Preparation of 2,2-disubstituted pentane-1,5-diamines

A process for the preparation of a 2,2-disubstituted pentane-1,5-diamine of the formula I ##STR1## where R.sup.1 and R.sup.2, independently of one another, are C.sub.1 - to C.sub.10 -alkyl or C.sub.2 - to C.sub.10 -alkenyl or together are a C.sub.4 - to C.sub.7 -alkylene chain which is unsubstituted or monosubstituted to pentasubstituted by C.sub.1 - to C.sub.4 -alkyl, from a 2,2-disubstituted 4-cyanobutanal of the formula II ##STR2## where R.sup.1 and R.sup.2 are as defined above, comprises, in two spatially separate reaction spaces, PA1 a) reacting the 4-cyanobutanal of the formula II, in a first reaction space, with excess ammonia on an acidic heterogeneous catalyst at from 20.degree. to 150.degree. C. and at from 15 to 500 bar, and PA1 b) hydrogenating the resultant reaction product, in a second reaction space, using excess hydrogen in the presence of excess ammonia on a catalyst containing cobalt, nickel, ruthenium and/or another noble metal, if desired with a basic component or on a basic or neutral carrier, at from 60.degree. to 150.degree. C. and at from 50 to 500 bar.

The present invention relates to a novel process for the preparation of 
2,2-disubstituted pentane-1,5-diamines from 2,2-disubstituted 
4-cyanobutanals. 
C.R. Acad. Sci., Paris, Ser. C 268 (1969), 1949-1952, describes the 
preparation of 2,2-dimethylpentane-1,5-diamine from 
4-cyano-2,2-dimethylbutanal and from 2,2-dimethylglutaronitrile. This 
aminative hydrogenation of 4-cyano-2,2-dimethylbutanal in ethanol in the 
presence of Raney cobalt at 650 bar gives 2,2-dimethylpentane-1,5-diamine 
in a yield of 34%. The 2,2-dimethylglutaronitrile, prepared by a complex 
route by reacting 4-cyano-2,2-dimethylbutanal with hydroxylamine and 
dehydrating the product, was converted into 
2,2-dimethylpentane-1,5-diamine in a yield of 70% in ethanol at a pressure 
of 200 bar. For industrial utilization of the process, the yield in the 
aminative hydrogenation of 4-cyano-2,2-dimethylbutanal is inadequate. In 
addition, the reaction requires a pressure of 650 bar and the use of the 
solvent ethanol. The preparation of 2,2-dimethylpentane-1,5-diamine from 
the corresponding dinitrile on an industrial scale fails in particular due 
to the inaccessibility of the starting material. 
DE-A-21 11 765 describes a process for the preparation of piperidines in 
which an N-substituted 4-cyanoaldimine is hydrogenated, forming a 
C-substituted piperidine and a primary amine, to the nitrogen atom of 
which the same substituent is bonded "as to the nitrogen atom of the 
aldimine". As byproducts, as can seen from page 3, lines 3 to 6, small 
amounts of 1,5-diamines are produced. Thus, according to Examples 1 and 2, 
hydrogenation of N-cyclohexyl-4-cyano-2,2-dimethylbutyraldimine on Raney 
nickel at 120.degree. C. and at from 55 to 60 bar gives from 6 to 7% of 
2,2-dimethylpentane-1,5-diamine, and, according to Example 5, a similar 
reaction of N-cyclohexyl-4-cyano-2-ethylbutyraldimine gives 4% of 
2-ethylpentane-1,5-diamine. 
DE-A-28 41 585 describes a process for the preparation of 
2,2-dialkylpentane-1,5-diamines in which, in a first step, a 
4-cyano-2,2-dialkylbutanal is reacted with hydrogen and ammonia at from 50 
to 250 bar and at from 80.degree. to 160.degree. C. in the presence of a 
group 8 metal as catalyst, to give the azomethine of 
4-cyano-2,2-dialkylbutanal and 4-cyano-2,2-dialkylbutylamine, and, in a 
second step, said azomethine is reacted with hydrogen and ammonia at from 
50 to 500 bar and at from 50.degree. to 250.degree. C. in the presence of 
a cobalt catalyst. As can be seen from Examples 1 to 4, this reaction 
proceeds in unsatisfactory yield and space-time yield for 
4-cyano-2,2-dimethylbutanal (step 1: yield 66.8%, step 2 yield 65.2%, 
overall yield: 43.5%). For 4-cyano-2,2-diethylbutanal and 
4-cyano-2-n-butyl-2-ethylbutanal, the yields for the first step drop to 
46.4% (Example 2) and 57.5% (Example 3) respectively. The hydrogenation of 
the azomethines prepared from 4-cyano-2,2-diethyl- and 
4-cyano-2-n-butyl-2-ethylbutanal is not described. 
