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Article

The Selective Oxidation of Sulfides to Sulfoxides or Sulfones with Hydrogen Peroxide Catalyzed by a Dendritic Phosphomolybdate Hybrid

by
Qiao-Lin Tong
†,
Zhan-Fang Fan
†,
Jian-Wen Yang
,
Qi Li
,
Yi-Xuan Chen
,
Mao-Sheng Cheng
and
Yang Liu
*
Key Laboratory of Structure-Based Drug Design & Discovery of Ministry of Education, School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang 110016, China
*
Author to whom correspondence should be addressed.
†
Qiao-Lin Tong and Zhan-Fang Fan contributed equally to this work.
Catalysts 2019, 9(10), 791; https://doi.org/10.3390/catal9100791
Submission received: 6 September 2019 / Revised: 18 September 2019 / Accepted: 20 September 2019 / Published: 22 September 2019
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Abstract

:
The oxidation of sulfides to their corresponding sulfoxides or sulfones has been achieved using a low-cost poly(amidoamine) with a first-generation coupled phosphomolybdate hybrid as the catalyst and aqueous hydrogen peroxide as the oxidant. The reusability of the catalyst was revealed in extensive experiments. The practice of this method in the preparation of a smart drug Modafinil has proved its good applicability.

Graphical Abstract

1. Introduction

Many biologically and chemically active molecules are constructed from sulfoxides and sulfones [1,2,3,4,5]. The oxidation of sulfides is a fundamental reaction as one of the most straightforward methods to afford sulfoxides and sulfones [6]. Many reagents, including peracids and halogen derivatives, are used in the common approaches of sulfoxidation reactions [7,8]. However, these common reactions often suffer from the formation of many environmentally unfriendly byproducts and low oxygen atom efficiency [6,9]. The development of environmentally benign catalysts and oxidants has become a research hotspot in recent green chemistry pursuits.
Among various oxidants, aqueous hydrogen peroxide, which is inexpensive, is readily available, has a high effective oxygen content, is safe in operation and storage, and yields stoichiometric amounts of environmentally friendly water as a byproduct, is generally considered one of the most environmentally benign “green oxidants”. These characteristics of aqueous hydrogen peroxide have led to the development of many valuable methods for the oxidation of sulfides to sulfoxides and sulfones with various transition metal catalysts, including Ti(SO4)2/GOF [10], PDDA-SiV2W10 [11], the cobalt(III)–salen ion [12], TiO2/AA/MoO2 [13], a copper–Schiff base complex [14], (C19H42N)2[MoO(O2)2(C2O4)]·H2O [6], vanadium Schiff base complexes [15], and so on [16,17,18,19].
Polyoxometalates (POMs), which are composed of anionic transition metal–oxygen clusters [20,21,22,23], have been widely studied in the field of catalysis due to their excellent catalytic characteristics, including efficient catalytic activity and selectivity, controllable redox potential and acidity through the choice of the countercations and constituent elements [24,25]. Among these POMs, Keggin-type phosphomolybdic acid (H3Mo12O40, HPMo) has shown excellent catalytic performance in oxidation reactions with aqueous hydrogen peroxide [26,27,28,29].
Dendritic poly(amidoamine) (PAMAM), which contains many amino groups, is an excellent organic modifier for POMs [30,31,32]. PAMAMs can be functionalized to couple to various POMs, and the dendritic structure, which is different from the common organic modifier, can provide a local microenvironment for the POMs, which may result in a helpful “dendritic effect” on the reaction [33,34]. PAMAM-G1 (poly(amidoamine) with the first generation) dendrimers have been used in industrial production and are relatively inexpensive. Moreover, the amino groups of the PAMAM-G1 dendrimer can be protonated by HPMo, and the PMo anions and PAMAM-G1 can strongly bond together through electrostatic interactions [35].
Herein, we report a heterogeneous, simple, recyclable, efficient, and green protocol for the oxidation of sulfides to sulfoxides and sulfones with 30 wt% H2O2 under mild conditions in excellent yield, catalyzed by a composite based on PAMAM-G1 and HPMo (denoted as PAMAM-G1-PMo). To the best of our knowledge, this is the first report of PAMAM-G1-PMo as the catalyst used in the oxidation of sulfides to sulfoxides and sulfones.

