Patent GB-581901-A (GB)
Title: Improvements in or relating to the manufacture of chlorinated olefines
IPC: C07C17/25
Filed: 1943-04-12
Abstract: Polychlorolefins and, in some cases, chloracetylenes are prepared by removal of hydrogen chloride from compounds of at least 5 carbon atoms and having the formula <FORM:0581901/IV/1> where X is H or halogen, R is a divalent hydrocarbon radical, and R1 is H or a monovalent hydrocarbon radical, by treatment with alkaline reagents, by application of heat in presence of water or sulphuric acid or a dehydrochlorination catalyst.  The reaction may be effected in the vapour phase at about 200-450, preferably 250-350 DEG  C., and generally at atmospheric or slightly increased pressure.  A diluent, particularly water, is preferably present, generally in a molecular ratio between 1 : 1 and 20 : 1 to the trichlormethyl compound which preferably contains 5-15 carbon atoms.  Heteropoly acids of which one radical contains an element of Group 5 or 6A of the Periodic Table are the preferred catalysts, for example phosphotungstic, silicotungstic, phosphomolybdic, borophosphoric, and silicovanadic acids, alone or on charcoal, silica, alumina or the like.  Other catalysts are chlorides of metals of Groups 2, 3, and 8, e.g. Mg, Zn, Ba, Al and Fe.  The space velocity is usually 1-5 c.c. of liquid feed per c.c. of catalyst per hour.  Liquid phase reaction is preferably effected at 100-200 DEG  C. with a Friedel Crafts' catalyst such as chlorides of Zn, Al, FeIII, SnIV and TiIV, and a hydroxylic promoter which reacts with the catalyst to produce hydrogen chloride, e.g. water and aliphatic acids.  Alkaline substances may alternatively be used, e.g. oxides, hydroxides, and carbonates of alkali and alkaline-earth metals, tertiary amines such as pyridine, quinoline, and triethylamine, and aliphatic amides such as formamide, and acetamide, alone or in a suitable solvent.  Such substances may, however, remove more than one molecule of HCl from a compound containing the group -CH2-CCl3 to form a chloracetylene.  Compounds of the formula Cl-R-CH2-CCl3 with alcoholic solutions of alkali may yield alcoholysis products of the chlorolefins or -acetylenes. Dehydrochlorination can also be effected by heating under pressure to 200 DEG  C. with water or dilute sulphuric acid. The initial trichlormethyl compounds may be prepared as described in Specification 581,899 by reaction of mono-olefins with carbon tetrachloride, chloroform or trichlorbrom (iodo or fluor) methane. Thus ethylene with carbon tetrachloride or chloroform gives compounds of the formula Cl(CH2CH2)nCCl3 or H(CH2CH2)n CCl3, where n is an integer greater than 1.  Dehydrochlorination gives compounds Cl(CH2 CH2)n1CH2CH=CCl2 or H(CH2CH2)n-1CH2 CH=CCl2.  Initial materials specified include 1,1,1-trichlor derivatives of pentane, nonane, 2,4-dimethylpentane, tridecane, 3,3,5,5-tetramethylpentane, 5-brompentane, 7-iodoheptane, and 5-fluorpentane, and 1,1,1,15-tetrachlorpentadecane.  The hydrocarbon radicals R and R1 may also be aryl or aralkyl. The reactors may be of glass, stainless steels or Ni-Fe-Mo alloys.  The chlor-olefins produced are stored in contact with an oxidation inhibitor, such as hydroquinone, pyrogallol or an aliphatic tertiary amine, or in an oxygen-free atmosphere. They are used as solvents in coating composition, cleaning fluids, and metal degreasing solvents.  They can be hydrolyzed to carboxylic acids as described in Specification 591,900.  In examples: (1) a vertical tube heated to 300-310 DEG  C. is packed in its lower part with phosphotungstic acid on silica gel, the upper part, serving as a vaporizer, containing small glass tubing. 1,1,1,5-Tetrachlorpentane and water are fed in at the top, the products leaving at the base being extracted with carbon tetrachloride and worked up to give 1,1,5-trichlorpentene-1; (2) granular borophosphoric acid at 255 DEG C. is used similarly or zinc chloride on alumina, the latter giving also what appears to be a di-dehydrochlorination product; (3) 1,1,1,5-tetrachlorpentane, zinc chloride and acetic acid are heated at 110-120 DEG  to give 1,1,5-trichlorpentene-1; (4) 1,1,1,7-tetrachlorheptane, zinc chloride, and acetic acid heated at 140-160 DEG  C. give 1,1,7-trichlorheptene-1.  Similarly, 1,1,1,9-tetrachlornonane yields 1,1,9-trichlornonene-1; (5) 1,1,1,1-trichlornonane is refluxed with formamide to give 1,1-dichlornonene-1; (6) 1,1,1,5-tetrachlorpentane is added to alcoholic potash while refluxing, the products being alcoholysis products of chlor-olefin and chloracetylene of the formul C2H5O(CH2)3 C­CCl and C2H5O(CH2)3CH=CCl2.