Finally, EP-A-42 119 describes a process for the preparation of primary 
monoamines and diamines from oxo compounds, which may, if desired, also 
contain other groups which are capable of reduction, using ammonia and 
hydrogen in the presence of a known hydrogenation catalyst, in which the 
reaction with ammonia and hydrogen in the presence of a hydrogenation 
catalyst is preceded by pre-reacting the oxo compound with ammonia at from 
10 to 200.degree. C. and at from 1 to 300 bar in the presence of an 
inorganic or organic ion exchanger in the ammonium form as imination 
catalyst. The use of the process is described in the examples exclusively 
for the aminative hydrogenation of 3-cyano-3,5,5-trimethylcyclohexanone 
(isophorone nitrile) and 2,2,6,6-tetramethyl-4-piperidone 
(triacetoneamine). In the aminative hydrogenation of isophorone nitrile, 
the use of the organic ion exchanger Lewatit SP.RTM. 120 in the imination 
achieves a slight improvement in yield compared with the uncatalyzed 
procedure (cf. Comparative Example 3 in EP-A-42 119: yield 90.3%, with 
Lewatit SP.RTM. 120: 93.9 to 94.7%). 
Thus, there was hitherto no process available by which 
4-cyano-2-ethylbutanal and 4-cyano-2,2-dimethylbutanal can be converted 
into the corresponding diamines under industrially practicable conditions 
and in economically satisfactory yields. Pentane-2,5-diamines having a 
relatively high degree of alkylation were hitherto unknown. 
It is therefore an object of the present invention to provide a process 
which permits industrially and economically satisfactory access to 
2,2-disubstituted pentane-1,5-diamines from 4-cyanobutanals and thus also 
the preparation of novel pentane-1,5-diamines having a relatively high 
degree of substitution in the 2-position. 
We have found that this object is achieved by a novel and improved process 
for the preparation of a 2,2-disubstituted pentane-1,5-diamine of the 
formula I 
##STR3## 
where R.sup.1 and R.sup.2, independently of one another, are C.sub.1 - to 
C.sub.10 -alkyl or C.sub.2 - to C.sub.10 -alkenyl or together are a 
C.sub.4 - to C.sub.7 -alkylene chain which is unsubstituted or 
monosubstituted to pentasubstituted by C.sub.1 - to C.sub.4 -alkyl, from a 
2,2-disubstituted 4-cyanobutanal of the formula II 
##STR4## 
where R.sup.1 and R.sup.2, are as defined above, which comprises, in two 
spatially separate reaction spaces, 
a) reacting the 4-cyanobutanal of the formula II, in a first reaction 
space, with excess ammonia on an acidic heterogeneous catalyst at from 
20.degree. to 150.degree. C. and at from 15 to 500 bar, and 
b) hydrogenating the resultant reaction product, in a second reaction 
space, using excess hydrogen in the presence of excess ammonia on a 
catalyst containing cobalt, nickel, ruthenium and/or another noble metal, 
if desired with a basic component or on a basic or neutral carrier, at 
from 60.degree. to 150.degree. C. and at from 50 to 500 bar. The present 
invention furthermore provides novel 2,2-disubstituted 
pentane-1,5-diamines of the formula I' 
##STR5## 
where R.sup.1' and R.sup.2', independently of one another, are C.sub.1 - 
to C.sub.4 -alkyl or C.sub.2 - to C.sub.10 -alkenyl or together are a 
C.sub.4 - to C.sub.7 -alkylene chain which is unsubstituted or 
monosubstituted to pentasubstituted by C.sub.1 - to C.sub.4 -alkyl, with 
the proviso that R.sup.1' and R.sup.2' are not simultaneously methyl. 
The process according to the invention can be carried out as follows in two 
spatially separate reaction spaces: 
a) In a first process step, a 2,2-disubstituted 4-cyanobutanal is reacted 
with excess ammonia while a pressure of from 15 to 500 bar, preferably 
from 100 to 350 bar, and a temperature of from 20 to 150.degree. C., 
preferably from 30.degree. to 100.degree. C., are maintained. The 
condensation is carried out in the presence of an acidic heterogeneous 
catalyst, such as a metal compound having a Lewis acid or Bronstedt acid 
character, eg. alumina, silica, titanium dioxide or zirconium dioxide, and 
furthermore phosphates, eg. aluminum phosphates, or silicates, eg. 
amorphous or crystalline aluminosilicates. Preference is given to alumina, 
titanium dioxide, zirconium dioxide and silica, in particular alumina and 
titanium dioxide The acidity of the catalyst may be increased, if 
necessary, by doping with a halide. Thus, for example, halogen-doped 
catalysts, such as chloride on alumina or chloride on titanium dioxide, 
are also used. 
