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Highly efficient oxidation of alcohols using Oxone® as oxidant catalyzed by ruthenium complex under mild reaction conditions
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Chinese Chemical Letters 19 (2008) 1031–1034 www.elsevier.com/locate/cclet
Highly efficient oxidation of alcohols using Oxone1 as oxidant catalyzed by ruthenium complex under mild reaction conditions Zi Qiang Lei *, Jian Qiang Wang, Peng Hua Yan Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China Received 10 March 2008
Abstract Aromatic and alkyl alcohols were oxidized to the corresponding aldehydes or ketones at room temperature with high conversion and selectivity using Oxone1 (2KHSO5KHSO4K2SO4) as oxidant catalyzed by ruthenium complex Quin-Ru-Quin (where Quin = 8-hydroxyquinoline). The reaction time is very short and the preparation of complex is simple. # 2008 Zi Qiang Lei. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Oxidation of alcohols; Oxone1; Ruthenium complex
The oxidation of alcohols into corresponding aldehydes and ketones is a crucial reaction in organic chemistry, both with academic and industry relevance [1–3]. Many systems have been reported in the literature for the catalytic oxidation of alcohols, mainly involving the use of catalysts containing transition metals, such as Co(II) [4], Pd(II) [5], Cu(I) [6], Ni(II) [7], and manganese oxides [8]. However, most of the metal containing catalysts are not effective with a broad range of alcohols. Moreover, the oxidant which the reactions generally used may lead to the environmental pollution. With the overgrowing environmental concerns the development of benign catalytic processes for highly efficient oxidation of alcohols is becoming increasingly important. Bolm et al. presented a metal-free oxidation system for the oxidation of alcohols using Oxone1 in the presence of a catalytic amount of TEMPO [9]. Recently, Bagherzadeh reported the highly efficient oxidation of alcohols using the tris[(2-oxazolinyl) phenolato] manganese(III)/Oxone1/n-Bu4NBr oxidation system [10]. Oxone1 has recently received much attention in the field of oxidation because the advantage of stability in store and facility to deal with after reaction [11]. In this paper we demonstrated the highly efficient oxidation of alcohols to their corresponding aldehydes and ketones under mild conditions at room temperature with Oxone1 catalyzed by Quin-Ru-Quin, a complex previously used in the oxidation of alcohols with iodosylbenzene [12]. The present work revealed that the ruthenium complex has potential applications in the oxidation of alcohols with excellent conversion and good selectivity. The reaction is carried out in biphasic solvents (Scheme 1).
* Corresponding author. E-mail address: [email protected] (Z.Q. Lei). 1001-8417/$ – see front matter # 2008 Zi Qiang Lei. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2008.06.019
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Z.Q. Lei et al. / Chinese Chemical Letters 19 (2008) 1031–1034
Scheme 1.
