3220
NOTES
silane had beeti added, the lowtemperature bath was removed and the suspension was stirred for 2.5 hours prior to being heated a t the reflux temperature for one hour. The reaction mixture was worked up in the usual way and the product was distilled. The yield of trimethyl-(p-bromophenyl)-silane, distilling at 53-56" at 0.2 mm., was 32.0 g. (79%). The constants observcd were nzO~1.5285, d2OZo 1.2206. Anal. Calcd. for CgHlaBrSi: Br, 34.9; Si, 12.2; J f X D , 57.63.g Foulid: Br, 34.7; Si, 12.1; MRD,57.53. I n subsequent preparations, the yields were between 75 and 83%, the quantities of trimethylchlorosilane used being 0.12 t o 0.40 mole. Burkhard,lo who prepared this compound from trimethylchlorosilane and p-bromophenylmagnesium bromide, lists the constants as @D 1.5302, d204 1.2197. Trimethyl-(p-bromopheny1)-silane and Lithium Dimethylamide.-Ten grams (0.0436 mole) of trimethyl-(p-bromophenyl)-silane in ether was added t o lithium dimethylamide (prepared in ether from 0.057 mole of n-butyllithium and dimethylaniine) .I1 The rnixturc was heated a t its reflux temperature with stirring for 48 hours. After hydrolysis, the ether laJ-er was extracted with five 10-ml. portions of hydrochloric acid. From the ether lager was obtained 2.0 g. (20% recover!-) of trimcthyl-(p-bromophenyl)-silane. The aqueous portion was made basic with 20% sodium hydroxide, and the yield of what was believed to be trimethyl(p-dimethglaminopli~ii~-l)-silarle, distilling a t 73-76' at 1 mm., was 4.7 g. (5G%), T Z * ~ 1.3211, D dZ0?00.9103. On the basis of the quantity of trimcthj-I-(p-bromophenyl)-silane reacting, the yield of the amine \vas 82.4%. d.l?7al. Calcd. for CIIIfIg?;Si: N,7.25; Si, 14.51; MRn, 04.80.8 F o u ~ i d : S,7.22; Si, 14.33; ,URD, 64.45. The 1)icratc i i i c l t c ~ l a t 134-1,X" (recrystallized froitt ctllallol). In a secoiid cspcriiiicnt, 10.0 g. (0.070 mole) of trimethyl(p-broiiiophenyl)-silane iii ether was added to an ether suspension of lithium dimethylamide (from 0.082 mole of nbutyllithium and dimethylamitic) .I1 Most of the ether was removed by distillation arid replaced with 65 ml. of pure benzene. The suspensioii was then refluxed for 108 hours. The yield of the supposed trimethyl-(p-dimethylaminophenyl)-silane obtained \vas 8.3 g. (62.2%), and 3.0 g. recovered. The melting (19%) of the starting silane point of the picrate of the amination product was 1.53155' ( d t c r recr)-stallizatioii from 95% ethanol). The ineltirig point of a iiiixture of this picrate and that of the previous run was iiot depressed. When adjustment was made to iiiclude only the quautity of trimethyl-(p-bromophenyl)-silarie reacting, the yield of amine was 90.2'%, ? z ? ~ D1.5280, d20zo 0.9194. I n another experiment, 45.8 g. (0.200 molc) of trimethyl-(p-bromophenyl)-silane in 150 rous cthcr !\\-as added to lithium dimethylamide (~ircparedi t 2
