首页   按字顺浏览 期刊浏览 卷期浏览 Catalytic Dehydrocoupling of Silane by a Homogenous Rhodium Complex with Water†
Catalytic Dehydrocoupling of Silane by a Homogenous Rhodium Complex with Water†

 

作者: Min Shi,  

 

期刊: Journal of Chemical Research, Synopses  (RSC Available online 1997)
卷期: Volume 0, issue 11  

页码: 400-401

 

ISSN:0308-2342

 

年代: 1997

 

DOI:10.1039/a702189e

 

出版商: RSC

 

数据来源: RSC

 

摘要:

PhMe2SiH PhMe2Si-OH + PhMe2Si-O-SiMe2Ph [(cod)RhCl]2, H2O room temp., 24 h 1c 2c 3c RR¢R¢¢SiH RR¢R¢¢Si-OH + RR¢R¢¢2Si-O-SiR¢¢R¢R [(cod)RhCl]2, H2O THF, room temp., 24 h 1a,b,d,e,f 2a,b,d,e,f 3a,b,d,e,f 400 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 400–401† Catalytic Dehydrocoupling of Silane by a Homogenous Rhodium Complex with Water† Min Shi* and Kenneth M. Nicholas Department of Chemistry and Biochemistry, The University of Oklahoma, Norman, Oklahoma 73019, USA Organosilicon hydrides are oxidized to the corresponding silanols in high yield in a homogenous phase in the presence of a small amount of water and a catalytic amount of a rhodium complex.Silanols or disiloxanes are generally formed in hydrolysis reactions of chlorosilanes. Many years ago, Sommer and Parker1 and Nagai et al.2 reported that treatment of R3SiH with excess of peroxybenzoic acid in benzene at room temperature for 12 hours gave a moderate yield of R3SiOH. Almost at the same time, Daughenbaugh also reported that the hydrolysis of organosilicon hydrides with catalysts such as palladium or ruthenium on charcoal was an excellent method of preparing the corresponding organosilanols.3 The reactions were carried out using a buffer solution rather than pure water in an effort to prevent reaction mixtures from becoming either acidic or basic.Results and Discussion During our investigation of the reactivity of dimethylphenylsilane (1c) with carbon dioxide in the presence of a catalytic amount of binuclear rhodium chloride dimer [(cod)RhCl]2 (cod=cyclooctane-1,5-diene) in tetrahydrofuran (THF), we found incidentally that the dehydrocoupling of 1c (200 mg, 1 mmol) could take place very easily to afford the corresponding silanol (2c) and 1,1,3,3-tetramethyl-1,3-diphenyldisiloxane (3c) in wet THF (50 ml water/8 ml solvent), respectively (Scheme 1).As shown in Table 1, the solvent effect was examined carefully. It was found that the solvents can dramatically change the reaction results.The use of a solvent such as benzene or pentane was confirmed to be a poorer choice than a polar solvent such as diethyl ether, dichloromethane or THF (Table 1). In the meantime, it was also found that, when wet diethyl ether or wet dichloromethane was used as solvent the formation of 2c became the dominant reaction. Thus, further reaction of 2c can be avoided by using dichloromethane as a solvent. The oxidation of the other kinds of silanes (1a,b,d,e,f) was carried out in the same reaction conditions as those mentioned above (Scheme 2).The results are summarized in Table 2. We found that, even though THF was used as solvent, the major reaction product was silanol in each case rather than disiloxane (3) and also found that 1f has no reactivity under the same reaction conditions. Other homogenous rhodium complexes such as RhCl(Ph3)3 and RhCl(CO)(Ph3)2 were also examined under the same reaction conditions for the dehydrocoupling of 1c and only 30 and 20% of 1c were converted into the products, respectively.Thus, obviously, they are not as effective as [(cod)RhCl]2. On the other hand, the catalytic oxidation dehydrocoupling reaction must be carried out in a deaerated solvent, otherwise the reaction products would be very complicated and the yield of silanol would be very low. The mechanism can be considered as a dehydrogenative coupling of a hydrosilane with water, i.e.dihydrogen is given off in the reaction. Efforts are under way to elucidate the mechanistic details of this reaction. In conclusion, these results elucidate that, using a soluble rhodium complex as a catalyst, i.e. in a homogenous phase, the oxidation of silane with water in a polar solvent can proceed efficiently. It is unnecessary to use a buffer solution for the oxidation of the silanes (1a,b,d,e) to prevent the corresponding silanols (2a,b,d,e) from further reaction and, in the case of silane 1c, the silanol (2c) can be exclusively obtained by using CH2Cl2 as solvent.Experimental Melting points were obtained with a Yanagimoto micro melting point apparatus and are uncorrected. 