In the reaction of the 2,2-disubstituted 4-cyanobutanal on the acidic 
heterogeneous catalyst, a weight hourly space velocity of from 0.01 to 10, 
preferably from 0.05 to 7, particularly preferably from 0.1 to 5, kg of 
2,2-disubstituted 4-cyanobutanal per kg of catalyst per hour is 
maintained. It is expedient, but not absolutely necessary, to employ from 
5 to 500 mol, preferably from 10 to 400 mol, particularly preferably from 
20 to 300 mol, of NH.sub.3 per mol of 2,2-disubstituted 4-cyanobutanal. 
The reaction of 4-cyanobutanal with ammonia may also be carried out in the 
presence of an inert solvent, such as an alkanol or tetrahydrofuran. 
The reaction of the 2,2-disubstituted 4-cyanobutanal can be carried out 
batchwise, but preferably continuously, for example in a pressurized 
reactor or in a pressurized reactor cascade. In a particularly preferred 
embodiment, the 2,2-disubstituted 4-cyanobutanal and NH.sub.3 are passed 
through a tubular reactor in which the catalyst is arranged in the form of 
a fixed bed. 
The overall residence time in step 1 is given by the weight hourly space 
velocity and the amount of ammonia employed, and is expediently in the 
range from 0.5 to 120 minutes, preferably from 1 to 40 minutes, 
particularly preferably from 1.5 to 20 minutes. 
b) The product obtained is fed to a second process step, a catalytic 
hydrogenation, together with from 3 to 10,000 mole equivalents, preferably 
from 4.5 to 30 mole equivalents, of hydrogen, if desired after 
introduction of further ammonia 
The hydrogenation is preferably carried out in liquid ammonia. From 5 to 
500 mol, preferably from 10 to 400 mol, particularly preferably from 20 to 
300 mol, of NH.sub.3 are used per mol of 2,2-disubstituted 3-cyanobutanal 
employed in step 1. The proportion of NH.sub.3 may, if desired, be 
increased to the desired level by feeding in NH.sub.3. 
The hydrogenation is generally carried out at from 60.degree. to 
150.degree. C., preferably from 70.degree. to 140.degree. C., particularly 
preferably from 80.degree. to 130.degree. C., and at from 50 to 500 bar, 
particularly from 100 to 350 bar, particularly preferably from 150 to 300 
bar. 
The weight hourly space velocity is expediently in the range from 0.01 to 5 
kg/[kg.h], preferably from 0.02 to 2.5 kg/[kg.h], particularly preferably 
from 0.05 to 2 kg/[kg.h]. 
In the case of continuous hydrogenation without product recycling, the 
overall residence time is given by the weight hourly space velocity and 
the amount of ammonia employed, and is in the range from 0.5 to 120 
minutes, preferably from 1 to 40 minutes, particularly preferably from 1.5 
to 20 minutes. 
Any conventional hydrogenation catalyst which contains nickel, cobalt, 
iron, copper, ruthenium or another sub-group VIII noble metal can in 
principle be employed in the hydrogenation. Preference is given to 
ruthenium, cobalt or nickel catalysts. Particular preference is given to 
ruthenium and cobalt catalysts. The catalytically active metal may be 
employed in supported or unsupported form. Examples of suitable carriers 
are alumina, titanium dioxide, zirconium dioxide, zinc oxide or magnesium 
oxide/alumina, but hydrogenation catalysts with basic components, such as 
oxides and hydroxides of alkali and alkaline earth metals are preferred. 
Particular preference is therefore given to basic carriers, eg. 
.beta.-alumina or magnesium oxide/aluminas. Particular preference is given 
to magnesium oxide/alumina containing from 5 to 40% of magnesium oxide. 
The carrier containing magnesium oxide and aluminas may be amorphous or in 
the form of spinel. 
The basic component may also be added, if desired, during the hydrogenation 
process, eg. as a solution of an alkali metal hydroxide or alkaline earth 
metal hydroxide in water. 
Particular preference is given in the hydrogenation to cobalt or ruthenium 
with a basic component. These catalysts are obtained industrially in a 
conventional manner; for example, ruthenium on a basic carrier is obtained 
by applying an aqueous ruthenium salt solution such as ruthenium chloride 
or ruthenium nitrate, to the appropriate carrier. The ruthenium 
concentration on the carrier is from 0.1 to 10%, preferably from 0.5 to 
5%, particularly preferably from 1 to 4%. 
