Iron-based nanomaterials used as magnetic mesoporous nanocomposites to catalyze the preparation of <i>N</i>-sulfonylimines

Akram Ashouri; Saadi Samadi; Behzad Nasiri; Zohre Bahrami

doi:10.1016/j.crci.2019.06.005

Iron-based nanomaterials used as magnetic mesoporous nanocomposites to catalyze the preparation of N-sulfonylimines

Akram Ashouri ¹ ; Saadi Samadi ¹ ; Behzad Nasiri ¹ ; Zohre Bahrami ²

¹ Laboratory of Asymmetric Synthesis, Department of Chemistry, Faculty of Science, University of Kurdistan, 66177-15175, Sanandaj, Iran
² Faculty of Nanotechnology, Semnan University, Semnan, 35131-19111, Iran

Comptes Rendus. Chimie, Volume 22 (2019) no. 8, pp. 549-556.

Résumé

A new magnetic nanocatalyzed synthetic method for the synthesis of aldimines was evidenced. The reaction was carried out in a Schlenk tube under reflux conditions using various solvents and different nanomaterials as catalysts. In these reactions, an excellent yield of aromatic aldimines was obtained in the presence of silica-coated magnetic nanomaterials. The prepared catalyst was also characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, nitrogen adsorption and desorption studies, energy dispersive X-ray spectroscopy, and small-angle X-ray scattering spectroscopy. It was shown that the magnetic nanocatalysts can be easily separated from the reaction mixture using an external magnet and reused.

Supplementary Materials:
Supplementary material for this article is supplied as a separate file:

mmc1.docx

Métadonnées

Reçu le : 2019-03-04
Accepté le : 2019-06-26
Publié le : 2019-07-29

DOI : 10.1016/j.crci.2019.06.005

Mots clés : N-Sulfonylimines, Magnetic mesoporous nanomaterials, Aldimine, Fe₃O₄@MCM-41, Recyclability

Affiliations des auteurs :

Akram Ashouri ¹ ; Saadi Samadi ¹ ; Behzad Nasiri ¹ ; Zohre Bahrami ²

¹ Laboratory of Asymmetric Synthesis, Department of Chemistry, Faculty of Science, University of Kurdistan, 66177-15175, Sanandaj, Iran
² Faculty of Nanotechnology, Semnan University, Semnan, 35131-19111, Iran

@article{CRCHIM_2019__22_8_549_0,
     author = {Akram Ashouri and Saadi Samadi and Behzad Nasiri and Zohre Bahrami},
     title = {Iron-based nanomaterials used as magnetic mesoporous nanocomposites to catalyze the preparation of {\protect\emph{N}-sulfonylimines}},
     journal = {Comptes Rendus. Chimie},
     pages = {549--556},
     publisher = {Elsevier},
     volume = {22},
     number = {8},
     year = {2019},
     doi = {10.1016/j.crci.2019.06.005},
     language = {en},
}

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%A Saadi Samadi
%A Behzad Nasiri
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Akram Ashouri; Saadi Samadi; Behzad Nasiri; Zohre Bahrami. Iron-based nanomaterials used as magnetic mesoporous nanocomposites to catalyze the preparation of N-sulfonylimines. Comptes Rendus. Chimie, Volume 22 (2019) no. 8, pp. 549-556. doi : 10.1016/j.crci.2019.06.005. https://comptes-rendus.academie-sciences.fr/chimie/articles/10.1016/j.crci.2019.06.005/

Version originale du texte intégral

1 Introduction

Currently, electron-deficient imines such as sulfonylimines are well known to be important as key intermediates in various chemical reactions [1,2]. Owing to the applicability of these compounds as anticancer agents, their anti-inflammatory nature, and their antibacterial and antifungal behavior, they are also known to be important for biological processes [3]. Owing to their electrophilic nature, relative stability, and reactivity, these electron-deficient imines have been used in the preparation of several important nitrogen-containing compounds [4–6]. Thus, the development and application of suitable methods for imine synthesis have attracted much attention in recent years.

