EQUILIBRATED ORGANO-POLYSILOXANE MIXTURES WITH TERMINAL SULFURIC ACID GROUPS AND PROCESS FOR THEIR PREPARATION

1306312 Equilibrated sulphated polysiloxanes TH GOLDSCHMIDT AG 6 Jan 1971 [28 Jan 1970] 689/71 Headings C3S and C3T An equilibrated mixture consists of linear organopolysiloxanes having terminal sulphuric acid groups of the Formula I: in which n=2-105 and R is a hydrocarbon or substituted hydrocarbon some of which may be replaced by the group The mixtures are in equilibrium with H 2 SO 4 and cyclic compounds of the general formula in which m = 1-10 and n1 is predominantly 2 to 20. If some of the R groups of Formula I. are replaced by groups V then two of the latter may condense to form the group This condensation may occur inter- or intramolecularly. R is preferably C 1-6 alkyl, or may be aryl. Examples of substituted R groups are -(CH 2 ) 3 OSO 3 SiR 3 ; -(CH 2 ) 3 OSO 3 H; -(CH 2 ) 3 - SO 3 H; -CH 2 Br; -(CH 2 ) 3 Cl; -(CH 2 ) 2 OR; -(CH 2 ) x R f (R f =perfluoroalkyl); -(CH 2 ) 3 OR f . The mixture may be prepared by (a) reacting an organopolysiloxane having the general formula in which b=0-20, a=1-105 when b=0, and a= 1-20, when b#1, with H 2 S 2 O 7 , the amount of H 2 S 2 O 7 calculated on siloxane linkages being 10-5-5À10-1 mole, or with H 2 SO 4 in a corresponding amount of 10-3-1 mole, and removing the water of reaction, or (b) reacting an organohalopolysiloxane of the general formula where X is a halogen atom, with H 2 SO 4 in quantities of 1-1À1 mole HgSO 4 /SiX group. The organohalopolysiloxanes may also contain groups which link 2 Si atoms. The resulting reaction product of (a) or (b) may be reacted with a dialkylcyclopolysiloxane, preferably a dimethylcyclopolysiloxane, having 3-10 dimethylsiloxy units, at temperatures up to 150‹ C. In Example 1 a mixture of Formula I in which n = 4 and R = CH 3 is prepared by reacting octamethylcyclotetrasiloxane with H 2 S 2 O 7 . The mixture is reacted, in Example 2, with more octamethylcyclotetrasiloxane to increase the value of n to 44. Other examples are described. Uses.-Equilibration catalysts for organo. polysiloxanes, e.g. for the production of silicone oils and highly viscous organopolysiloxanes with terminal OH groups; water repellent agents for glass, ceramics, textiles and paper.