After drying and possibly after calcination at from 120.degree. to 
500.degree. C., preferably at from 200.degree. to 400.degree. C., the 
ruthenium catalyst is activated in a stream of hydrogen at from 
180.degree. to 250.degree. C., preferably at from 190.degree. to 
230.degree. C., and at from 1 to 500 bar, preferably at from 20 to 300 
bar, for from 1 to 20 hours, preferably for from 2 to 10 hours. 
The ruthenium catalyst may, if desired, contain further metals, eg. 
palladium or iron. The iron content is generally in the range from 0.5 to 
5%, and the palladium content in the range from 0.1 to 5%. 
The reaction is preferably carried out continuously, eg. in a 
pressure-tight stirred reactor or in a stirred reactor cascade. In a 
particularly preferred embodiment, a tubular reactor is employed in which 
the hydrogenation mixture is passed over a fixed catalyst bed using the 
pool or trickle method. 
Process steps a and b may likewise be carried out in a single reactor in 
which the imination catalyst and the hydrogenation catalyst are arranged 
in two separate layers. In this case, the imination is expediently carried 
out in the presence of hydrogen. 
After the hydrogenation, any excess ammonia is removed under pressure. The 
2,2-disubstituted pentane-1,5-diamine obtained in this way (eg. 
2,2-dimethylpentane-1,5-diamine from 4-cyano-2,2-dimethylbutanal, 
2-methyl-2-propylpentane-1,5-diamine from 4-cyano-2-methyl-2-propylbutanal 
or 2-n-butyl-2-ethylpentane-1,5-diamine from 
4-cyano-2-butyl-2-ethylbutanal) can be isolated by fractional 
distillation. 3-Substituted piperidines (eg. 3,3-dimethylpiperidine from 
4-cyano-2-methyl-2-propylbutanal or 3-butyl-3-ethylpiperidine from 
4-cyano-2-butyl-2-ethylbutanal) are only formed to a minor extent as a 
byproduct. 
The starting materials for the process, the 2,2-disubstituted 
4-cyanobutanals, are accessible from 2,2-disubstituted aldehydes- and 
acrylonitrile. The process according to the invention makes it possible 
for the first time to convert a 2,2-disubstituted 4-cyanobutanal into the 
2,2-disubstituted pentane-1,5-diamine in high yield and high space-time 
yield. 
R.sup.1 and R.sup.2 in the compounds I and II have the following meanings: 
R.sup.1 and R.sup.2, independently of one another, 
are C.sub.1 - to C.sub.10 -alkyl, preferably C.sub.1 - to C.sub.8 -alkyl, 
particularly preferably C.sub.1 - to C.sub.4 -alkyl, such as methyl, 
ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl, 
C.sub.2 - to C.sub.10 -alkenyl, preferably C.sub.2 - to C.sub.8 -alkenyl, 
particularly preferably C.sub.2 - to C.sub.4 -alkenyl, such as allyl or 
1-butenyl, 
together are a C.sub.4 - to C.sub.7 -alkylene chain which is unsubstituted 
or monosubstituted to pentasubstituted by C.sub.1 - to C.sub.4 -alkyl, 
such as --(CH.sub.2).sub.4 --, --(CH.sub.2).sub.5 --, --(CH.sub.2).sub.6 
--, --(CH.sub.2).sub.7 -- or --CH(CH.sub.3)--(CH.sub.2).sub.3 --. 
Examples of preferred 2,2-disubstituted 4-cyanobutanals of the formula II 
are 2,2-dimethyl-4-cyanobutanal, 2-methyl-2-propenyl-4-cyanobutanal, 
2-ethyl2-butenyl-4-cyanobutanal, 2-methyl-2-propyl-4-cyanobutanal, 
2-ethyl-2-butyl-4-cyanobutanal, 2-methyl-2-nonyl-4-cyanobutanal, 
1-cyanoethylcyclohexanecarboxaldehyde and 
1-cyanoethylcyclopentanecarboxaldehyde. These starting materials are 
readily accessible from isobutyraldehyde, 2-methylpentanal, 
2-methylpentanal, 2-ethylhexanal, 2-ethylhexanal, 2-methylundecanal, 
cyclohexanecarboxaldehyde and cyclopentanecarboxaldehyde. Preferred 
2,2-disubstituted pentane-1,5-diamines of the formula I are 
2,2-dimethylpentane-1,5-diamine, 2-methyl-2-propylpentane-1,5-diamine, 
2-methyl-2-propenylpentane-1,5-diamine, 
2-ethyl-2-n-butyl-pentane-1,5-diamine, 
2-ethyl-2-n-butenylpentane-1,5-diamine, 
2-methyl-2-nonylpentane-1,5-diamine, 
1-(3-aminopropyl)-1-aminomephylcyclohexane and 
1-(3-aminopropyl-)-1-aminomethylcyclopentane. 