The most widely used and direct method for the preparation of an N-sulfonylimine involves the condensation of an aldehyde with sulfonamide, but the low nucleophilic activity of the nitrogen atom of sulfonamide and the difficulty in the removal of the produced water have limited the use of this method [7–9]. To suppress this limitation and increase the efficiency, various methods in the presence of Lewis and Brønsted acids or metal oxides are being developed [10], with some of these suffering from harsh reaction conditions, use of toxic materials, long reaction times, and use of high loading.

Magnetite-based nanomaterials have been used as catalysts for a very wide range of catalytic processes and organic transformations such as coupling reactions [11–13], C–H activation [14], oxidation reactions [15], reduction reactions [16], and synthesis of heterocyclic compounds [17,18]. Therefore, multifunctional nanoparticles are in high demand because of their wide-ranging applications in the field of catalysis. In addition, magnetite nanoparticles are highly desirable for catalytic activity, but under reflux conditions, some aggregation can occur [19,20].

Despite the availability of numerous procedures for the synthesis of imines, the design and development of a new efficient method for the synthesis of aldimines that are more facile and economically advantageous are still of interest. Herein, we attempted to introduce a simple, clean, and efficient process to synthesize aldimines using silica-coated magnetic nanoparticles.

2 Experimental

2.1 Materials

All of the chemicals were obtained from Sigma–Aldrich or Merck and were used without purification. The reaction progress was monitored by thin-layer chromatography (GF254). Fourier transform infrared (FT-IR) (KBr) spectra were recorded using a Bruker Vector 22 FT-IR spectrophotometer. The ¹H NMR and ¹³C NMR spectra were recorded using a Bruker AVIII HD-500 MHz instrument using tetramethylsilane (TMS) as the internal standard.

2.2 Synthesis of different catalysts

The different nanomaterials were synthesized according to reports in the literature [21–24].

2.2.1 Preparation of MCM-41 mesoporous silica

MCM-41 mesoporous silica samples were prepared using a general method [25,26]. The water solution of cetyltrimethylammonium bromide (142 mg, 0.39 mmol) was added to diethanolamine (9.46 mg, 0.09 mmol) and stirred at 40 °C for at least 30 min, followed by the addition of tetraethyl orthosilicate (333 mg, 1.6 mmol) dropwise within 2 min. After 2 h, the solution was cooled to room temperature, and a white residue powder precipitate was obtained that was then centrifuged and washed with ethanol and distilled water. The surfactant cetyltrimethylammonium bromide was extracted from the obtained mesoporous materials by refluxing with ethanol and a small amount of concentrated HCl. The final product was centrifuged and washed with ethanol several times.

2.2.2 Preparation of nanomagnetic Fe₃O₄

Nanomagnetic Fe₃O₄ was prepared using the typical solvothermal method. A round-bottomed flask containing ethylene glycol (30 mL) was filled with ferric chloride hexahydrate (1.48 g, 5.5 mmol) and sodium acetate (2.62 g, 32 mmol). The mixture was heated for 8 h at 200 °C in an autoclave and then cooled to room temperature. The black nanomagnetic Fe₃O₄ was separated using an external magnet, washed with deionized water several times, and dried in an oven at 60 °C overnight [25,26].

2.2.3 Preparation of Fe₃O₄@MCM-41

The procedure for the preparation of Fe₃O₄@MCM-41 was the same as that for nanomagnetic Fe₃O₄ except that in the first step, the prepared MCM-41 (2.0 g) was added to the reaction mixture [29].

2.2.4 General procedure for the synthesis of products

To a Schlenk tube filled with Fe₃O₄@MCM (15 mg) and toluene (0.5 mL), aldehyde (0.12 mmol) and p-toluenesulfonamide (17.12 mg, 0.1 mmol) were added under nitrogen atmosphere. The reaction mixture was stirred for 1 h at 100 °C. Then, the silica-coated magnetic nanoparticles were separated using a simple magnet. The solution of the reaction-separated system was transferred into a round-bottomed flask. After the organic phase was evaporated under reduced pressure, the obtained crude product was purified by recrystallization from ethyl acetate and n-hexane, affording the pure product in high yield (up to 98%).

