chapter 2 palladium catalysts in suzuki cross- coupling reaction

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While the SiO4 units are neutral, the AlO4 results in a net negative charge since the trivalent aluminum is bonded to four oxygen anions. Negative charge is neutralized by a cation generally from the groups IA or IIA. These cations are highly mobile and can be exchanged for other cationic species. There are two building blocks so-called the sodalite and pentasil units which are shown in Figure 3.14. Figure 3.14. SiO4 and AlO4 building blocks of zeolites (Source: Weitkamp and Puppe 1999) The position, size, and numbers of cations and the position and number of water molecules located in the cages, cavities, and channels of the zeolites can significantly change the properties of the zeolite. 3.3.2. The Advantages of Zeolites Due to high thermal stability, ease of handling, ready availability, being environmental friendly, inexpensive cost of zeolites, they have been used as the support materials for immobilization of the catalysts. Moreover, the use of zeolite as support material should have the following advantages (Sen et al. 1999); 38
• Complexes immobilized in zeolite super cages may have almost the same activity as the free complexes in solution. • The zeolite microstructure (micro-reactor) could help to overcome the problems of metal leaching. • Zeolites are capable of stabilizing intermediate active species retained in their cavities and may show the product shape-selectivity. • They should regenerate the catalyst after deactivation. In the literature, [Pd]-loaded NaY zeolites were used for C-C coupling reactions for the first time by Djakovitch and Koehler (Figure 3.15) (Djakovitch and Koehler 1999). They reported that the catalysts exhibited a high activity and selectivity toward the Heck reaction of aryl bromides with olefins in low palladium concentrations (0.1 mol% of Pd). In another study, the Heck reactions were performed for industrially more interesting chloroactophenone with styrene at 100 ºC (Djakovitch et al. 1999). The authors observed that the catalysts could be separated from the reaction mixture. However it could not be reused with same activity. The catalyst used in a first run at 100 ºC was regenerated by increasing temperature to 140 ºC under reaction conditions (Djakovitch and Koehler 2001). R Br + [Pd] zeo R = H, F, NO 2, CH 3CO R trans and cis-isomers + Figure 3.15. The Heck reactions of aryl bromides with olefins (Source: Djakovitch and Koehler 1999) The leaching test was also performed and it was found that only small amount of palladium was leached, depending on temperature of the reaction and the nature of the Pd species immobilized in the zeolite cage. For the [Pd(NH3)4] 2+ -NaY which we also R 39
Page 1 and 2: SHORT-TIME SUZUKI REACTIONS OF ARYL
Page 3 and 4: ACKNOWLEDGEMENTS Firstly, I’d lik
Page 5 and 6: ÖZET ARİL HALOJENÜRLERİN HAVA A
Page 7 and 8: 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: Smith et al introduced the use of P
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 and 64: 51 Table 4.1. Purification of coupl
Page 65 and 66: CHAPTER 5 RESULTS AND DISCUSSIONS I
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
Page 117 and 118:
Figure A.23. 13 C NMR of 4-phenylbe
Page 119 and 120:
Figure A.25. 13 C NMR of 4-acetylbi
Page 121 and 122:
Figure A.27. 13 C NMR of 4-cyanobip
Page 123 and 124:
Figure A.29. 13 C NMR of 4-nitrobip
Page 125 and 126:
Figure A.31. 13 C NMR of 4-phenylan
Page 127 and 128:
APPENDIX B MASS SPECTRUMS OF SUZUKI
Page 129 and 130:
Figure B.2. Mass spectrum of 2-acet
Page 131 and 132:
Figure B.4. Mass spectrum of 2-meth
Page 133 and 134:
Figure B.6. Mass spectrum of 3-acet
Page 135 and 136:
Figure B.8. Mass spectrum of 3-phen
Page 137 and 138:
Figure B.10. Mass spectrum of 4-phe
Page 139 and 140:
Figure B.12. Mass spectrum of 4-met
Page 141 and 142:
Figure B.14. Mass spectrum of 4-cya
Page 143:
Figure B.16. Mass spectrum of 4-met
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