Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1995-11-02
1998-02-03
Ivy, C. Warren
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
546252, 502 79, 502415, C07D21102, C07D21308
Patent
active
057146101
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/EP94/01005, Mar. 30, 1994.
The present invention relates to a process for the preparation of 3-methylpyridine (MPI) or 3-methylpyridine (PIC) from 2-methyl-1,5-diaminopentane (MPDA).
3-Methylpiperidine is used as a vulcanization accelerator and as an additive to lubricant oil. 3-Methylpyridine is used both as a solvent and as an intermediate in the preparation of nicotinic acid.
PCT application WO 90/00546 discloses the preparation of mixtures of 3-methylpiperidine and 3-methylpyridine starting from 2-methyl-1,5-diaminopentane by passing the gaseous starting material over a catalyst comprising metal oxides at 500.degree.-600.degree. C. Preferred catalysts are copper chromite, molybdenumoxide and vanadium oxide. These catalysts are preferably applied to a support. Depending on the reaction temperature, the ratio between piperidine and pyridine can be shifted to one or the other side. This patent specification also mentions the possibility of using acidic oxides, such as SiO.sub.2 or silicon aluminium oxides, without further additives as catalysts. However, the yields achieved in this way are only moderate. No information is given on the catalyst activity over extended operating times.
U.S. Pat. No. 3,903,079 discloses a process for the cycloammonolysis of disubstituted alkanes containing primary am
o and/or hydroxyl groups. The catalyst used is a metal aluminosilicate molecular sieve. Preferred metals are copper, palladium, manganese, nickel and chromium. The reaction is carried out in the presence of ammonia. The yields achieved are modest. A yield of 75% is achieved in the preparation of piperidine from 1,5-pentanediol.
The object of the present invention is to provide a process for the preparation of 3-methylpiperidine from 2-methyl-1,5-diaminopentane which can be carried out on a commercial scale and achieves high yields. The catalyst activity should be maintained over long times. A further object is to provide a process for the preparation of 3-methylpiperidine by further reaction of the 3-methylpiperidine over a dehydrogenation catalyst.
The object is achieved according to the invention by the process according to Patent claim 1.
The term "oxides of Al and/or Si" used in claim 1 is taken to mean the individual oxides, such as Al.sub.2 O.sub.3, mixed oxides of Al.sub.2 O.sub.3 /SiO.sub.2 and crystallized compounds thereof, such as aluminium silicates, in particular zeolites. It is important that they have a predominantly acidic character and a specific surface area of greater than 40 m.sup.2 /g. The acidic character arises from the ratio between acidic and basic centers on the surface, which must, in accordance with the invention, be greater than 2. The acidic centers are determined analytically by irreversible adsorption of NH.sub.3 at 80.degree. C., and the basic centres by irreversible adsorption of CO.sub.2 at 80.degree. C. Preferred catalysts for the novel process are activated Al.sub.2 O.sub.3, mixed oxides of Al.sub.2 O.sub.3 /SiO.sub.2, or zeolites. Zeolites are crystalline natural or synthetic aluminium silicates which have a highly ordered structure with a rigid three-dimensional network of SiO.sub.4 and AlO.sub.4 tetrahedra connected by common oxygen atoms. The ratio between the number of Si and Al atoms and oxygen is 1:2. The electrovalence of the aluminium-containing tetrahedra is compensated by inclusion of cations in the crystal, for example alkali metal or hydrogen ions. Cation exchange is possible. The spaces between the tetrahedra are occupied by water molecules before dehydration by drying or calcination.
If the zeolite, owing to its preparation method, is not in the catalytically active, acidic H form, but instead, for example, in the Na form, it can be converted fully or partially into the desired H form by ion exchange, for example with ammonium ions, followed by calcination or by treatment with acids.
The catalysts are preferably employed as fixed-bed catalysts, and the starting material is expediently passed through the catalyst using hydrogen o
REFERENCES:
patent: 3903079 (1975-09-01), Heinz et al.
patent: 5149816 (1992-09-01), Goe et al.
patent: 5179014 (1993-01-01), Watanabe et al.
patent: 5258305 (1993-11-01), Yamada et al.
patent: 5334519 (1994-08-01), Yamada et al.
Armbruster Erich
Heveling Josef
Siegrist Walter
Dahlen Garth M.
Ivy C. Warren
Lonza Ltd.
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