Patent GB-667435-A (GB)
Title: Improvements in or relating to the manufacture of organo-silicon polymers
IPC: C08G77/60
Filed: 1950-02-08
Abstract: Cyclic compounds of the formula [-CH2 SiR2-]n, where n has an average value from 3 to 50 inclusive, are made by reacting an alkali metal with a mixture, in the liquid phase, of the compounds (X.CH2)2SiR2 and X.R2.SiCH2SiR2X, wherein R is an alkyl radical, e.g. methyl to octadecyl or a monocyclic aryl radical, e.g. phenyl, tolyl or xylyl, and X is a halogen atom.  Of the alkali metals, sodium and potassium or eutectic alloy thereof are preferred, and the amount used is preferably at least equivalent to the halogen in the silmethylene reactants.  The alkali metal may be finely divided, suspended, solid metal or finely divided molten metal.  Thus the organosilicon reactants may be added to the alkali metal in a solvent such as toluene or xylene, boiling above the melting point of the alkali metal at the operating pressure, or the reactants may be reacted with the solid metal. After completion of the reaction, the products may be filtered, washed and distilled.  In examples: (1) the cyclic compound [-CH2-Si(CH3)2-]3 was obtained from (ClCH2)2Si(CH3)2 and (CH3)2 ClSiCH2Si(CH3)2Cl; (2) a mixture of high molecular weight cyclics of unit formula [-CH2Si(CH3)2CH2SiC-H-.CH3] was obtained from <FORM:0667435/IV (a)/1> (3) a mixture of high molecular weight cycles of unit formula <FORM:0667435/IV (a)/2> was obtained from (ClCH2)2SiC6H5CH3 and (CH3)2ClSiCH2Si(CH3)2Cl.  The compounds may be used as hydrophobing agents, lubricants, hydraulic fluids, heat transfer media and thermal expansion regulator fluids.  Specification 624,551 is referred to.ALSO:Cyclic compounds of the formula [-CH2SiR2-]n where n has an average value from 3 to 50 inclusive, are made by reacting an alkali metal with a mixture, in the liquid phase, of the compounds (XCH2)2SiR2 and X.R2SiCH2SiR2X, wherein R is an alkyl radical, e.g. methyl to octadecyl, or a monocyclic aryl radical, e.g. phenyl, tolyl or xylyl, and X is a halogen atom.  Of the alkali metals sodium and potassium or eutectic alloy thereof are preferred, and the amount used is preferably at least equivalent to the halogen in the silmethylene reactants.  The alkali metal may be finely divided, suspended, solid metal or finely-divided molten metal.  Thus the organo-silicon reactants may be added to the alkali metal in a solvent, such as toluene or xylene, boiling above the melting point of the alkali metal at the operating pressure, or the reactants may be reacted with the solid metal. After completion of the reaction, the products may be filtered, washed and distilled.  In example (1) the cyclic compound [-CH2.Si (CH3)2-]3 is obtained from (ClCH2)2Si(CH3)2 and (CH3)2ClSiCH2Si(CH3)2Cl.  Compounds of the general formula (XCH2)2 SiR2 : chlorination of (CH3)4Si produces some (ClCH2)2Si(CH3)2 but mainly ClCH2.Si(CH3)3, and the chlorination of (CH3)2SiCl2 produces (ClCH2)2SiCl2, which may then be reacted with a methyl or phenyl Grignard reagent to give either (CH2Cl)2Si(CH3)2 or (CH2Cl)2Si(C6H5)2.  Compounds of the general formula R2XSiCH2SiR2X may be made by reacting the compounds XCH3SiR2OR and R2SiXOR in liquid phase with an alkali metal, as described in Specification 624,551, and the resulting compound may then be converted to the halide, e.g. the chloride, by reacting it with acetyl chloride.