2. Results and Discussion

In this oxidation system, PAMAM-G1-PMo is utilized as the catalyst, and 30 wt% H2O2 is used as the oxidant. We selected thioanisole (1a) as a model substrate and found that less than 5% of 1a could be directly oxidized by 30 wt% H2O2 alone, even when the reaction time lasted to 6 h (Table 1, entry 1). However, when 50 mg of PAMAM-G1PMo was added to the above mixture, sulfoxide (1b) was generated soon as the oxidation product. In addition, control experiments were performed to assess the individually catalytic activity of HPMo and PAMAM-G1 dendrimer. Regrettably, only 8% of starting material could be oxidized by 30 wt% H2O2 catalyzing by HPMo alone (Table 1, entry 2), and much less yield was obtained when catalyzing by PAMAM-G1 dendrimer alone (Table 1, entry 3). When the reaction was carried out in the presence of PAMAM-G1-PMo, up to 85% of 1a could be oxidized within 4 h (Table 1, entry 4), indicating that PAMAM-G1-PMo played a very significant role in prompting the process of this oxidation effectively.
To optimize the conditions for the oxidation of sulfides to sulfoxides, we first investigated the effects of the solvent in the PAMAM-G1-PMo-catalyzed reaction system. The results are listed in Table 1. After screening different solvents, we observed that when MeOH or 95% EtOH was used as the solvent in the presence of PAMAM-G1-PMo, we obtained the desired sulfoxide products (1b) in relatively high yields of 85–90% and a minor amount of starting material (1a) remained, without any sulfones (Table 2, entries 1–2). However, the conversion was relatively poor when the reaction was carried out in other solvents, including EtOH, CH3COCH3, CH3COOC2H5, and i-PrOH (Table 2, entries 3–6). After comprehensive considerations of various factors, we selected environmentally friendly and low-cost 95% EtOH as the solvent. Next, the temperature of the reaction was optimized. As shown in Table 2, when the temperature increased from 25 °C to 30 °C, the yield of the desired product increased to more than 90% and reaction time reduced to 2 h, but when the temperature increased to 35 °C, the yield of the sulfoxide appeared to decrease due to the increase in byproduct sulfone formation (Table 2, entries 2, 7–9). Hence, 30 °C was the optimal temperature for the oxidation of sulfides to sulfoxides in the system of 30 wt% H2O2/PAMAM-G1-PMo.
Furthermore, 1a was still chosen to be the model substrate to optimize the conditions for the oxidation of sulfides to sulfones. In our experience, the formation of sulfones needs higher concentration of the oxidant. The contrast experiments demonstrated that 30 wt% H2O2 itself, even if the amount was increased to 300 mol%, could not complete the oxidation. However, once more, this process was greatly promoted by the catalyst PAMAM-G1-PMo. The temperature of the reaction was firstly optimized. As shown in Table 3, when the temperature increased from 30 °C to 40 °C in the system of 30 wt% H2O2/PAMAM-G1-PMo, the yield of the desired sulfone product (1c) increased, but when the temperature increased to 50 °C, the yield of sulfone did not notably change (Table 3, entries 1–3). Hence, 40 °C was the optimal temperature for the oxidation of sulfides to sulfones in the system of 30 wt% H2O2/PAMAM-G1-PMo. In addition, the effects of 30 wt% H2O2 in the reaction were investigated. When the amount of 30 wt% H2O2 increased from 300 mol% to 400 mol%, there was no major difference in the yield of the desired product (Table 3, entries 2,4). However, if the amount of 30 wt% H2O2 decreased to 200 mol%, the yield of the desired product decreased accordingly (Table 3, entry 5). Hence, 300 mol% was an optimal quantity of 30 wt% H2O2 for this catalytic oxidation reaction.
Next, we studied the scope of application of this system by testing a diverse range of sulfides, and the results are presented in Table 4. Notably, we observed that most of the substrates tested in the oxidation system were converted to their corresponding products in excellent yields under the optimized reaction conditions. However, we found that (2-chloro-4-nitrophenyl)(phenyl)sulfane (5a), with a strong electron-deficient phenyl group, did not successfully convert to 2-chloro-4-nitro-1-(phenylsulfinyl)benzene (5b) (Table 4, entry 5) and 2-chloro-4-nitro-1-(phenylsulfonyl)benzene (5c) (Table 4, entry 12). Additionally, (2-chlorophenyl)(methyl)sulfane (6a) did not successfully convert to 1-chloro-2-(methylsulfonyl)benzene (6c) (Table 4, entry 13), partially because the ortho-substituted chlorine on the benzene ring is also an electron-withdrawing group and has a certain steric hindrance.
To study the recyclability of the PAMAM-G1-PMo catalyst, we again chose the oxidation of thioanisole (1a) to (methylsulfinyl)benzene (1b) or (methylsulfonyl)benzene (1c) as model reactions. The catalyst PAMAM-G1-PMo was easily recovered by filtration after the reaction, washed with 95% EtOH, and dried in a vacuum at room temperature. After the above treatment, the catalyst was reused for subsequent experiments (up to five runs), and no major differences in the yield or required reaction times were observed, as summarized in Figure 1.
After being used for five times and separated from the reaction system, the catalysts were characterized by Fourier-transform infrared spectroscopy (FT-IR, Figure 2), X-ray diffraction (XRD, Figure 3), and scanning electron microscopy (SEM, Figure 4). As shown in Figure 2, the IR frequencies of reused PAMAM-G1-PMo (958, 3373, 3100 cm−1) are consistent with those of fresh-prepared PAMAM-G1-PMo, indicating the PMo anions are still successfully immobilized on protonated PAMAM-G1. As shown in Figure 3, the XRD patterns for both fresh-prepared PAMAM-G1-PMo and reused one show a broad band in the range of 2θ = 14−40°, which confirms the high dispersion of the PMo anions on PAMAM-G1 support. At last, it can be observed via the SEM spectra (Figure 4) that fresh-prepared PAMAM-G1-PMo and reused one have similar micromorphology, such as the tiny projections on the amorphous surface. The results of all the above detections prove that the PAMAM-G1-PMo, no matter fresh-prepared or reused, has a higher surface-to-volume ratio and more reactive cavities. Besides, there are no noticeable differences between the fresh-prepared catalysts and the reused ones, demonstrating that the catalysts have good stability in the process of oxidation reaction.
The present catalytic system was also applied to the preparation of a well-known smart drug Modafinil (2-[(diphenylmethyl)sulfinyl]acetamide, 9), which is a clinically wakefulness-promoting agent to treat disorders such as narcolepsy and excessive daytime sleepiness. Traditionally, Modafinil was produced by the oxidation of 2-[(diphenylmethyl)thio]acetamide (8) with 30 wt% H2O2 in acetic acid. However, a considerable amount of sulfone as the main by-product was often generated and difficult to be removed by recrystallization due to its similar physical property with Modafinil [36]. Inspired by the selective oxidation property of the 30 wt% H2O2/PAMAM-G1-PMo system, we practiced its application for the oxidation process in preparation of Modafinilf. The final product was obtained in a good yield of 89% and excellent purity of 99.79% after the crude product was collected and recrystallized with acetone (Scheme 1).