N-(4-Chlorobenzylidene)-4-methylbenzenesulfonamide (Table 3, entry 1) mp: 175–179 °C, ¹H NMR (500 MHz, CDCl₃) δ (ppm): 2.43 (3H, s), 7.35 (d, J = 8.1 Hz, 2H), 7.46 (2H, d, J = 8.5 Hz), 7.86 (2H, d, J = 8.5 Hz), 7.88 (2H, d, J = 8.3 Hz), 8.99 (1H, s); ¹³C NMR (125 MHz, CDCl₃) δ (ppm): 168.6, 144.8, 141.4, 134.8, 132.3, 130.8, 129.8, 129.5, 128.1, 21.6.

Table 3

Entry^a	R	Yield (%)^b	Mp (°C)	Mp (°C)^c
1	p-Cl-Phenyl	98	175–179	172–173 [33]
2	o-Cl-Phenyl	82	134–137	131–132 [34]
3	m-Cl-Phenyl	92	84–88	98 [34]
4	p-F-Phenyl	88	129–130	117–118 [35]
5	p-NO₂-Phenyl	85	203–207	162–170 [35]
6	p-CH₃-Phenyl	90	113–115	116–118 [36]
7	p-Br-Phenyl	92	190–193	198–199 [37]
8	p-OCH₃-Phenyl	87	129–130	128–129 [35]
9	o–OCH₃-Phenyl	85	111–114	111–113 [38]
10	p-CF₃-Phenyl	90	154–156	159–160 [39]
11	-Phenyl	86	79–82	105–108 [35]
12	-Naphthyl	89	140–144	142–144 [40]
13	-Anthracyl	82	199–204	214–217 [41]
14	-Benzyl	Oily mixture	–	–
15	-Hexyl	Oily mixture	–	–
16	-Propenyl	Oily mixture	–	–

^a Reaction conditions: aldehyde (0.12 mmol), p-toluenesulfonamide (0.1 mmol), toluene (0.5 mL), and Fe₃O₄@MCM-41 (15 mg).

^b Isolated yield.

^c Reported Mp.

N-(4-Methylbenzylidene)-4-methyl-benzenesulfonamide (Table 3, entry 6) mp: 116–118 °C. ¹H NMR (500 MHz, CDCl₃) δ (ppm): 8.99 (s, 1 H), 7.89 (d, J = 7.5 Hz, 2 H), 7.82 (d, J = 7.4 Hz, 2 H), 7.34 (d, J = 7.49 Hz, 2 H), 7.29 (d, J = 7.43 Hz, 2 H), 2.43 (s, 3 H), 2.42 (s, 3 H); ¹³C NMR (125 MHz, CDCl₃) δ (ppm): 168.9, 145.3, 143.4, 134.4, 130.4 (2C), 128.9 (2C), 128.8, 128.7 (2C), 127.0 (2C), 20.9, 20.6.

N-(4-Methoxybenzylidene)-4-methyl-benzenesulfonamide (Table 3, entry 8) mp: 128–129 °C, ¹H NMR (500 MHz, CDCl₃) δ (ppm): 8.94 (s, 1 H), 7.87 (d, J = 8 Hz, 4 H), 7.32 (d, J = 7.7 Hz, 2 H), 6.96 (d, J = 8.2 Hz, 2 H), 3.87 (s, 3 H), 2.42 (s, 3 H); ¹³C NMR (125 MHz, CDCl₃) δ (ppm): 168.1, 164.3, 143.2, 134.7, 132.6 (2C), 128.7 (2C), 126.8 (2C), 124.2, 113.6 (2C), 54.6, 20.5.