In order to evaluate the catalytic activities of the complex for the oxidation of alcohols, the reaction condition was optimized according to the oxidation of benzyl alcohol through the investigation of the influence factors of the oxidation, such as the reaction time, the amount of the catalyst used and the amount of Oxone1 consumed. The results showed that 1.1 equiv. of Oxone1 and 3 mg of ruthenium complex are needed for the benzyl alcohol to be completely transferred in 0.5 h at room temperature. In the oxidation, benzaldehyde was the main product. We confirmed that in the absence of the Ru-complex catalyst, benzaldehyde was only formed in 19% yield. A series of other alcohols were treated with this catalyst system. The results were shown in Table 1. Benzyl alcohol was transformed to benzaldehyde with the conversion of 99% and the selectivity of 98%. Benzyl alcohol derivatives possess both electro-with-drawing and -donating groups on the benzene ring were oxidized to give the corresponding aldehyde with high conversion (Entries 2–5). Cyclopentanol and cyclohexanol could convert to the corresponding ketones in high conversion and selectivity in 0.5 h (Entries 6–7). The results obtained from this study also indicated that the system oxidizes benzhydrol and substituted benzhydrol such as 4-methylbenzhydydrol and 4chlorobenzhydrol to the corresponding ketones efficiently in good-to-excellent yields and purities (Entries 10– 12). It is interesting to find that this oxidation system is also efficient for the oxidation of aliphatic chain alcohols (Entries 8–9). 1. Experimental 1.1. Preparation of ruthenium complex The complex was prepared through simple procedures according to the literatures [12]. The IR spectra showed characteristic absorption signal of N–Ru and O–Ru peaks at 486 and 609 cm 1. Elemental anal. Found: C: 32.54; H: 2.13; N: 5.73. The content of ruthenium in the complex was also well determined with ICP method, and the results were 13.8%. 1.2. General procedure for the oxidation of alcohols A typical reaction was carried out as follows: to a solution of the ruthenium complex (3 mg) and n-Bu4NBr (40 mol%, 0.12 mmol) in 1 mL of methylene chloride is added Oxone1 (1.1 equiv., 0.33 mmol, 2 mL solution of the H2O) and alcohol (0.3 mmol). The mixture is then stirred for 0.5 h at room temperature. Percentage conversion and reaction selectivity were determined by GC analysis. The identity of products was determined either by comparison with authentic samples using gas chromatography or by NMR. The conversion and product selectivity were determined using GC analysis. To obtain the pure isolated products, the reacted mixtures were extracted with ethyl acetate (3 5 mL), dried (MgSO4), evaporated to rude products, refined by column chromatograph (Entries 4–5, 10–12). The NMR data: 4nitrobenzaldehyde (Table 1, Entry 4): 1H NMR (CDCl3, 400 MHz, d ppm): 10.17 (1H, CHO), 8.42–8.40 (2H, Ar–H), 8.10–8.08 (2H, Ar–H); 13C NMR (400 MHz, d ppm): 190.28, 151.10, 140.01, 130.47, 124.30. 4-Chlorobenzaldehyde (Table 1, Entry 5): 1H NMR (CDCl3, 400 MHz, d ppm): 10.00 (1H, CHO), 7.83–7.85 (2H, Ar–H), 7.54–7.52 (2H, Ar– H); 13C NMR (400 MHz, d ppm): 190.84, 140.92, 134.67, 130.88, 129.42. Benzophenone (Table 1, Entry 10): 1H NMR (CDCl3, 400 MHz, d ppm): 7.82–7.79 (4H, Ar–H), 7.60–7.58 (2H, Ar–H), 7.56–7.45 (4H, Ar–H); 13C NMR (400 MHz, d ppm): 196.67, 137.49, 132.35, 129.98, 128.20. 4-Methylbenzophenone (Table 1, Entry 11): 1H NMR (CDCl3, 400 MHz, d ppm): 7.80–7.79 (2H, Ar–H), 7.78–7.77 (2H, Ar–H), 7.59–7.56 (1H, Ar–H), 7.49–7.46 (2H, Ar– H), 7.29–7.26 (2H, Ar–H), 2.44 (3H, CH3); 13C NMR (400 MHz, d ppm): 196.50, 143.22, 137.91, 134.83, 132.14, 130.29, 129.90, 128.94, 128.17, 21.63. 4-Chlorobenzophenone (Table 1, Entry 12): 1H NMR (CDCl3, 400 MHz, d ppm): 7.80–7.79 (2H, Ar–H), 7.78–7.77 (2H, Ar–H), 7.63–7.59 (1H, Ar–H), 7.51–7.48 (2H, Ar–H), 7.47–7.45 (2H, Ar–H); 13C NMR (400 MHz): d = 195.51, 138.88, 137.21, 135.83, 132.63, 131.45, 129.92, 128.62, 128.39.
