Patent GB-807668-A (GB)
Title: A process for the production of alkylated heterocyclic compounds
Filed: 1957-05-06
Abstract: Nuclearly alkylated heterocyclic nitrogen compounds are obtained by contacting a heterocyclic nitrogen compound with an aliphatic olefine at elevated temperature and pressure in the presence of one or more of the following classes of catalysts: aluminium or an aluminium alloy with an aromatic amine; an aluminium compound of an aromatic amine; a mixture of aluminium or an aluminium alloy with a FriedelCrafts catalyst of the metal halide type; a mixture of an aluminium compound of an aromatic amine with a Friedel-Crafts catalyst of the metal halide type; a mixture of an alkali or alkaline earth metal or of a compound of one of these with an aromatic amine and an aluminium halide; and a mixture of aluminium or an aluminium alloy or of an aluminium compound of an aromatic amine with iodine or an iodide of an element of the third to eighth groups of the Periodic System. Suitable olefines are ethylene, propylene, butylene and isobutylene and those obtained from petroleum cracking, as well as mixtures of these.  The heterocyclic compounds may have 5 or 6 atoms in the ring, to which may be fused aromatic or hydroaromatic nuclei; advantageously the N atom carries a hydrogen atom.  The heterocyclic ring may also contain other hetero-atoms, such as O and S; they may be substituted, e.g. by halogen, alkyl or aryl groups.  They contain preferably up to 20-30 carbon atoms.  Suitable Friedel-Crafts catalysts include aluminium chloride and bromide, ferric chloride and boron fluoride.  Iodides mentioned are metal iodides such as nickel, cobalt, aluminium and lead iodides, and non-metallic iodides such as phosdhorus tri-iodide.  Suitable reaction conditions are temperatures of approximately 100-500 DEG  C., preferably 150-400 DEG  C., and pressures of 20-1000 atmospheres, preferably 100-400. The catalysts are generally added in an amount of approximately 0.5-10 per cent by weight of the heterocyclic compound; when using a mixed catalyst containing a Friedel-Crafts catalyst, the second catalyst may be employed in an amount of 10-100 per cent of the Friedel-Crafts catalyst.  When using iodine or an iodide as a catalyst activator, it may be used in an amount of 0.1-1 per cent of the reaction mixture. When using aluminium compounds of aromatic amines, excess amine may be used as a solvent.  In examples, phenthiazine and ethylene give 4-ethyl-phenthiazine (which is compared with the product obtained by ringclosing 2-ethyldiphenylamine with sulphur), characterized by the acetyl compound; carbazole and ethylene give 1-ethyl-carbazole; carbazole and propylene give 1-propyl-carbazole, characterized by the picrate; 1,2,3,4-tetrahydroquinoline and ethylene give 8-ethyl-1,2,3,4-tetrahydroquinoline (benzoyl compound prepared) which on dehydration with sulphur gives 8-ethyl-quinoline, identical with the compound prepared by the Skraup synthesis on o-ethyl-aniline; a -methyl-indole and ethylene give 2-methyl-7-ethyl-indole (picrate prepared) identical with the compound obtained from o-ethyl-phenylhydrazine and acetone; 2,3-dimethyl-indole and ethylene give 2,3-dimethyl-7-ethyl-indole (picrate prepared); and a -phenyl-indole and ethylene give 2-phenyl-7-ethyl-indole.  As by-products there are obtained 2,6-diethylaniline, 2-isopropylaniline and 2,6-diisopropylaniline.  Aluminium compounds of aromatic amines may be obtained by reacting aluminium or an aluminium alloy with an aromatic amine, or by reacting for example aluminium hydride or aluminium alkyls with the amine.  Activators, such as mercuric chloride, may be used. Compounds of the alkali or alkaline earth metals may be produced similarly.