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Iron (III)-doped, ionic liquid matrix-immobilized, mesoporous silica nanoparticles: Application as recyclable catalyst for synthesis of pyrimidines in water
Microporous and Mesoporous Materials 227 (2016) 23e30
Contents lists available at ScienceDirect
Microporous and Mesoporous Materials journal homepage: www.elsevier.com/locate/micromeso
Iron (III)-doped, ionic liquid matrix-immobilized, mesoporous silica nanoparticles: Application as recyclable catalyst for synthesis of pyrimidines in water Hossein Naeimi a, *, Vajihe Nejadshafiee a, Mohammad Reza Islami b a b
Department of Organic Chemistry, Faculty of Chemistry, University of Kashan, Kashan 87317, Islamic Republic of Iran Chemistry Department, Shahid Bahonar University of Kerman, Kerman 76169, Islamic Republic of Iran
a r t i c l e i n f o
a b s t r a c t
Article history: Received 5 December 2015 Received in revised form 13 February 2016 Accepted 17 February 2016 Available online 21 February 2016
A novel ionic liquid functionalized iron-containing mesoporous silica nanoparticles (Fe-MCM-41-IL) was prepared by anchoring a triazolium ionic liquid on the surface of Fe loaded MCM. The result samples were characterized by XRD, FT-IR, EDS, XRF, HRTEM, FE-SEM, VSM, N2 adsorptionedesorption analysis and AAS techniques. The use of Fe-MCM-41-IL as an efficient reusable heterogeneous catalyst allows onepot synthesis of pyrimidine derivatives under mild condition in high yields from substituted aldehydes, two moles of 2-thiobarbituric acid and ammonium acetate. Operational simplicity, low cost, high yields, eco-friendly reaction conditions, economical catalyst, reusability and easy recovery of the catalyst make this procedure greener than the other reported works. © 2016 Elsevier Inc. All rights reserved.
Keywords: Mesoporous Nanoparticles Synthesis Ionic liquid Pyrimidines Catalyst
1. Introduction Within the past decade, mesoporous silica materials (MCM-41) have increased in popularity for heterogenous catalyst purposes, in part because their large pore volume, high surface area, uniform pore size distribution, regular structure and high thermal stability [1e4]. Generally, the pure silica MCM has limited catalytic activity but active catalytic sites can be generated in MCM by isomorphously substituting silicon with a metal [5]. Several studies have been dedicated to the investigation of transition-metalsubstituted MCM-41 because of their wide range of applications in catalysis [6,7]. Specifically, the substitution of iron species in the framework of MCM such as Fe-MCM-41 has a higher specific activity in the organic reactions [8e16]. In recent decades ionic liquids phases have attracted significant attention in the scientific community as an alternative reaction medium for homogeneous catalysis [17,18]. Although the ability of liquideliquid biphase catalysis in ionic liquid has successfully been demonstrated but heterogeneous catalysts are still preferred by industry because the
* Corresponding author. E-mail address: [email protected] (H. Naeimi). http://dx.doi.org/10.1016/j.micromeso.2016.02.036 1387-1811/© 2016 Elsevier Inc. All rights reserved.
ease of separation. Recently, the ionic liquids supported on the solid such as amorphous silica and mesoporous silica hybrid [19e24], magnetic nanoparticle [25], especially acidic types have attracted increasing interest in organic synthesis, because they can provide green and efficient media for organic reactions. The development of efficient methods for constructing substituted six-membered nitrogen-containing heterocycles such as; 1,4-dihydropyridines (1,4DHPs) has been the subject of extensive research due to the vast number of natural products, pharmaceutical and agrochemical agents, and functional materials containing these ring systems [26e29]. The traditional procedures for the synthesis of 1,4-DHPs rely on condensation of amine and carbonyl compounds. Much effort has been dedicated to the development of new methodologies to access 1,4-DHPs [30]. Among a number of methodologies developed to date, the [2þ2þ1þ1] Hantzsch reaction using two 1,3-dicarbonyl compounds, an amine and an aldehyde is a conventional and succinct approach to synthesize symmetrical 1,4-DHPs [31,32]. Various methods for the preparation of 1,4-DHPs and pyrimidine-fused heterocycles by using cyclic diketone, aromatic aldehydes and amines or ammonium acetate under different conditions have been reported [26,33,34]. Initially, herein, we present the preparation and characterization of supported novel ionic liquid catalyst based
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H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30
on functionalized iron-containing mesoporous silica nanoparticles (Fe-MCM-41-IL). Then, we focus our attention on a simple, green and efficient method for the synthesis of biological active pyrimidine derivatives from a wide variety of aldehydes, 2-thiobarbituric acid and ammonium acetate in high yields and short reaction times. 2. Results and discussion 2.1. Catalyst preparation Novel ionic liquid functionalized iron-containing MCM-41, named Fe-MCM-41-IL as a nanocatalyst was prepared based on the following procedure. Initially, the Fe-MCM-41 was prepared by the direct-hydrothermal technique of ferric chloride (FeCl3$6H2O), TEOS as source silica and cetyl trimethyl ammonium bromide (CTAB) as a structural directing surfactant in an alkaline solution according to the literature procedure [35]. Then, the triazole ammonium based ionic liquid including 1,2,3-triazole functionality on one side and a triethoxysilyl moiety on the other side was synthesized and subsequently grafted to the surface of Fe-MCM-41 in refluxing toluene for 24 h (Scheme 1). 2.2. Catalyst characterization Fig. 1. FT-IR spectra of a) MCM-41, b) Fe-MCM-41 and c) Fe-MCM-41-IL.
Fourier transform-infrared (FT-IR) spectra of MCM-41, Fe-MCM41 and Fe-MCM-41-IL are shown in Fig. 1. For all samples the bands characteristic of the MCM-41 framework can be clearly seen. The slight shift of the 1109 cm1 band of SieOeSi into the 1081 cm1 band of SieOeFe vibrations allowed the conclusion that the heteroatoms were incorporated into the framework of MCM-41 and
H3CO
OCH3 Si OCH3
i) Cl N Ph
N
N
N
the formation of FeeOeSi bonds [36]. In Fig. 1c, the absorption peaks at 2924 and 2855 cm1 were assigned to aromatic CeH and aliphatic CeH of the IL structure, respectively. The presence of these peaks confirms successful immobilization of IL on the surface of
C2H5 N
O
Ph
N
OH
OCH3 Si OCH3 H3CO
N
HO3S
N
N
O (IL)
CTAB
iii) H2SO4
C2H5
Ph
NaOH
O S O O
C2H5 HSO4-
FeCl3.6H2O
ii)
OCH3 Si OCH3 H3CO
1) Washed
stirred
550 oC, 6h
TEOS 2 h, rt
2) Dried at 100 oC
H2O
Fe-MCM-41 IL
HSO4HO3S
N N Ph
N
C2H5 O
Toluene, 24 h
Si O H3CO O
Fe-MCM-41-IL Scheme 1. Different Steps for Synthesis of Fe-MCM-41-IL.
H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30
Fig. 2. XRD pattern of Fe-MCM-41.
