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Nickel-Catalyzed Reduction of Carbon Monoxide by Hexamethyldisilane a New Reaction Leading to a Novel Synthesis of Siloxanes.

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to 5 . Moreover, no trapping reactions occurred when monoolefins, conjugated dienes, or dimethyl sulfide were used.
These results, as a whole, showed that the h3-phosphinonitrene reacts as a nitrilo-h'-phosphane. This is in perfect
agreement with the calculated structure with a polarized
phosphorus-nitrogen triple bondL3].It is noteworthy that, in
contrast to tetra- or pentacoordinated phosphorus azides''1,
no Curtius rearrangement takes place, supporting the stabilization of the nitrene.
Received: February 29, 1984:
revised: April 24, 1984 [Z 729 IE]
German version: Angew. Chem. 96 (1984) 450
[1] a) G. Bertrand, G. Trinquier, P. Mazerolles, J . Organomet. Chem. Libr.
Organomet. Chem. Rev. I2 (1981) I : b) L. E. Gusel'nikov, N. S. Nametkin, Chem. Reu. 79 (1979) 529; c) R. Appel, F. Knoll, I. Ruppert, Angew.
Chem. 93 (1981) 771; Angew. Chem. I n f . Ed. Engl. 20 (1981) 731; d) E.
Fluck, Top. Phosphorus Chem. 1 0 (1980) 193: e) M. Regitz, G. Maas, Top.
Current Chem. 97 (1981) 71; f) B. Potter, K. Seppelt, Angew. Chem. 94
(1984) 138: Angew. Chem. I n t . Ed. Engl. 23 (1984) 150.
[2] R. Appel, V. Barth, J. Peters, I n t . Conf: Phosphorus Chemistry, Halle 1979;
R. Appel, J. Peters, R. Schmitz, Z . Anorg. Allg. Chem. 475 (1981) 18.
[3] G. Trinquier, J. Am. Chem. Soc. 104 (1982) 6969.
[4] 0. J. Scherer, W. Glabel, Chem.-Ztg. 99 (1975) 246.
[5] K. C. Paciorek, R. Kratzer, Inorg. Chem. 3 (1964) 594; G. Tesi, C. P. Haber, C. M. Douglas, Proc. Chem. Sac. 1960, 219.
[6] H. G. Schafer, Dissertation, Universitat Bielefeld 1981: D. A. Wildbredt,
Dissertation, Universitat Bielefeld 1981.
[7] N o reaction occurred in the absence of UV light or upon heating to 70°C
for 12 h.
[8] 2 : "P-NMR (C6H6): 6 = + 3 4 ; 'H-NMR (C6H6): 6=1.17 (d, 12H,
' J H H = 7 Hz), 1.22 (d, 12H, i J l l l l = 7 Hz), 3.42 (m, 4H), 3.45 (d, 3H,
'JPI1
= 12 Hz); MS: m/z 277 (M+).3: "P-NMR (C,H,): 6= +32.2; 'HNMR(CsH6): 6=1.21 (d, 12H, 3 J ~ ~ * = 6 . Hz),
2 5 1.32 (d, 12H, ' J ~ ~ = 6 . 2 5
Hz), 2.59 (d, 6 H , 'JPH=9.S Hz), 3.46 (m, 4H); IR (KBr): 1306 cm-I
- 4 : "P-NMR (C6H6): 6= -7.9; 'H-NMR
(P=N); MS: m/z 290 (M+).
(ChH6):6=0.27(~,9H),1.24(d, 12H,'J1411=7 Hz), 1.27(d, 12H,3JH11=7
Hz), 3.53 (m,4 H ) ; IR (C,H,): 1265 cm-' (P=N); MS: m / z 354 (hi+). 5 : "P-NMR (C6H6): & = + I S ; 'H-NMR (CDC13): 6=1.18 (d, 12H,
' J H H = 7 Hz), 1.22(d, 12H, ' J H H = 7 Hz),2.53 (br. s,2H),3,40(m,4H); IR
(CCL): 3485, 3355,3200 (NH2), 1210 cm-' (P=O); MS: m/z 263 (M+).
