Tertiary diamine, its use as catalyst, and process for preparing

Details Tertiary diamine, its use as catalyst, and process for preparing Tertiary diamine, its use as catalyst, and process for preparing

1997-01-30

1997-12-16

Ivy, C. Warren

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Cellular products or processes of preparing a cellular...

524839, 528 44, 540596, 546184, 546186, 548524, 553459, C07D40106

Patent

active

056986076

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/EP95/01773 filed May 10, 1995.


BACKGROUND OF THE INVENTION

1. Field of the Invention
Tertiary diamine, its use as catalyst, and process for preparing tertiary diamines
The present invention relates to a process for preparing tertiary diamines having two saturated heterocyclic rings of aliphatic dinitriles, which rings are connected by an aliphatic carbon chain, and to a novel tertiary diamine and its use as a catalyst for the preparation of polyurethanes.
Tertiary diamines, for example 1,5-dipiperidino-pentane, are valuable compounds owing to their high basicity and relatively low volatility and can be employed, for example, as hardeners in epoxy resins (German Patent No. C10 32 920).
2. Background of the Invention
A relatively new use of such compounds is as starting material for the preparation of emulsion stabilizers for blood substitutes (European Published Patent Application No. A 0 415 263).
The preparation processes known to date for these compounds (see for example European Published Application No. A 0 415 263, p. 8) generally require two different starting substances and in some cases produce unwanted waste products (salts) and in some cases give unsatisfactory yields. Also known are processes in which, for example, piperidine is reacted under the influence of a catalyst to form 1,5-dipiperidinopentane (German Patent No. C10 34 180). These processes too often give rise to only poor yields.


BROAD DESCRIPTION OF THE INVENTION

It was therefore an object of the present invention to provide a simple process which gives tertiary diamines having two saturated heterocyclic rings, connected by an aliphatic carbon chain, in good yield without the production of relatively large quantities of waste products.
This object is achieved in accordance with the invention by the process.
It has surprisingly been found that tertiary diamines of the general formula ##STR2## in which each A is identical and is a two- to four-membered aliphatic carbon chain, and which may if desired be substituted by one or more C.sub.1 -C.sub.4 -alkyl groups, can be prepared in one stage by hydrogenating the corresponding aliphatic dinitriles of the general formula ammonia per mole of diamine.
The hydrogenation is expediently carried out at a temperature of 100.degree.-250.degree. C. and under elevated pressure in the presence of a supported palladium catalyst.
As supported palladium catalyst it is preferred to employ palladium on alumina. Good results have been obtained with relatively low palladium contents of, for example, 1%.
The hydrogen pressure in the course of the hydrogenation is preferably greater than 10 bar and is, for example, about 50 bar. The reaction temperature established is preferably a temperature from 150.degree. to 220.degree. C., for example 180.degree. C.
The hydrogenation is preferably carried out continuously. For this purpose, the dinitrile is passed over the catalyst together with hydrogen in a suitable reactor.
A suitable carbon chain A is preferably 1,2-ethanediyl, 1,3-propanediyl, 1,4-butanediyl or 1,3-butanediyl (.tbd.1-methyl-1,3-propanediyl), corresponding to the dinitriles succinonitrile, glutaronitrile, adiponitrile or 2-methylglutaronitrile.
To the dinitrile II it is possible to add up to twice the molar quantity of the corresponding cyclic amine ##STR3## in which A is as defined above, i.e. addition up to a molar ratio of II to III of 1:2, the amine III being incorporated into the product I. This has the advantage that it is possible by this means to recycle the cyclic amine III, which is also formed in the novel process as a by-product, and ultimately to convert it into the desired product I.
Preferably, 3-methylpiperidine is employed as cyclic amine II and 2-methylglutaronitrile as dinitrile II.
A particularly preferred starting material is 2-methylglutaronitrile, which as novel product gives 1,5-bis(3-methylpiperidino)-2-methylpentane of the formula ##STR4## This compound is particularly suitable as a catalyst for the preparation of polyurethanes, polyureth

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