Mesoporous Organosilicas with Acidic Frameworks and Basic Sites in the Pores: An Approach to Cooperative Catalytic Reactions

Transcription

1 Literature Report Mesoporous rganosilicas with Acidic Frameworks and Basic Sites in the Pores: An Approach to Cooperative Catalytic Reactions Yan Yang Shylesh, S.;* Thiel, W. R.* et al. Angew. Chem. Int. Ed. DI: /anie

2 Synthetic Procedure N 2 (Me) 3 Si Si(Me) 3 + CTAB Na (Me) 3 Si Si Si (Me) 3 Si N 2 PM-N 2 DiBoc (Me) 3 Si S 3 Si Si N Boc S 3 Cl (Me) 3 Si Si Si N Boc PM-S 3 -NBoc PM-NBoc N 2 (Me) 3 Si S 3 Si Si PM-S 3 -N

3 Modified Mesoporous rganic Inorganic ybrid Materials ---post-modification 1) Post-Modification of mesoporous silica by grafting Kemner, K. M. et al. Science 1997, 276, 923. Mou, C. Y. et al. Langmuir 2004, 20, 3231.

4 Modified Mesoporous rganic Inorganic ybrid Materials ----in situ co-condensation Mann, S. et al. Chem. Commun. 1996, Macquarrie, D. J. et al. Chem. Commun. 1996, Schroden, R. C. et al. Adv. Mater. 2000, 12, 1403.

5 Periodic Mesoporous rganosilicas (PMs) Schematic synthesis procedure of PMs.

6 Periodic Mesoporous rganosilicas (PMs) Modeling images of phenylene-bridged PMs with a crystal-like pore wall structure zin, G. A. et al. Nature 1999, 402, 867. Stein, A. et al. Chem. Mater. 1999, 11, Inagaki, S. et al. J. Am. Chem. Soc. 1999, 121, Inagaki, S. et al. Nature 2002, 416, 304

7 PMs in eterogeneous Catalysis 1.Graft or co-condensation N 3 Yang, Q.. et al. J. Phys. Chem. B. 2004, 108, Yang, Q..; Inagaki, S. et al. J. Am. Chem. Soc. 2002, 124, Yang, Q..; Inagaki, S. J. Mol. Catal. A: Chem. 2005, 230, 85.

8 Characteration Figure C CP-MAS NMR spectra of a) PM-N 2, b) PM-NBoc, and c) PM-S 3 -N 2. * in (a) denotes residual peaks of CTAB, which disappear after the sulfonation reaction (c).

9 Characteration Figure 2. Powder X-ray diffraction patterns of a) PM, b) PM-N 2, c) PM-NBoc, and d) PM-S 3 -N 2.

10 Characteration Figure 3. Nitrogen adsorption desorption isotherms of a) PM-N 2, b) PM-NBoc, and c) PM-S 3 -N 2.

11 ne pot reaction Me Me acid 2 base C 3 N 2 N Entry Catalyst Conv. of 1 [%] Yield of 2 [%] Yield of 3 [%] 1 PM-S 3 -N PM-S 3 -NBoc PM-N 2 trace trace trace 4 PM-S 3 -N 2 + trace trace trace tert-butyl amine 5 PM-S 3 -N trace p-toluenesulfonic acid

12 Previous Work Chem. Eur. J. 2009, 15, 7052.

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14 Catalyst N 2 C 3 N 2 Entry Catalyst Time [h] Yield [%] 1 MSN N MSN NN MSN NEt 2 12 trace 4 MSN S MSN N 2 S MSN NN 2 S MSN NN 2 + MSN S MSN NN 2 S Sil MSN NN 2 S MSN NN 2 Cl MSN MSN NN 2 S 3 + p-toluene sulfonic acid 6 trace 13 MSN NN 2 S 3 + n-hexylamine p-toluene sulfonic acid + n-hexylamine 6 0

15 Bifunctionalized PMs Alauzun, J.; Corriu, R. J. P. et al. J. Am. Chem. Soc. 2006, 128, Jaroniec, M. et al. Nature 2006, 442, 638.

16 Functional Groups and Reactions Used Angew. Chem. Int. Ed. 2005, 44, 1826.

17 Functional Groups and Reactions Used 2 N Catalyst Acetone 2 N + 2 N Angew. Chem. Int. Ed. 2006, 45, 6332.

18 Functional Groups and Reactions Used J. Catal. 2007, 247, 379.

19 Functional Groups and Reactions Used + NC Et catalyst CN Et J. Catal. 2009, 263, 181.

20 ne-pot Reaction Me Me + NC C 2 Et catalyst C 3 CN CN C 2 Et + J. Am. Chem. Soc. 2009, 131, Me Me acid base N 2 2 C 3 N 2 Angew. Chem. Int. Ed. DI: /anie

21 ther Reactions + NC Et catalyst CN Et J. Am. Chem. Soc. 2007, 129, J. Catal. 2009, 263, N Catalyst Acetone 2 N + 2 N Catalyst N 2 2 N C 3 N 2 TMS Angew. Chem. Int. Ed. 2005, 44, Catalyst CN 2 N (C 3 ) 3 SiCN 2 N

22 Locations of the Functional Groups R R R R R R J. Am. Chem. Soc. 2007, 129,

23 The Cooperative Ion-pair Mechanism NC C 2 Et N N A NC C 2 Et + N N N N + CEt 2 D B CN NC C 2 Et C NC C 2 Et N N N N

24 Cooperative Primary Amine Mechanism A N 2 N CN C 2 Et D B 2 C N NC C 2 Et N NC C 2 Et

25 New Silica Precursor toluene (Et) 3 Si NC S Si(Et) 3 (Et) 3 Si N S reflux, 24h Si(Et) 3 Chem. Eur. J. 2009, 15, 8310.

26 J. Catal. 2007, 247, 379.

27 Recently there has been significant progress in mimicking natures multistep reaction cascades for the synthesis of structurally complex organic molecules. Wellcontrolled multifunctionalization of solid supports can be an efficient strategy for the design of cooperative catalytic systems. This approach requires that the relative concentrations and the proper spatial arrangement of all functional groups are controlled. Biocatalysts such as enzymes immobilize mutually incompatible functional groups without destruction and allow these functional groups to act independently or in a cooperative manner. To mimic such multistep reaction sequences in one-pot reactions will be effective in terms of waste and cost reduction.

28 In summary, bifunctional mesoporous organosilicas possessing organic amines and sulfonic acid groups were successfully generated and used in a cooperative catalytic transformation. Compared to earlier reports, the current methodology benefits from a precise location and concentration of the active functional groups in a mesoporous phenylene silica with crystalline pore walls, in which the acidic groups reside mainly on hydrophobic benzene layers and the basic amino groups on hydrophilic silica layers for cooperative effects. Further investigation is currently underway regarding enhancement of the acid base properties of the materials, additional catalytic enhancements, and advanced applications.

29 Thank You!