6 : "P-NMR (C,H,): 6 = i 6 . 4 ; 'H-NMR (C6D,): 6= 1.17 (d, 12H,
3 J H H = 7Hz), 1.20 (d, 12H, 3JH11=7Hz), 3.30 (m.4H), 7.05 (m,5H); IR
(C6Hs): 2165 (N=C=O), 1315 c m . . ' (P=N); MS: m / z 364 (M+).
[9] A. Baceiredo, J. P. Majoral, G. Bertrand, Nouu. J. Chim. 7 (1983) 255; M.
Mulliez, J. P. Majoral, G. Bertrand, J. Chem. Soc. Chem. Commun. 1984,
285; J. P. Majoral, G. Bertrand, A. Baceiredo, M. Mulliez, R. Schmutzler,
Phosphorus Sulfur 18 (1983) 221.
~
Nickel-Catalyzed Reduction of Carbon Monoxide by
Hexamethyldisilane: a New Reaction Leading to
a Novel Synthesis of Siloxanes**
By K . Peter C. VoNhardt* and Zhen-Yu Yang
The oxophilicity of silicon['] has been exploited in a
number of organic transformations[',21.Particularly intriguing are reports on the oxidation of disilanes with a variety
of oxidizing agents to furnish ~ i l o x a n e s [These
~ ~ . observa[*I Prof. Dr. K. P. C. Vollhardt, Dr. Z.-Y. Yang
Department of Chemistry, University of California
and the Materials and Molecular Research Division
Lawrence Berkeley Laboratory
Berkeley, CA 94720 (USA)
[**I This work was supported by the National Science Foundation (CHE-8200049) and by equipment funds of the Director, Office of Energy Research, Office of Basic Energy Sciences, Chemical Sciences Division of
the U S . Department of Energy (Contract DE-AC03-76SF00098). K . P.
C. V . was a Camille and Henry Dreyfus Teacher-Scholar (19781983).
460
0 Verlag Chernie GmbH, 0-6940 Weinheim, 1984
tions, in conjunction with the hydrogen-like reactivity of
disilanes in the presence of transition
suggested
the attractive possibility of utilizing hexamethyldisilane 1
as a reducing agent for carbon monoxide, a fundamentally
new transformation potentially analogous to the FischerTropsch reaction[51,but leading to silicon-containing products. We report that 50% nickel on kieselguhr does indeed
mediate this reaction, furnishing siloxanes and surface-deposited carbon :
R3Si-SiR,
+ CO
+'"2'
+ 11,SiOSiR3 + R,SiOSiRzOSiR, . . .
1
2
In the presence of hydrogen this carbon is converted into
methane. The results of a series of experiments and the experimental conditions are delineated in Table 1.
Table I . Major products from the reaction of C O and Me3SiSiMe3 1 in the
presence of 50% Ni-kieselguhr [a, h].
Run
I
2
3
4
5
6
7
Changes in
conditions
Convcrsion
of I I'HI]
Yield [%]
(Me3Si)20 Siloxane
(total)
170°C
250°C
no CO,
(carrier gas N2)
with Hz
(CO :H2= 1 : I )
batch reaction [f, g]
Et3SiH
instead of 1
62.4
lcl
72.0
12.6
25.8
4. I
33.2
2.0 [d]
35.6
6.5
41.8
3.6 [d]
7.3
[cl
[cl
trace
91.8
59.0
68.0
42.1 [el
26. I
94.0 Ih]
10.3
57.0 [i]
18.8
57.0
6.0
10.3 ti]
CH4
(in gas
phase)
[a] United Catalysts Inc.: C46-7-01. [b] Conditions: flow system; catalyst 8.0
g; 200°C; I bar; HMDS 1.6 mL h I, added by syringe pump; C O 900 mL
h - ' ; time on stream: 2 h. [c] Nol quantified. [d] Impurity in commercial 1
(Alfa). [el Yield based on CO. [q Solvent, xylene (10 mL), 100 m L FischerPorterglass bomb; catalyst I g: 180"C;p(H2)=p(CO)= =2,45 bar at RT; 1 :
0.73 g; reaction time 20 h. [g] A similar result was observed using decalin as
solvent. [h] Conversion of triethylsilane. [i] Yield of hexaethyldisiloxane. fi]
In addition to methane, ethane W U Y formed.