3. Materials and Methods

All reactants and solvents were directly obtained from commercial sources and used without further purification. 1H and 13C NMR spectra were recorded with a Bruker Avance-III 600 spectrometer (Bruker, Zürich, Switzerland). The purity of the products was determined by HPLC with areas of peak normalization method (pump: waters 1525, detector: waters 2489. Chromatographic column: WondaSil C-18, monitoring wavelength used 210 nm).
Infrared spectra were obtained from Fourier-transform infrared spectroscopy (FT-IR, Thermo Scientific IS5) at universal attenuated total reflection (ATR) mode in the range 400–4000 cm−1, using catalyst samples supported on KBr wafers. X-ray diffractometer (XRD, PERSEE XD-3, Beijing Persee instrument co. LTD, Beijing, China.) with monochromated Cu–Kα radiation source at 30 kV and 30 mA was used to investigate the crystal structure change between fresh-prepared and reused catalysts, and X-ray diffraction patterns were obtained in a scan range 2θ = 10–80° with a scan rate of 4°/min. SEM spectra was obtained from Scanning electron microscope (SEM, FEIQ45, Hitachi, Tokyo, Japan.).

3.1. Preparation and Characterization of PAMAM-G1-PMo

In a typical experiment, PAMAM-G1 (1.0 g, 2.0 mmol) was dissolved in deionized water (35 mL) under room temperature, and Keggin-type H3PMo12O40 (7.3 g, 4.0 mmol) was added while stirring. The resulting mixture was stirred for 48 h and filtered. The solids were washed with deionized water and ethanol, and dried under vacuum at 40 °C for 12 h to afford an aqua powder of PAMAM-G1-PMo.

3.2. Catalytic Reactions

3.2.1. General Experimental Procedure for the Oxidation of Sulfides to Sulfoxides

A 50 mL, three-necked flask was charged with sulfide (0.5 mmol), the catalyst (50 mg), and 95% EtOH (8 mL). The resulting solution was stirred at 30 °C, and 30 wt% H2O2 (63 mg, 0.55 mmol) was added slowly into the above mixture. The reaction was monitored by TLC (petroleum ether:ethyl acetate = 7:3). After the reaction was finished, the catalyst was separated from the mixture by filtration, washed with 95% EtOH, and dried in a vacuum at room temperature overnight for recycle use. The filtrate and the washing solution were combined, concentrated under reduced pressure, followed by a freeze-drying. The crude products were purified by column chromatography on a silica gel column with n-hexane/ethyl acetate (2:1) as eluent to afford the desired products. The 1H NMR and 13C NMR data and spectra for corresponding products are available online at Supplementary Materials.

