Patent GB-659439-A (GB)
Title: Improvements in and relating to fluorinated organopolysiloxanes
IPC: C08G77/00
Filed: 1949-03-01
Abstract: A polysiloxane, containing the benzotrifluoro group CF3C6H4- attached directly to a silicon atom by a C-Si linkage, is made by (1) preparing a Grignard reagent between magnesium and bromobenzotrifluoride; (2) reacting the Grignard reagent with SiCl4; (3) isolating the resulting mixture of chlorosilanes containing the three compounds (C6H4CF3)3 SiCl, (C6H4CF3)2SiCl2, and (C6H4CF3)SiCl3; (4) hydrolyzing the mixture of chlorosilanes, and (5) isolating the resulting resinous condensation product.  The ratio of benzotrifluoro radicals to silicon atoms may be varied up to and including 3.  In a modification a polysiloxane is prepared having 1.98 to 2 radicals of the formula (CF3)nC6H5-n per silicon atom, where n is an integer of 1 to 3.  In examples: (2) the benzotrifluorochlorosilanes, made by fractionating the reaction product of SiCl4 with the Grignard reagent, are hydrolysed to give resinous sticky masses containing recurring units p  C6H4CF3.SiO1,5, (C6H4CH3)2SiO, and (C6H4CF3)3SiO0,5; (3) polysiloxane having the empirical formula [(CF3)2,C6H3]2SiO and the formula [(CF3)2C6H3]2Si2O, are obtained respectively by hydrolysing [(CF3)2C6H3]2SiCl2 and [(CF3)2C6H3]3SiCl. Co-polymers of benzotrifluoropolysiloxane with methyl-, ethyl-, propyl-, phenyl-, naphthyl-, benzyl-, phenylethyl-, tolyl-, ethylphenyl-, &c. siloxanes, may be made by co-hydrolysing hydrocarbon-substituted silanes with the benzotrifluorosilanes. The compositions may be used as hydraulic fluids, lubricants, liquid coating compositions, varnishes, impregnating solutions for fibrous materials and for impregnating and coating fibrous sheets, such as asbestos, glass, cotton or paper, which may be superimposed and thereafter bonded under heat and pressure to yield laminated products.  Fillers, such as asbestos, glass, fibres, talc, quartz powder and wood flour, may be incorporated into the compositions and moulded under heat and pressure.  The individual copolymerized or mixed polysiloxanes may be incorporated in other materials, such as natural and synthetic rubber, tars, asphalts and pitches; rosin, shellac; synthetic resins, e.g. phenol-aldehyde, urea-aldehyde, alkyd, vinyl and acrylic acid ester resins; cellulose acetate and cellulose ethers. The polymers may also be used as plasticizers for other organopolysiloxane resins, and as adhesives for polymeric tetrafluoroethylene and other polymeric fluorinated hydrocarbons and chlorinated and fluorinated hydrocarbons.  Specification 544,143 is referred to.  The Specification as open to inspection under Sect. 91 comprises also polysiloxanes containing benzotrifluoro radicals having 4 and 5 CF3-radicals attached to the benzene nucleus.  This subject-matter does not appear in the Specification as accepted.ALSO:In making benzotrifluorohalogen silanes of the general formula <FORM:0659439/IV (b)/1> where X=halogen and n=1 to 3, according to examples: (1) meta - bromobenzotrifluoride, CF3.C6H4Br, prepared by direct bromination of benzotrifluoride using an iron catalyst (see J.A.C.S. 65, 391, 1943), is reacted in ether with magnesium to give the Grignard reagent CF3C6H4MgBr, which is reacted with SiCl4 i ether to give a mixture of silanes consisting predominantly of (C6H4.CF3)2SiCl2; (3) 3 : 5-bis-(trifluoromethyl) phenyl bromide, prepared by nitrating di-(trifluoromethyl) benzene, reducing the nitro group to amino group and diazotizing to convert to the bromide, is reacted with SiCl4 in ether to give a mixture of silanes, which on vacuum distillation gave two fractions, (a) [(CF3)2C6H3]2SiCl2 and (b) [(CF3)2C6H3]3SiCl.  The number of CF3-radicals attached to the benzene nucleus may be varied from 1 to 3, inclusive.  The Specification as open to inspection under Sect. 91 comprises also benztrifluorohalogen silanes containing 4 and 5 CF3-groups attached to the benzene nucleus.  This subject-matter does not appear in the Specification as accepted.