3 Results and discussion

Initially, in a sealed Schlenk tube under nitrogen atmosphere, the reaction of p-chlorobenzaldehyde (1a) and p-toluenesulfonamide (2) was selected as a model reaction in refluxing toluene; but after 24 h, product 3a was obtained which was not the desired product. Following the reports in the literature, we attempted to carry out the condensation reaction in the presence of catalysts that act as Lewis acids and dehydrating reagents. For this purpose, we carried out the reaction in the presence of several metal oxide nanocatalysts. The obtained results are shown in Table 1. According to entries 2–6, the reaction proceeded in the presence of Al₂O₃, TiO₂, MgO, SiO₂, and Fe₃O₄ metal oxide nanoparticles with moderate yields. On the other hand, owing to its unique properties such as narrow pore size distribution, ultrahigh surface area, well-defined pore structure, and thermal stability, MCM-41 mesoporous silica has been used in several catalytic organic reactions [27–32]. A review of the literature showed that the use of MCM-41 mesoporous silica for the synthesis of aldimines has not been reported. It occurred to us that this class of nanomaterials may be a catalyst for this reaction. When we used MCM-41, the reaction yield increased to 67% (entry 7). To enhance the efficiency of MCM-41 mesoporous silica, we decided to use the silica-coated magnetic nanoparticles denoted as Fe₃O₄@MCM-41 (entry 8). When the reaction was carried out in the presence of Fe₃O₄@MCM-41, the desired product was obtained with the yield of 98% (entry 10). We also used K10 montmorillonite clays as the catalyst under these conditions; but after 1 h, the yield was lower than that obtained using other nanocatalysts (entry 9). Subsequently, we optimized other parameters that affect the reaction. In particular, the effect of different loading amounts of Fe₃O₄@MCM-41 was investigated (entries 10–13). However, it was found that the best yield was achieved using 15 mg of silica-coated magnetic nanocatalysts.

Table 1

Entry^a	Type of nanocatalysts	Loading of nanocatalysts (mg)	Yield (%)^b
1	–	–	–
2	Al₂O₃	15
3	TiO₂	15	52
4	MgO	15	40
5	Fe₃O₄	15	55
6	SiO₂	15	62
7	MCM-41	15	67
8	Fe₃O₄@MCM-41	15	98
9	K10	15	40
10	Fe₃O₄@MCM-41	5	65
11	Fe₃O₄@MCM-41	10	80
12	Fe₃O₄@MCM-41	20	75
13	Fe₃O₄@MCM-41	25	58

^a Reaction conditions: p-chlorobenzaldehyde (0.12 mmol), p-toluenesulfonamide (0.1 mmol), toluene (0.5 mL), and nanocatalysts.

^b Isolated yield.

As presented in Table 2, the effect of the solvent was also observed for this reaction. No product was observed using tetrahydrofuran, 1,4-dioxane ,and acetonitrile (entries 1–3). When dichloromethane, chloroform, diethyl ether, and dimethyl sulfoxide were used, the desired aldimine was produced in low to moderate yields (entries 4–7), whereas the use of toluene as solvent promoted the reaction with an extremely high yield (entry 8).

Table 2

Entry^a	Solvent	Yield (%)^b
1	1,4-Dioxane	–
2	Tetrahydrofuran	–
3	Acetonitrile	–
4	Dichloromethane	10
5	Chloroform	20
6	Diethyl ether	35
7	Dimethyl sulfoxide	38
8	Toluene	98

^a Reaction condition: p-chlorobenzaldehyde (0.12 mmol), p-toluenesulfonamide (0.1 mmol), solvent (0.5 mL), and Fe₃O₄@MCM-41 (15 mg).

^b Isolated yield.

After achieving optimum conditions, the scope of the reaction was evaluated by applying different aldehydes. Several aromatic and aliphatic aldehydes were used, as presented in Table 3. It was found that aromatic aldehydes with an electron-donating group reacted, as did those with electron-withdrawing groups. An aromatic aldimine substituted with bulky aryl groups was synthesized in high yields (entries 12 and 13). As expected, aromatic aldehydes reacted better than the aliphatic aldehydes (entries 14–16). In nearly all of the investigated reactions, the conversion was over 95% under the reaction conditions.

3.1 Characterization of materials

The prepared materials were characterized using a Bruker Vector 22 FT-IR spectrophotometer. The surface morphology of the samples was examined using a ZEISS SIGMA VP field emission scanning electron microscope (FE-SEM) equipped with a field emission gun and an energy dispersive (EDS) detector. The surface areas were calculated according to the Brunauer–Emmett–Teller (BET) equation and the pore size distribution was calculated using the Barrett–Joyner–Halenda (BJH) equation. Elemental analysis was performed quantitatively using an Infinite 200 PRO NanoQuant instrument (Tecan, Switzerland). The nanoscale density differences were evaluated by small-angle X-ray scattering (SAXS) spectroscopy.

