Sept., 1947
2247
COMMUNICATIONS T O T H E EDITOR THE USE OF SODIUM IN THE PREPARATION OF METHYLENE-LINKED SILANES
0 1 2 and ( C H ~ ) Z S ~ [ C H Z S ~ ( Chave H ~ ) ~been ] ~ Oisolated and identified. Sir: A typical experiment in this series of reactions The use of sodium in the preparation of com- involves the following procedure: 800 g. of tolupounds of the type 4Si(CH&[CHzSi(CH&],B ene and 4 moles of sodium were placed in a flasl? has been investigated. These compounds have and heated to 110’ with vigorous stirring. A been made wherein the A and/or B m?y be mixture of 2 moles of (CH&SiCl and 2 moles of methyl, chloride, or ethoxy. The compounds CICHZS~(CH&OCZHE, was added at such a rate where both A and B are methyl groups have been that the temperature was maintained at 110’. tentatively called “silahydrocarbons.” The materials were then filtered and distilled. Compounds of the above type where A and B Distillation gave 1.57 moles of (CH3)zSi[CHzSiare methyl groups may be prepared from reactions (CH&]10CzHs, b. p. 160’ at 740 mm., n z 51.4148, ~ of materials such as (CH3)3SiCl, CH,[(CH&- dZ50.8060, a yield of 78.5%. Anal. Calcd. for SiCHz],Cl and sodium. This reaction gives C&izHzzO: Si, 29.51 C, 50.55; MRD, 59.15. products of the type formula (CH&Si [CHzSi- Found: Si, 29.65; C, 50.6; M R D 58.9. Similar (CH&],CH3. Yields of these reactions are experiments have produced the compounds indi6570% of the desired product. Two of these cated up to n values of 4. compounds also have been prepared by reacting There is a good reason for using ClCH2Si(CH&SiCl and (CH&SiClz with (CH&SiCHz- (CH3)20C2Hsrather than C ~ C H Z S ~ ( C H ~ in) ~ C ~ these reactions. The reaction of ClCHzSi(CH3)2MgCl. The preparation of compounds where both A C1 with other molecules like itself is so rapid that and B are ethoxy groups may be carried out by the simpler members of the series are very difficult to isolate. The products of the reaction of several (1) and (2) as follows. molecules of ClCHzSi(CH&Cl and sodium are materials with high molecular weights and with the basic unit [Si(CH&CH2], predominating in + ClCH2Si(CH3)zCI+ 2Na + the molecule. (2) (CH3)zSi(OC2Hs)z
+
C2H60Si(CH3)z [CH2Si(CH3)2]10CzH62NaCl
DEPARTMENT O F CHEMISTRY OF THE
In (2) it appears that NaOC2H6 is formed and UNIVERSITY OF PITTSBURGH, AND J. T. GOODWIN, JR. W. E. BALDWIN reacts with the CIS~(CH~)ZS~CHZ(CH~)ZOCZHS to THEMELLONINSTITUTE 13, PENNA. R. R. MCGREGOR give CZHSOS~(CH~)~CH~S~(CH&OCZHS. PITTSBURGH RECEIVED AUGUST15, 1947 The preparation of compounds where. A is a methyl group and B is ethoxy is easily effected by a reaction such as A NEW SYNTHESIS OF 1-(2’,6’,6’-TRIMETHYL(CH&SiCI ClCHzSi(CH&0C2H~ 2Na ----f (CH&SiCHzSi(CH&OCZH6 2NaCl CYCLOHEXEN-1’-YL) -3-METHYLHEXA-l13,5-TRIEN-
+
+
+
7-ONE (Cis KETONE)
This reaction gives yields of 7540% of the de- Sir: sired product and smaller amounts of higher The Cl8 ketone (1I)l is an important intermembers. The subsequent preparation of higher mediate in the synthesis of “vitamin A acid” members of this series is best achieved by conver- and vitamin A itself. Recently we have synthesion of the ethoxy group to the chloride by reaction with acetyl chloride or benzoyl chloride and the H3C CHs CHa reaction of the chloride with C1CH2Si(CH3)20C2H~ and sodium. In this way materials of the type (CH3)3Si[CH2Si(CHa)2]nOC2H6 may be produced. Hz The reaction of either the ethoxy materials or Hz I the chloride-ended materials with Grignard reagents will give the corresponding “silahydroHsC CHI CHI carbons.” The monofunctional ethoxy and chlo\/ ~H=CH-&=CH-CH=CH-C=O I ride compounds also may be hydrolyzed to give materials of the type [(CH3).Si[CHzSi(CHa)2],]20 while hydrolysis of the difunctional compounds gives cyclic materials with the type formula Z;@CH, Hz I1 [ [-(CH3)2SiCH,]nSi(CH3)z0-]m. Two cyclic (1) (a) k e n s and van Dorp, Nature, 167, 190 (1946); Rcc. IraEi. materials with formulas [(CH&SiCHzSi(CH&- chim., 613, 338 (1946); (b) Heilbron, Jones a4d O’Sullivan, Nature,
~z~-~=~ -~=~ -~ z~
(1) Whitmgre, Sommer, Goldberg and Gold, THISJOURNAL, 69,
980 (1947).
167,485 (1946); J . Chem. Soc., 868 (1946); ( c ) Karrer, Jucker and Schick, Helo. Chim. Acto, 39, 704 (1946).