R.sup.1' and R.sup.2' in the compounds I' have the following meanings: 
R.sup.1' and R.sup.2', independently of one another, 
are C.sub.1 - to C.sub.10 -alkyl, preferably C.sub.1 - to C.sub.8 -alkyl, 
particularly preferably C.sub.1 - to C.sub.4 -alkyl, such as methyl, 
ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl, 
with the proviso that R.sup.1' and R.sup.2' are not simultaneously 
methyl, 
C.sub.2 - to C.sub.10 -alkenyl, preferably C.sub.2 - to C.sub.8 -alkenyl, 
particularly preferably C.sub.2 - to C.sub.4 -alkenyl, such as allyl or 
butenyl, 
together are a C.sub.4 - to C.sub.7 -alkylene chain which is unsubstituted 
or monosubstituted to pentasubstituted by C.sub.1 - to C.sub.4 -alkyl, 
such as --(CH.sub.2).sub.4 --, --(CH.sub.2).sub.5 --, --(CH.sub.2).sub.6 
--, --(CH.sub.2).sub.7 -- or --CH(CH.sub.3)--(CH.sub.2).sub.3 --. 
Preferred compounds I' are: 
2,2-dimethylpentane-1,5-diamine 
2-ethyl-2-methylpentane-1,5-diamine 
2-methyl-2-n-propylpentane-l,5-diamine 
2-n-butyl-2-ethylpentane-l,5-diamine 
2-methyl-2-n-nonylpentane-1,5-diamine 
2-methyl-2-n-propenylpentane-1,5-diamine 
2-n-butenyl-2-ethylpentane-1,5-diamine 
2-n-pentyl-2-propylpentane-1,5-diamine 
2-n-pentenyl-2-propylpentane-1,5-diamine 
1-(3-aminopropyl)-1-aminomethyl oyclohexane 
1-(3-aminopropyl)-1-aminomethyl cyclopentane 
The diamines claimed have lower volatility and greater asymmetry (various 
reactivity of the amine functions) than the known alkylpentanediamines, 
such as 2-methyl- and 2,2-dimethylpentanediamine, as a consequence of the 
greater degree of substitution. This results, inter alia, in better 
processing properties of the diamines, e.g., as components curing agents 
for epoxides and components for nylons, and lower odor nuisance caused by 
unreacted diamines and the diisocyanates which can be prepared thereform.

EXAMPLES 
Example 1 
A vertical tubular reactor (diameter 16 mm, fill level 50 cm, oil-heated 
twin jacket) was filled with 81.9 g (93 ml) of a catalyst containing 3% of 
ruthenium on a magnesium oxide/alumina carrier (10% of MgO, 90% of 
Al.sub.2 O.sub.3) in the form of 1 to 1.5 mm grit (catalyst preparation by 
impregnating the pores of a magnesium oxide/alumina carrier with an 
aqueous ruthenium nitrate solution and drying the catalyst at 120.degree. 
C.). The reduction was carried out at 100 bar while simultaneously passing 
100 l(S.T.P.)/h of hydrogen through the catalyst, which was kept at 
220.degree. C. for 7 hours after increasing the temperature in steps from 
100.degree. to 220.degree. C. over the course of 6 hours. 
34.0 g per hour of 2,2-dimethyl-4-cyanobutanal (purity 93.4%, 31.8 g, 0.254 
mol) and 1450 ml (870 g, 51.1 mol) per hour of liquid ammonia were pumped 
at 250 bar and 60.degree. C. through a tubular reactor (diameter 16 mm, 
fill level 50 cm, oil-heated twin jacket) upstream of the hydrogenation 
reactor and filled with 63.5 g (100 ml) of TiO.sub.2 (anatase) in the form 
of 1.5 mm pellets. The discharge from the reactor was subsequently passed 
through the hydrogenation reactor from bottom to top at 250 bar and 
120.degree. C. while simultaneously passing 100 l (S.T.P.)/h (4.5 mol) of 
hydrogen through the reactor. The product stream was decompressed to 
atmospheric pressure and NH.sub.3 was removed by distillation. The product 
from 32.4 hours was separated by fractional distillation on a 30 cm packed 
column (3 mm glass rings), giving 344.8 g of 3,3-dimethylpiperidine (b.p. 
50.degree.-52.degree. C./210 mmHg) and 753.6 g of 
2,2-dimethylpentane-1,5-diamine (b.p.=72.degree. C./8 mmHg). The diamine 
yield was 70.5% of theory. 