3.2 Composition and morphology of Fe₃O₄, MCM-41, and Fe₃O₄@MCM-41

The FT-IR spectra of the prepared MCM-41, Fe₃O₄, and Fe₃O₄@MCM-41 are shown in Fig. 1. The asymmetric and symmetric stretching vibrations of the siloxane groups (Si–O–Si) of MCM-41 are ascribed to the bands at 1074 and 796 cm⁻¹ that are observed to be unchanged in Fe₃O₄@MCM-41. The strong absorption band related to the Fe–O bond observed at approximately 586 cm⁻¹ in the Fe₃O₄ and Fe₃O₄@MCM-41 spectra confirms the preparation and the presence of magnetite nanoparticles, respectively.

Fig. 1
FT-IR spectra of (a) MCM-41, (b) Fe₃O₄, and (c) Fe₃O₄@MCM-41.

The surface morphologies of Fe₃O₄, MCM-41, and Fe₃O₄@MCM-41 were observed by scanning electron microscopy (SEM) and are shown in Fig. 2. Bare Fe₃O₄ nanoparticles have a quasi-spherical shape with a heterogeneous surface and slight aggregation. The shape of the resulting silica-coated magnetic nanoparticles was also spherical after grafting on MCM-41. These results indicated that Fe₃O₄ nanoparticles were successfully grafted on the MCM-41 nanoparticles without considerable changes during the functionalization process.

Fig. 2
SEM images of (a) Fe₃O₄, (b) MCM-41, and (c) Fe₃O₄@MCM-41.

N₂ adsorption–desorption isotherms and pore size distributions of MCM-41 and Fe₃O₄@MCM-41 silica-coated magnetic nanoparticles are shown in Fig. 3. The isotherms and pore size distributions of MCM-41 magnetic mesoporous silica and corresponding silica-coated magnetic nanoparticles are nearly same, indicating that the pore structures of the MCM-41 mesoporous silica were still preserved even after the grafting of Fe₃O₄ nanoparticles on the MCM-41 mesoporous silica. The textural properties of MCM-41 and Fe₃O₄@MCM-41 nanoparticles are summarized in detail in Table 4. It is clear that the surface area and pore volume of silica-coated magnetic nanoparticles were lower than those of the MCM-41 mesoporous silica; however, the surface areas and large pore volumes of the Fe₃O₄@MCM-41 nanoparticles are still high.

Fig. 3
N₂ adsorption/desorption isotherm of MCM-41 and Fe₃O₄@MCM-41 nanoparticles.

Table 4

Sample	Specific surface area (S_BET) (m² g⁻¹)	Pore volume (V_p) (cm³ g⁻¹)	Pore diameter (D_p) (nm)
MCM-41 nanoparticles	817	1.068	2.42
Fe₃O₄@MCM-41 nanoparticles	690	0.873	2.42

Fig. 4 shows the energy-dispersive X-ray (EDX) spectrum of the obtained Fe₃O₄@MCM-41 nanoparticles that reveals the presence of Fe, O, and Si elements, confirming that MCM-41 was successfully coated by magnetite nanoparticles.

The small angle X-ray scattering (SAXS) patterns of MCM-41 and silica-coated magnetic nanoparticles are presented in Fig. 5 and are in good agreement with those reported in the literature [42]. The SAXS pattern of the silica-coated magnetic nanoparticles was almost identical to that of the corresponding mesoporous silica. This result also supports the conclusion that the pore structures of mesoporous silica were preserved even after the grafting of Fe₃O₄ nanoparticles.

Fig. 5
SAXS patterns of MCM-41 and Fe₃O₄@MCM-41 nanoparticles.

3.3 Proposed mechanism

A proposed mechanism for the synthesis of aldimine derivatives in the presence of silica-coated magnetic nanoparticles is shown in Scheme 1. After activation of the aldehyde carbonyl group by Fe₃O₄@MCM-41, the nucleophilic attack of the nitrogen atom of sulfonamide occurred, and an intermediate (Ι) was formed. Consequently, the aldimine product 3a was prepared by the dehydration of the intermediate (Ι).

Scheme 1
Proposed mechanism for the synthesis of aldimine derivatives in the presence of silica-coated magnetic nanoparticles.

