Patent GB-702985-A (GB)
Title: Improvements in and relating to imines and amino compounds prepared therefrom
IPC: C10L1/228
Filed: 1949-12-09
Abstract: Imines are made by dehydrating at below about 100 DEG C. a compound <FORM:0702985/IV(b)/1> wherein R1 and R2 are each alkyl, aralkyl, substituted aralkyl or alicyclic radicles or together complete a cycloaliphatic radicle, and R is a lower alkyl radicle, by means of an alkaline dehydrating agent in the substantial absence of oxygen. Compounds of formula <FORM:0702985/IV(b)/2> where R is restricted to Me or Et and R1 and R2 are restricted to alkyl, aralkyl or substituted aralkyl groups are claimed as being novel.  The hydroxy amine may be made by reacting a ketone R1 COR2 with an amine R N H2 and need not be isolated before dehydration.  The substituted aralkyl group contains non-interfering substituents such as alkyl, amino, chloro, hydroxy or lower alkoxy radicles in the ring. Advantageously the hydroxy amine is kept in the liquid form by pressure and temperature adjustments.  Dehydrating agents are those alkaline compounds whose cations fall within the Groups IA and IIA metals of the Periodic Table, e.g. potassium hydroxide and carbonate, calcium oxide and sodium hydroxide containing at least about 10 per cent. of potassium hydroxide.  Sodium hydroxide is only weakly effective. Temperatures specified for dehydration are 5-80 DEG C., preferably room temperature.  Oxygen may be excluded by the use of an inert atmosphere, e.g. ethane, propane, carbon monoxide, heluim, nitrogen or hydrogen.  For best results 80-90 per cent. of the water should be removed.  The product may be distilled in an inert atmosphere or in the presence of an antioxidant such as hydroquinone.  Ketones specified are 4-methyl-2-hexanone, 2-heptanone, 4-methyl-2-heptanone, 6-methyl-2 heptanone, phenylacetone, p- or m-tolyl acetone, anisyl acetone, vanillyl acetone and piperonyl acetone.  The imines may be hydrogenated, preferably in the presence of a hydrogenating catalyst to provide amines having a vasoconstrictor action, e.g. d 1-desoxyephedrine is made by hydrogenating the N-methyl imine of phenyl acetone.  Conventional hydrogenation catalysts are specified and reaction may be effected in a solvent.  Compounds thus made include the N-lower alkyl derivatives of 2-amino heptane, 1-m-tolyl-2-aminopropane, 1-p-tolyl-2-aminopropane, 1-m-hydroxyphenyl-2-aminopropane, 1-p-hydroxyphenyl-2-aminopropane and 1- (m, p-dihydroxyphenyl)-2-aminopropane.  N - Methyl - omega - phenyl - tertiary butylamine may also be obtained c.f.  Specification 688,129.  The imines may also be reacted with a benzyl or substituted benzyl magnesium halide in the presence of an organic solvent to yield an amine on hydrolysis of the reaction product. Thus N-methylomegaphenyl-tertiary butylamine may be made from N - methyl - iso - propylidenimine.  Temperatures specified are 110-135 DEG C., preferably 128 DEG C.  The Grignard complex is decomposed by hydrochloric or sulphuric acid at a pH of at least 1-2 or p preferably in an acid concentration of about 10-20 per cent. acid, the aqueous layer is distilled to remove terpenelike impurities and steam distilled from a strongly alkaline solution, preferably of pH about 10-11 or more, to recover the amine.  The amines may be converted to their salts many of which are specified.  In Examples methylamine is reacted with potassium hydroxide and (1) and (4) acetone to yield N-methyl isopropylidenimine, (5) phenylacetone to yield the N-methyl imine thereof, (6) n-amyl methyl ketone to yield N-methyl heptylidene-2-imine, (8) cyclohexanone to yield N-methyl cyclohexylidenimine, (14) 8-pentadecanone to yield N-methyl-8-pentadecylidenimine and (15) diethylketone to yield N-methyl-n-pentylidene-3-imine, in (2) and (3) N-methyl isopropylidenimine is made by reacting methylamine and acetone with potassium carbonate and calcium oxide respectively, in (7) methylamine, methyl isopropyl ketone and calcium oxide yield N - methyl-1, 2-dimethyl propylidenimine, (9) methylamine, cyclopropyl methyl ketone and calcium oxide yield N-methyl-a -cyclopropylethylidenimine, in (10) and (11) benzyl magnesium chloride reacted with the N-methyl imine of acetone yields N-methyl-o -phenyltertiary-butylamine on hydrolysis of the product, in (12) the ketimine product of (5) is hydrogenated over palladium on charcoal to yield desoxyephedrine and in (13) dibenzyl ketone, methylamine and potassium hydroxide yield N - methyl - b , b 1-diphenylisopropylidenimine which is hydrogenated over palladium on charcoal with subsequent addition of Raney nickel to yield N-methyl-b , b 1-diphenylisopropylamine.ALSO:Imines made by dehydrating at below about 100 DEG C. a compound <FORM:0702985/III/1> wherein R1 and R2 are each alkyl, aralkyl, substituted aralkyl or alicyclic radicles or together complete a cycloaliphatic ring, and R is a lower alkyl radicle by means of an alkaline dehydrating agent in the substantial absence of oxygen are antioxidants for gasoline.  The substituted aralkyl group contains non-interfering substituents such as alkyl, amino, chloro, hydroxy or lower alkoxy radicles in the ring. Representative of imines mentioned are the N lower alkyl imines of acetone, 4-methyl-2-hexanone, 2-heptanone.  4-methyl - 2 - heptanone, 6-methyl-2-heptanone. phenylacetone, p or m-tolylacetone, anisyl acetone, vanillyl acetone, piperonyl acetone, cyclohexanone, cyclopropyl methyl ketone and dibenzyl ketone.