Fe-MCM. The additional peak was observed at 1520 cm1 related to C]N bond. Furthermore, the bands at 3438 and 3425 cm1 suggest that there are OH groups on the mesoporous Fe-MCM-41 and after the immobilization of IL on the Fe-MCM-41 surface (Fig. 1a and b). The low-angle X-ray diffraction (XRD) pattern of Fe-MCM-41 is depicted in Fig. 2. Fe-MCM-41pattern showed a distinct broad peak which account for the Bragg plane (100) intense reflection, indicating the regular arrangement of mesoporous with hexagonal symmetry [12,37]. The structure of the prepared materials was further verified using field emission-scanning electron microscopy (FE-SEM) and
25
high-resolution transmission electron microscopy (HRTEM) images. As can be clearly seen, Fe-MCM-41 have a well-defined spherical structure with relatively narrow size distribution and its FE-SEM image indicated that the diameter of the spherical particles in the about 85e87 nm (Fig. 3a). After functionalization with IL, the Fe-MCM-41-IL kept their spherical structure with particle size of about 95e98 nm as shown in the FE-SEM images (Fig. 3b). The results indicated that the FE-SEM images of Fe-MCM-41 and FeMCM-41-IL exhibited similar structure with increase of particles size which provided strong evidence that the mesoporous structure of the supporting retained after the grafting process. Fig. 3c and d are shown the HRTEM images of Fe-MCM-41 and Fe-MCM-41-IL samples. As can be seen from these images, the wellordered pore arrangements and the iron uniform introduction into mesoporous silicate framework were visible. Also, the long-rang order and mesoporous structure arrays were not disturbed significantly after Fe doping. The Fe and Si contents in Fe-MCM-41 were determined using Xray fluorescence analysis (XRF) and their results were shown that the molar ratio of Fe/Si was 13.47. Furthermore, the closeness of ionic liquid groups on the Fe-MCM-41-IL surface was further confirmed by energy dispersive spectrometer (EDS) (Fig. 4). The obtained results by EDS were as follows (%): C, 5.40; N, 5.25; Si, 17.38; O, 61.32; S, 6.92; Fe, 3.72. N2 adsorptionedesorption isotherms and the BarretteJoynereHalenda (BJH) pore-size distribution curves of FeMCM and Fe-MCM-41-IL are depicted in Fig. 5. The samples displayed type II isotherms [38] and capillary condensation at relative pressures of 0.3 < P/P0 < 0.5, which was the characteristic of mesoporous materials. The textural properties of Fe-MCM-41 were substantially maintained after immobilization of triazolium ionic liquid.
Fig. 3. FE-SEM images of a) Fe-MCM-41, b) Fe-MCM-41-IL and TEM images of c) Fe-MCM-41, d) Fe-MCM-41-IL.
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H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30
Fig. 6. Magnetization curves for the prepared Fe-MCM-41 and Fe-MCM-41-IL.
Fig. 4. EDS pattern of Fe-MCM-41-IL.
can be related to incorporation of high Fe content into the framework of MCM-41. The magnetic properties of the Fe-MCM-41 and Fe-MCM-41-IL catalyst were investigated using a vibrating sample magnetometer at room temperature. As illustrated in Fig. 6, the magnetization curves of the prepared materials exhibit no hysteresis loop which demonstrates its super paramagnetic characteristics. Moreover, the good magnetic properties of the prepared catalyst were revealed by complete and easy attraction using an external magnet. The saturation magnetization of the Fe-MCM-41 and Fe-MCM-41-IL were found to be 2.80 emu g1 and 1.74 emu g1, respectively as measured using vibrating sample magnetometer (VSM). Since, ionic liquid was coated with Fe-MCM-41 mesoporous hybrid a decrease in saturation magnetization can be observed after coating. Furthermore, the total surface acidity for the Fe-MCM-41 and Fe-MCM-41-IL were determined by sodium hydroxide titration. In this measurement procedure, the pH of Fe-MCM-41 and Fe-MCM41-IL catalyst were 5.87 and 1.04 that can be equal to loading the 3.37 105 and 2.19 mmol (Hþ) g1, respectively. 2.3. Investigation of catalyst activity in synthesis of pyrimidines
Fig. 5. N2 adsorptionedesorption isotherms Fe-MCM-41 and Fe-MCM-41-IL.
The surface area, pore volume, and pore diameters of Fe-MCM and Fe-MCM-41-IL are listed in Table 1. The surface area decreased from 307 to 225 m2 g1 with supported IL on the FeMCM-41. Also, there is a negligible change in pore volume from 0.42 to 0.38 cm3 g1 after grafting process. It could be concluded that introduction of ionic liquid significantly affected the surface area and pore volume of the support. Moreover, the smaller surface area of Fe-MCM-41 compared with previous Fe-MCM-41 samples
For the purpose of the catalytic activity comparison of Fe-MCM41 and Fe-MCM-41-IL, the treatment of 2-thiobarbituric acid, benzaldehyde and ammonium acetate affording pyrimidine were examined in the amount of different catalysts. The results of the optimized conditions are summarized in Table 2. These observations clearly emphasized the existence of a significant effect between grafted ionic liquid groups and without ionic liquid on the Fe-MCM-41 surface. Therefore, the Fe-MCM-41-IL catalyst showed excellent catalytic performance rather than Fe-MCM-41 that accordance to strong acidic properties of Fe-MCM-41-IL catalyst was justified.
Table 1 Surface Properties of Fe-MCM-41 and Ionic-liquid modified Fe-MCM-41 (Fe-MCM-41-IL). Sample
Surface areaa (m2 g1)
Pore sizeb (nm)
Pore volumec (cm3 g1)
Fe-MCM-41 Fe-MCM-41-IL
307.98 225
8.42 8.25
0.42 0.38
a b c
Calculated by the BET model. Calculated by the BJH model from the desorption isotherm. Total pore volume at P/P0 ¼ 0.99.
H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30 Table 2 Effect of catalyst amount on the reaction.a
Fe-MCM-41-IL
Fe-MCM-41
Entry
Amount of catalyst (mg)
Yield (%)
Amount of catalyst (mg)
Yield (%)
1 2 3 4
10 15 20 25
80 84 89 89
10 15 20 25
trace trace trace trace
a Reaction condition: aldehyde (1 mmol), 2-Thiobarbituric acid (2 mmol), acetate ammonium (1 mmol), and H2O (5 mL).
The Fe-MCM-41-IL catalyst with concentration of 20 mg, afforded the best yield of product (Table 2, entry 3). Increasing the amount of catalyst did not change the yield, whereas reducing the catalyst amount, significantly decreased the product yield of the reaction. With the optimal conditions, we embarked on an investigation of the substrate scope of this multi-component process with two moles of 2-thiobarbituric acid, aromatic aldehydes and ammonium acetate to afford the desired pyrimidines in high yields. The corresponding results are indicated in Table 3. In terms of electronic effects, it appears that these reactions are favored by electron withdrawing groups. Aldehydes with electronwithdrawing groups were more active than the electron-donating substituents and underwent facile conversion yielding the corresponding pyrimidines in good yield (Table 3). However, the reaction time of aldehydes with electron-withdrawing groups was shorter than those of with electron-rich groups due to the lower reactivity of the later aldehydes. A good linear correlation between values of log (kX/kH) and the BrowneOkamoto constants (R2 ¼ 0.99; Fig. 7) was observed for the competitive reaction of substituted aldehydes (sþ ¼ p-NO2, p-Cl, p-H, p-Me, and p-OMe) [39]. The resulting
Table 3 Three component synthesis of pyrido[2,3-d:6,5-d]dipyrimidinesa (ael).
