Patent GB-596668-A (GB)
Title: Process for the production of polymeric di-alkenyl silicones
IPC: C08G77/00
Filed: 1945-04-10
Abstract: Dialkenyl silicones in which the alkenyl radicals contain an olefinic carbon atom not more than once removed from the silicon atom are prepared by reacting one or two alkenyl magnesium halides with a tetrahalosilicane and hydrolysing the resulting reaction product. Suitable alkenyl radicals mentioned are vinyl, isopropenyl, buten-1-yl-2, propen-1-yl-1, buten-1-yl-1, cyclohexen-1-yl-1, cyclo-penten-1-yl-1, allyl, methallyl, ethallyl, buten-1-yl-3, penten-1-yl-3, hexen-1-yl-3, 3-methyl-buten-1-yl-3, 3-methyl-penten-1-yl-3, 2-methyl-buten-1-yl-3, 2-methyl-penten-1-yl-3, 2,3-dimethyl-buten-1-yl-3, hepten-1-yl-3, 4-methyl-hexen-1-yl-3, 5-methyl-hexen-1-yl-3, 4,41-dimethyl-penten-1-yl-3, oceten-1-yl-3, 6-methyl-hepten-1-yl-3, 4-methyl-hepten-1-yl-3, 4,41-dimethyl-hexen-1-yl-3, pentadien-1,4-yl-3, hexen-1-yn-syl-3, 2-methyl-penten-1-yn-4-yl-3, 2,5-dimethylhexadien-1,5-yl-4, crotyl, tiglyl, hexadien-2,4-yl-1, hexadien-2,5-yl-1, butadien-2,3-yl-1, hexadien-3,5-yl-2, 2-methyl-hexen-2-yl-1, 2-methyl-penten-2-yl-1 and 3,7-dimethyl-octadien-2,7-yl-1.  Di-allyl silicone is preferred. The dialkenyl silicon dihalide may, if desired, be purified from mono- and tri-alkenyl derivatives before hydrolysis.  It is hydrolysed with water preferably below room temperature.  Acids or salts may be present as catalysts.  The dialkenyl silicones may be used as textile assistants, as plasticisers or tackifiers for plastics and elastomers and as ingredients of coating compositions.  They may also be polymerized by virtue of the double bonds they contain.  Premature polymerization may be prevented by addition of inhibitors or by addition of an inert solvent.  Shipment and storage in darkness and absence of oxygen-containing gases are preferred.  For use, the silicones may be separated from inhibitors by distillation, solvent extraction or selective absorption, or the inhibitor may be destroyed in situ or addition of catalyst or raising of the temperature may permit polymerization in presence of the inhibitor.  Suitable catalysts are peroxides, per acids, perborates, persulphates, ozone, oxygen, metals and metallic salts.  Polymerization may take place at -15 DEG  C. to 250 DEG  C.  Light may be employed.  It may be in bulk, solution or dispersion.  Mixed dialkenyl silicones may be polymerized or a dialkenyl silicone may be copolymerized with another unsaturated compound, e.g.l styrene, vinyl halide, vinylidene halide, viny, esters, acrylates, allyl halides or allyl esters esters or polyesters containing two or more non-conjugated double bonds, butadiene, chlorbutadiene, isoprene, hexadiene, pentadiene. Polymerization may be partial yielding a syrup which may be further polymerized in a mould or after use as a coating or impregnating agent.  The products may be mixed with other synthetic resins, e.g. alkyd resins, phenol or urea-aldehyde resins or polyamides, natural resins, cellulose derivatives, and drying oils.  Plasticisers, stabilizers, lubricants, dyes, pigments or fillers may be added.  A list of the conventional uses for plastic materials for which the present products are also useful is given in the Specification. Dryers, e.g. oxygen, peroxides, red lead, litharge, magnesium oxide, metallic resinates, linoleates or naphthenates may be added to the dialkenyl silicone.  In the examples, a reaction mixture containing diallyl silicon dichloride is prepared by adding ethereal allyl bromide to an ether suspension of magnesium containing iodine, and adding the ethereal allyl magnesium bromide drop-wise to ethereal silicon tetrachloride at -5 DEG  to -10 DEG  C.  In examples (1) and (2) diallyl silicone is prepared by pouring the ethereal solution of diallyl silicon dichloride reaction mixture on to ice and water containing sulphuric acid and shaking, separating, washing and drying the ethereal layer and evaporating off the ether; (3) a sample of diallyl silicone was allowed to stand in diffuse light in a glass container.  It gelled and passed through a rubbery state to a non-tacky resinous one.  A solution of diallyl silicone in acetone-benzene flowed on to glass evaporated and heated at 60-70 DEG C. yielded a rigid, transparent, non-tacky film.  The Specification as open to inspection under Sect. 91 includes specifically a number of other unsaturated alkenyl radicals and also covers the manufacture of silicones from silicon halides containing one alkenyl radical and one saturated organic radical. This subject-matter does not appear in the Specification as accepted.