Preparation of amines by reductive amination using zeolite catalyst

Amines of the general formula I ##STR1## where R.sup.1 and R.sup.2 are each C.sub.1 -C.sub.20 -alkyl, C.sub.3 -C.sub.20 -cycloalkyl, C.sub.4 -C.sub.20 -alkylcycloalkyl, C.sub.4 -C.sub.20 -cycloalkylalkyl, aryl, C.sub.7 -C.sub.20 -alkylaryl, C.sub.7 -C.sub.20 -aralkyl or a heterocyclic radical and n is an integer of from 3 to 7, are prepared by a process in which a ketone of the general formula II ##STR2## where R.sup.1 and R.sup.2 have the abovementioned meanings, is reacted with a cyclic amine of the general formula III ##STR3## where n has the abovementioned meanings, in the presence of a zeolite and/or SiO.sub.2 having a zeolite structure and/or a phosphate and/or a phosphate having a zeolite structure as catalysts at from 50.degree. to 500.degree. C. and from 0.01 to 50 bar.

The present invention relates to a process for the preparation of amines by 
reductive amination of ketones. 
The preparation of tertiary amines by reductive amination is known from 
Organic Reactions, Vol. 4, Chapter 3, (1948) pages 174-256, or 
Houben-Weyl, Methoden der organischen Chemie, 4th Edition, G. Thieme 
Verlag Stuttgart, Vol. 11/1 (1957), pages 611 to 663. The reductive 
amination is carried out by reacting the ketone or aldehyde with the amine 
and hydrogen in the presence of a metal-containing catalyst. The metallic 
component of the catalyst may be, for example, nickel, platinum or 
palladium. In Organic Reactions, it is stated in particular that platinum 
is most suitable as a catalyst for the reaction of ketones having a low 
molecular weight with amines having a low molecular weight. According to 
this publication yields of up to 47% of theory are achieved in the 
reaction of secondary amines with ketones over a platinum catalyst. 
In DE-A 25 35 725, reductive amination is carried out in the liquid phase 
over a supported nickel catalyst. Here, amine yields of up to 96% are 
achieved in the medium pressure range. The process is carried out in the 
liquid phase and has very long residence times (from 3 to 10 hours) and 
hence a low space/time yield. 
The processes known to date have the disadvantage that low yields and/or 
long residence times have to be accepted. 
It is an object of the present invention to remedy the abovementioned 
disadvantages. 
We have found that this object is achieved by a novel and improved process 
for the preparation of amines of the general formula I 
##STR4## 
where R.sup.1 and R.sup.2 are each C.sub.1 -C.sub.20 -alkyl, C.sub.3 
-C.sub.20 -cycloalkyl, C.sub.4 -C.sub.20 -alkylcycloalkyl, C.sub.4 
-C.sub.20 -cycloalkylalkyl, aryl, C.sub.7 -C.sub.20 -alkylaryl, C.sub.7 
-C.sub.20 -aralkyl or a heterocyclic radical and n is an integer of from 3 
to 7, where a ketone of the general formula II 
##STR5## 
where R.sup.1 and R.sup.2 have the abovementioned meanings, is reacted 
with a cyclic amine of the general formula III 
##STR6## 
where n has the abovementioned meanings, in the presence of a zeolite 
and/or SiO.sub.2 having a zeolite structure and/or a phosphate and/or a 
phosphate having a zeolite structure as catalysts at from 50.degree. to 
500.degree. C. and from 0.01 to 50 bar. 
The novel process for the preparation of amines I can be carried out as 
follows: 
The reaction is effected by bringing the mixture of a ketone II and an 
amine III into contact with a zeolite and/or SiO.sub.2 having a zeolite 
structure and/or a phosphate and/or a phosphate having a zeolite structure 
as catalysts of from 50.degree. to 500.degree. C. and from 0.01 to 50 bar. 
The reaction can be carried out both in the liquid phase (suspension, 
trickle-bed or liquid-phase procedure) at from 50.degree. to 200.degree. 
C. and from 0.05 to 5 bar and, preferably, in the gas phase at from 
100.degree. to 500.degree. C., preferably from 200.degree. to 400.degree. 
C., and from 0.01 to 50, preferably from 0.1 to 30, particularly 
preferably from 0.5 to 5, bar, batchwise or, preferably, continuously. The 
space velocity WHSV should as a rule be from 0.1 to 20, preferably from 
0.5 to 5, h.sup.-1 (g of starting mixture per g of catalyst per hour). 