3.4 Recyclability and reusability of the catalyst

Recyclability and reusability of the catalyst are important for designing a new synthesis method. Therefore, the reusability of the silica-coated magnetic nanoparticles was also evaluated for the condensation reaction. The conversion and yield of the reaction were over 90% and 83%, respectively, until five cycles, demonstrating that the catalytic activity of the silica-coated magnetic nanoparticles was preserved without a significant loss (see Fig. 6). After each reaction, magnetic nanocatalysts were simply separated by an external magnet, washed with ethanol, dried under reduced pressure and reused. The FT-IR spectrum and SEM image of the recycled catalyst confirmed that the structure of the catalyst was maintained.

Fig. 6
Effect of catalyst recycling on the yield of product 3a.

4 Conclusions

In this work, a simple and new synthetic method of silica-coated magnetic nanoparticles via the condensation of aldehyde and p-toluenesulfonamide using silica-coated iron-based magnetic nanoparticles was introduced. The synthesis of aldimines was carried out in a Schlenk tube that can be easily handled in comparison with a Dean–Stark apparatus. The excellent yield of aromatic aldimines, short reaction time, facile separation, reusability of catalysts, and lack of catalyst pollution in the products are the prominent advantages of this method.

Acknowledgements

We are grateful to the University of Kurdistan, Iran Research Councils for the support of this work.

Bibliographie

[1] M.E. Belowich; J.F. Stoddart Chem. Soc. Rev., 41 (2012), pp. 2003-2024

[2] A. Kajal; S. Bala; S. Kamboj; N. Sharma; V. Saini J. Catal., 2013 (2013)

[3] A.T. Baviskar; U.C. Banerjee; M. Gupta; R. Singh; S. Kumar; M.K. Gupta; S. Kumar; S.K. Raut; M. Khullar; S. Singh Bioorg. Med. Chem., 21 (2013), pp. 5782-5793

[4] J.L. Garcia Ruano; J. Alemán; M. Belen Cid; A. Parra Org. Lett., 7 (2005), pp. 179-182

[5] A. Vass; J. Dudás; R.S. Varma Tetrahedron Lett., 40 (1999), pp. 4951-4954

[6] L. Wu; X. Yang; X. Wang; F. Yan J. Sulfur Chem., 31 (2010), pp. 509-513

[7] S. Nakamura; M. Hayashi; Y. Hiramatsu; N. Shibata; Y. Funahashi; T. Toru J. Am. Chem. Soc., 131 (2009), pp. 18240-18241

[8] S. Kobayashi; Y. Mori; J.S. Fossey; M.M. Salter Chem. Rev., 111 (2011), pp. 2626-2704

[9] R.N. Ram; A.A. Khan Synth. Commun., 31 (2001), pp. 841-846

[10] J.H. Wynne; S.E. Price; J.R. Rorer; W.M. Stalick Synth. Commun., 33 (2003), pp. 341-352

[11] Y. Long; K. Liang; J. Niu; X. Tong; B. Yuan; J. Ma New J. Chem., 39 (2015), pp. 2988-2996

[12] W. Li; Y. Tian; B. Zhang; L. Tian; X. Li; H. Zhang; N. Ali; Q. Zhang New J. Chem., 39 (2015), pp. 2767-2777

[13] J. Niu; F. Wang; X. Zhu; J. Zhao; J. Ma RSC Adv., 4 (2014), pp. 37761-37766

[14] R. Sharma; S. Dutta; S. Sharma Dalton Trans., 44 (2015), pp. 1303-1316

[15] L. Lykke; C. Rodríguez-Escrich; K.A. Jørgensen J. Am. Chem. Soc., 133 (2011), pp. 14932-14935

[16] T.C. Nugent; M. El-Shazly Adv. Synth. Catal., 352 (2010), pp. 753-819

[17] A.V. Kel'in; A.W. Sromek; V. Gevorgyan J. Am. Chem. Soc., 123 (2001), pp. 2074-2075

[18] Y.-L. Shi; M. Shi Org. Biomol. Chem., 5 (2007), pp. 1499-1504

[19] W. Xie; J. Wang Energy Fuel., 28 (2014), pp. 2624-2631

[20] W. Xie; X. Zang Food Chem., 194 (2016), pp. 1283-1292

[21] B. Li; X. Wang; M. Yan; L. Li Mater. Chem. Phys., 78 (2003), pp. 184-188

[22] F. Liu; M.M. Abed; K. Li J. Membr. Sci., 366 (2011), pp. 97-103

[23] C.H. Kwon; J.H. Kim; I.S. Jung; H. Shin; K.H. Yoon Ceram. Int., 29 (2003), pp. 851-856