Z.Q. Lei et al. / Chinese Chemical Letters 19 (2008) 1031–1034
1033
Table 1 Oxidation results of a series of alcohols Entry
Alchol
Product
Conversion (%)
Selectivity (%)
1
99
98
2
100
96
3
97
96
4
100
100
5
100
100
6
100
100
7
100
100
8
78
41 59
9
61
67 33
10
100
100
11
99
100
12
95
100
Reaction condition: alcohol 0.30 mmol, Oxone1 0.33 mmol and n-Bu4NBr 0.12 mmol, 3 mL H2O/CH2Cl2(V/V = 2/1), 0.5 h at room temperature. Percentage conversion and reaction selectivity were determined by GC analysis.
Acknowledgments This work is financially supported by National Natural Science Foundation of China (No. 20774074 and 20674063) and Specialized Research Fund for the Doctoral Program of Higher Education (No. 20050736001). References [1] W.H. Fung, W.Y. Yu, C.M. Che, J. Org. Chem. 63 (1998) 2873. [2] S.S. Stahl, Science 309 (2005) 1824.
1034 [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]
Z.Q. Lei et al. / Chinese Chemical Letters 19 (2008) 1031–1034 P.H. Yan, R.R. Wang, S. Wu, Z.Q. Lei, Catal. Commun. 9 (2008) 406. S. Das, T. Punniyamurthy, Tetrahedron Lett. 44 (2003) 6033. T.L. Stuchinskaya, I.V. Kozhevnikov, Catal. Commun. 4 (2003) 417. X.J. Meng, K.F. Lin, X.Y. Yang, J. Catal. 218 (2003) 460. K.O. Xavier, J. Chacko, K.K. Mohammed Yusuff, J. Mol. Catal. A: Chem. 178 (2002) 275. J.E. Remias, A. Sen, J. Mol. Catal. A: Chem. 189 (2002) 33. C. Bolm, A.S. Magnus, J.P. Hilderbrand, Org. Lett. 2 (2000) 1173. M. Bagherzadeh, Tetrahedron Lett. 44 (2003) 8943. A.P. Thottumkara, M.S. Bowsher, T.K. Viond, Org. Lett. 7 (2005) 2933. Z.W. Yang, Q.X. Kang, Z.Q. Lei, J. Mol. Catal. A: Chem. 261 (2007) 190.
Chinese Chemical Letters 19 (2008) 1031–1034 www.elsevier.com/locate/cclet
Highly efficient oxidation of alcohols using Oxone1 as oxidant catalyzed by ruthenium complex under mild reaction conditions Zi Qiang Lei *, Jian Qiang Wang, Peng Hua Yan Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China Received 10 March 2008
Abstract Aromatic and alkyl alcohols were oxidized to the corresponding aldehydes or ketones at room temperature with high conversion and selectivity using Oxone1 (2KHSO5KHSO4K2SO4) as oxidant catalyzed by ruthenium complex Quin-Ru-Quin (where Quin = 8-hydroxyquinoline). The reaction time is very short and the preparation of complex is simple. # 2008 Zi Qiang Lei. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Oxidation of alcohols; Oxone1; Ruthenium complex
The oxidation of alcohols into corresponding aldehydes and ketones is a crucial reaction in organic chemistry, both with academic and industry relevance [1–3]. Many systems have been reported in the literature for the catalytic oxidation of alcohols, mainly involving the use of catalysts containing transition metals, such as Co(II) [4], Pd(II) [5], Cu(I) [6], Ni(II) [7], and manganese oxides [8]. However, most of the metal containing catalysts are not effective with a broad range of alcohols. Moreover, the oxidant which the reactions generally used may lead to the environmental pollution. With the overgrowing environmental concerns the development of benign catalytic processes for highly efficient oxidation of alcohols is becoming increasingly important. Bolm et al. presented a metal-free oxidation system for the oxidation of alcohols using Oxone1 in the presence of a catalytic amount of TEMPO [9]. Recently, Bagherzadeh reported the highly efficient oxidation of alcohols using the tris[(2-oxazolinyl) phenolato] manganese(III)/Oxone1/n-Bu4NBr oxidation system [10]. Oxone1 has recently received much attention in the field of oxidation because the advantage of stability in store and facility to deal with after reaction [11]. In this paper we demonstrated the highly efficient oxidation of alcohols to their corresponding aldehydes and ketones under mild conditions at room temperature with Oxone1 catalyzed by Quin-Ru-Quin, a complex previously used in the oxidation of alcohols with iodosylbenzene [12]. The present work revealed that the ruthenium complex has potential applications in the oxidation of alcohols with excellent conversion and good selectivity. The reaction is carried out in biphasic solvents (Scheme 1).