Compound
R
t (min)
Yieldb (%)
a b c d e f g h i j k l m n
C6H6 4-Cl-C6H4 4-NO2-C6H4 4-Me-C6H4 4-OMe-C6H4 2-NO2-C6H4 2-OMe-C6H4 2-OH-C6H4 2-F-C6H4 3-OMe-C6H4 4-Cl-3-NO2-C6H4 2-Pyrimidinyl 2-hydroxy naphthalenyl 4-CHO-C6H4
40 34 25 46 57 30 40 40 45 40 42 35 35 35
89 91 95 87 84 93 85 82 80 92 87 90 91 89
a Reaction condition: aldehyde (1 mmol), 2-Thiobarbituric acid (2 mmol), acetate ammonium (1 mmol), Fe-MCM-41-IL (20 mg) and H2O (5 mL). b Isolated yields.
27
Hammett parameter r was þ0.32, indicating that the electronwithdrawing groups facilitate the reaction. This finding is in agreement with the proposed reaction mechanism for synthesis of pyrimidines as shown in Scheme 2. According to a plausible mechanism which is outline in Scheme 2, the formation of the pyrimidine derivatives is expected to proceed via initial condensation of aldehyde with 1,3-dimethyl-2amino uracil which is formed through the reaction of a molecule of 2-thiobarbituric acid and ammonium acetate to yield intermediate I. The second molecule of 2-thiobarbituric acid is added to the intermediate I via Michael addition to generate intermediate II, which is then cyclized to the final product. As shown in Scheme 2, Fe-MCM-41-IL as a catalyst provides a proton source in all steps of the synthesis of pyrimidines. The recycling and recovery of the supported catalysts are a very important issue from both the practical and environment points of view. We further explored the reusability of the catalyst in the model reaction between 4-nitro-benzaldehyde, 2-thiobarbituric acid and ammonium acetate in the presence of 20 mg of FeMCM-41-IL. Then, the catalyst was simply recycled via attaching an external magnet after completion the reaction and washed with hot water, dried under vacuum and reused in a subsequent reaction. The results indicated that this simple separation method could be repeated for five consecutive runs and the recovered aqueous phase containing the Fe-MCM-41-IL catalyst remarkably showed constant catalytic activity in all the six cycles (Fig. 8). Also, the total surface acidity for the recyclable catalyst was determined by sodium hydroxide titration and this measurement was shown that the pH of recyclable catalyst was with slight decrease 1.07 that can be equal to loading the 2.09 mmol (Hþ) g1.
3. Conclusion We successfully developed a novel Fe-MCM-41 supported acidic IL and used in a facile, one-pot four-component condensation reaction of 2-thiobarbituric acid (2 mol) with aromatic aldehydes and ammonium acetate to prepare pyrimidine compounds in excellent yields (up to 95%). Moreover, the catalyst recovery test was performed using an external magnet device, and showed that the catalyst can be reused several times without a significant decrease in its performance and catalytic activity.
Fig. 7. Hammett plots for the synthesis of pyrimidines using Fe-MCM-41-IL as catalyst.
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H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30
Scheme 2. Proposed mechanism for the multicomponent reaction using Fe-MCM-41-IL catalyst.
4. Experimental section
vibrating sample magnetometer (VSM, Meghnatis Daghigh Kavir Company, Iran).
4.1. General All chemicals were purchased from Fluka, Merck and Aldrich chemical companies. FT-IR spectra were obtained as KBr pellets on a Perkin-Elmer 781 spectrophotometer and on an impact 400 Nicolet FT-IR spectrophotometer. 1H NMR and 13C NMR were recorded in CDCl3 and DMSO solvents on a Bruker DRX-400 spectrometer with tetramethylsilane as internal reference. The XRD patterns were recorded on an X-ray diffractometer (Bruker, D8 ADV ANCE, Germany) using a Cu-Ka radiation (l ¼ 0.154056 nm) in the range 2q ¼ 0.5e5 . The N2 adsorption/desorption analysis (BET) was performed at 196 C using an automated gas adsorption analyzer (Tristar 3000, Micromeritics). The surface morphology of the supported catalyst was studied by scanning electron microscopy. FE-SEM and elemental analysis were carried out using a Jeol SEM instrument (model-VEGA/TESCAN) combined with an INCA instrument for energy dispersive X-ray spectroscopy scanning electron microscopy (EDS-SEM), with scanning electron electrode at 15 kV. The magnetic property of the catalyst was studied by
4.2. Preparation of ionic liquid functionalized iron-containing MCM-41 (Fe-MCM-41-IL) Iron-containing MCM-41 was synthesized under directhydrothermal conditions in the presence of cetyl trimethyl ammonium bromide (CTAB) as template. In a typical synthesis, 2.24 g of ferric chloride (FeCl3$6H2O) was added to a mixture of 480 mL of distilled water, 1.0 g of CTAB and 3.5 mL of 2 M NaOH aqueous solution. 5 mL of tetraethyl orthosilicate (TEOS) was subsequently dropped into the homogeneous solution under stirring. After stirring for 2 h at ambient temperature, the product was separated by filtration, washed with deionized water, and dried at 100 C. The solid product was collected and calcined at 550 C for 6 h in air. The iron content in Fe-MCM-41 was determined to be 0.002 mmol g1 based on AAS. To prepare the ionic liquid, the 1,2,3-triazole (1-(4-Phenyl-1H1,2,3-triazol-1-yl)butan-2-ol) was synthesized using a reported procedure [40] then, to a solution of 1,2,3-triazole (3.4 g, 50 mmol)
H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30 100 95
96
90
95
95
95
94
94
93
85 80 75
% Yield
70 65 60 55 50 45 40 35 30
29
of the product solution. This solution was concentrated to generate the pure crude product. The solid crude product was recrystallized from hot ethanol to afford the pyrimidine as a pure product. The obtained products were confirmed and completely characterized by physical and spectral data (see the Supporting Information). 5-(pyridine-2-yl)-2,8-dithioxo-2,3,7,8,9,10-hexahydropyrido [2,3-d:6,5-d′]dipyrimidine-4,6(1H,5H)-dione (l). Red powder; mp 280 C dec; IR (KBr) n 3398, 3210, 2881, 1605, 1455, 1533; 1H NMR (DMSO-d6, 400 MHz) d 6.20 (s, 1H, CH), 7.83 (s, 2H, HeAr), 8.42 (m, 1H, HeAr), 8.6 (s, 1H, NH), 11.84 (s, 4H, NH); 13C NMR (DMSO-d6, 100 MHz) d 32.03, 92.94, 124.86, 126.21, 141.98, 146.83, 158.93,163.41, 174.28; EI-MS (70 ev) m/z (%) 51 (8.31), 77 (23.27), 124 (37.53), 126 (4.96), 228 (100), 352 (3.91), 358 (0.06). Acknowledgments
25 20 1
2
3
4
5
6
Number of recycles Fig. 8. Recycling of the catalyst.