Example 2 
Example 1 was repeated using 2-methyl-2-propyl-4-cyanobutanal as the 
starting material. 33.5 g per hour of 2-methyl-2-propyl-4-cyanobutanal 
(purity 88.9%, 29.8 g, 0.195 mol) and 1400 ml (840 g, 49.4 mol) per hour 
of liquid ammonia were pumped at 250 bar and 60.degree. C. through the 
imination reactor. The product stream was subsequently passed through the 
hydrogenation reactor from bottom to top at 250 bar and 120.degree. C. 
while simultaneously passing 100 l(S.T.P.)/h (4.5 mol) of hydrogen through 
the reactor. The product stream was decompressed to atmospheric pressure 
and NH.sub.3 was removed by distillation. The product from 37.5 hours was 
separated by fractional distillation on a 30 cm packed column (3 mm glass 
rings), giving 277.0 g of 3-methyl-3-propylpiperidine (b.p.=46.degree. 
C./2 mmHg) and 842.1 g of 2-methyl-2-propylpentane-1,5-diamine 
(b.p.=78.degree.- 81.degree. C./2 mmHg). The diamine yield was 72.9% of 
theory. 
Example 3 
Example 2 was repeated, with 55.9 g of 2-methyl-2-propyl-4-cyanobutanal 
(purity 86.6%, 48.4 g, 0.316 mol) per hour and 1365 ml (819 g, 48.2 mol) 
per hour of liquid ammonia at 250 bar and 60.degree. C. being pumped 
through the imination reactor. The product stream was subsequently passed 
through the hydrogenation reactor from bottom to top at 250 bar and 
120.degree. C. while simultaneously passing 100 l(S.T.P.)/h (4.5 mol) of 
hydrogen through the reactor. The product stream was decompressed to 
atmospheric pressure and NH.sub.3 was removed by distillation. The product 
from 16.8 hours was separated by fractional distillation on a 30 cm packed 
column (3 mm glass rings), giving 174.4 g of 3-methyl-3-propylpiperidine 
and 501.6 g of 2-methyl-2-propylpentane-1,5-diamine. The diamine yield was 
59.6% of theory. 
Example 4 
Example 3 was repeated, with 78.5 g per hour of 
2-methyl-2-propyl-4-cyanobutanal (purity 86.6%, 68.0 g, 0.444 mol) and 
1340 ml (804 g, 47.3 mol) per hour of liquid ammonia at 250 bar and 
60.degree. C. being pumped through the imination reactor. The product 
stream was subsequently passed through the hydrogenation reactor from 
bottom to top at 250 bar and 120.degree. C. while simultaneously passing 
150 l(S.T.P.)/h (6.7 mol) of hydrogen through the reactor. The product 
stream was decompressed to atmospheric pressure and NH: was removed by 
distillation. The product from 4.2 hours was separated by fractional 
distillation on a 30 cm packed column (3 mm glass rings), giving 96.0 g of 
3-methyl-3-propylpiperidine and 162.8 g of 
2-methyl-2-propylpentane-1,5-diamine. The diamine yield was 55.1% of 
theory. 
Example 5 
Example 1 was repeated using 2-butyl-2-ethyl-4-cyanobutanal as the starting 
material. To this end, 33.6 g per hour of 2-butyl-2-ethyl-4-cyanobutanal 
(purity 89.0%, 29.9 g, 0.165 mol) and 1344 ml (806 g, 47.4 mol) per hour 
of liquid ammonia were pumped at 250 bar and 60.degree. C. through the 
imination reactor. The product stream was subsequently passed through the 
hydrogenation reactor from bottom to top at 250 bar and 120.degree. C. 
while simultaneously passing 100 l(S.T.P.)/h (4.5 mol) of hydrogen through 
the reactor. The product stream was decompressed to atmospheric pressure 
and NH.sub.3 was removed by distillation. The product from 16.7 hours was 
separated by fractional distillation on a 30 cm packed column (3 mm glass 
rings), giving 166.8 g of 3-butyl-3-ethylpiperidine (b.p.=73.degree. to 
75.degree. C./2 mmHg) and 267.5 g of 2-butyl- 2-ethylpentane-1,5-diamine 
(b.p.=105.degree. C./2 mmHg). The diamine yield was 52.1% of theory. 
Example 6 
A vertical tubular reactor (diameter 16 mm, fill level 50 cm, oil-heated 
twin jacket) was filled with 90.1 g (87 ml) of a catalyst containing 3% of 
ruthenium on .beta.-alumina in the form of 1.2 mm pellets (catalyst 
preparation by impregnating the pores of .beta.-alumina with aqueous 
ruthenium nitrate solution and drying the catalyst at 120.degree. C.). The 
reduction was carried out at 100 bar while simultaneously passing 150 
l(S.T.P.)/h of hydrogen through the catalyst, which was kept at 
220.degree. C. for 9 hours after increasing the temperature in steps from 
100.degree. to 220.degree. C. over the course of 7 hours. 
