TRANSFORMATION i ,i , 3 , 3 - T E

OF

TR A M ETHYL-I

IN P R E S E N C E

OF

,3-DISILA C Y C LOBU

ALUMINUM

]~. D. B a b i c h , V. M . V d o v i n ,

TAN E

CHLORIDE UDC 542.91:547.1'128

V. N. Karel'skii, and N. S. N a m e t k i n

F o u r - m e m b e r e d silicocarbon h e t e r o c y c l e s have a high activity in the reactions with protic acids. H e r e the main d i r e c t i o n of the t r a n s f o r m a t i o n is addition via opening of the ring at the endocyclic Si - C bond in h a r m o n y with its polarity [1-3]. The action of aprotic acids has r e c e i v e d little study. It was shown that in the p r e s e n c e of AICI a the m o n o - and disilacyclobutanes r e a c t with PCI 3 to give organosilicon p h o s phorus compounds [3]. It was also mentioned that the aluminum halides in catalytic amounts do not cause the silacyclobutanes to p o l y m e r i z e , in c o n t r a s t to the 5- and 7 - m e m b e r e d silicon h e t e r o c y c l e s [4], which f o r m oily o l i g o m e r s u n d e r these conditions. The r e a c t i o n of e q u i m o l a r amounts of 1,1,3,3-tetramethyl-l,3--disilacyclobutane [1] and anhydrous A1CI3 was studied in the p r e s e n t paper. Even at ~20 ~ the silacyclobutane compound undergoes a number of t r a n s f o r m a t i o n s , which lead to linear and cyclic silmethylene compounds.

(')

(CH3hSi/ ~ Si(CI-I3hAml. -'--~ Si(CI~h + (CHs).SiCIt2Si(CHs).+ (CltshSi Si(eH.h + ~/~ ~29~ " '/ (II) Si O) (cH.),

..~StCHa

'~z t" ..S,CHa + oligomers CH3

(l|l~

The f o r m a t i o n of (CHa)4Si, which is always o b s e r v e d in the condensation of compounds of type (CH3)sSi(Cii2)nSi(Ciia)3 [5], and also of cyclic organosilicon d e r i v a t i v e s [6], is the r e s u l t of Lewis acid-catalyzed disproportionation involving the S i - C bonds [7]. The s i x - m e m b e r e d h e t e r o c y c l e (II), which t h e r m o d y n a m ically is the m o s t favorable s t r u c t u r e , apparently can be the t r a n s f o r m a t i o n product of both the l i n e a r and cyclic sihnethylene compounds. The f o r m a t i o n of the silaadamantane s t r u c t u r e (III) can be the consequence of s e c o n d a r y r e a c t i o n s , which w e r e studied in [6]. It is i n t e r e s t i n g that compound (III) is not formed from (1I) when the l a t t e r is t r e a t e d with an e q u i m o l a r amount of A1CI 3 (20~ More drastic conditions a r e required for this (AIBr 3, 70 ~ [6]. The use of catalytic amounts of aluminum halides (5 mole 70, 25 ~ does not cause the t r a n s f o r m a t i o n of (19 by the indicated scheme. 1 , 1 - D i m e t h y l - l - s i l a c y c l o b u t a n e also r e m a i n s unchanged u n d e r these conditions. I s o m e r i z a t i o n with an expansion of the ring of carbon-substituted silacyclobutanes (RCISiCH2CH2CH(CH3), R = CI, CH3), which is c h a r a c t e r i s t i c for s i m i l a r l y constructed c a r b o c y c l e s [8], I

I

was also not observed. The action of e q u i m o l a r amounts of A1C13 on 1-silacyclobutanes (including those with a Si - CI bond) leads, a f t e r decomposition with w a t e r , to benzene-insoluble products. EXPERIMENTAL

METHOD

Reaction of Silacyclobutanes with AICI 3. In a dry ampul, filled with argon, was placed 8.14 g (0.061 mole) of f r e s h l y sublimed AIC13. Then 8.8 g (0.061 mole) of dry (I) was recondensed on it in vacuo. The ampul was evacuated to 10 -8 m m of Hg, sealed, and kept for 4 h at 20 ~ Then 4.66 g of the liquid portion was distilled off. Based on the GLC analysis the condensate consisted of (CH3)4Si, hexamethyldisilmethane, and (II).* F r a c t i o n a l distillation of the condensate gave 1.26 g of hexamethyldisihnethane [9], bp 60-65 ~ *Standard compounds, obtained by known p r o c e d u r e s [9], w e r e used to identify the reaction products. A. V. Topchiev Institute of P e t r o c h e m i c a l Synthesis, Academy of Sciences of the USSR, Moscow. T r a n s l a t e d f r o m Izvestiya Akademii Nauk SSSH, Seriya Khimicheskaya, No. 4, pp. 953-955, April, 1975. Original a r t i c l e submitted August 21, 1974. 9 19 75 Plenum Publishing Corporation, 22 7 West 17th Street, New York, N. Y. 10011. No part o1:this publica~on may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise/without written permission of the publisher. ,4 copy of this article is available from the publisher for $15.00.