in dry toluene (50 mL), 3-chloropropyltrimethoxysilane (12.0 mL, 50 mmol) was added and the mixture was refluxed overnight under a nitrogen atmosphere. The solvent was removed by rotatory evaporation under reduced pressure and the product was obtained as an intermediate. Next step, this intermediate (2.72 g, 10 mmol) was dissolved in toluene (30 mL). The 1,4-butanesultone was added to the reaction mixture at room temperature for 8 h to produce the zwitterionic triazoleneammonium salt. The concentrated H2SO4 (0.54 mL, 10 mmol) was added drop wise into the solution of the above residue in ethanol (30 mL) over 30 min and the final mixture was stirred at 50 C for another 8 h. The final mixture was evaporated under reduced pressure to give the ionic liquid as a viscous yellow liquid. The spectral data for IL is as follows: 1H NMR (400 MHz, D2O) d 8.05 (s, 1H), 7.07 (d, 1H), 6.88 (m, 3H), 3.88 (m, 2H), 3.39 (s, 4H), 2.95 (s, 9H) 2.59 (m, 2H), 1.50 (m, 2H), 1.16 (m, 2H), 0.57 (m, 3H), 0.46 (m, 2H); 13C NMR (100 MHz, D2O) d 140.61, 129.65, 127.55, 124.62, 120.11, 74.04, 64.09, 56.47, 56.14, 45.78, 20.59, 20.11, 14.17, 14.10, 12.13, 7.15. For immobilization of IL onto Fe-MCM-41, the solution of IL (containing 0.3 g IL) was diluted with dry CHCl3 and was then added slowly to a suspension of 1 g hydrated Fe-MCM-41 in dry CHCl3 (180 mL), under argon atmosphere. The resulting mixture was refluxed for 24 h. After cooling, the solid materials were filtered off and the residue was washed with hot CHCl3 and then dried in oven at 90 C overnight to give IL matrix immobilized on Fe-MCM-41. A 0.08 M solution of sodium hydroxide was used for measurement of total surface acidity for the Fe-MCM-41-IL and Fe-MCM-41. Then, 0.02 g of solid was suspended in this solution for 24 h, and the excess amount of base was titrated against hydrochloric acid using phenolphthalein as an indicator. 4.3. General procedure for the synthesis of pyrimidine derivatives using Fe-MCM-41-IL as a catalyst An equimolar mixture of benzaldehyde (1 mmol), 2thiobarbituric acid (2 mmol), ammonium acetate (1 mmol) and 20 mg Fe-MCM-41-IL in H2O (5 mL) was stirred at room temperature for 30 min. The progress of the reaction was monitored by TLC. After completion of reaction, the reaction mixture was filtered. Then, the product was dissolved in mixture of water/ethanol and the catalyst easily separated from the product by attaching an external magnet onto the reaction vessel, followed by decantation
The authors are grateful to University of Kashan for supporting this work by Grant No. 159148/52. Appendix A. Supplementary data Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.micromeso.2016.02.036. References [1] J. Choma, M. Jaroniec, W. Burakiewicz-Mortka, M. Kloske, Appl. Surf. Sci. 196 (2002) 216. [2] C.T. Kresge, M.E. Leonowicz, W.J. Roth, J.C. Vartuli, J.S. Beck, Nature 359 (1992) 710. [3] J.S. Beck, K.D. Schmitt, J.B. Higgins, J.L. Schlenkert, J. Am. Chem. Soc. 114 (1992) 10834. [4] C. Cheng, W. Zhou, J. Klinowski, Chem. Phys. Lett. 4 (1996) 2. [5] A. Corma, Chem. Rev. 97 (1997) 2373. [6] R. Savidha, A. Pandurangan, M. Palanichamy, V. Murugesan, J. Mol. Catal. A Chem. 211 (2004) 165. [7] M. Stockenhuber, M.J. Hudson, R.W. Joyner, J. Phys. Chem. B 104 (2000) 3370. [8] P.B. Amama, S. Lim, D. Ciuparu, Y. Yang, L. Pfefferle, G.L. Haller, J. Phys. Chem. B (2005) 2645. [9] J.-S. Choi, S.-S. Yoon, S.-H. Jang, W.-S. Ahn, Catal. Today 111 (2006) 280. [10] M. Esther Leena Preethi, S. Revathi, T. Sivakumar, D. Manikandan, D. Divakar, A. Valentine Rupa, M. Palanichami, Catal. Lett. 120 (2007) 56. [11] N. Gokulakrishnan, A. Pandurangan, P.K. Sinha, Ind. Eng. Chem. Res. 48 (2009) 1556. [12] R. Huang, B. Lan, Z. Chen, H. Yan, Q. Zhang, J. Bing, L. Li, Chem. Eng. J. 180 (2012) 19. [13] D. Pinkert, C. Limberg, Chem. Eur. J. 20 (2014) 9166. [14] A. Wingen, N. Anastasievi c, A. Hollnagel, D. Werner, F. Schüth, J. Catal. 193 (2000) 248. [15] C. Wu, Y. Kong, F. Gao, Y. Wu, Y. Lu, J. Wang, L. Dong, Microporous Mesoporous Mater. 113 (2008) 163. [16] S.V. Sirotin, I.F. Moskovskaya, B.V. Romanovsky, Catal. Sci. Technol. 1 (2011) 971. [17] R. Sheldon, Chem. Commun. (2001) 2399. [18] P. Wasserscheid, W. Keim, Angew. Chem. Int. Ed. 39 (2000) 3772. [19] S. Das, T. Asefa, ACS Catal. 1 (2011) 502. ro ^ me, J. Barrault, Org. Lett. 9 (2007) 3145. [20] Y. Gu, A. Karam, F. Je [21] D.A. Links, Chem. Commun. (2012) 3327. [22] C.P. Mehnert, R.A. Cook, N.C. Dispenziere, M. Afeworki, J. Am. Chem. Soc. 124 (2002) 12932. [23] C.P. Mehnert, J. Mozeleski, R.A. Cook, Chem. Commun. (2002) 3010. [24] J. Xiong, W. Zhu, H. Li, Y. Xu, W. Jiang, S. Xun, H. Liu, Z. Zhao, C. R. Chim. 59 (2013) 4696. [25] A. Khalafi-Nezhad, S. Mohammadi, ACS Comb. Sci. 15 (2013) 512. [26] A. Bazgir, M.M. Khanaposhtani, R. Ghahremanzadeh, A.A. Soorki, C. R. Chim. 12 (2009) 1287. [27] M. Kawase, A. Shah, H. Gaveriya, N. Motohashi, H. Sakagami, A. Varga, J. Molnar, Bioorg. Med. Chem. 10 (2002) 1051. [28] A. Boumendjel, D. Baubichon-Cortay, H. Trompier, T. Perrotton, A. Di Pietro, Med. Res. Rev. 25 (2005) 453. [29] A. Agarwal, Ramesh, Ashutosh, N. Goyal, P.M.S. Chauhan, S. Gupta, Bioorg. Med. Chem. 13 (2005) 6678. [30] W. Jie-Ping, L. Yunyun, Rsc Adv. 2 (2012) 9763. [31] A. Hantzsch, Justus Liebigs Ann. Chem. 1 (1892) 215. [32] B. Guillaume, A.B. Charette, J. Am. Chem. Soc. 130 (2008) 18. [33] M. Kidwai, R. Mohan, S. Saxena, Russ. Chem. Bull. Int. Ed. 52 (2003) 2457. [34] G.-W. Wang, C.-B. Miao, Green Chem. 8 (2006) 1080.
30
H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30
[35] Y. Jiang, K. Lin, Y. Zhang, J. Liu, G. Li, J. Sun, X. Xu, Appl. Catal. A 445e446 (2012) 172. [36] H. Kosslick, G. Lischke, G. Walther, W. Storek, a. Martin, R. Fricke, Microporous Mesoporous Mater. 9 (1997) 13.
[37] Li Baoshan, K. Wu, T. Yuan, C. Han, J. Xu, X. Pang, Microporous Mesoporous Mater. 151 (2012) 277. [38] G. Leofanti, M. Padovan, G. Tozzola, B. Venturelli, Catal. Today 41 (1998) 207. [39] H.C. Brown, Y. Okamoto, J. Am. Chem. Soc. 80 (1958) 4979. [40] H. Naeimi, V. Nejadshafiee, New J. Chem. 38 (2014) 5429.