41.6 g per hour of 2-butyl-2-ethyl-4-cyanobutanal (purity 90%, 37.4 g, 
0.207 mol) and 1073 ml (646 g, 38.0 mol) per hour of liquid ammonia were 
pumped at 250 bar and 50.degree. C. through a tubular reactor (diameter 16 
mm, fill level 50 cm, oil-heated twin jacket) upstream of the 
hydrogenation reactor and filled with 43.3 g (96 ml) of a Y-zeolite 
pelleted with Aerosil 200 (HY-zeolite: Aerosil 200 =9:1, SiO.sub.2 
:Al.sub.2 O.sub.3 =6:1). The product stream was subsequently passed 
through the hydrogenation reactor from bottom to top at 250 bar and 
120.degree. C. while simultaneously passing 80 l(S.T.P.)/h (3.6 mol) of 
hydrogen through the reactor. The product stream was decompressed to 
atmospheric pressure and NH.sub.3 was removed by distillation. The product 
from 34.1 hours was separated by fractional distillation on a 30 cm packed 
column (3 mm glass rings), giving 358.3 g of 3-butyl-3-ethylpiperidine and 
747.7 g of 2-butyl-2-ethylpentane-1,5-diamine. The diamine yield was 56.9% 
of theory. 
Example 7 
A vertical tubular reactor (diameter 16 mm, fill level 50 cm, oil-heated 
twin jacket) was filled with 90.1 g (87 ml) of a catalyst containing 3% of 
ruthenium on .beta.-alumina in the form of 1.2 mm pellets (catalyst 
preparation by impregnating the pores of .beta.-alumina with aqueous 
ruthenium nitrate solution and drying the catalyst at 120.degree. C.). The 
reduction was carried out at 100 bar while simultaneously passing 150 
l(S.T.P.)/h of hydrogen through the catalyst, which was kept at 
220.degree. C. for 9 hours after increasing the temperature in steps from 
100 to 220.degree. C. over the course of 7 hours. 
45.1 g per hour of 2-butenyl-2-ethyl-4-cyanobutanal (purity 64.0%, 28.9 g, 
0.161 mol) and 950 ml (570 g, 33.5 mol) per hour of liquid ammonia were 
pumped at 250 bar and 50.degree. C. through a tubular reactor (diameter 16 
mm, fill level 50 cm, oil-heated twin jacket) upstream of the 
hydrogenation reactor and filled with 43.3 g (96 ml) of a Y-zeolite 
pelleted with Aerosil 200 (HY-zeolite: Aerosil 200=9:1, SiO.sub.2 
:Al.sub.2 O.sub.3 =6:1). The product stream was subsequently passed 
through the hydrogenation reactor from bottom to top at 250 bar and 
120.degree. C. while simultaneously passing 100 l(S.T.P.)/h (4.5 mol) of 
hydrogen through the reactor. The product stream was decompressed to 
atmospheric pressure and NH.sub.3 was removed by distillation. From the 
product from 23.9 hours, 205.7 g of 3-butyl-3-ethylpiperidine and 438.4 g 
of a mixture of 2-butyl- and 2-butenyl-2-ethylpentane-1,5-diamine (8:1), 
corresponding to a diamine yield of 61.9% of theory, were isolated by 
fractional distillation on a 30 cm packed column (3 mm glass rings). 
Example 8 
A vertical tubular reactor (diameter 16 mm, fill level 50 cm, oil-heated 
twin jacket) was filled with 183.1 g (100 ml) of an unsupported cobalt 
catalyst (composition: CoO with 5% of Mn.sub.3 O.sub.4 and 3% of P.sub.2 
O.sub.5) in the form of 1 to 1.5 mm grit. The reduction was carried out at 
100 bar while simultaneously passing 150 l(S.T.P.)/h of hydrogen through 
the catalyst, which was kept at 330.degree. C. for 30 hours after 
increasing the temperature in steps from 100.degree. to 330.degree. C. 
over the course of 23 hours. 