3.2.2. General Experimental Procedure for the Oxidation of Sulfides to Sulfones

A 50 mL, three-necked flask was charged with sulfide (0.5 mmol), the catalyst (150 mg), and 95% EtOH (10 mL). The resulting solution was stirred at 40 °C, and 30 wt% H2O2 (170 mg, 1.5 mmol) was added slowly into the above mixture. The reaction was monitored by TLC (petroleum ether:ethyl acetate = 7:3). After the reaction was finished, the catalyst was separated from the mixture by filtration, washed with 95% EtOH, and dried in a vacuum at room temperature overnight for recycle use. The filtrate and the washing solution were combined, concentrated under reduced pressure, followed by a freeze-drying. The crude products were purified by column chromatography on a silica gel column with n-hexane/ethyl acetate (2:1) as eluent to afford the desired products. The 1H NMR and 13C NMR data and spectra for corresponding products are available online at Supplementary Materials.

3.2.3. Synthesis of Modafinil

A 250 mL, three-necked flask was charged with 2-[(diphenylmethyl)thio]acetamide (13 g, 50 mmol), the catalyst (5 g), and 95% EtOH (80 mL). The resulting solution was stirred at 30 °C, and 30 wt% H2O2 (6.3 g, 55 mmol) was added slowly into the reaction mixture. The mixture was allowed stirring for 2 h at 30 °C. After the reaction was finished, the catalyst was separated from the mixture by filtration, washed with 95% EtOH, and treated for recycle use. The filtrate and washings were combined and transferred to a 1 L beaker containing 500 mL deionized water to form white solid, which was collected by filtration and purified by a recrystallization with 30 mL of acetone to provide 12.3 g of desired product with a HPLC purity of 99.79%. 1H NMR (400 MHz, DMSO-d6) δ 7.66–7.49 (m, 5H), 7.44–7.28 (m, 7H), 5.34 (s, 1H), 3.36 (d, J = 13.7 Hz, 1H), 3.22 (d, J = 13.6 Hz, 1H). 13C NMR (151 MHz, CDCl3) δ 165.22, 133.37, 133.06, 128.46, 128.37, 127.93, 127.85, 127.79, 127.66, 70.50, 50.56. The 1H NMR, 13C NMR and HPLC spectra for Modafinil are available online at Supplementary Materials.

4. Conclusions

In summary, we developed a PAMAM-G1-PMo-catalyzed method for the oxidation of sulfides to sulfoxides or sulfones via an efficient and mild procedure. This system is environmentally benign since 30 wt% H2O2 and 95% EtOH are used as the oxidant and solvent, respectively, and the catalysts are recyclable. Moreover, the catalysts are inexpensive, stable during the reaction, and easily recovered by filtration after the reaction and for reuse in additional runs without a noticeable loss of catalytic activity. This is the first report of PAMAM-G1-PMo as the heterogeneous catalyst used in the oxidation of sulfides to sulfoxides or sulfones, which will help the enrichment and development of future research on the dendrimers’ hybrid.

Supplementary Materials

The following are available online at https://www.mdpi.com/2073-4344/9/10/791/s1, Figure S1: XRD patterns of HMo.

Author Contributions

Y.L. and M.-S.C. supervised the whole experiment and provided technical guidance. Q.-L.T. and Z.-F.F. performed the preparation and identification of the catalysts, and the investigation of the oxidation conditions. J.-W.Y., Q.L. and Y.-X.C. assisted in the synthesis work.