Contents lists available at ScienceDirect
Microporous and Mesoporous Materials journal homepage: www.elsevier.com/locate/micromeso
Iron (III)-doped, ionic liquid matrix-immobilized, mesoporous silica nanoparticles: Application as recyclable catalyst for synthesis of pyrimidines in water Hossein Naeimi a, *, Vajihe Nejadshafiee a, Mohammad Reza Islami b a b
Department of Organic Chemistry, Faculty of Chemistry, University of Kashan, Kashan 87317, Islamic Republic of Iran Chemistry Department, Shahid Bahonar University of Kerman, Kerman 76169, Islamic Republic of Iran
a r t i c l e i n f o
a b s t r a c t
Article history: Received 5 December 2015 Received in revised form 13 February 2016 Accepted 17 February 2016 Available online 21 February 2016
A novel ionic liquid functionalized iron-containing mesoporous silica nanoparticles (Fe-MCM-41-IL) was prepared by anchoring a triazolium ionic liquid on the surface of Fe loaded MCM. The result samples were characterized by XRD, FT-IR, EDS, XRF, HRTEM, FE-SEM, VSM, N2 adsorptionedesorption analysis and AAS techniques. The use of Fe-MCM-41-IL as an efficient reusable heterogeneous catalyst allows onepot synthesis of pyrimidine derivatives under mild condition in high yields from substituted aldehydes, two moles of 2-thiobarbituric acid and ammonium acetate. Operational simplicity, low cost, high yields, eco-friendly reaction conditions, economical catalyst, reusability and easy recovery of the catalyst make this procedure greener than the other reported works. © 2016 Elsevier Inc. All rights reserved.
Keywords: Mesoporous Nanoparticles Synthesis Ionic liquid Pyrimidines Catalyst
1. Introduction Within the past decade, mesoporous silica materials (MCM-41) have increased in popularity for heterogenous catalyst purposes, in part because their large pore volume, high surface area, uniform pore size distribution, regular structure and high thermal stability [1e4]. Generally, the pure silica MCM has limited catalytic activity but active catalytic sites can be generated in MCM by isomorphously substituting silicon with a metal [5]. Several studies have been dedicated to the investigation of transition-metalsubstituted MCM-41 because of their wide range of applications in catalysis [6,7]. Specifically, the substitution of iron species in the framework of MCM such as Fe-MCM-41 has a higher specific activity in the organic reactions [8e16]. In recent decades ionic liquids phases have attracted significant attention in the scientific community as an alternative reaction medium for homogeneous catalysis [17,18]. Although the ability of liquideliquid biphase catalysis in ionic liquid has successfully been demonstrated but heterogeneous catalysts are still preferred by industry because the
* Corresponding author. E-mail address: [email protected] (H. Naeimi). http://dx.doi.org/10.1016/j.micromeso.2016.02.036 1387-1811/© 2016 Elsevier Inc. All rights reserved.
ease of separation. Recently, the ionic liquids supported on the solid such as amorphous silica and mesoporous silica hybrid [19e24], magnetic nanoparticle [25], especially acidic types have attracted increasing interest in organic synthesis, because they can provide green and efficient media for organic reactions. The development of efficient methods for constructing substituted six-membered nitrogen-containing heterocycles such as; 1,4-dihydropyridines (1,4DHPs) has been the subject of extensive research due to the vast number of natural products, pharmaceutical and agrochemical agents, and functional materials containing these ring systems [26e29]. The traditional procedures for the synthesis of 1,4-DHPs rely on condensation of amine and carbonyl compounds. Much effort has been dedicated to the development of new methodologies to access 1,4-DHPs [30]. Among a number of methodologies developed to date, the [2þ2þ1þ1] Hantzsch reaction using two 1,3-dicarbonyl compounds, an amine and an aldehyde is a conventional and succinct approach to synthesize symmetrical 1,4-DHPs [31,32]. Various methods for the preparation of 1,4-DHPs and pyrimidine-fused heterocycles by using cyclic diketone, aromatic aldehydes and amines or ammonium acetate under different conditions have been reported [26,33,34]. Initially, herein, we present the preparation and characterization of supported novel ionic liquid catalyst based
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on functionalized iron-containing mesoporous silica nanoparticles (Fe-MCM-41-IL). Then, we focus our attention on a simple, green and efficient method for the synthesis of biological active pyrimidine derivatives from a wide variety of aldehydes, 2-thiobarbituric acid and ammonium acetate in high yields and short reaction times. 2. Results and discussion 2.1. Catalyst preparation Novel ionic liquid functionalized iron-containing MCM-41, named Fe-MCM-41-IL as a nanocatalyst was prepared based on the following procedure. Initially, the Fe-MCM-41 was prepared by the direct-hydrothermal technique of ferric chloride (FeCl3$6H2O), TEOS as source silica and cetyl trimethyl ammonium bromide (CTAB) as a structural directing surfactant in an alkaline solution according to the literature procedure [35]. Then, the triazole ammonium based ionic liquid including 1,2,3-triazole functionality on one side and a triethoxysilyl moiety on the other side was synthesized and subsequently grafted to the surface of Fe-MCM-41 in refluxing toluene for 24 h (Scheme 1). 2.2. Catalyst characterization Fig. 1. FT-IR spectra of a) MCM-41, b) Fe-MCM-41 and c) Fe-MCM-41-IL.
Fourier transform-infrared (FT-IR) spectra of MCM-41, Fe-MCM41 and Fe-MCM-41-IL are shown in Fig. 1. For all samples the bands characteristic of the MCM-41 framework can be clearly seen. The slight shift of the 1109 cm1 band of SieOeSi into the 1081 cm1 band of SieOeFe vibrations allowed the conclusion that the heteroatoms were incorporated into the framework of MCM-41 and
H3CO
OCH3 Si OCH3
i) Cl N Ph
N
N
N
the formation of FeeOeSi bonds [36]. In Fig. 1c, the absorption peaks at 2924 and 2855 cm1 were assigned to aromatic CeH and aliphatic CeH of the IL structure, respectively. The presence of these peaks confirms successful immobilization of IL on the surface of
C2H5 N
O
Ph
N
OH
OCH3 Si OCH3 H3CO
N
HO3S
N
N
O (IL)
CTAB
iii) H2SO4
C2H5
Ph
NaOH
O S O O
C2H5 HSO4-
FeCl3.6H2O
ii)
OCH3 Si OCH3 H3CO
1) Washed
stirred
550 oC, 6h
TEOS 2 h, rt
2) Dried at 100 oC
H2O
Fe-MCM-41 IL
HSO4HO3S
N N Ph
N
C2H5 O
Toluene, 24 h
Si O H3CO O
Fe-MCM-41-IL Scheme 1. Different Steps for Synthesis of Fe-MCM-41-IL.
H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30
Fig. 2. XRD pattern of Fe-MCM-41.