1H NMR spectra were determined for solutions in CDCl3 with tetramethylsilane (TMS) as internal standard on a XL-300 spectrometer. Mass spectra were recorded with a JMS D-300 instrument. All compounds reported in this paper gave satisfactory HRMS results or CH microanalyses with a Perkin-Elmer Model 240 analyser.Typical Reaction Procedure.·1,1-Dimethylphenylsilane (200 mg, 1.0 mmol) was added to a THF (8 ml) solution of [(cod)RhCl]2 (3.4 mg, 0.69Å10µ3 mmol) and then water (50 ml) was added. The reaction mixture was stirred at room temperature for 12 h and the products were qualitatively analysed by GC and isolated by a flash column (SiO2). Trimethylsilanol. dH (CDCl3) 0.23 (9 H, s, CH3), 1.67 (1 H, s, OH); MS (EI), m/z 90 (10%) [M+], 75 (100) [M+µ15] (Found: C, *To receive any correspondence.Current address: Japan Science and Technology Corporation (JST), 4-6-3 Kamishinden, Toyonaka 565, Japan. †This is a Short Paper as defined in the Instructions for Authors, Section 5.0 [see J. Chem. Research (S), 1997, Issue 1]; there is therefore no corresponding material in J. Chem. Research (M). Table 1 The reaction of 1c in the presence of water and solvent and 0.69 mol% of rhodium complex Yield (%)a Solvent Conversion of 1c (%) 2c 3c THF Et2O CH2Cl2 Pentane Benzene 100 100 100 10 8 55 85 95 87 42 10 trace —— aIsolated yields Table 2 The results of the reaction of 1a, b,d,e,f in the presence of water and 0.69 mol% of rhodium complex in THF Yield (%)a Compound RRpRPSiH 2 3 1a 1b 1d 1e 1f Me3SiH Et3SiH Ph2MeSiH Ph3SiH (EtO)3SiH 90 94 98 98 trace trace trace ——— aYields were determined by GLC analyses using naphthalene as internal standardJ.CHEM. RESEARCH (S), 1997 401 39.94; H, 11.10%; M+, 90.0489.C3H10SiO requires C, 39.95; H, 11.18%; Mr, 90.0501). Triethylsilanol. dH (CDCl3) 0.52 (6 H, q, J 7.8 Hz, CH2), 0.95 (9 H, t, J 7.8 Hz, CH3), 2.05 (1 H, s, OH); MS (EI), m/z 132 (10%) [M+], 103 (100) [M+ µ29], 75 (90) [M+ µ57] (Found: C, 54.39; H, 12.09%; M+, 132.0970. C6H16SiO requires C, 54.48; H, 12.19%; Mr, 132.0971). 1,1-Dimethylphenylsilanol. dH (CDCl3) 0.25 (6 H, s, CH3), 1.70 (1 H, s, OH), 7.25–7.80 (5 H, m, Ar); MS (EI), m/z, 153 (10%) [M+], 137 (100) [M+µ16], 91 (70) [M+µ62] (Found: C, 63.12; H, 7.87%; M+, 152.0654.C8H12SiO requires C, 63.11; H, 7.94% Mr, 152.0658). 1,1-Diphenylmethylsilanol. Mp 88–90 °C; dH (CDCl3) 0.25 (3 H, s, CH3), 1.70 (1 H, s, OH), 7.25–7.80 (10 H, m, Ar); MS (EI), m/z 214 (10%) [M+], 198 (100) [M+µ16] (Found: C, 72.81; H, 6.57%; M+, 214.0810. C13H14SiO requires C, 78.22; H, 5.84%; Mr 214.0814). Triphenylsilanol. Mp 152–154 °C; dH (CDCl3) 1.70 (1 H, s, OH), 7.25–7.80 (15 H, m, Ar); MS (EI), m/z 276 (10%) [M+], 260 (100) [M+ µ16] (Found: C, 78.30; H, 5.82%; M+, 276.0965.C18H16SiO requires C, 78.22; H, 5.84%; Mr 276.0971). 1,1,1,3,3,3-Hexamethyldisiloxane. dH (CDCl3) 0.21 (s, CH3); MS (EI), m/z 162 (10%) [M+], 147 (100) [M+ µ15] (Found: C, 44.32; H, 11.15%; M+, 162.0891. C6H18Si2O requires C, 44.38; H, 11.17%; Mr, 162.0896). 1,1,1,3,3,3-Hexaethyldisiloxane. dH (CDCl3) 0.50 (2 H, q, J 7.8 Hz, CH2), 0.95 (3 H, t, J 7.8 Hz, CH3); MS (EI), m/z 246 (10%) [M+], 217 (15) [M+ µ29] (Found: C, 58.43; H, 12.12%; M+, 246.1832. C12H30Si2O requires C, 58.46; H, 12.27%; Mr, 246.1836). 1,1,3,3-Tetramethyl-1,3-diphenyldisiloxane. dH (CDCl3) 0.20 (6 H, s, CH3), 7.25–7.80 (5 H, m, Ar); MS (EI), m/z 286 (10%) [M+], 271 (100) [M+ µ15], 193 (70) [M+ µ93] (Found: C, 67.09; H, 7.81%; M+, 286.5208. C16H22Si2 requires C 67.07; H, 7.74%; Mr, 286.5211). Received, 1st April 1997; Accepted, 7th July 1997 Paper E/7/02189E References 1 L. H. Sommer and G. A. Parker, unpublished work cited in L. H. Sommer, Stereochemistry, Mechanism and Silicon, McGraw-Hill, New York, 1965, p. 110. 2 Y. Nagai, K. Honda and T. Migita, J. Organomet. Chem., 1967, 8, 372. 3 G. H. Barnes, Jr. and N. E. Daughenbaugh, J. Org. Chem., 1966, 31, 885.

 



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