Patent GB-610898-A (GB)
Title: Improvements in and relating to chloromethyl silicon compounds
IPC: C07F7/08
Filed: 1946-05-02
Abstract: A silane or a siloxane containing a monochloromethyl group directly attached to silicon is prepared by reacting a methylchlorosilane or a methylpolysiloxane with chlorine in the presence of ultra-violet radiation, but without the application of heat, and fractionally distilling the reaction products.  The polysiloxanes may be prepared by hydrolysis of the monochloromethyl silanes such as dimethyl (chloromethyl) chlorosilane and methyl (chloromethyl) dichloro-silane or by co-hydrolysis of one or more of these compounds with a methylhalogenosilane such as methyltrichloro-, dimethyldichloro- and trimethylchlorosilane.  In examples: (1) dimethyldichlorosilane is reacted with chlorine in the presence of ultra-violet radiation and the fraction distilling at 122 DEG  C. is methyl (chloro-methyl) dichlorosilane which is hydrolysed to yield a chlorinated methylpolysiloxane; methyl (dichloromethyl)- and methyl (trichloromethyl)-dichlorosilane are also obtained; (2) trimethylchlorosilane is similarly reacted and the fraction boiling at 115 DEG  to 115.6 DEG  C. is dimethyl (chloromethyl)-chlorosilane which is hydrolysed to yield tetramethyl-1 : 3-di(chloromethyl) disiloxane; dimethyl (chloromethyl) chlorosilane is hydrolysed with trimethylchlorosilane to yield hexamethyldisiloxane, tetramethyl-1 : 3-di(chloromethyl) disiloxane and pentamethylchloromethyldisiloxane; (3) octamethylcyclotetrasiloxane is reacted with chlorine in the presence of ultra-violet radiation to yield chloromethylheptamethylcyclotetrasiloxane which is polymerised with ferric chloride.  The silanes containing a monochloromethyl group may be cohydrolysed and condensed with various aryl- or alkylhalogenosilanes such as phenylchloro or diethyldichloro-silane to form polysiloxanes containing both monochloromethyl groups and silicon bonded ethyl or phenyl radicals.  Specification 610,899 is referred to.  The Specification as open to inspection under Sect. 91 gives an additional example in which chloromethylheptamethylcyclotetrasiloxane and hexamethyl disiloxane are shaken with concentrated sulphuric acid to yield an oil comprising a mixture of polysiloxanes.  The hexamethyl-disiloxane may be replaced completely or in part by other polysiloxane chain compounds containing hydrocarbon substituents other than the methyl radical such as hexaethyldisiloxane or hexaphenyldisiloxane.  This subject-matter does not appear in the Specification as accepted.ALSO:A silone or a siloxane containing a monochloromethyl group directly attached to silicon is prepared by reacting a methylchlorosilane or a methylpolysiloxane with chlorine in the presence of ultra-violet radiation, but without the application of heat, and fractionally distilling the reaction products.  The polysiloxanes may be prepared by hydrolysis of the monochloromethyl silones such as dimethyl (chloromethyl) chlorosilane and methyl (chloromethyl) dichlorosilane or by co-hydrolysis of one or more of these compounds with a methylhalogenosilane such as methyltrichloro-, dimethyldichloro- and trimethylchlorosilane.  In examples: (1) dimethyldichlorosilane is reacted with chlorine in the presence of ultra-violet radiation and the fraction distilling at 122 DEG  C. is methyl (chloromethyl) dichlorosilone which is hydrolysed to yield a chlorinated methylpolysiloxane; methyl (dichloromethyl)- and methyl (trichloromethyl)-dichlorosilane are also obtained; (2) trimethylchlorosilane is similarly reacted and the fraction boiling at 115 DEG  to 115-6 DEG  C. is dimethyl (chloromethyl)-chlorosilane which is hydrolysed to yield tetramethyl-1 : 3 - di - (chloromethyl) disiloxane; dimethyl (chloromethyl) chlorosilane is hydrolysed with trimethylchlorosilane to yield hexamethyldisiloxane, tetramethyl-1 : 3-di-(chloromethyl) disiloxane and pentamethylchloromethyldisiloxane; (3) octamethylcyclotetrasiloxane is reacted with chlorine in the presence of ultra-violet radiation to yield chloromethylheptamethylcyclotetrasiloxane which is polymerized with ferric chloride.  Specification 610,899 is referred to.