Fe-MCM. The additional peak was observed at 1520 cm1 related to C]N bond. Furthermore, the bands at 3438 and 3425 cm1 suggest that there are OH groups on the mesoporous Fe-MCM-41 and after the immobilization of IL on the Fe-MCM-41 surface (Fig. 1a and b). The low-angle X-ray diffraction (XRD) pattern of Fe-MCM-41 is depicted in Fig. 2. Fe-MCM-41pattern showed a distinct broad peak which account for the Bragg plane (100) intense reflection, indicating the regular arrangement of mesoporous with hexagonal symmetry [12,37]. The structure of the prepared materials was further verified using field emission-scanning electron microscopy (FE-SEM) and
25
high-resolution transmission electron microscopy (HRTEM) images. As can be clearly seen, Fe-MCM-41 have a well-defined spherical structure with relatively narrow size distribution and its FE-SEM image indicated that the diameter of the spherical particles in the about 85e87 nm (Fig. 3a). After functionalization with IL, the Fe-MCM-41-IL kept their spherical structure with particle size of about 95e98 nm as shown in the FE-SEM images (Fig. 3b). The results indicated that the FE-SEM images of Fe-MCM-41 and FeMCM-41-IL exhibited similar structure with increase of particles size which provided strong evidence that the mesoporous structure of the supporting retained after the grafting process. Fig. 3c and d are shown the HRTEM images of Fe-MCM-41 and Fe-MCM-41-IL samples. As can be seen from these images, the wellordered pore arrangements and the iron uniform introduction into mesoporous silicate framework were visible. Also, the long-rang order and mesoporous structure arrays were not disturbed significantly after Fe doping. The Fe and Si contents in Fe-MCM-41 were determined using Xray fluorescence analysis (XRF) and their results were shown that the molar ratio of Fe/Si was 13.47. Furthermore, the closeness of ionic liquid groups on the Fe-MCM-41-IL surface was further confirmed by energy dispersive spectrometer (EDS) (Fig. 4). The obtained results by EDS were as follows (%): C, 5.40; N, 5.25; Si, 17.38; O, 61.32; S, 6.92; Fe, 3.72. N2 adsorptionedesorption isotherms and the BarretteJoynereHalenda (BJH) pore-size distribution curves of FeMCM and Fe-MCM-41-IL are depicted in Fig. 5. The samples displayed type II isotherms [38] and capillary condensation at relative pressures of 0.3 < P/P0 < 0.5, which was the characteristic of mesoporous materials. The textural properties of Fe-MCM-41 were substantially maintained after immobilization of triazolium ionic liquid.
Fig. 3. FE-SEM images of a) Fe-MCM-41, b) Fe-MCM-41-IL and TEM images of c) Fe-MCM-41, d) Fe-MCM-41-IL.
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H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30
Fig. 6. Magnetization curves for the prepared Fe-MCM-41 and Fe-MCM-41-IL.
Fig. 4. EDS pattern of Fe-MCM-41-IL.
can be related to incorporation of high Fe content into the framework of MCM-41. The magnetic properties of the Fe-MCM-41 and Fe-MCM-41-IL catalyst were investigated using a vibrating sample magnetometer at room temperature. As illustrated in Fig. 6, the magnetization curves of the prepared materials exhibit no hysteresis loop which demonstrates its super paramagnetic characteristics. Moreover, the good magnetic properties of the prepared catalyst were revealed by complete and easy attraction using an external magnet. The saturation magnetization of the Fe-MCM-41 and Fe-MCM-41-IL were found to be 2.80 emu g1 and 1.74 emu g1, respectively as measured using vibrating sample magnetometer (VSM). Since, ionic liquid was coated with Fe-MCM-41 mesoporous hybrid a decrease in saturation magnetization can be observed after coating. Furthermore, the total surface acidity for the Fe-MCM-41 and Fe-MCM-41-IL were determined by sodium hydroxide titration. In this measurement procedure, the pH of Fe-MCM-41 and Fe-MCM41-IL catalyst were 5.87 and 1.04 that can be equal to loading the 3.37 105 and 2.19 mmol (Hþ) g1, respectively. 2.3. Investigation of catalyst activity in synthesis of pyrimidines
Fig. 5. N2 adsorptionedesorption isotherms Fe-MCM-41 and Fe-MCM-41-IL.
The surface area, pore volume, and pore diameters of Fe-MCM and Fe-MCM-41-IL are listed in Table 1. The surface area decreased from 307 to 225 m2 g1 with supported IL on the FeMCM-41. Also, there is a negligible change in pore volume from 0.42 to 0.38 cm3 g1 after grafting process. It could be concluded that introduction of ionic liquid significantly affected the surface area and pore volume of the support. Moreover, the smaller surface area of Fe-MCM-41 compared with previous Fe-MCM-41 samples
For the purpose of the catalytic activity comparison of Fe-MCM41 and Fe-MCM-41-IL, the treatment of 2-thiobarbituric acid, benzaldehyde and ammonium acetate affording pyrimidine were examined in the amount of different catalysts. The results of the optimized conditions are summarized in Table 2. These observations clearly emphasized the existence of a significant effect between grafted ionic liquid groups and without ionic liquid on the Fe-MCM-41 surface. Therefore, the Fe-MCM-41-IL catalyst showed excellent catalytic performance rather than Fe-MCM-41 that accordance to strong acidic properties of Fe-MCM-41-IL catalyst was justified.
Table 1 Surface Properties of Fe-MCM-41 and Ionic-liquid modified Fe-MCM-41 (Fe-MCM-41-IL). Sample
Surface areaa (m2 g1)
Pore sizeb (nm)
Pore volumec (cm3 g1)
Fe-MCM-41 Fe-MCM-41-IL
307.98 225
8.42 8.25
0.42 0.38
a b c
Calculated by the BET model. Calculated by the BJH model from the desorption isotherm. Total pore volume at P/P0 ¼ 0.99.
H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30 Table 2 Effect of catalyst amount on the reaction.a
Fe-MCM-41-IL
Fe-MCM-41
Entry
Amount of catalyst (mg)
Yield (%)
Amount of catalyst (mg)
Yield (%)
1 2 3 4
10 15 20 25
80 84 89 89
10 15 20 25
trace trace trace trace
a Reaction condition: aldehyde (1 mmol), 2-Thiobarbituric acid (2 mmol), acetate ammonium (1 mmol), and H2O (5 mL).
The Fe-MCM-41-IL catalyst with concentration of 20 mg, afforded the best yield of product (Table 2, entry 3). Increasing the amount of catalyst did not change the yield, whereas reducing the catalyst amount, significantly decreased the product yield of the reaction. With the optimal conditions, we embarked on an investigation of the substrate scope of this multi-component process with two moles of 2-thiobarbituric acid, aromatic aldehydes and ammonium acetate to afford the desired pyrimidines in high yields. The corresponding results are indicated in Table 3. In terms of electronic effects, it appears that these reactions are favored by electron withdrawing groups. Aldehydes with electronwithdrawing groups were more active than the electron-donating substituents and underwent facile conversion yielding the corresponding pyrimidines in good yield (Table 3). However, the reaction time of aldehydes with electron-withdrawing groups was shorter than those of with electron-rich groups due to the lower reactivity of the later aldehydes. A good linear correlation between values of log (kX/kH) and the BrowneOkamoto constants (R2 ¼ 0.99; Fig. 7) was observed for the competitive reaction of substituted aldehydes (sþ ¼ p-NO2, p-Cl, p-H, p-Me, and p-OMe) [39]. The resulting
Table 3 Three component synthesis of pyrido[2,3-d:6,5-d]dipyrimidinesa (ael).
Compound
R
t (min)
Yieldb (%)
a b c d e f g h i j k l m n
C6H6 4-Cl-C6H4 4-NO2-C6H4 4-Me-C6H4 4-OMe-C6H4 2-NO2-C6H4 2-OMe-C6H4 2-OH-C6H4 2-F-C6H4 3-OMe-C6H4 4-Cl-3-NO2-C6H4 2-Pyrimidinyl 2-hydroxy naphthalenyl 4-CHO-C6H4
40 34 25 46 57 30 40 40 45 40 42 35 35 35
89 91 95 87 84 93 85 82 80 92 87 90 91 89
a Reaction condition: aldehyde (1 mmol), 2-Thiobarbituric acid (2 mmol), acetate ammonium (1 mmol), Fe-MCM-41-IL (20 mg) and H2O (5 mL). b Isolated yields.