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(60 mm); n~ 1.4211. Found: C 50.15; H 11.45; Si 38.24%. t o o l wt. 161. C~tt24Si3. Calculated: C 50; H 11; Si 39%; mol. wt. 160.4. In addition, from the condensate was obtained 2.1 g of (II), bp 115-117 ~ (55 ram); n}~ 1.4603; mol. wt. 210, which is also in good a g r e e m e n t with [9]. The residue in tile ampul was hydrolyzed in neutral medium (in the p r e s e n c e of K2CO3), extracted with e t h e r , dried o v e r CaCl2, and vacuum-distilled. We isolate 0.25 g of c r y s t a l l i n e product with bp 123 ~ (2-3 mm); mp 122 ~ (from pentane); tool. wt. 258. Found: C 45.60; H 9.58; Si 42.32%. C10H24Si3. Calculated: C 46.9; H 9.37; Si 43.73%; mol. wt. 256. The obtained constants a r e in good a g r e e m e n t with the data given in [10]. The residue was an oily m i x t u r e of o l i g o m e r s . Reaction of 1 , 1 - D i m e t h y l - l - s i l a c y c l o b u t a n e with AlCl 3. Under the conditions of the preceding e x p e r i m e n t , f r o m 10 g (0.1 mole) of 1 , 1 - d i m e t h y l - l - s i l a c y c l o b u t a n e and 13.4 g (0.1 m o l e ) o f AIC13 was obtained a crosslinked p o l y m e r i c product (85% yield), which was h y d r o l y z ed in neutral medium and then dried. Found: C 53.95; H 10.36; Si 26.12%. Calculated p e r -[-(CH2)3Si(CH3)2-]- unit: C 60; H 12; Si 28%. Action of Aluminum Halides on 3 - M e t h y l - l - s i l a c y c l o b u t a n e Derivatives. A m i x t u r e of 5 g (0.037 mole) of 1 , 3 - d i m e t h y l - 1 - - c h l o r o - l - s i l a c y c l o b u t a n e and 0.25 g (5 mole %) of AlBr 3 was refluxed in an argon s t r e a m for 6 h. GLC analysis of the r e a c t i o n m i x t u r e disclosed the absence of t r a n s f o r m a t i o n products. A m i x t u r e of 7.7 g (0.05 mole) of CH3CHCH2CH2~Cl 2 and 6.7 g (0.05 mole) of AIC13 was kept at 20 ~ for 72 h. Analysis of the condensate disclosed the absence of t r a n s f o r m a t i o n products. CONCLUSIONS The r e a c t i o n of equimolar amounts of 1,1,3,3-tetramethyl-l,3--disilacyclobutar~e and aluminum chloride gives t e t r a m e t h y l s i l a n e and a mixture of l i n e a r and cyclic silmethylene compounds. LITERATURE I. 2.

3. 4. 5. 6. 7. 8. 9. 10.

CITED

L.H. Sommer and G. Baum, J. Amer. Chem. Soc., 7_66, 5002 (1954). N . S . Nametkin, ]~. D. Babich, V. N. K a r e l ' s k i i , and V. M. Vdovin, Dokl. Akad. Nauk SSSR, 18__99, 334 (1969). E . A . Chernyshev and E. F. Bugerenko, USSR P a t e n t No. 229516, June 23, 1963; ByulL .Izobr., No. 33 (1968). N . S . Nametkin and V. M. Vdovia, C h e m i s t r y of SiUcocarbon Compounds. T r a n s a c t i o n s of Conf e r e n c e " P o l y m e r s with P o l a r and Functional Groups" [in Russian], NIITC, KhIM, Moscow (1967). K. S. Pushchevaya, D i s s e r t a t i o n [in Russian], Moscow (1965). C . L . F r y e , J. M. Klosowski, and D. R. Weyenberg, J. A m e r . Chem. Soc., 92, 21, 6380 (1970). G. R u s s e l , J. A m e r . Chem. Soe., 8._1.1,4815, 4825, 4831 (1959). M. Yu. Lukina, Usp. Khim., 1..~2, 1425 (1963). V. Bazaar and V. Chvalovsky, Organosilicon Compounds, Pub. House of the Czechoslovak Acad. Sci., P r a g u e (1965). G. F r i t z and J. Grobe, Z. Anorg. Allgem. Chem., 31__.55,157 (1962).

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