Patent GB-669324-A (GB)
Title: Process for the preparation of 3-amino alcohols
IPC: C07C215/02
Filed: 1948-12-17
Abstract: 3-Amino alcohols are made by reacting a pyrimidine compound with water and hydrogen at elevated temperature and pressure.  The term pyrimidine compound is defined as pyrimidine or a derivative thereof which has only hydrogen and/or a hydrocarbon group or groups attached to the nucleus.  The preferred group of such compounds contain alkyl radicles and many are specified including 2-methyl-, 2,2-dimethyl - 1,2 - dihydro -, 2,2,4,4,6 - pentamethylhexahydro -, 1,2,2,3,4,4,5,5,6,6 - decamethylhexahydro-, 2,5-diethyl-, 2,4-diethyl-2,4,6 - trimethyltetrahydro - and 2 - isopropyl - pyrimidine.  Compounds containing aralkyl, aryl and cycloaliphatic radicles are also specified, illustrative being 2,2,4,4,6-penta-(p-tolylmethyl)-tetrahydro-, 2-benzyl-, 2,5-di-(naphthylmethyl) - 1,2 - dihydro -, 2,2,4,4,6 - pentaphenyltetrahydro-, 2-naphthyl-, 2,2,4,4,6-pentacyclopentyltetrahydro - and 2,2 - dimethyl - 4,4,6 - tri - (3 - ethyl - cyclohexyl) - tetrahydro-pyrimidine.  A preferred compound is 2,2,4,4,6 - pentamethyltetrahydropyrimidine when diacetone alkamine is obtained, together with isopropylamine, 2-amino-4-methylpentane, 2,2,4,6 - tetramethylpiperidine, diacetone - diamine and various ketone and alcohol derivatives of propane and hexane as by-products.  Pyrimidine yields 3-amino-n-propanol and methylamine.  Mol. ratios mentioned are about at least 1 : 1 of water and pyrimidine compound, a ratio of 1 to 5 mols. of water per mol. of pyrimidine compound being preferred.  Hydrogen is preferably in excess.  A hydrogenation-dehydrogenation catalyst is preferably present and many are specified although those of the Raney nickel type are preferred.  In general the catalyst is used in amounts of about 0.5-10 per cent of pyrimidine compound.  Temperatures specified are about 75-300 DEG  C., 100-150 DEG  C. being preferred for liquid phase and 150-250 DEG  C. for vapour phase operation.  Pressures specified are 500-1500, preferably 800-1200, p.s.i.g.  Reaction may be completed in about 0.5-10 hours.  Diacetone alkamine may be isolated from the mixture obtained by steam distillation followed by fractional distillation of the residue.  A non-aqueous solvent medium may be used, e.g. high-boiling alcohols and ethers. In examples, water and hydrogen are reacted in the presence of Raney nickel catalyst with (1) and (2) 2,2,4,4,6 - pentamethyltetrahydropyrimidine to produce diacetone alkamine; (3) a mixture of 2,4,5,6 - tetramethyl - 2,4 - diethyl - and 2,4 - dimethyl - 2,4,6 - triethyltetrahydropyrimidine to produce 3,4-dimethyl-2-hydroxy-4-amino and 3 - hydroxy - 5 - methyl - 5 - amino - hexane; (4) 2-benzylpyrimidine to yield 3-aminopropanol; (5) 2,2,4-tri-(p-ethylphenyl)-1,2-dihydropyrimidine to yield 3-amino-3-(p-ethylphenyl)-propanol; (6) 2,2,5-trimethyl-3-phenyl-1,2-dihydropyrimidine to produce 2-methyl-N-phenyl-3-aminopropanol; (7) 5-(2-methylcyclopentyl)-pyrimidine to give 3-amino-2-(2-methylcyclopentyl)-propanol; and (8) pyrimidine which yields 3-aminopropanol. 2,2,4,4,6-Pentamethyltetrahydropyrimidine is made by reacting acetone and ammonia in the presence of a catalyst such as a strong mineral acid, zinc, ferric or ammonium chloride or ammonium nitrate and the mixture used as starting material for (3) is made by condensing methyl ethyl ketone with ammonia.  The Specification as open to inspection under Sect. 91 is not restricted to the pyrimidine compounds defined above but includes derivatives and substituted compounds of pyrimidine, e.g. substituents such as halogen, nitro, carbonitrile, carbyloxy and sulphone are specified. This subject-matter does not appear in the Specification as accepted.