Table 1 The functionalization of hexamethylsiloxanes in IL (P = 1 bar, T = 22 °C)
Q/F
mol21
Run
Silanone precursor
Siloxane
Medium
Products
Yield (%)a
1
2
Ph2Si(OMe)2
Ph2Si(OMe)2
HMDS
HMDS
(n-Bu)4NPF6/DMF
Me3BuN·NTf2
2.2
2.3
(Me3SiO)2SiPh2
(Me3SiO)2SiPh2
46b
71
3
4
5
PhSi(OMe)3
D3
[C5H5N+C18H38]·NTf2
[C5H5N+C8H18]·NTf2
Me3BuN·NTf2
1.6
2.2
2.0
28 + 7
67
NC(CH2)3(Me)SiCl2
NC(CH2)3(Me)SiCl2
HMDS
D3
(Me3SiO)2Si(Me)(CH2)3CN
(Me3SiO)2Si(Me)(CH2)3NH2
39
6
7
H2N(CH2)3(Me)Si(OEt)2
Cl(CH2)3Si(OMe)3
HMDS
D3
[C5H5N+C8F18]·NTf2
[C5H5N+C8F18]·NTf2
2.1
2.0
32
48
8
9
CF3(CH2)3(Me)SiCl2
CF3(CH2)3(Me)SiCl2
D3
D3
[C5H5N+C8F18]·NTf2
2.1
2.4
64
59
Bc
B
a Isolated yields. b Literature data.11a c The IL used in run 8, after the extraction of products and addition of a new load of CF3(CH2)3(Me)SiCl2 and D3.
1999, 99, 2071; (d) C. M. Gordon, Appl. Catal. A: Gen., 2001, 222,
101.
2 D. Bradley, P. Dyson and T. Welton, Chem. Rev. (Deddington, UK),
2000, 9, 18.
Scheme 3
3 (a) K. Xu, M. S. Ding and R. R. Jow, J. Electrochem. Soc., 2001, 148,
A267; (b) V. R. Koch, L. A. Dominey, C. Nanjundhia and M. J.
Ondrechen, J. Electrochem. Soc., 1996, 143, 789; (c) U. Schröder, J. D.
Wadhawan, R. G. Compton, F. Marken, P. A. Z. Suarez, C. S. Consorti,
R. F. de Souza and J. Dupont, New J. Chem., 2000, 24, 1009; (d) R. G.
Evans, O. V. Klymenko, C. Hardacre, K. R. Seddon and R. G. Compton,
J. Electroanal. Chem., 2003, 556, 179; (e) A. J. Fry, J. Electroanal.
Chem., 2003, 546, 35.
4 (a) Y. Katayama, S. Dan, T. Miura and T. Khishi, J. Electrochem. Soc.,
2001, 148, C102; (b) V. M. Hultgren, A. W. A. Mariotti, A. M. Bond
and A. G. Wedd, Anal. Chem., 2002, 74, 3151; (c) B. K. Sweeny and D.
G. Peters, Electrochem.Commun., 2001, 3, 712; (d) C. Lagrost, D.
Carrié, M. Vaultier and P. Hapiot, J. Phys. Chem. A, 2003, 107, 745.
5 (a) L. Janiszewska and R. A. Osteryoung, J. Electrochem. Soc., 1987,
134, 2787; (b) L. Janiszewska and R. A. Osteryoung, J. Electrochem.
Soc., 1988, 135, 116; (c) S. A. Arnautov, Synth. Met., 1997, 84, 295.
6 G. Hondrogiannis, C. W. Lee, R. M. Pagni and G. Mammantov, J. Am.
Chem. Soc., 1993, 115, 9828.
Table 1). After run 8 had been accomplished and the product was
extracted from the electrolyte with diethyl ether, new portions of
the starting compounds were added to the same IL and the
electrolysis (run 9) continued till 2.4 F mol21 of electricity were
passed. Thorough extraction withether gave 59% more of the cyclic
methyl(trifluoromethylpropyl)siloxo product. Thus no visible deg-
radation of the efficiency of this second load electrolysis (run 9)
was found compared to that with the first load (run 8).
The viscosity of the used IL remarkably decreases when
dissolving HMDS and silanone precursor which allows to intensify
mass transfer and to reduce ohmic drops. So the studied IL provided
sufficiently high concentrations of O2 for practical electrosynthetic
purposes, good conductivity and allowed the formation of func-
tional siloxanes selectively, easily and in good isolated yields. The
study of these and other IL for silicon electrochemistry and their
turn-over efficiency is in progress.
