GB684763A - A process for treating halogenated organic compounds - Google Patents

Abstract

Halogenated organic compounds in which one or more halogen atoms are linked to an aliphatic group are hydrolysed by mixing with an aqueous alkaline-reacting hydrolysing agent with which the halide is immiscible or only partly miscible, passing through a reactor consisting of a plurality of mixing tubes disposed in series, the mixture being heated to the desired temperature before and/or during its passage through the reactor, the hydrolysing agent being injected in portions at a plurality of points into the liquid passing through the reactor in order to control the pH of the liquid and gas is separated from the reaction mixture in a separate gas separator from which the reaction mixture is drawn off and either sent to a vaporizing system or recirculated through the reactor according to the nature of the reactant halide and its speed of hydrolysis. Mono- and poly-halides and halohydrins may be reacted to yield mono- and polyhydric alcohols, aldehydes, halogenated alcohols, e.g. chloro-butanol, unsaturated halides, e.g. vinyl chloride and chlorobutene, and unsaturated alcohols, e.g. butenol. Specified organic reactants are ethyl chloride and bromide, n- and isopropyl chlorides, allyl, benzyl and butyl chlorides, chloro acetone, 1,1-or 1,2-dichloroethane, 1,2-dibromoethane, 1-methyl - 1,2 - dichloroethane, 1 - phenyl - 1,2 - dichloroethane, dichloro- and dibromo-butanes, dichloro-octadecane, benzal chloride and 1,2,3-trichloropropane. The halides may be dissolved in a solvent. A preferred arrangement of apparatus consists of a plurality of tubes, each having a jacket for heating with hot vapours or liquids, and connected by bends which contain branches for pH checking and injection of hydrolysing agent. Temperature of reaction depends upon the halide treated, a preferred range being 100-300 DEG C. Halogen atoms attached to a tertiary carbon atom are readily hydrolysed at about 100 DEG C., a preferred range for secondary halides is 100-150 DEG C. and for primary halides 150-300 DEG C. Pressures specified are 1-100 atmos., preferably 1-50 atmos. The pH required depends upon the nature of the reactants and the products desired. A range of 7-12 is preferred. When dihalides are hydrolysed to glycols the pH range should be 7-9, and for unsaturated halides such as chloro butene and vinyl chloride a pH of not less than 11 should be maintained. Illustrations are provided of apparatus that may be used in conjunction with such hydrolytic agents as aqueous or aqueous-alcoholic solutions of caustic alkalies, alkali metal carbonates and bicarbonates. In examples, ethylene dichloride is treated with (1) aqueous sodium carbonate at 136-140 DEG C., 12 atmos. and pH 8.5-9.0 to yield ethylene glycol and a small amount of vinyl chloride and (2) and (4) are similar except that in (2) pH control is effected with aqueous caustic soda and the pressure is 10 atmos. and in (4) aqueous sodium bicarbonate is used initially, adjustment of pH to 8.4-8.7 being made by aqueous sodium carbonate, and the temperature is 150-155 DEG C. Example (3) illustrates the fall in yield in ethylene glycol when ethylene dichloride is hydrolysed without pH adjustment along the route of the reaction. According to the Provisional Specification, halogenated organic compounds in general may be treated and the entire content of hydrolysing agent may be added at the commencement of the reaction.