Patent GB-709920-A (GB)
Title: Improvements in and relating to chlorinated organopolysiloxanes
IPC: C08G77/00
Filed: 1951-02-12
Abstract: Siloxanes of the general formula <FORM:0709920/IV (a)/1> where m is 1 or 2, and n is an integer equal to 1 or more, are prepared by reacting methyltrichlorosilane with a phenyl Grignard reagent containing one or two chlorine atoms attached to the phenyl radical, separating the methyl chlorophenyl dichlorosilane thus produced, hydrolysing this compound with a mixture of ether and water to obtain a silicone oil, and reacting the silicone oil with hexamethyldisiloxane in the presence of sulphuric acid.  The above process may be modified to form a siloxane of the general formula <FORM:0709920/IV (a)/2> where m is 1 or 2, n and p are integers each equal to 1 or more, and the positions of the substituted siloxy groups between the terminal groups being in no definite order, by hydrolysing the methyl chlorophenyl dichlorosilane in the presence of dimethyl dichlorosilane, and reacting the hydrolysis product with hexamethyldisiloxane in the presence of sulphuric acid.  The integers m and n may vary from 1 to 20.  In example 1, methyl p-chlorophenyl-dichlorosilane is prepared by a Grignard reaction, is hydrolysed with water in the presence of ether to give a mixture of cyclic polymers of methyl p-chlorophenyl siloxane and is then mixed with hexamethyldisiloxane and concentrated sulphuric acid to form a mixture of siloxanes corresponding to the formula <FORM:0709920/IV (a)/3> where n is an integer equal to 1 or more.  In examples (2) and (3), a similar procedure is followed to form siloxanes of the formul <FORM:0709920/IV (a)/4> where n is an integer equal to 1 or more. Similar siloxanes may be prepared having two chlorine atoms substituted in the 2, 3-, 2, 4-, 2, 5-, 3, 5- and 2, 6- positions of the phenyl radicals.  The siloxanes may be mixed with metallic soaps, inhibitors or antioxidants.  Specification 586,187 is referred to.ALSO:Organic compounds containing silicon of the general formula <FORM:0709920/IV (b)/1> where m is 1 or 2 and n is an integer equal to 1 or more, are prepared by reacting methyltrichlorosilane with a phenyl Grignard reagent containing one or two chlorine atoms attached to the phenyl radical, separating the methyl chlorophenyl dichlorosilane thus produced, hydrolysing this compound with a mixture of ether and water to obtain a silicone oil and reacting the silicone oil with hexamethyl disiloxane in the presence of sulphuric acid. The above process may be modified to form a compound of the general formula <FORM:0709920/IV (b)/2> where m is 1 or 2, n and p are integers each equal to 1 or more and the positions of the substituted siloxy groups between the terminal groups being in no definite order, by hydrolysing the methyl chlorophenyl dichlorosilane in the presence of dimethyl dichlorosilane, and reacting the hydrolysis product with hexamethyldisiloxane in the presence of sulphuric acid.  In the compounds of both the above general formul , m and n may be an integer from 1 to 20.  In the examples compounds of the first general formula given above are prepared using p-chlorophenyl-, m-chlorophenyl-and 3,4-dichlorophenyl-magnesium bromide.  Similar compounds may be prepared having two chlorine atoms in the 2,3-, 2,4-, 2,5-, 3,5-and 2,6-positions.  Specification 586,187 is referred to.  1,3,5 - Trimethyl - 1,3,5 - tris - p - chlorophenylcyclotrisiloxane is prepared by hydrolysing methyl p-chlorophenyldichlorosilane with water in the presence of ether. Methyl-bis-(3,4-dichlorophenyl) chlorosilane is prepared by the reaction of 3,4-dichlorophenyl magnesium bromide and methyltrichlorosilane.