The process is generally carried out at atmospheric pressure or, depending 
on the volatility of the starting compound, at reduced or superatmospheric 
pressure (see above). 
Sparingly volatile or solid starting materials II or III are used in 
dissolved form, for example in solution in tetrahydrofuran, toluene and/or 
petroleum ether. In general, dilution of the starting materials II or III 
with such solvents or with inert gases, such as N.sub.2, Ar or steam, is 
possible. 
After the reaction, the resulting products are isolated from the reaction 
mixture by a conventional method, for example by distillation; unconverted 
starting mixture is, if required, recycled to the novel reaction. 
In a particularly preferred embodiment, the gaseous reaction products are 
introduced into a separation stage directly (immediately) after leaving 
the reactor and are then separated into their individual components. 
Separation of this type can be carried out, for example, in a 
fractionation column. This is advisable for suppressing the reverse 
reaction and for achieving a high conversion. 
Acidic zeolite catalysts are used as catalysts for the novel process. 
Zeolites are crystalline aluminosilicates which have a highly ordered 
structure with a rigid three-dimensional network of SiO.sub.4 and 
AlO.sub.4 tetrahedra which are linked by common oxygen atoms. The ratio of 
Si and Al atoms to oxygen is 1 : 2 (cf. Ullmanns Encyclopadie d. techn. 
Chemie, 4th Edition, Volume 24, (1983) page 575. The electrovalency of the 
aluminum-containing tetrahedra is balanced by the inclusion of cations in 
the crystal, for example of an alkali metal or hydrogen ion. Cation 
exchange is possible. The voids between the tetrahedra are occupied by 
hydrogen molecules prior to dehydration by drying or calcination. 
In the zeolites, instead of aluminum other elements such as B, Ga, Fe, Cr, 
Ti, V, As, Sb, Bi or Be or mixtures thereof, may also be incorporated in 
the lattice, or the silicon may be replaced with a tetravalent element, 
such as Ge, Ti, Zr or Hf. 
Depending on their structure, zeolites are divided into different groups 
(cf. Ullmanns Encyclopadie d. techn. Chemie, 4th Edition, Vol. 24, (1983) 
page 575). Thus, the zeolite structure is formed by chains of tetrahedra 
in the mordenite group or by sheets of tetrahedra in the chabasite group, 
while in the faujasite group the tetrahedra are arranged to form 
polyhedra, for example in the form of a cubo-octahedron which consists of 
fourmembered rings or six-membered rings. Depending on the bonding of the 
cubo-octahedra, resulting in voids and pores of different sizes, a 
distinction is made between zeolites of the A, L, X or Y type. Catalysts 
suitable for the novel process are zeolites of the mordenite group or 
narrow-pore zeolites of the erionite or chabasite type or zeolites of the 
faujasite type, for example Y-, X-, beta- or L-zeolites. This group of 
zeolites includes the ultrastable zeolites of the faujasite type, ie. 
dealuminated zeolites. Processes for the preparation of such zeolites are 
described in Catalysis by Zeolites, Volume 5, from Studies in Surface 
Science and Catalysis, ed. B. Imelik et al., Elsevier Scientific 
Publishing Comp. 1980, page 203, and Crystal Structures of Ultra-stable 
Faujasites, Advances in Chemistry Series No. 101, American Chemical 
Society Washington, DC, (1971) page 226 et seq. and in U.S.-A-4,512,961. 
Zeolites of the pentasil type (MFI structure; G. T. Kokotailo and W. M. 
Meier, Spec. Publ. Chem. Soc. 33 (1980), 133) are particularly 
advantageous. 
They have, as a common base building block, a five-membered ring consisting 
of SiO.sub.4 tetrahedra. They possess a high SiO.sub.2 /Al.sub.2 O.sub.3 
ratio and pore sizes which are between those of the zeolites of the A type 
and those of the X or Y type (cf. Ullmanns Encyclopadie d. techn. Chem., 
4th Edition, Vol. 24, 1983). 