7 K. Sekiguchi, M. Atobe and T. Fuchigami, Electrochem. Commun.,
2002, 4, 881.
Voltammetric tests were performed using a PAR-362 potentio-
stat with a glassy carbon (GC) 0.8 mm disk used as working
electrode and a GC rod as auxiliary electrode. The reference
electrode was Ag/0.1 M AgNO3 in CH3CN. In large-scale
electrolyses a porous graphite cathode and a GC felt anode were
used. Diorganosilanes, HMDS and D3 were purchased from ABCR
and used as received. The ionic liquids were prepared according to
refs. 1a,17 and dried overnight in vacuum (3 mmHg at 80 °C)
before use. Oxygen (Air Liquide, France) was dried passing it
through a cartridge filled with P2O5 on glass wool. All experiments
were performed under inert argon atmosphere. A typical elec-
trolysis procedure was as follows. 1 mmol Me3SiCl was added to
7.5 ml IL and electrolyzed for about 2.5 h to reduce H+ formed in
hydrolysis of the chlorosilane by residual water. A silanone
precursor (50 mmol) and a silanone trap (55 mmol) were then added
via a syringe and the electrolysis was carried out with a constant
flow of O2 (5 ml min21) with the current density j = 0.5–1 mA
cm22. After passing 2 F mol21, the products were isolated by
thorough extracting the IL with diethyl ether, evaporation of the
latter and column separation of the organic residue.
8 R. T. Carlin, P. C. Treulove and R. A. Osteryoung, J. Electrochem. Soc.,
1994, 141, 1709.
9 (a) R. Barhdadi, C. Courtinard, J.-Y. Nedelec and M. Troupel, Chem.
Commun., 2003, 1434; (b) M. Mellah, S. Gmouh, M. Vaultier and V.
Jouikov, Electrochem. Commun., 2003, 5, 591; (c) T. Fuchigami, M.
Hasegawa and H. Ishii, 203rd ECS Meeting, Paris 2003, Proc. CD.
10 (a) D. S. Fattakhova, V. V. Jouikov and M. G. Voronkov, Dokl. Akad.
Nauk, 2000, 371, 629; (b) D. S. Fattakhova, V. V. Jouikov and M. G.
Voronkov, J. Organomet. Chem., 2000, 613, 170.
11 (a) R. Keyrouz and V. Jouikov, New J. Chem., 2003, 27, 902; (b) R.
Keyrouz and V. Jouikov, Silicon Chem., 2004, in press.
12 (a) M. T. Carter, C. L. Hussey, S. K. D. Strubinger and R. A.
Osteryoung, Inorg. Chem., 1991, 30, 1149; (b) I. M. AlNashef, M. L.
Leonard, M. A. Matthews and J. W. Weidner, Ind. Chem. Res., 2002, 41,
4475; (c) M. C. Buzzeo, O. V. Klymenko, J. D. Wadhawan, C.
Hardacre, K. R. Seddon and R. G. Compton, J. Phys. Chem. A, 2003,
107, 8872; (d) Y. Katayama, H. Onodera and T. Miura, 203rd ECS
Meeting, Paris 2003, Proc. CD.
13 The concentration of oxygen was determined by comparison of the
diffusional peak currents of saturated solutions of O2 with the one-
electron current of ferrocene ([Fc] = 1023 mol L21), the data were not
corrected for the difference of DO and DFc; 0.8 mm GC electrode was
2
The authors are grateful to Rennes Metropöle for the financial
support of this work.
used at v = 200 mV s21
.
14 B. Betzemeier and P. Knochel, Top. Curr. Chem., 1999, 206, 61.
15 H. Sugimoto, S. Matsumoto and D. T. Sawyer, J. Am. Chem. Soc., 1988,
110, 5193.
16 [C5H5N+C8F18]·NTf2 is solid at room temperature, so its 10 : 1 mixture
with non-fluorinated liquid analog [C5H5N+C8H18]·NTf2 was used.
17 (a) J. D. Holbrey and K. R. Seddon, J. Chem. Soc., Dalton Trans., 1999,
2133; (b) M. Freemantle, Chem. Eng. News, 2001, 72, 21.
Notes and references
1 (a) P. Bonhoˆte, A. Dias, N. Papageorgiou, K. Kalyanasundaram and M.
Grätzel, Inorg. Chem., 1996, 35, 1168; (b) A. E. Visser, R. P. Swatloski
and R. D. Rogers, Green Chem., 2000, 2, 1; (c) T. Welton, Chem. Rev.,
C h e m . C o m m u n . , 2 0 0 4 , 6 7 4 – 6 7 5
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