Funding

The financial supports from the Program for Liaoning Innovative Talents in University (LR2017043) and the Career Development Support Plan for Young and Middle-aged Teachers in Shenyang Pharmaceutical University (ZQN2016005) are gratefully appreciated.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Sipos, G.; Drinkel, E.E.; Dorta, R. The emergence of sulfoxides as efficient ligands in transition metal catalysis. Chem. Soc. Rev. 2015, 44, 3834–3860. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  2. Yu, X.; Liu, Y.; Li, Y.; Wang, Q. Design, Synthesis, Acaricidal/Insecticidal Activity, and Structure-Activity Relationship Studies of Novel Oxazolines Containing Sulfone/Sulfoxide Groups Based on the Sulfonylurea Receptor Protein-Binding Site. J. Agric. Food Chem. 2016, 64, 3034–3040. [Google Scholar] [CrossRef] [PubMed]
  3. Skoda, E.M.; Sacher, J.R.; Kazancioglu, M.Z.; Saha, J.; Wipf, P. An uncharged oxetanyl sulfoxide as a covalent modifier for improving aqueous solubility. ACS Med. Chem. Lett. 2014, 5, 900–904. [Google Scholar] [CrossRef] [PubMed]
  4. Petroff, J.T.; Skubic, K.N.; Arnatt, C.K.; McCulla, R.D. Asymmetric Dibenzothiophene Sulfones as Fluorescent Nuclear Stains. J. Org. Chem. 2018, 83, 14063–14068. [Google Scholar] [CrossRef] [PubMed]
  5. Yan, Q.; Xiao, G.; Wang, Y.; Zi, G.; Zhang, Z.; Hou, G. Highly Efficient Enantioselective Synthesis of Chiral Sulfones by Rh-Catalyzed Asymmetric Hydrogenation. J. Am. Chem. Soc. 2019, 141, 1749–1756. [Google Scholar] [CrossRef] [PubMed]
  6. Chakravarthy, R.D.; Ramkumar, V.; Chand, D.K. Molybdenum based metallomicellar catalyst for controlled and selective sulfoxidation reactions in aqueous medium. Green Chem. 2014, 16, 2190–2196. [Google Scholar] [CrossRef]
  7. Clifford, G.V.; Squires, T.G.; Chen, Y.Y. Peroxytrifluoroacetic Acid. A Convenient Reagent for the Preparation of Sulfoxides and Sulfones. J. Org. Chem. 1982, 47, 3773–3774. [Google Scholar]
  8. Kowalski, P.; Mitka, K.; Ossowska, K.; Kolarska, Z. Oxidation of sulfides to sulfoxides. Part 1: Oxidation using halogen derivatives. Tetrahedron 2005, 61, 1933–1953. [Google Scholar] [CrossRef]
  9. Yang, C.; Jin, Q.; Zhang, H.; Liao, J.; Zhu, J.; Yu, B.; Deng, J. Tetra-(tetraalkylammonium)octamolybdate catalysts for selective oxidation of sulfides to sulfoxides with hydrogen peroxide. Green Chem. 2009, 11, 1401–1405. [Google Scholar] [CrossRef]
  10. Zhang, M.; Pan, Y.; Dorfman, R.G.; Yin, Y.; Zhou, Q.; Huang, S.; Liu, J.; Zhao, S. Sirtinol promotes PEPCK1 degradation and inhibits gluconeogenesis by inhibiting deacetylase SIRT2. Sci. Rep. 2017, 7, 7. [Google Scholar] [CrossRef]
  11. Zhao, W.; Yang, C.X.; Cheng, Z.G.; Zhang, Z.H. A reusable catalytic system for sulfide oxidation and epoxidation of allylic alcohols in water catalyzed by poly(dimethyl diallyl) ammonium/polyoxometalate. Green Chem. 2016, 18, 995–998. [Google Scholar] [CrossRef]
  12. Mary Imelda Jayaseeli, A.; Ramdass, A.; Rajagopal, S. Selective H2O2 oxidation of organic sulfides to sulfoxides catalyzed by cobalt(III)–salen ion. Polyhedron 2015, 100, 59–66. [Google Scholar] [CrossRef]
  13. Jafarpour, M.; Rezaeifard, A.; Ghahramaninezhad, M.; Feizpour, F. Dioxomolybdenum(vi) complex immobilized on ascorbic acid coated TiO2 nanoparticles catalyzed heterogeneous oxidation of olefins and sulfides. Green Chem. 2015, 17, 442–452. [Google Scholar] [CrossRef]
  14. Gogoi, P.; Kalita, M.; Bhattacharjee, T.; Barman, P. Copper–Schiff base complex catalyzed oxidation of sulfides with hydrogen peroxide. Tetrahedron Lett. 2014, 55, 1028–1030. [Google Scholar] [CrossRef]
  15. Jain, S.L.; Rana, B.S.; Singh, B.; Sinha, A.K.; Bhaumik, A.; Nandi, M.; Sain, B. An improved high yielding immobilization of vanadium Schiff base complexes on mesoporous silica via azide–alkyne cycloaddition for the oxidation of sulfides. Green Chem. 2010, 12, 374–377. [Google Scholar] [CrossRef]
  16. Jiang, J.; Luo, R.C.; Zhou, X.T.; Chen, Y.J.; Jia, H.B. Photocatalytic Properties and Mechanistic Insights into Visible Light-Promoted Aerobic Oxidation of Sulfides to Sulfoxides via Tin Porphyrin-Based Porous Aromatic Frameworks. Adv. Synth. Catal. 2018, 360, 4402–4411. [Google Scholar] [CrossRef]
  17. Heidari, L.; Shiri, L. CoFe2O4@SiO2-CPTES-Guanidine-Cu(II): A novel and reusable nanocatalyst for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones and polyhydroquinolines and oxidation of sulfides. Appl. Organomet Chem. 2019, 33, e4636. [Google Scholar] [CrossRef]
