about 80 u00b0 c it is not generally necessary to exceed a temperature of 50 u00b0 c the reaction is preferably carried out at a temperature between about 15 u00b0 and about 30 u00b0 c although it is not generally necessary to operate under pressure it can be advantageous to carry out the reaction under autogenous pressure when one of the reactants is a gas under the reaction conditions the process according to the invention can be carried out in the absence of any solvent or in the presence of an organic solvent which is inert under the reaction conditions examples of suitable such solvents are carbon disulphide carbon tetrachloride chloroform nitrobenzene nitrotoluene nitromethane nitroethane and nitropropane the presence of small amounts of water in the reaction medium is not disadvantageous and it is not necessary to use anhydrous reactants in particular the catalysts which can be used are metal halides which need not undergo a suitable treatment for rendering them anhydrous from a practical point of view various methods can be used for carrying out the process according to the invention for example it is possible to gradually introduce the alkyl halide and the acylating agent successively or simultaneously into the alkane containing the catalyst whereby the temperature of the reaction medium is maintained at the chosen value the alkyl halide is preferably added to a mixture comprising the alkane the catalyst the acylating agent and optionally an inert solvent in this case this mixture is advantageously kept at as low a temperature as possible during the addition of the alkyl halide this.