GB340474A - Improvements in the polymerisation of diolefines - Google Patents

Abstract

The polymerization of diolefines by means of metals or alkali metal hydrides or organometallic compounds is facilitated by the addition of organic compounds which are capable of reacting with organo-metallic compounds of the general type Me. (diolefine)x. Me or R. (diolefine)x. Me with the replacement of the metal atoms in these organometallic compounds by hydrogen atoms or organic groups, and which do not react, or react but slowly, with alkali metals. The said organic compounds react in a similar manner with triphenyl methyl sodium, which, therefore, can be used in determining the suitability of an organic compound for use as a regulator of the polymerization. To carry out this test, a solution of the organic compounds in ether or some other indifferent solvent is added to an ethereal solution of triphenyl methyl sodium. If a reaction takes place the intensity of the orange-red colouration of the solution will diminish. The rate of reaction of the organic substance with sodium may be determined by pressing sodium wire into the substance, if it is liquid, or into a solution of the substance in an inert solvent. The rate of reaction, if any, may be observed by watching the rate of evolution of hydrogen. Unsaturated ethers, e.g. aliphatic ethers such as allyl ether, ethyl propenyl ether, ethyl propargyl ether, vinyl-ethyl, -isopropyl and -butyl ethers, and furane, or mixed aliphatic aromatic ethers, e.g. a -phenylvinyl ethyl ether, vinyl m-cresyl ether, vinyl o-cresyl ether, vinyl a -naphthyl ether, and vinyl b -naphthyl ether, or mixed aliphatic hydroaromatic ethers, e.g. ethyl cyclohexenyl (2 : 3) ether, may be used to regulate the polymerization, but among other substances which may be used are such organic sulphur compounds as thiophene, thionaphthene, allyl sulphide and allyl mustard oil, and other suitable regulators are acrylic acid nitrile, benzyl cyanide, acetylene, methyl acetylene, and dimethyl acetylene. Several of these substances may be employed simultaneously and organic solvents which do not react with alkali metals, e.g. liquid hydrocarbons such as gasoline, benzine, benzene, petrol ether, and cyclohexane, or ethers such as methyl and ethyl ethers and dioxane may also be employed. The weight of regulator added may be 20 per cent of the weight of diolefine, but it is preferred to use between 0,01 and 5 per cent. By using large quantities of regulator, e.g. 2 per cent of thiophene, oily products are obtained. The temperature employed in the polymerization lies between 0 DEG and 150 DEG C.; in the examples, the temperatures selected are from 30 DEG to 50 DEG C. The products obtained in the above polymerization of diolefines are suitable for the preparation of artificial silk, artificial wool, coatings, films, lacquers, and the like. The product of Example 6 is said to be very tacky and suitable for the production of coatings and films, and the product of Example 7 dissolves in benzene to give a solution of low viscosity suitable for the production of rayon or artificial wool. In Example 11 it is stated that the viscosity of solutions of the product in benzene decreases as the amount of thiophene used in the polymerization is increased. Triphenylmethyl sodium.-A solution of triphenyl methyl sodium in ether is prepared by the action of sodium amalgam on triphenyl chlormethane in a sealed tube, air being absent. The reaction is complete after 12 hours in an agitating machine.