  18. Han, M.; Niu, Y.; Wan, R.; Xu, Q.; Lu, J.; Ma, P.; Zhang, C.; Niu, J.; Wang, J. A Crown-Shaped Ru-Substituted Arsenotungstate for Selective Oxidation of Sulfides with Hydrogen Peroxide. Chem. Eur. J. 2018, 24, 11059–11066. [Google Scholar] [CrossRef] [PubMed]
  19. Sato, K.; Hyodo, M.; Aoki, M.; Zheng, X.Q.; Noyori, R. Oxidation of sulfides to sulfoxides and sulfones with 30% hydrogen peroxide under organic solvent- and halogen-free conditions. Tetrahedron 2001, 57, 2469–2476. [Google Scholar] [CrossRef]
  20. Yvon, C.; Surman, A.J.; Hutin, M.; Alex, J.; Smith, B.O.; Long, D.L.; Cronin, L. Polyoxometalate clusters integrated into peptide chains and as inorganic amino acids: Solution- and solid-phase approaches. Angew. Chem. Int. Ed. 2014, 53, 3336–3341. [Google Scholar] [CrossRef]
  21. Fu, H.; Qin, C.; Lu, Y.; Zhang, Z.M.; Li, Y.G.; Su, Z.M.; Li, W.L.; Wang, E.B. An ionothermal synthetic approach to porous polyoxometalate-based metal-organic frameworks. Angew. Chem. Int. Ed. 2012, 51, 7985–7989. [Google Scholar] [CrossRef] [PubMed]
  22. Nohra, B.; El Moll, H.; Rodriguez Albelo, L.M.; Mialane, P.; Marrot, J.; Mellot-Draznieks, C.; O’Keeffe, M.; Ngo Biboum, R.; Lemaire, J.; Keita, B.; et al. Polyoxometalate-based metal organic frameworks (POMOFs): Structural trends, energetics, and high electrocatalytic efficiency for hydrogen evolution reaction. J. Am. Chem. Soc. 2011, 133, 13363–13374. [Google Scholar] [CrossRef] [PubMed]
  23. Long, D.L.; Burkholder, E.; Cronin, L. Polyoxometalate clusters, nanostructures and materials: From self assembly to designer materials and devices. Chem. Soc. Rev. 2007, 36, 105–121. [Google Scholar] [CrossRef] [PubMed]
  24. Ma, F.J.; Liu, S.X.; Sun, C.Y.; Liang, D.D.; Ren, G.J.; Wei, F.; Chen, Y.G.; Su, Z.M. A sodalite-type porous metal-organic framework with polyoxometalate templates: Adsorption and decomposition of dimethyl methylphosphonate. J. Am. Chem. Soc. 2011, 133, 4178–4181. [Google Scholar] [CrossRef] [PubMed]
  25. Poli, E.; De Sousa, R.; Jérome, F.; Pouilloux, Y.; Clacens, J.M. Catalytic epoxidation of styrene and methyl oleate over peroxophosphotungstate entrapped in mesoporous SBA-15. Catal. Sci. Technol. 2012, 2, 910–914. [Google Scholar] [CrossRef] [Green Version]
  26. Wang, B.; Zhang, J.; Zou, X.; Dong, H.; Yao, P. Selective oxidation of styrene to 1,2-epoxyethylbenzene by hydrogen peroxide over heterogeneous phosphomolybdic acid supported on ionic liquid modified MCM-41. Chem. Eng. J. 2015, 260, 172–177. [Google Scholar] [CrossRef]
  27. Li, X.; Zhang, J.; Zhou, F.; Wang, Y.; Yuan, X.; Wang, H. Oxidative desulfurization of dibenzothiophene and diesel by hydrogen peroxide: Catalysis of H3PMo12O40 immobilized on the ionic liquid modified SiO2. Mol. Catal. 2018, 452, 93–99. [Google Scholar] [CrossRef]
  28. Zhao, W.; Zhang, Y.; Ma, B.; Ding, Y.; Qiu, W. Oxidation of alcohols with hydrogen peroxide in water catalyzed by recyclable keggin-type tungstoborate catalyst. Catal. Commun. 2010, 11, 527–531. [Google Scholar] [CrossRef]
  29. Ichihara, J.; Yamaguchi, S.; Nomoto, T.; Nakayama, H.; Iteya, K.; Naitoh, N.; Sasakic, Y. Keggin-type polyacid clusters on apatite: Characteristic catalytic activities in solvent-free oxidation. Tetrahedron Lett. 2002, 43, 8231–8234. [Google Scholar] [CrossRef]
  30. Méry, D.; Astruc, D. Dendritic catalysis: Major concepts and recent progress. Coord. Chem. Rev. 2006, 250, 1965–1979. [Google Scholar] [CrossRef]
  31. Peng, M.; Chen, Y.; Tan, R.; Zheng, W.; Yin, D. A highly efficient and recyclable catalyst—Dendrimer supported chiral salen Mn(iii) complexes for asymmetric epoxidation. RSC Adv. 2013, 3, 20684–20692. [Google Scholar] [CrossRef]
  32. Caminade, A.M.; Ouali, A.; Keller, M.; Majoral, J.P. Organocatalysis with dendrimers. Chem. Soc. Rev. 2012, 41, 4113–4125. [Google Scholar] [CrossRef] [PubMed]
  33. Breinbauer, R.; Jacobsen, E.N. Cooperative Asymmetric Catalysis with Dendrimeric [Co(salen)] Complexes. Angew. Chem. Int. Ed. 2000, 39, 3604–3607. [Google Scholar] [CrossRef]
  34. Nlate, S.; Jahier, C. Dendritic Polyoxometalate Hybrids: Efficient and Recoverable Catalysts for Oxidation Reactions. Eur. J. Inorg. Chem. 2013, 2013, 1606–1619. [Google Scholar] [CrossRef]