These zeolites can have different chemical compositions. They are 
aluminosilicate, borosilicate, ferrosilicate, gallosilicate, 
chromosilicate, arsenosilicate, antimonosilicate and bismuth silicate 
zeolites or mixtures thereof, as well as aluminogermanate, borogermanate, 
gallogermanate and ferrogermanate zeolites or mixtures thereof or 
titanosilicate zeolites, such as TS-1, ETS 4 and ETS 10. 
The aluminosilicate, borosilicate, gallosilicate and ferrosilicate zeolites 
of the pentasil type are particularly suitable for the novel process. 
The aluminosilicate zeolite is prepared, for example, from an aluminum 
compound, preferably Al(OH).sub.3 or Al.sub.2 (SO.sub.4).sub.3, and a 
silicon component, preferably finely divided silica, in aqueous amine 
solution, in particular in a polyamine, such as 1,6-hexanediamine or 
1,3-propanediamine or triethylenetetramine solution, with or, in 
particular, without the addition of an alkali or an alkaline earth at from 
100.degree. to 220.degree. C. under autogenous pressure. Such zeolites 
include the isotactic zeolites according to EP-A-34 727 and EP-A-46 504. 
The aluminosilicate zeolites obtained have an SiO.sub.2 /Al.sub.2 O.sub.3 
ratio of from 10 to 40,000, depending on the choice of the amount of 
starting materials. Such aluminosilicate zeolites can also be synthesized 
in an ether medium, such as diethylene glycol dimethyl ether, in an 
alcoholic medium, such as methanol or 1,4-butanediol, or in water. 
The borosilicate zeolite is synthesized, for example, at from 90.degree. to 
200.degree. C. under autogenous pressure by reacting a boron compound, eg. 
H.sub.3 BO.sub.3 with a silicon compound, preferably finely divided 
silica, in aqueous amine solution, in particular in 1,6-hexanediamine or 
1,3-propanediamine or triethylenetetramine solution, with or, in 
particular, without the addition of an alkali or alkaline earth. These 
zeolites include the isotactic zeolites according to EP-A-34 727 and 
EP-A-46 504. Such borosilicate zeolites can also be prepared if the 
reaction is carried out in solution in an ether, eg. diethylene glycol 
dimethyl ether, or in alcoholic solution, eg. 1,6-hexanediol, instead of 
in aqueous amine solution. 
The gallosilicate zeolite of the pentasil type is synthesized, for example, 
at from 90.degree. to 200.degree. C. under autogenous pressure by reacting 
a gallium compound, for example an alkali metal gallate, preferably sodium 
gallate, or a gallium oxide or gallium halide or another suitable gallium 
salt, with a silicon compound, for example an alkali metal silicate, a 
silica sol, a silicic ester or, preferably, finely divided silica, in 
aqueous amine solution, for example in a primary, secondary or tertiary 
amine or quaternary alkylammonium compound, where one or more amine 
functions may be present per molecule, for example in 1,6-diaminohexane 
solution or in particular tetrapropylammonium hydroxide solution, with or 
without the addition of an alkali or an alkaline earth. The preparation of 
the zeolites in the presence of these amines is described in, for example, 
U.S.-A-3,702,886, BE-A-886 833, BE-A-882 484 and DE-A-30 06 471. 
The ferrosilicate zeolite is obtained, for example, from iron compound, 
preferably Fe.sub.2 (SO.sub.4).sub.3 and a silicon compound, preferably 
finely divided silica, in aqueous amine solution, in particular 
1,6-hexanediamine, with or without the addition of an alkali or alkaline 
earth, at from 100.degree. to 220.degree. C. under autogenous pressure. 
The suitable silicon-rich zeolites (SiO.sub.2 /Al.sub.2 O.sub.3 &gt; 10) 
include the ZSM types, beta-zeolite, ferrierite, EU-1, NU-1 and silicalits 
(a molecular sieve, a silica polymorph), ie. SiO.sub.2 phases having a 
pentasil structure, whose characteristics and a process for whose 
preparation are described in, for example, DE-A-27 51 443 
(US-A-4,061,724) and EP-A-64 372, EP-A-93 476 and EP-A-123 060. 
The ultrastable zeolites, for example those of the faujasite type or 
mordenite type, ie. dealuminated Y-zeolites or dealuminated mordenite, 
whose preparation is described, for example, in US-A-4 512 961 and in H. 
K. Beyer and S. Belenykaja, Stud. Surf. Sci. Catal. 5 (1980), 203-209 and 
in I. M. Newsam, Science, 231 (1986), 1094, can also be used for the novel 
process. 