[24] Z.-X. Tang; L.-E. Shi Ecletica Quim., 33 (2008), pp. 15-20

[25] W. Xie; Y. Han; H. Wang Renew. energ., 125 (2018), pp. 675-681

[26] S. Luo; G. Fan; M. Luo; J. Li; G. Song J CO₂ UTIL, 14 (2016), pp. 23-30

[27] S.C. Tang; I.M. Lo Water Res., 47 (2013), pp. 2613-2632

[28] A. Yan; X. Liu; G. Qiu; H. Wu; R. Yi; N. Zhang; J. Xu J. Alloy. Comp., 458 (2008), pp. 487-491

[29] S.V. Kolotilov; O. Shvets; O. Cador; N. Kasian; V.G. Pavlov; L. Ouahab; V.G. Ilyin; V.V. Pavlishchuk J. Solid State Chem., 179 (2006), pp. 2426-2432

[30] M. Vallet-Regi; A. Ramila; R. Del Real; J. Pérez-Pariente Chem. Mater., 13 (2001), pp. 308-311

[31] K. Chaudhari; T. Das; P. Rajmohanan; K. Lazar; S. Sivasanker; A. Chandwadkar J. Catal., 183 (1999), pp. 281-291

[32] X. Zhao; G. Lu; X. Hu Microporous Mesoporous Mater., 41 (2000), pp. 37-47

[33] C.-Y. Chen; H.-X. Li; M.E. Davis Microporous Mater., 2 (1993), pp. 17-26

[34] S. Samadi; K. Jadidi; B. Khanmohammadi; N. Tavakoli J. Catal., 340 (2016), pp. 344-353

[35] S. Samadi; A. Ashouri; M. Ghambarian RSC Adv., 7 (2017), pp. 19330-19337

[36] T.S. Jin; M.J. Yu; L.B. Liu; Y. Zhao; T.S. Li Synth. Commun., 36 (2006), pp. 2339-2344

[37] R. Patel; V.P. Srivastava; L.D.S. Yadav Adv. Synth. Catal., 352 (2010), pp. 1610-1614

[38] D. Huang; X. Wang; X. Wang; W. Chen; X. Wang; Y. Hu Org. Lett., 18 (2016), pp. 604-607

[39] A. Zare; F. Bahrami; M. Merajoddin; M. Bandari; A.R. Moosavi-Zare; M.A. Zolfigol; A. Hasaninejad; M. Shekouhy; M.H. Beyzavi; V. Khakyzadeh Org. Prep. Proced. Int., 45 (2013), pp. 211-219

[40] M.D. Hopkins; K.A. Scott; B.C. DeMier; H.R. Morgan; J.A. Macgruder; A.A. Lamar Org. Biomol. Chem., 15 (2017), pp. 9209-9216

[41] A.K. Bhattacharya; K.C. Rana; C. Pannecouque; E. De Clercq ChemMedChem, 7 (2012), pp. 1601-1611

[42] C.-J. Wang; M. Shi J. Org. Chem., 68 (2003), pp. 6229-6237

Commentaires - Politique

1 Introduction

2 Experimental

2.1 Materials

2.2 Synthesis of different catalysts

2.2.1 Preparation of MCM-41 mesoporous silica

2.2.2 Preparation of nanomagnetic Fe3O4

2.2.3 Preparation of Fe3O4@MCM-41

2.2.4 General procedure for the synthesis of products

3 Results and discussion

3.1 Characterization of materials

3.2 Composition and morphology of Fe3O4, MCM-41, and Fe3O4@MCM-41

3.3 Proposed mechanism

3.4 Recyclability and reusability of the catalyst

4 Conclusions

Acknowledgements

2.2.2 Preparation of nanomagnetic Fe₃O₄

2.2.3 Preparation of Fe₃O₄@MCM-41

3.2 Composition and morphology of Fe₃O₄, MCM-41, and Fe₃O₄@MCM-41