Patent GB-574648-A (GB)
Title: Manufacture of unsaturated hydrocarbons
IPC: C10G11/00
Filed: 1943-02-26
Abstract: Unsaturated hydrocarbons are made by subjecting high molecular weight interpolymers of ethylene with other polymerizable organic compounds, for example propylene, isobutene, butadiene, and other aliphatic mono- and diolefins, vinyl acetate and chloride, vinylidene halides, acrylic and methacrylic acids and their derivatives, to a high temperature, preferably 325 DEG -700 DEG  C., until the desired degree of cracking has occurred.  Pressure may vary from a few millimetres of mercury to considerably above atmospheric.  The interpolymers used are those prepared at a pressure exceeding 500 atm. with or without oxygen as catalyst or at a pressure exceeding 50 atm. with a peroxide compound in the presence of water.  Thus, they may be made by the process of Specification 497,643 by subjecting the components to pressures of at least 500 atm. at 100 DEG -400 DEG  C., if desired in the presence of oxygen, or by contacting with water and a peroxide, preferably a diacyl peroxide, at 40 DEG -350 DEG  C. and 50-1500 atm.  The properties of the cracking products such as molecular weight and degree of unsaturation depend upon the starting materials and the cracking conditions.  They are generally greases or waxes especially with a preferred cracking temperature of 350 DEG -550 DEG  C. Thus, a hydrocarbon mixture of average molecular weight 300-400 in the form of a colourless solid grease is obtained at about 400 DEG -450 DEG  C. and 10 mm.  Slight cracking only may be effected, for example by heating at a high temperature for only a few minutes, to give products containing no substantial amount of distillable hydrocarbons although all or most of the elements other than carbon and hydrogen are eliminated.  Alternatively, products which are distilled off from the reaction mixture may be produced. Catalysts may be present such as cobalt, platinum, and iron, oxides such as alumina, silica, chromium oxide, and thoria, and halides such as aluminium and zinc chlorides.  The use of a nickel or kieselguhr catalyst results in a more unsaturated product.  An inert carrier material such as nitrogen or carbon dioxide, water or alcohols may be used to agitate the mixture and carry off the products.  The polymer may be suspended or dissolved in an inert medium such as hydrocarbon solvents and the mixture passed continuously through the cracking zone.  The products are used in waxes, polishes, coating compositions and drying oils. They can be condensed with aromatic hydrocarbons using halide catalysts to give products used in waxes and petroleum, and as coating materials.  With sulphuric acid as catalyst, sulphonated products are formed.  The unsaturated hydrocarbons can be oxidized to carboxylic and hydroxy carboxylic acids or to other hydroxylated compounds using nitric or chromic acid, potassium permanganate, nitrogen oxides, or molecular oxygen with catalysts to yield products of value in waxes and lubricants, as rust inhibitors or for the preparation of water-repellants.  They can be reacted with sulphur and the products oxidized to sulphonic acids or reduced to thiols, hydrogenated to give products resembling paraffin wax, chlorinated, and amino, cyano, alkoxy or aryloxy groups then introduced or hydroxylated to give compounds which may be reacted with aldehydes, diisocyanates or chlorsulphonic acid giving plasticisers or softeners.  In examples: (1) an ethylene-propylene interpolymer of molecular weight 6000 is heated for 1/2 hour at 450 DEG  C. and 5 mm.  The product is then distilled to give an unsaturated grease of molecular weight 500; (2) ethylene-butadiene interpolymer of M.W. 8060 is heated at 430 DEG -450 DEG  C. and 6 mm. The product distilling as formed is a highly unsaturated fluid; (3) ethylene-vinyl chloride interpolymer of M.W. 24,450 is heated at 350 DEG  C. and 10 mm., HCl being evolved to give a hard residue which distils on further heating to give a hydrocarbon grease; (4) ethylene-vinyl acetate interpolymer of M.W. 11,400 is heated at 340 DEG -400 DEG  C. and 30-40 mm. for 1/2 hour, then distilled at 450 DEG  C. and 12 mm. to give, after separation of acetic acid, a hydrocarbon grease.  The interpolymers used in the examples are prepared in presence of water and a peroxide catalyst.