10.8 g per hour of 2-butyl-2-ethyl-4-cyanobutanal (purity 98.2%, 9.3 g, 
0.052 mol) and 478 ml (287 g, 16.9 mol) per hour of liquid ammonia were 
pumped at 200 bar and 80.degree. C. through a tubular reactor (diameter 16 
mm, fill level 50 cm, oil-heated twin jacket) upstream of the 
hydrogenation reactor and filled with 63.5 g (100 ml) of TiO.sub.2 
(anatase) in the form of 1.5 mm pellets. The product stream was 
subsequently passed through the hydrogenation reactor from bottom to top 
at 200 bar and 110.degree. C. while simultaneously passing 60 l(S.T.P.)/h 
(2.7 mol) of hydrogen through the reactor. The product stream was 
decompressed to atmospheric pressure and NH.sub.3 was removed by 
distillation. According to GC, the hydrogenation product stream contained 
67.2% of 2-butyl-2-ethylpentane-1,5-diamine and 24.7% of 
3-butyl-3-ethylpiperidine, corresponding to a diamine yield of 66.2% of 
theory. 
Example 9 
A vertical tubular reactor (diameter 16 mm, fill level 100 cm, oil-heated 
twin jacket) was filled with 354 g (200 ml) of a basic unsupported cobalt 
catalyst (CoO containing 5% of Mn.sub.2 O.sub.3 and 1.4% of Na.sub.2 O) in 
the form of 1 to 1.5 mm grit. The catalyst was reduced at 100 bar while 
simultaneously passing 150 l(S.T.P.)/h of hydrogen through the catalyst, 
which was kept at 330.degree. C. for 30 hours after increasing the 
temperature in steps from 100.degree. to 330.degree. C. over the course of 
23 hours. 
80.0 g per hour of 2-butyl-2-ethyl-4-cyanobutanal (purity 99.3%, 0.44 mol) 
and 200 g (330 ml, 11.76 mol) per hour of liquid ammonia were pumped from 
bottom to top at 250 bar and 80.degree. C. through a tubular reactor 
(diameter 16 mm, fill level 20 cm, oil-heated twin jacket) upstream of the 
hydrogenation reactor and filled with 25.4 g (40 ml) of TiO.sub.2 
(anatase) in the form of 1.5 mm pellets. 100 l(S.T.P.)/h of hydrogen were 
then fed in, and the product stream from the upstream imination reactor 
was passed through the hydrogenation reactor from bottom to top at 250 bar 
and 110.degree. C. The product stream was decompressed to atmospheric 
pressure and the ammonia was removed by distillation. According to 
gas-chromatographic analysis, the hydrogenation product stream contained 
89.2% of 2-butyl-2-ethylpentane-1,5-diamine and 4.3% of 
3-butyl-3-ethylpiperidine. The product from 80.5 hours was separated by 
fractional distillation on a 30 cm packed column (3 mm glass rings), 
giving 5738 g of 2-butyl-2-ethylpentane-1,5-diamine, corresponding to a 
yield of 87.3% of theory. 
Example 10 
A vertical tubular reactor (diameter 16 mm, fill level 50 cm, oil-heated 
twin jacket) was filled with 176.7 g (100 ml) of a basic unsupported 
cobalt catalyst (CoO containing 5% of Mn.sub.2 O.sub.3 and 1.4% of 
Na.sub.2 O) in the form of 1 to 1.5 mm grit. The catalyst was reduced at 
100 bar while simultaneously passing 150 l(S.T.P.)/h of hydrogen through 
the catalyst, which was kept at 330.degree. C. for 30 hours after 
increasing the temperature in steps from 100.degree. to 330.degree. C. 
over the course of 23 hours. 
20.0 g per hour of 2-butyl-2-ethyl-4-cyanobutanal (purity 99.3%, 0.11 mol) 
and 140 g (230 ml, 8.23 mol) per hour of liquid ammonia were pumped from 
bottom to top at 250 bar and 80.degree. C. through a tubular reactor 
(diameter 16 mm, fill level 50 cm, oil-heated twin jacket) upstream of the 
hydrogenation reactor and filled with 70.0 g (100 ml) of .sub..gamma. 
-Al.sub.2 O.sub.3 in the form of 1.5 mm pellets. 60 l(S.T.P.)/h of 
hydrogen were then fed in, and the product stream from the upstream 
imination reactor was passed through the hydrogenation reactor from bottom 
to top at 250 bar and 110.degree. C. The product stream was decompressed 
to atmospheric pressure and the ammonia was removed by distillation. 
According to gas-chromatographic analysis, the hydrogenation product 
stream contained 95.4% of 2-butyl-2-ethylpentane-1,5-diamine and 2.3% of 
3-butyl-3-ethylpiperidine. The product from 48.0 hours was separated by 
fractional distillation on a 30 cm packed column (3 mm glass rings), 
giving 920 g of 2-butyl-2-ethylpentane-1,5-diamine, corresponding to a 
yield of 93.9% of theory.