Piperidinopentanamines, process for producing them and their use

Details Piperidinopentanamines, process for producing them and their use Piperidinopentanamines, process for producing them and their use

1997-10-20

2000-06-27

Kight, John

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C07D21126

Patent

active

060808659

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to new piperidino-pentanamines, both individually and as a mixture, namely 2-methyl-5-(3-methylpiperidino)pentanamine and the isomeric 4-methyl-5-(3-methylpiperidino)pentanamine, which can be represented by the common formula ##STR2## In this formula, in both cases, one of the two radicals R.sup.1 and R.sup.2 is hydrogen and the other is methyl. In the case of 2-methyl-5-(3-methylpiperidino)pentanamine (Ia), R.sup.1 =methyl and R.sup.2 =H, in the case of 4-methyl-5-(3-methylpiperidino)pentanamine (Ib), R.sup.1 =H and R.sup.1 =methyl. Each of the two compounds can exist in four different stereoisomeric forms (two diastereomeric pairs). Here and in the following, the formulae and the associated names of compounds represent all possible stereoisomers in each case.
The invention further relates to a process for preparing the abovementioned compounds from 2-methylglutaronitrile and the use of the compounds as catalysts for producing polyurethanes from polyisocyanates and polyols.
2. Background Art
Polyurethanes are customarily produced using nitrogen bases, in particular tertiary amines such as 1,4-diazabicyclo[2.2.2]octane (DABCO.RTM.), cyclic amidines such as 1,8-diazabicyclo[5.4.0]undec-7-ene ("DBU") or guanidine derivatives such as tetramethylguanidine as catalysts. Decisive for the suitability as catalyst are, inter alia, the basicity, solubility behavior and volatility. While the basicity primarily determines the catalytic effectiveness, solubility behavior and volatility are likewise important for the processing properties. For example, volatility which is too high can lead to irritation or danger to people as a result of liberation into the atmosphere during the production of the polyurethanes or during their use.


BROAD DESCRIPTION OF THE INVENTION

It is an object of the present invention to provide new amines which are suitable as catalysts for producing polyurethanes, have favourable use properties and can be prepared simply and inexpensively.
According to the invention, object is achieved by means of the piperidinopentanamines of the invention and preparation process of the invention.
It has been found that the 2-methylglutaronitrile formed as by-product in adiponitrile production can be reacted with hydrogen in the presence of a catalyst in one stage to give, apart from other products, a mixture of the two isomeric methyl-5- (3-methylpiperidino)pentanonitriles of the general formula ##STR3## where one of the two radicals R.sup.1,R.sup.2 is hydrogen and the other is methyl, which can be hydrogenated in a second stage in the presence of a second catalyst to give the mixture of the two isomeric methyl-5-(3-methylpiperidino)pentanamines Ia and Ib.
The isomer mixture Ia/Ib can, if desired, be separated by distillation or chromatography into the two structural isomers Ia and Ib, but is preferably used as such.
The catalyst used for the first stage is preferably a supported palladium catalyst, particular preference being given to palladium on aluminium oxide.
The reaction of the 2-methylglutaronitrile with hydrogen is preferably carried out at a temperature of from 100.degree. to 250.degree. C. and a pressure of from 20 to 70 bar.
It has been found to be advantageous to add some 3-methylpiperidine to the 2-methylglutaronitrile. The 3-methylpiperidine is preferably added in an amount of from 1 to 5 mol per 1 mol of 2-methylglutaronitrile. This significantly increases the selectivity of the reaction. 3-Methylpiperidine can be prepared by known methods, likewise from 2-methylglutaronitrile (WO 90/00 546).
The reaction of the 2-methylglutaronitrile with hydrogen is preferably carried out continuously in a fixed-bed reactor.
The hydrogenation of the methyl-5-(3-methylpiperidino)pentanonitriles II to give the methyl-5-(3-methylpiperidino)pentanamines Ia/Ib is advantageously carried out in the presence of ammonia so as to suppress undesired secondary reactions.
Catalysts which can be used for this second stage are essentially

REFERENCES:
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Katsamberis et al., J. Applied Polymer Science, vol. 41, No. 9/10, (1990), pp. 2059 to 2065.

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