Production of n-alkyl derivatives of cyclic alkylenimines

Claim 1

In a process for the production of an N-alkylated cyclic amine of the formula ##STR3## wherein R is an alkyl radical selected from the group consisting of methyl, ethyl and isopropyl, by reacting in the gas phase at a temperature of from 150° to 350° C an alcohol selected from the group consisting of methanol, ethanol and isopropanol or an ether selected from the group consisting of dimethyl ether, diethyl ether and diisopropyl ether with a cyclic amine of the formula ##STR4## said latter amine being selected from the group consisting of pyrrolidine, 1-methylimidazolidine, oxazolidine, thiazolidine, dihydroisoindole, piperidine, 3-propylpiperidine, piperazine, N-methylpiperazine, perhydro-(1,3)-oxazine, perhydro-(1,3)-thiazine, hexamethylenimine, perhydrothiazepine, decamethylenimine, 3,5-dimethylmorpholine, and morpholine, in the presence of a catalyst containing a phosphorus compound on a carrier, the improvement which comprises carrying out said reaction in the presence of a silicon dioxide catalyst having a specific surface area of from 50 to 500 m 2 /g and containing from 0.1 to 20% by weight of phosphoric acid, said catalyst being obtained by converting an aqueous colloidal sodium silicate solution by addition of sulfuric acid to a silicic acid hydrogel, desalting said hydrogel with ammoniacal water, adding oxalic acid and an appropriate amount of phosphoric acid, milling the mixture so obtained until peptization takes place and spray drying to give a particulate powder.