C NMR of 4-methoxyb
Page 115 and 116:
Figure A.21. 13 C NMR of 4-methylbi
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Figure A.23. 13 C NMR of 4-phenylbe
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Figure A.25. 13 C NMR of 4-acetylbi
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Figure A.27. 13 C NMR of 4-cyanobip
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Figure A.29. 13 C NMR of 4-nitrobip
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Figure A.31. 13 C NMR of 4-phenylan
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APPENDIX B MASS SPECTRUMS OF SUZUKI
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Figure B.2. Mass spectrum of 2-acet
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Figure B.4. Mass spectrum of 2-meth
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Figure B.6. Mass spectrum of 3-acet
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Figure B.8. Mass spectrum of 3-phen
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Figure B.10. Mass spectrum of 4-phe
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Figure B.12. Mass spectrum of 4-met
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Figure B.14. Mass spectrum of 4-cya
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Figure B.16. Mass spectrum of 4-met
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