Tolyl silicone

Silicotoluic anhydride is prepared from tolyl silicon trichloride by decomposing it with ammonium hydroxide and heating the product at 200° C. The formula correspomls to ( 7X17810)20, but at a lower temperature it is probably C7H7SiOj,H, the corresponding acid. It has similar properties to the silicobenzoic anhydride. 

Related examples of silicon-containing titanocycles have also been prepared (282). These compounds are air-stable and not decomposed by methanol. When CpCpWiClOAr reacts with Grignard reagents, the aryloxy group is replaced by R, not by Cl (283). Compounds of the formula (Cp2TiR)20 prepared from (CP2TiCl)20 + RLi, where Ris CH, C2H, CgH, y)-tolyl, CgH CM2, or CH2=CH, are thermally stable and quite stable to air (283,284). 

Isomerically pure 1 is obtained when HMes2SiSiPh2SiPh2SiMes2H (Mes = mesityl) 5 is used as a starting material, because bonds between silicon and methyl substituted aryl groups like p-tolyl or mesityl are cleaved much faster by hydrogen halides than Si-Ph bonds [3], Further reaction of I with HCl or HBr leads to the formation of the corresponding halo-derivatives 2 and 3 ... 

Styrenes with less bulky alkyl groups at silicon, such as 1-phenyl-2-trimethylsilylethene 335, l-p-tolyl-2-trimethylsilylethene 337 and even the relatively more bulky substituted l-p-tolyl-2-dimethylisopropylsilyl ethene 338, on protonation using either FSC>3H/SbF5 or FSO3H, do not lead to solutions of persistent /i-trimethylsilyl-substituted carbocations such as 336 from 335 but undergo fast /i-silyl fragmentation to silyl-free cations such as 78 (equation 51). 

Other examples of aromatic normal alkyls are the tetra-m-tolyl (m.p 151°)32 and the tetra-p-tolyl (m.p. 228°).33 Silicon tetra-benzyl34 more properly is grouped as an aliphatic compound, but it closely resembles silicon tetraphenyl in that it is a very stable substance of high melting point and exceedingly high boiling point (550°). 

An in stereoisomer of fluorosilaphane 260 was obtained as depicted in Scheme 44 in overall 0.4% yield. First, tri(o-tolyl)fluorosilane 258 was fluorinated at silicon with AgF and then brominated with NBS to give tris[2-(bromomethyl)phenyl]fluorosilane 259. Condensation of 259 with l,3,5-tris(mercaptomethyl)benzene yielded the final product 260 <1998JA6421, 1999JOC5626>. The inside location of the fluorine atom was established by X-ray crystallographic analysis. The Si-F bond distance is very short (1.591 A) compared to the mean Si-F distance for all tetracoordinate tris[(alkyl(aryl)]fluorosilanes found in the Cambridge Structural Database. The 19F NMR resonance for 260 appears at a = 5.3 ppm, that is, 155 ppm upfield from that of tri(o-tolyl)fluorosilane 258. 

Displacement of a good leaving group from silicon in a noncoordinating solvent (equation 5) allows solvent-free complexes (1) to be prepared when the substituents on silicon are bound via sulfur. As would be expected by analogy with carbene complexes, the Si NMR chemical shift for these complexes is at very low held (264.4 and 268.7 ppm, respectively, for R = S-/ -tolyl and SEt, respectively) and they also react readily with donor molecules such as MeCN to give four-coordinate, donor stabilized silylene species. (See Section 6 below for further details of transition metal silyl complexes.)... 

The pure compound crjrstallises in needles, M.pt. 288 C., which are soluble in benzene, xylene, or chloroform, less soluble in alcohol, and insoluble in water. Mercury di-p-tolyl gives the same type of products as mercury diphenyl (see table, p. 74) when it reacts with halogens, halogen acids, mercuric chloride, boron or arsenic trichlorides, phosphorus trichloride, silicon tetrachloride, nitrogen tri- and tetr-oxides, sulphur, selenium, and tellurium. ... 

P"Toiyl silicon trichloride. -Tetrachloro-silicane and mercury di p-tolyl are heated in sealed tubes at 300° to 320° C., when the above compound occurs as a strongly refractive, fuming liquid, B.pt. 21S° to 220° C. It is Ibiind to be decomposed by water, giving a convpound having the a]) )arent composition C H SiOoH, and this when heated at 200° C, seems to be transformed into the oxide, (07117810)20,... 

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