27
Hammett parameter r was þ0.32, indicating that the electronwithdrawing groups facilitate the reaction. This finding is in agreement with the proposed reaction mechanism for synthesis of pyrimidines as shown in Scheme 2. According to a plausible mechanism which is outline in Scheme 2, the formation of the pyrimidine derivatives is expected to proceed via initial condensation of aldehyde with 1,3-dimethyl-2amino uracil which is formed through the reaction of a molecule of 2-thiobarbituric acid and ammonium acetate to yield intermediate I. The second molecule of 2-thiobarbituric acid is added to the intermediate I via Michael addition to generate intermediate II, which is then cyclized to the final product. As shown in Scheme 2, Fe-MCM-41-IL as a catalyst provides a proton source in all steps of the synthesis of pyrimidines. The recycling and recovery of the supported catalysts are a very important issue from both the practical and environment points of view. We further explored the reusability of the catalyst in the model reaction between 4-nitro-benzaldehyde, 2-thiobarbituric acid and ammonium acetate in the presence of 20 mg of FeMCM-41-IL. Then, the catalyst was simply recycled via attaching an external magnet after completion the reaction and washed with hot water, dried under vacuum and reused in a subsequent reaction. The results indicated that this simple separation method could be repeated for five consecutive runs and the recovered aqueous phase containing the Fe-MCM-41-IL catalyst remarkably showed constant catalytic activity in all the six cycles (Fig. 8). Also, the total surface acidity for the recyclable catalyst was determined by sodium hydroxide titration and this measurement was shown that the pH of recyclable catalyst was with slight decrease 1.07 that can be equal to loading the 2.09 mmol (Hþ) g1.
3. Conclusion We successfully developed a novel Fe-MCM-41 supported acidic IL and used in a facile, one-pot four-component condensation reaction of 2-thiobarbituric acid (2 mol) with aromatic aldehydes and ammonium acetate to prepare pyrimidine compounds in excellent yields (up to 95%). Moreover, the catalyst recovery test was performed using an external magnet device, and showed that the catalyst can be reused several times without a significant decrease in its performance and catalytic activity.
Fig. 7. Hammett plots for the synthesis of pyrimidines using Fe-MCM-41-IL as catalyst.
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H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30
Scheme 2. Proposed mechanism for the multicomponent reaction using Fe-MCM-41-IL catalyst.
4. Experimental section
vibrating sample magnetometer (VSM, Meghnatis Daghigh Kavir Company, Iran).
4.1. General All chemicals were purchased from Fluka, Merck and Aldrich chemical companies. FT-IR spectra were obtained as KBr pellets on a Perkin-Elmer 781 spectrophotometer and on an impact 400 Nicolet FT-IR spectrophotometer. 1H NMR and 13C NMR were recorded in CDCl3 and DMSO solvents on a Bruker DRX-400 spectrometer with tetramethylsilane as internal reference. The XRD patterns were recorded on an X-ray diffractometer (Bruker, D8 ADV ANCE, Germany) using a Cu-Ka radiation (l ¼ 0.154056 nm) in the range 2q ¼ 0.5e5 . The N2 adsorption/desorption analysis (BET) was performed at 196 C using an automated gas adsorption analyzer (Tristar 3000, Micromeritics). The surface morphology of the supported catalyst was studied by scanning electron microscopy. FE-SEM and elemental analysis were carried out using a Jeol SEM instrument (model-VEGA/TESCAN) combined with an INCA instrument for energy dispersive X-ray spectroscopy scanning electron microscopy (EDS-SEM), with scanning electron electrode at 15 kV. The magnetic property of the catalyst was studied by
4.2. Preparation of ionic liquid functionalized iron-containing MCM-41 (Fe-MCM-41-IL) Iron-containing MCM-41 was synthesized under directhydrothermal conditions in the presence of cetyl trimethyl ammonium bromide (CTAB) as template. In a typical synthesis, 2.24 g of ferric chloride (FeCl3$6H2O) was added to a mixture of 480 mL of distilled water, 1.0 g of CTAB and 3.5 mL of 2 M NaOH aqueous solution. 5 mL of tetraethyl orthosilicate (TEOS) was subsequently dropped into the homogeneous solution under stirring. After stirring for 2 h at ambient temperature, the product was separated by filtration, washed with deionized water, and dried at 100 C. The solid product was collected and calcined at 550 C for 6 h in air. The iron content in Fe-MCM-41 was determined to be 0.002 mmol g1 based on AAS. To prepare the ionic liquid, the 1,2,3-triazole (1-(4-Phenyl-1H1,2,3-triazol-1-yl)butan-2-ol) was synthesized using a reported procedure [40] then, to a solution of 1,2,3-triazole (3.4 g, 50 mmol)
H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30 100 95
96
90
95
95
95
94
94
93
85 80 75
% Yield
70 65 60 55 50 45 40 35 30
29
of the product solution. This solution was concentrated to generate the pure crude product. The solid crude product was recrystallized from hot ethanol to afford the pyrimidine as a pure product. The obtained products were confirmed and completely characterized by physical and spectral data (see the Supporting Information). 5-(pyridine-2-yl)-2,8-dithioxo-2,3,7,8,9,10-hexahydropyrido [2,3-d:6,5-d′]dipyrimidine-4,6(1H,5H)-dione (l). Red powder; mp 280 C dec; IR (KBr) n 3398, 3210, 2881, 1605, 1455, 1533; 1H NMR (DMSO-d6, 400 MHz) d 6.20 (s, 1H, CH), 7.83 (s, 2H, HeAr), 8.42 (m, 1H, HeAr), 8.6 (s, 1H, NH), 11.84 (s, 4H, NH); 13C NMR (DMSO-d6, 100 MHz) d 32.03, 92.94, 124.86, 126.21, 141.98, 146.83, 158.93,163.41, 174.28; EI-MS (70 ev) m/z (%) 51 (8.31), 77 (23.27), 124 (37.53), 126 (4.96), 228 (100), 352 (3.91), 358 (0.06). Acknowledgments
25 20 1
2
3
4
5
6
Number of recycles Fig. 8. Recycling of the catalyst.