The major silicon-containing product in most cases (exceptions are runs 4 and 6, cf. Table 1) was hexamethyldisiloxane, but, clearly, substantial amounts of higher molecular weight products were formed. Careful analysis (GCMS ; preparative GC ; spectral identification by comparison with authentic materials) revealed the presence of
higher siloxanes. A typical product distribution (run 1)
was: tetramethylsilane (0.2%), hexamethyldisiloxane
(38.3%), unreacted hexamethyldisilane (46.9%), hexamethylcyclotrisiloxane (LO%), octamethyltrisiloxane (5.2%),
and decamethyltetrasiloxanes (1.3%), in addition to traces
of other materials. The proportions of these products d o
not change, but the activity of the catalyst decreases with
time. The observation of higher siloxanes is important in
light of the commercial significance of silicones[6'. We do
not know yet whether these products are generated
through direct oxidative Si-C bond cleavage or catalyzed
redi~tribution['~.In this connection, we have found that
doping the reaction with hexamethyldisiloxane gave relatively more of the higher siloxanes.
In the absence of CO, only a certain amount of decomposition of 1 was noted['] (run 4). The efficiency of siloxane formation increased dramatically in the presence of
added H2 (run 5), with the concomitant emergence of me-
0570-0833/84/0606-0460 $02.50/0
Angew. Chem. Int. Ed. Eng1. 23 (1984) No. 6
thane in good yield. A similar increase in activity was observed when using triethylsilane (run 7), which furnished
only hexaethyldisiloxane as oxidation product[’]. On the
other hand, a batch reaction revealed decreased catalyst
efficiency in terms of conversion of 1, although a much
higher production of higher siloxanes (run 6) was noted, in
a ratio similar to that obtained under flow conditions.
In order to pinpoint the origin of the component atoms
in the methane formed, as well as that of the oxygen in the
siloxanes, several labeling experiments were performed.
Execution of run 5 (Table 1) with DZ instead of H2 gave
mainly CD4 (84%) in addition to some protic (predominantly CH3D) methane. None of the silicon-containing
products (and 1) showed incorporation of deuterium. Similarly, use of 13C0gave mainly 13CH4(84.4%) and revealed
the absence of I3C in the other product molecules. Thus,
clearly, the major contributors to methane formation are
CO and H1,minor amounts arising from 1 and siloxane
decomposition or as part of the pathways which lead to
higher siloxanes.
Since it was of interest whether the oxygen in the siloxane product was, in fact, somehow derived from the kieselguhr support or other oxygen sources, an additional control was carried out involving Cl’O. This experiment revealed completely clean incorporation of “ 0 into all isolated siloxanes.
Mechanistically, it is tempting to formulate surface
pathways analogous to those found in the Fischer-Tropsch
reaction“’], involving not only CO and H-H, but also
Si-Si and Si-C activation on the nickel surface. Current
work is directed at further mechanistic elucidation of the
pathways controling these unprecedented transformations
and at finding other substrates for the carbon left after it
has been stripped of its oxygen by 1.
Received: March 5, 1984 [ Z 738 IE]
German version: Angew. Chem. 96 (1984) 449
[l] E. Colvin: Silicon in Organic Synrheris. Butterworths, London 1981.
121 a) C. Eaborn, Organosilicon Comlmmds, Academic Press, New York
1960; b) S . Murai, N. Sonoda, Angew. Chem. 91 (1979) 896; Angew.
Chem. Int. Ed. Eng1. 18 (1979) 837; c) K. C. Brinkman, J. A. Gladysz,
OrganometaNics 3 (1984) 147, and references cited therein: d) K. Tamao,
N. Ishida, T. Tanaka, M. Kamada, ihid. 2 (1983) 1694.
131 1. S. Alnaimi, W. P. Weber, Organometa//ic.$2 (1983) 903 and references
cited therein.
[4] Cf. K. Tamao, M. Akita, R. Kanalani, N. Ishida, M. Kumada, J. Organomef. Chem. 226 (1982) CY; T. J. Groshens, K. J . Klabunde, OrganomefaNics 1 (1982) 564; E. Colomer, I<.J. P. Corriu, C. Marzin, A. Vioux,
Inorg. Chem. 21 (1982) 368; G . SiiO-Fink, Angew. Chem. 94 (i982) 72;
Angew. Chem. Int. Ed. Engl. 21 (1982) 73: Angew. Chem. Suppl. 1982,
71; M.-J. Fernandez, P. M. Maitlis, J . Chem. Soc. Chem. Commun. 1982,
310.
