GB748130A - Improvements in or relating to production of halogen-substituted organic compounds - Google Patents

Abstract

Halogen-substituted organic compounds are obtained by reacting an organic compound consisting of an alcohol, ether, aldehyde, ketone, ester, thioalcohol, thioether, thioester, or amine, with an ammonium or organic substituted ammonium halide (but excluding iodides) containing at least one H atom attached to the N atom at 250-500 DEG C. in the presence of both a dehydrochlorination catalyst comprising a metal halide in which the metal is selected from Groups I and II of the Periodic Table and the halogen has an atomic number of from 9 to 35 inclusive, the ammonium or organicsubstituted ammonium halide being fused with said metal halide, and a dehydrochlorination catalyst of acidic to mildly alkaline character other than a metal halide. Specified metal halides are cuprous chloride, zinc chloride, sodium chloride, and potassium chloride and the corresponding metal bromides and fluorides. The different dehydrochlorination catalyst which is used in conjunction with the metal halide catalyst is of the type described in the parent Specification. From about 60 per cent up to 99 per cent by weight of the fused metal halide catalyst-ammonium halide mixture may be metal halide, the remainder consisting of ammonium halide. The mixture is maintained in the fused state by suitable heating means such as heating with hot producer gas, high pressure steam or electrical means. The process may be operated so that all the reaction occurs in a single zone containing the two catalysts but it is preferred to carry out a two-stage operation, the first stage containing the fused catalyst and the vapour products from this stage being passed through a second stage which contains the different dehydrochlorination catalyst. The catalyst in the second stage is preferably alumina which may be in the form of a fixed bed, a fluidized bed, or a moving compact bed in pill form. The organic reactant is preferably introduced in the vapour phase and the vapour may be diluted with an inert carrier to assist in the removal of the vapour products from the fused system. The process is normally operated at atmospheric pressure but may also be operated at reduced or elevated pressure. It is preferably carried out by passing vapours of the organic reactant into a body of the fused mixture and ammonium halide may be added to the fused mixture to make the operation continuous. Alternatively, vapours of the organic reactant are contacted countercurrently with the fused mixture in a reaction tower. In another method the fused mixture is continuously circulated through a heated pipe system and the organic reactant as vapour or liquid is continuously injected into the fused mixture in a reaction zone and the gaseous product separated from the fused medium in a separating zone. The separated fused catalyst is preferably returned to the circulating fused mixture and the separated vapours are then passed to a separate reaction zone containing the different dehydrochlorination catalyst. The resulting vapours are passed to a fractionating column where the organic halide is separated, residual organic compound and by-products being returned to the fused mixture while the organic halide is taken off overhead. A process of this type is described and illustrated with particular reference to the conversion of alcohol to the corresponding organic chloride using, e.g. cuprous chloride as the metal halide. An example is also given in which ethanol vapour is passed through a fused catalyst mixture of zinc chloride, ammonium chloride and alumina at 345 DEG -355 DEG C. to form ethyl chloride. Other starting materials referred to are aliphatic alcohols, e.g. methanol, isopropanol, isoamyl alcohol and lauryl alcohol; cycloaliphatic alcohols, e.g. cyclohexanol, and aromatic substituted alcohols, e.g. diphenyl carbinol.