* Corresponding author. E-mail address: [email protected] (Z.Q. Lei). 1001-8417/$ – see front matter # 2008 Zi Qiang Lei. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2008.06.019
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Z.Q. Lei et al. / Chinese Chemical Letters 19 (2008) 1031–1034
Scheme 1.
In order to evaluate the catalytic activities of the complex for the oxidation of alcohols, the reaction condition was optimized according to the oxidation of benzyl alcohol through the investigation of the influence factors of the oxidation, such as the reaction time, the amount of the catalyst used and the amount of Oxone1 consumed. The results showed that 1.1 equiv. of Oxone1 and 3 mg of ruthenium complex are needed for the benzyl alcohol to be completely transferred in 0.5 h at room temperature. In the oxidation, benzaldehyde was the main product. We confirmed that in the absence of the Ru-complex catalyst, benzaldehyde was only formed in 19% yield. A series of other alcohols were treated with this catalyst system. The results were shown in Table 1. Benzyl alcohol was transformed to benzaldehyde with the conversion of 99% and the selectivity of 98%. Benzyl alcohol derivatives possess both electro-with-drawing and -donating groups on the benzene ring were oxidized to give the corresponding aldehyde with high conversion (Entries 2–5). Cyclopentanol and cyclohexanol could convert to the corresponding ketones in high conversion and selectivity in 0.5 h (Entries 6–7). The results obtained from this study also indicated that the system oxidizes benzhydrol and substituted benzhydrol such as 4-methylbenzhydydrol and 4chlorobenzhydrol to the corresponding ketones efficiently in good-to-excellent yields and purities (Entries 10– 12). It is interesting to find that this oxidation system is also efficient for the oxidation of aliphatic chain alcohols (Entries 8–9). 1. Experimental 1.1. Preparation of ruthenium complex The complex was prepared through simple procedures according to the literatures [12]. The IR spectra showed characteristic absorption signal of N–Ru and O–Ru peaks at 486 and 609 cm 1. Elemental anal. Found: C: 32.54; H: 2.13; N: 5.73. The content of ruthenium in the complex was also well determined with ICP method, and the results were 13.8%. 1.2. General procedure for the oxidation of alcohols A typical reaction was carried out as follows: to a solution of the ruthenium complex (3 mg) and n-Bu4NBr (40 mol%, 0.12 mmol) in 1 mL of methylene chloride is added Oxone1 (1.1 equiv., 0.33 mmol, 2 mL solution of the H2O) and alcohol (0.3 mmol). The mixture is then stirred for 0.5 h at room temperature. Percentage conversion and reaction selectivity were determined by GC analysis. The identity of products was determined either by comparison with authentic samples using gas chromatography or by NMR. The conversion and product selectivity were determined using GC analysis. To obtain the pure isolated products, the reacted mixtures were extracted with ethyl acetate (3 5 mL), dried (MgSO4), evaporated to rude products, refined by column chromatograph (Entries 4–5, 10–12). The NMR data: 4nitrobenzaldehyde (Table 1, Entry 4): 1H NMR (CDCl3, 400 MHz, d ppm): 10.17 (1H, CHO), 8.42–8.40 (2H, Ar–H), 8.10–8.08 (2H, Ar–H); 13C NMR (400 MHz, d ppm): 190.28, 151.10, 140.01, 130.47, 124.30. 