  35. Chen, Y.; Tan, R.; Zheng, W.; Zhang, Y.; Zhao, G.; Yin, D. Dendritic phosphotungstate hybrids efficiently catalyze the selective oxidation of alcohols with H2O2. Catal. Sci. Technol. 2014, 4, 4084–4092. [Google Scholar] [CrossRef]
  36. Fornaroli, M.; Velardi, F.; Colli, C.; Baima, R. Process for the synthesis of Modafinil. U.S. Patent US 2004/0106829 A1, 3 June 2004. [Google Scholar]
Catalysts 09 00791 g001 550
Figure 1. Study of the PAMAM-G1-PMo recyclability for the oxidation of thioanisole to sulfoxide (left) and sulfone (right).
Figure 1. Study of the PAMAM-G1-PMo recyclability for the oxidation of thioanisole to sulfoxide (left) and sulfone (right).
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Catalysts 09 00791 g002 550
Figure 2. The IR spectra of fresh-prepared PAMAM-G1-PMo (left) and reused PAMAM-G1-PMo (right).
Figure 2. The IR spectra of fresh-prepared PAMAM-G1-PMo (left) and reused PAMAM-G1-PMo (right).
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Catalysts 09 00791 g003 550
Figure 3. The XRD patterns of fresh-prepared PAMAM-G1-PMo (left) and reused PAMAM-G1-PMo (right).
Figure 3. The XRD patterns of fresh-prepared PAMAM-G1-PMo (left) and reused PAMAM-G1-PMo (right).
Catalysts 09 00791 g003
Catalysts 09 00791 g004 550
Figure 4. The SEM spectra of fresh-prepared PAMAM-G1-PMo (top) and reused PAMAM-G1-PMo (bottom).
Figure 4. The SEM spectra of fresh-prepared PAMAM-G1-PMo (top) and reused PAMAM-G1-PMo (bottom).
Catalysts 09 00791 g004
Catalysts 09 00791 sch001 550
Scheme 1. The oxidation process in preparation of Modafinil.
Scheme 1. The oxidation process in preparation of Modafinil.
Catalysts 09 00791 sch001
Table
Table 1. Control experiments with different components as catalyst a.
Table 1. Control experiments with different components as catalyst a.
Catalysts 09 00791 i001
EntryCatalystTime (h)Temperature (°C)Yield b (%)
1—6.0254
2HPMo8.0258
3PAMAM-G18.0250.5
4PAMAM-G1-PMo4.02585
a Reaction conditions: 1a (62 mg, 0.5 mmol), solvent (8 mL), catalyst (50 mg), 30 wt% H2O2 (63 mg, 0.55 mmol); b Isolated yield. HPMo: Keggin-type phosphomolybdic acid. PAMAM-G1: poly(amidoamine) with the first generation. PAMAM-G1-PMo: composite based on PAMAM-G1 and HPMo.
Table
Table 2. Oxidation of sulfide to sulfoxide in different conditions a.
Table 2. Oxidation of sulfide to sulfoxide in different conditions a.
Catalysts 09 00791 i002
EntrySolventTime (h)Temperature (°C)Yield b (%)
1MeOH4.02590
295%EtOH4.02585
3EtOH4.02560
4CH3COCH34.02545
5CH3COOC2H54.02540
6i-PrOH4.02552
795%EtOH2.02572
895%EtOH2.03091
995%EtOH2.03588
a Reaction conditions: 1a (62 mg, 0.5 mmol), solvent (8 mL), catalyst (50 mg), 30 wt% H2O2 (63 mg, 0.55 mmol); b Isolated yield.
Table
Table 3. Oxidation of sulfide to sulfone in different conditions a.
Table 3. Oxidation of sulfide to sulfone in different conditions a.
Catalysts 09 00791 i003
Entry30 wt% H2O2 (mol%)Time (h)Temperature (°C)Yield b (%)
13003.03060
23003.04093
33003.05092
44003.04093
52003.04081
a Reaction conditions: 1a (62 mg, 0.5 mmol), 95% EtOH (10 mL), catalyst (150 mg); b Isolated yield.
Table
Table 4. The oxidation of sulfides to sulfoxides and sulfones with 30 wt% H2O2 catalyzed by PAMAM–G1–PMo a,b.
Table 4. The oxidation of sulfides to sulfoxides and sulfones with 30 wt% H2O2 catalyzed by PAMAM–G1–PMo a,b.
EntrySubstratesProductsTime (h)Yield c (%)
1 Catalysts 09 00791 i0041a Catalysts 09 00791 i0051b2.091
2 Catalysts 09 00791 i0062a Catalysts 09 00791 i0072b1.590
3 Catalysts 09 00791 i0083a Catalysts 09 00791 i0093b3.085
4 Catalysts 09 00791 i0104a Catalysts 09 00791 i0114b3.585
5 Catalysts 09 00791 i0125a Catalysts 09 00791 i0135b5.0trace
6 Catalysts 09 00791 i0146a Catalysts 09 00791 i0156b6.093
7 Catalysts 09 00791 i0167a Catalysts 09 00791 i0177b4.593
8 Catalysts 09 00791 i0181a Catalysts 09 00791 i0191c3.593
9 Catalysts 09 00791 i0202a Catalysts 09 00791 i0212c2.094
10 Catalysts 09 00791 i0223a Catalysts 09 00791 i0233c4.092
11 Catalysts 09 00791 i0244a Catalysts 09 00791 i0254c4.093
12 Catalysts 09 00791 i0265a Catalysts 09 00791 i0275c5.0NA d
13 Catalysts 09 00791 i0286a Catalysts 09 00791 i0296c5.0trace
14 Catalysts 09 00791 i0307a Catalysts 09 00791 i0317c4.091
a Reaction conditions of sulfides to sulfoxides: sulfide (0.5 mmol), 95% EtOH (8 mL), catalyst (50 mg), 30 wt% H2O2 (63 mg, 0.55 mmol), 30 °C; b Reaction conditions of sulfides to sulfones: sulfide (0.5 mmol), 95% EtOH (10 mL), catalyst (150 mg), 30 wt% H2O2 (170 mg, 1.5 mmol), 40 °C; c Isolated yield; d Not available.

