Patent GB-742790-A (GB)
Title: Improvements in or relating to alkali metal amides
Filed: 1952-06-26
Abstract: An alkali metal amide is obtained by reacting a dispersion of finely divided solid alkali metal having a particle size from about 1 to 50 microns with an amine having at least one hydrogen atom bonded to an amino nitrogen atom in the presence of a conjugated polyene at a temperature below the melting point of the alkali metal.  Any primary or secondary amine can be employed and the hydrocarbon residue or residues of the amine may be alkyl, aryl, or both alkyl and aryl, or the amine may be a cycloaliphatic or heterocyclic amine.  Specified amines are monoalkyl amines such as methyl, ethyl, propyl, butyl, amyl, hexyl, and other alkyl amines up to and including amines having 16 carbon atoms in the hydrocarbon chain, branched chain monoalkyl amines such as isobutylamine, 3-amino-4-methylpentane, 2-amino propane and 2-amino butane, dialkyl amines such as diethylamine, dipropylamine, dibutylamine, 2-methylaminobutane, 2-ethylamino butane, aryl amines such as aniline, o-, m-, and p-aminodiphenylmethane, 1-amino-4-tert.-butyl benzene, o-, m- and p-ethylaniline, p - isobutyl aniline, p - isopropyl aniline, o- and p-propyl anilines, p-phenyl aniline, 2,3,4,5-tetramethyl aniline, 2,3,4,6-tetramethylaniline, 2,4,5- (or 2,4,6-)-trimethyl aniline, o-, m- and p-toluidines, anthramyl amines, benzidine, naphthylamines, aminophenanthrene, diphenyl amines, ditolyl amines, N-butylaniline, N-ethyl aniline, N-benzyl aniline, N-isoamyl aniline, N-isobutyl aniline, N-propyl aniline, N-butyl o-toluidine, N-butyl-p-toluidine, cyclohexyl amine, N-butyl cyclohexylamine, N-ethyl cyclohexyl amine, and heterocyclic amines such as a , b , g  aminopyridines, aminoquinolines, aminoacridines, piperidine, and aminoisoquinolines. The alkali metal dispersions may be prepared by fusing an alkali metal in an inert liquid medium and subjecting the mixture to vigorous agitation while maintaining a temperature above the melting point of the alkali metal.  Suitable dispersing media include kerosene, gasoline, mineral oil, benzene, toluene, xylene, n-octane, n-decane and heavy alkylate isoparaffin mixture obtained in petroleum refining.  The above-mentioned amines can also be employed as the dispersing medium and it is preferred to employ the same amine as that with which the alkali metal is intended to react upon addition of the polyene.  The alkali metal concentration in the dispersion should preferably be between 10 and 50 per cent.  The process may be carried out by introducing equivalent amounts of amine and dispersed alkali metal into a reaction vessel and then passing a conjugated polyene into the reaction mixture.  The reaction temperature is maintained at below the melting point of the alkali metal and may range from 65 DEG  C. to -20 DEG  C.  It is desirable to exclude air from the reaction system and to flush the equipment with an inert gas such as dry nitrogen prior to the reaction.  Another method of operation comprises initially dispersing the alkali metal in the amine with which the alkali metal is to react and then introducing the polyene.  Specified polyenes are 1,3-butadiene; 1,3,5-hexatriene; 1,3,5,7-octatetraene; 2-methyl butadiene, 2,3-dimethyl butadiene, 1,3-pentadiene, cyclo-octatetraene, 1-phenyl butadiene, styrene, and mixtures thereof.  Another suitable polyene material is that known as "hydropolymer" which is obtained in the aluminium chloride catalysed addition of hydrogen chloride to ethylene.  The polyene can be introduced into the reaction mixture as a gas by means of a submerged bubble tube or it can be passed over the surface of the reaction mixture while the mixture is being agitated.  It can also be introduced as a liquid.  In examples (1) sodium N-sec.-butylamide is obtained from the corresponding amine using a dispersion of sodium in n-octane and using liquid 1,3-butadiene as the diene; (2) sodium N-sec.-butyl amide is obtained by introducing a dispersion of sodium in n-octane to a reaction flask, removing the n-octane by vacuum distillation, adding sec.-butylamine agitating the mixture to form a dispersion of the sodium in the amine, cooling to 0 DEG  C. and then introducing gaseous 1,3-butadiene; (3) sodium isopropyl amide is obtained from the corresponding amine using a dispersion of sodium in kerosene and using gaseous 1,3-butadiene as the diene; (4) sodium diethylamide is obtained by reacting a dispersion of sodium in n-octane with an excess of diethylamine and directing a gaseous stream of 1,3-butadiene over the surface of the reactants while stirring.  Other specific alkali metal amides which are stated to be obtainable are sodium anilide, N-ethyl sodium anilide, N-isopropyl sodium anilide, sodium o-toluidide, 2-sodium amido pyridine, sodium cyclohexylamide, sodium piperidide, potassium diethylamide, potassium N-sec.-butyl-amide, N-isopropyl potassium anilide and lithium diethyl amide.  Specification 430,607 is referred to.