in dry toluene (50 mL), 3-chloropropyltrimethoxysilane (12.0 mL, 50 mmol) was added and the mixture was refluxed overnight under a nitrogen atmosphere. The solvent was removed by rotatory evaporation under reduced pressure and the product was obtained as an intermediate. Next step, this intermediate (2.72 g, 10 mmol) was dissolved in toluene (30 mL). The 1,4-butanesultone was added to the reaction mixture at room temperature for 8 h to produce the zwitterionic triazoleneammonium salt. The concentrated H2SO4 (0.54 mL, 10 mmol) was added drop wise into the solution of the above residue in ethanol (30 mL) over 30 min and the final mixture was stirred at 50 C for another 8 h. The final mixture was evaporated under reduced pressure to give the ionic liquid as a viscous yellow liquid. The spectral data for IL is as follows: 1H NMR (400 MHz, D2O) d 8.05 (s, 1H), 7.07 (d, 1H), 6.88 (m, 3H), 3.88 (m, 2H), 3.39 (s, 4H), 2.95 (s, 9H) 2.59 (m, 2H), 1.50 (m, 2H), 1.16 (m, 2H), 0.57 (m, 3H), 0.46 (m, 2H); 13C NMR (100 MHz, D2O) d 140.61, 129.65, 127.55, 124.62, 120.11, 74.04, 64.09, 56.47, 56.14, 45.78, 20.59, 20.11, 14.17, 14.10, 12.13, 7.15. For immobilization of IL onto Fe-MCM-41, the solution of IL (containing 0.3 g IL) was diluted with dry CHCl3 and was then added slowly to a suspension of 1 g hydrated Fe-MCM-41 in dry CHCl3 (180 mL), under argon atmosphere. The resulting mixture was refluxed for 24 h. After cooling, the solid materials were filtered off and the residue was washed with hot CHCl3 and then dried in oven at 90 C overnight to give IL matrix immobilized on Fe-MCM-41. A 0.08 M solution of sodium hydroxide was used for measurement of total surface acidity for the Fe-MCM-41-IL and Fe-MCM-41. Then, 0.02 g of solid was suspended in this solution for 24 h, and the excess amount of base was titrated against hydrochloric acid using phenolphthalein as an indicator. 4.3. General procedure for the synthesis of pyrimidine derivatives using Fe-MCM-41-IL as a catalyst An equimolar mixture of benzaldehyde (1 mmol), 2thiobarbituric acid (2 mmol), ammonium acetate (1 mmol) and 20 mg Fe-MCM-41-IL in H2O (5 mL) was stirred at room temperature for 30 min. The progress of the reaction was monitored by TLC. After completion of reaction, the reaction mixture was filtered. Then, the product was dissolved in mixture of water/ethanol and the catalyst easily separated from the product by attaching an external magnet onto the reaction vessel, followed by decantation
The authors are grateful to University of Kashan for supporting this work by Grant No. 159148/52. Appendix A. Supplementary data Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.micromeso.2016.02.036. References [1] J. Choma, M. Jaroniec, W. Burakiewicz-Mortka, M. Kloske, Appl. Surf. Sci. 196 (2002) 216. [2] C.T. Kresge, M.E. Leonowicz, W.J. Roth, J.C. Vartuli, J.S. Beck, Nature 359 (1992) 710. [3] J.S. Beck, K.D. Schmitt, J.B. Higgins, J.L. Schlenkert, J. Am. Chem. Soc. 114 (1992) 10834. [4] C. Cheng, W. Zhou, J. Klinowski, Chem. Phys. Lett. 4 (1996) 2. [5] A. Corma, Chem. Rev. 97 (1997) 2373. [6] R. Savidha, A. Pandurangan, M. Palanichamy, V. Murugesan, J. Mol. Catal. A Chem. 211 (2004) 165. [7] M. Stockenhuber, M.J. Hudson, R.W. Joyner, J. Phys. Chem. B 104 (2000) 3370. [8] P.B. Amama, S. Lim, D. Ciuparu, Y. Yang, L. Pfefferle, G.L. Haller, J. Phys. Chem. B (2005) 2645. [9] J.-S. Choi, S.-S. Yoon, S.-H. Jang, W.-S. Ahn, Catal. Today 111 (2006) 280. [10] M. Esther Leena Preethi, S. Revathi, T. Sivakumar, D. Manikandan, D. Divakar, A. Valentine Rupa, M. Palanichami, Catal. Lett. 120 (2007) 56. [11] N. Gokulakrishnan, A. Pandurangan, P.K. Sinha, Ind. Eng. Chem. Res. 48 (2009) 1556. [12] R. Huang, B. Lan, Z. Chen, H. Yan, Q. Zhang, J. Bing, L. Li, Chem. Eng. J. 180 (2012) 19. [13] D. Pinkert, C. Limberg, Chem. Eur. J. 20 (2014) 9166. [14] A. Wingen, N. Anastasievi c, A. Hollnagel, D. Werner, F. Schüth, J. Catal. 193 (2000) 248. [15] C. Wu, Y. Kong, F. Gao, Y. Wu, Y. Lu, J. Wang, L. Dong, Microporous Mesoporous Mater. 113 (2008) 163. [16] S.V. Sirotin, I.F. Moskovskaya, B.V. Romanovsky, Catal. Sci. Technol. 1 (2011) 971. [17] R. Sheldon, Chem. Commun. (2001) 2399. [18] P. Wasserscheid, W. Keim, Angew. Chem. Int. Ed. 39 (2000) 3772. [19] S. Das, T. Asefa, ACS Catal. 1 (2011) 502. ro ^ me, J. Barrault, Org. Lett. 9 (2007) 3145. [20] Y. Gu, A. Karam, F. Je [21] D.A. Links, Chem. Commun. (2012) 3327. [22] C.P. Mehnert, R.A. Cook, N.C. Dispenziere, M. Afeworki, J. Am. Chem. Soc. 124 (2002) 12932. [23] C.P. Mehnert, J. Mozeleski, R.A. Cook, Chem. Commun. (2002) 3010. [24] J. Xiong, W. Zhu, H. Li, Y. Xu, W. Jiang, S. Xun, H. Liu, Z. Zhao, C. R. Chim. 59 (2013) 4696. [25] A. Khalafi-Nezhad, S. Mohammadi, ACS Comb. Sci. 15 (2013) 512. [26] A. Bazgir, M.M. Khanaposhtani, R. Ghahremanzadeh, A.A. Soorki, C. R. Chim. 12 (2009) 1287. [27] M. Kawase, A. Shah, H. Gaveriya, N. Motohashi, H. Sakagami, A. Varga, J. Molnar, Bioorg. Med. Chem. 10 (2002) 1051. [28] A. Boumendjel, D. Baubichon-Cortay, H. Trompier, T. Perrotton, A. Di Pietro, Med. Res. Rev. 25 (2005) 453. [29] A. Agarwal, Ramesh, Ashutosh, N. Goyal, P.M.S. Chauhan, S. Gupta, Bioorg. Med. Chem. 13 (2005) 6678. [30] W. Jie-Ping, L. Yunyun, Rsc Adv. 2 (2012) 9763. [31] A. Hantzsch, Justus Liebigs Ann. Chem. 1 (1892) 215. [32] B. Guillaume, A.B. Charette, J. Am. Chem. Soc. 130 (2008) 18. [33] M. Kidwai, R. Mohan, S. Saxena, Russ. Chem. Bull. Int. Ed. 52 (2003) 2457. [34] G.-W. Wang, C.-B. Miao, Green Chem. 8 (2006) 1080.
30
H. Naeimi et al. / Microporous and Mesoporous Materials 227 (2016) 23e30
[35] Y. Jiang, K. Lin, Y. Zhang, J. Liu, G. Li, J. Sun, X. Xu, Appl. Catal. A 445e446 (2012) 172. [36] H. Kosslick, G. Lischke, G. Walther, W. Storek, a. Martin, R. Fricke, Microporous Mesoporous Mater. 9 (1997) 13.
[37] Li Baoshan, K. Wu, T. Yuan, C. Han, J. Xu, X. Pang, Microporous Mesoporous Mater. 151 (2012) 277. [38] G. Leofanti, M. Padovan, G. Tozzola, B. Venturelli, Catal. Today 41 (1998) 207. [39] H.C. Brown, Y. Okamoto, J. Am. Chem. Soc. 80 (1958) 4979. [40] H. Naeimi, V. Nejadshafiee, New J. Chem. 38 (2014) 5429.