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MDPI and ACS Style

Tong, Q.-L.; Fan, Z.-F.; Yang, J.-W.; Li, Q.; Chen, Y.-X.; Cheng, M.-S.; Liu, Y. The Selective Oxidation of Sulfides to Sulfoxides or Sulfones with Hydrogen Peroxide Catalyzed by a Dendritic Phosphomolybdate Hybrid. Catalysts 2019, 9, 791. https://doi.org/10.3390/catal9100791

AMA Style

Tong Q-L, Fan Z-F, Yang J-W, Li Q, Chen Y-X, Cheng M-S, Liu Y. The Selective Oxidation of Sulfides to Sulfoxides or Sulfones with Hydrogen Peroxide Catalyzed by a Dendritic Phosphomolybdate Hybrid. Catalysts. 2019; 9(10):791. https://doi.org/10.3390/catal9100791

Chicago/Turabian Style

Tong, Qiao-Lin, Zhan-Fang Fan, Jian-Wen Yang, Qi Li, Yi-Xuan Chen, Mao-Sheng Cheng, and Yang Liu. 2019. "The Selective Oxidation of Sulfides to Sulfoxides or Sulfones with Hydrogen Peroxide Catalyzed by a Dendritic Phosphomolybdate Hybrid" Catalysts 9, no. 10: 791. https://doi.org/10.3390/catal9100791

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