[5] A curious rate acceleration of the transition metal-catalyzed reduction
of carbon monoxide by hydrogen in the presence of hydrosilanes has
been reported: L. Kaplan, OrganometaNics 1 (1982) 1102.
161 W. NO11: Chemistry and Techno1ug.v .f Silicones, Academic Press, New
York 1968. B. Arkles, CHEMTECH 1Y83, 542.
[7] M. D. Curtis, P. S . Epstein, Adu. Organornet. Chem. 19 (1981) 213.
[S] 1. M. T. Davidson, A. V. Howard, J. Chem. Sac. Faraday Trans. 1 1 9 7 s .
69.
[Y] There are indications that the Et- Si bond is oxidatively cleaved more
slowly than the Me-Si bond: L. Spialter, D. J. Austin, Inorg. Chem. 5
(1966) 1975.
[lo] C. K. Rofer-DePorter, Chem. Reu. 81 (1981) 447.
BOOK R E V I E W S
The Chemistry of the Allenes. Edited by S. R. Landor. Academic Press, London 1982. Vol. 1: Synthesis, p. 1-234,
bound, $ 66.00; Vol. 2: Reactions, p. 235-578, bound,
$ 86.00; Vol. 3: Stereochemical, Spectroscopic and Special Aspects, p. 579-882, bound, $ 86.00. Each volume
contains index to whole work (pp. 26).
The subjects of all three volumes are presented in a short
introduction (Chapter 1, 17 pp.) in Volume 1 by S . R.
Landor. The remainder of the first volume is devoted to P.
D. Landor’s description of allene synthesis. Chapter 2
deals with the synthetic methods for the hydrocarbons, for
halogenated allenes, then for allenes containing alcohol,
ether, aldehyde, ketene, carboxylic acid and carboxylic
acid derivative functions, and finally for allenes bearing
heteroelements (B, Si, Sn, N, P, S, Se, Te). The shorter,
third chapter covers the synthesis of allenes containing additional olefinic, acetylenic or allenic functions. Each class
of substance is dealt with in a separate section with an independent reference list. It is here that the need for an additional author index (with reference number and page
number) becomes apparent, with which to keep track of allenes with several functional groups and to keep a better
check on the comprehensiveness of the literature citations.
This applies not only to this volume devoted to synthesis,
but to the whole series, since a complete author index allows the rapid tracking down of a whole range of publications which describe not just the synthesis of allene derivaAngew. Chem. I n t . Ed. Engl. 23 (1984) No. 6
tives but also their reactivities and/or other properties.
Random sampling of the synthesis volume revealed that
the literature citations (up to 1980), though not comprehensive, d o at least cover the most important literature.
The text does not reveal whether comprehensiveness or a
review of the most important methods was the intention.
Nor are the somewhat older but excellent reviews of various aspects of allene chemistry referred to. In the interests
of a clearer conspectus the reviewer would like to have
seen a distinction made in the various sections between
reactions in which allenes merely undergo transformations
without the cumulene being affected or altered and syntheses where the cumulene is actually created. A classification according to mechanism would have been preferable
to the formal one used: For instance, Section 2.3.1 o n the
synthesis of allenic alcohols (“Reduction Methods”) deals
with the addition of hydride ions to 1,3-enynes, the addition of a hydride ion to the carbonyl group of allenic ketones and the nucleophilic substitution (SN2’) of halogen
atoms in the propargyl position by hydride ions, while in
Section 2.3.4 (“Use of Organometallic Reagents”) the reaction of allenic Grignard reagents with ketones, of Grignard
reagents with allenic ketones, and the fragmentation of tosyl hydrazones by butyllithium are discussed as well as the
reaction of organometallic compounds with propargyl halides and suitable epoxides. The addition of organometallic
compounds to 1,3-enynes is dealt with separately in Sec46 1
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nickell, synthesis, reaction, monoxide, leading, reduction, hexamethyldisilane, novem, siloxane, carbon, new, catalyzed
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