4-Chlorobenzaldehyde (Table 1, Entry 5): 1H NMR (CDCl3, 400 MHz, d ppm): 10.00 (1H, CHO), 7.83–7.85 (2H, Ar–H), 7.54–7.52 (2H, Ar– H); 13C NMR (400 MHz, d ppm): 190.84, 140.92, 134.67, 130.88, 129.42. Benzophenone (Table 1, Entry 10): 1H NMR (CDCl3, 400 MHz, d ppm): 7.82–7.79 (4H, Ar–H), 7.60–7.58 (2H, Ar–H), 7.56–7.45 (4H, Ar–H); 13C NMR (400 MHz, d ppm): 196.67, 137.49, 132.35, 129.98, 128.20. 4-Methylbenzophenone (Table 1, Entry 11): 1H NMR (CDCl3, 400 MHz, d ppm): 7.80–7.79 (2H, Ar–H), 7.78–7.77 (2H, Ar–H), 7.59–7.56 (1H, Ar–H), 7.49–7.46 (2H, Ar– H), 7.29–7.26 (2H, Ar–H), 2.44 (3H, CH3); 13C NMR (400 MHz, d ppm): 196.50, 143.22, 137.91, 134.83, 132.14, 130.29, 129.90, 128.94, 128.17, 21.63. 4-Chlorobenzophenone (Table 1, Entry 12): 1H NMR (CDCl3, 400 MHz, d ppm): 7.80–7.79 (2H, Ar–H), 7.78–7.77 (2H, Ar–H), 7.63–7.59 (1H, Ar–H), 7.51–7.48 (2H, Ar–H), 7.47–7.45 (2H, Ar–H); 13C NMR (400 MHz): d = 195.51, 138.88, 137.21, 135.83, 132.63, 131.45, 129.92, 128.62, 128.39.
Z.Q. Lei et al. / Chinese Chemical Letters 19 (2008) 1031–1034
1033
Table 1 Oxidation results of a series of alcohols Entry
Alchol
Product
Conversion (%)
Selectivity (%)
1
99
98
2
100
96
3
97
96
4
100
100
5
100
100
6
100
100
7
100
100
8
78
41 59
9
61
67 33
10
100
100
11
99
100
12
95
100
Reaction condition: alcohol 0.30 mmol, Oxone1 0.33 mmol and n-Bu4NBr 0.12 mmol, 3 mL H2O/CH2Cl2(V/V = 2/1), 0.5 h at room temperature. Percentage conversion and reaction selectivity were determined by GC analysis.
Acknowledgments This work is financially supported by National Natural Science Foundation of China (No. 20774074 and 20674063) and Specialized Research Fund for the Doctoral Program of Higher Education (No. 20050736001). References [1] W.H. Fung, W.Y. Yu, C.M. Che, J. Org. Chem. 63 (1998) 2873. [2] S.S. Stahl, Science 309 (2005) 1824.
1034 [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]
Z.Q. Lei et al. / Chinese Chemical Letters 19 (2008) 1031–1034 P.H. Yan, R.R. Wang, S. Wu, Z.Q. Lei, Catal. Commun. 9 (2008) 406. S. Das, T. Punniyamurthy, Tetrahedron Lett. 44 (2003) 6033. T.L. Stuchinskaya, I.V. Kozhevnikov, Catal. Commun. 4 (2003) 417. X.J. Meng, K.F. Lin, X.Y. Yang, J. Catal. 218 (2003) 460. K.O. Xavier, J. Chacko, K.K. Mohammed Yusuff, J. Mol. Catal. A: Chem. 178 (2002) 275. J.E. Remias, A. Sen, J. Mol. Catal. A: Chem. 189 (2002) 33. C. Bolm, A.S. Magnus, J.P. Hilderbrand, Org. Lett. 2 (2000) 1173. M. Bagherzadeh, Tetrahedron Lett. 44 (2003) 8943. A.P. Thottumkara, M.S. Bowsher, T.K. Viond, Org. Lett. 7 (2005) 2933. Z.W. Yang, Q.X. Kang, Z.Q. Lei, J. Mol. Catal. A: Chem. 261 (2007) 190.