The beta-zeolite as described in, for example, US-A-4,891,458 can also 
advantageously be used for the novel reaction. 
Titanosilicates having a pentasil structure, for example TS-1, which are 
described, for example, by B. Kraushaar and I.H.C. van Haaff in Catalysis 
Letters 1 (1988), 81-89 or G. Perego et al. in Stud. Surf. Sci. Catal. 28 
(1986), 129-136, are also suitable. The ETS molecular sieves, for example 
ETS-1, ETS-4 and ETS-10 (US-A-4,853,202 and ZA 88 09 457), can also be 
used. 
The aluminosilicate, gallosilicate, borosilicate, titanosilicate and 
ferrosilicate zeolites or silicalits thus prepared can be isolated, dried 
at from 100.degree. to 160.degree. C., preferably 110.degree. C. and 
calcined at from 450.degree. to 550.degree. C., preferably 500.degree. C., 
before being molded with a binder in weight ratio of from 90 : 10 to 40 : 
60 to give extrudates or pellets. Suitable binders are various aluminas, 
preferably boehmite, amorphous aluminosilicates having an SiO.sub.2 
/Al.sub.2 O.sub.3 ratio of from 25 : 75 to 90 : 5, preferably 75 : 25, 
silica, preferably finely divided SiO.sub.2, mixtures of finely divided 
SiO.sub.2 and finely divided Al.sub.2 O.sub.3, TiO.sub.2, ZrO.sub.2 and 
clay. After the molding process, the extrudates or pellets are dried at 
110.degree. C. for 16 hours and calcined at 500.degree. C. for 16 hours. 
Advantageous catalysts are also obtained if the zeolites isolated, such as 
the aluminosilicate or borosilicate zeolite, are molded directly after 
drying and are not subjected to calcination until after the molding 
process. For example, the aluminosilicate and borosilicate zeolites 
prepared can also be used in pure form, without a binder, as extrudates or 
pellets, the extrusion or peptizing assistants used being, for example, 
ethylcellulose, stearic acid, potato starch, formic acid, oxalic acid, 
acetic acid, nitric acid, ammonia, amine, silicoesters and graphite or 
mixtures thereof. 
If, owing to its method of preparation, the zeolite is not in the acidic H 
form but, for example, in the Na form, the latter can be converted 
completely or partially in the desired H form by ion exchange, for example 
with ammonium ions, and subsequent calcination or by treatment with acids. 
If deactivation due to coking occurs during the novel use of the zeolite 
catalysts, it is advisable to regenerate the zeolites by burning off the 
coke deposit with air or with an air/N.sub.2 mixture at from 400.degree. 
to 550.degree. C., preferably 500.degree. C. The zeolites thus regain 
their initial activity. 
By precoking, it is possible to adjust the activity of the catalyst for 
optimum selectivity of the desired reaction product. 
To achieve very high selectivity, high conversion and long lives, it is 
advantageous to modify the zeolites. 
In a suitable method for modifying the catalysts, for example, the unmolded 
or molded zeolites are doped with metal salts by ion exchange or by 
impregnation. Metals used are alkali metals, such as Li, Cs or K, alkaine 
earth metals, such as Mg, Ca or Sr, metals of the 3rd, 4th and 5th main 
groups, such as Al, Ga, Ge, Sn, Pb or Bi, transition metals of the 4th to 
8th subgroups, such as Ti, Zr, V, Nb, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, 
Rh, Ir, Ni, Pd or Pt, transition metals of the 1st and 2nd subgroups, such 
as Cu, Ag or Zn, and rare earth metals, such as La, Ce, Pr, Nd, Fr, Yb and 
U. In particular, the elements Pd, Pt, Rh, Ru, Re, Co, Cu, Zr, Fe, Ag, Zn, 
Mo and W are used for the novel process. 
The doping is advantageously carried out by a procedure in which, for 
example, the molded zeolite is initially taken in a riser tube and, for 
example, an aqueous on ammoniacal solution of a halide or of a nitrate or 
the metals described above is passed over at from 20.degree. to 
100.degree. C. Ion exchange of this type can be carried out, for example, 
over the hydrogen, ammonium and alkali metal forms of the zeolite. Another 
possible method for applying metals to the zeolite is to impregnate the 
zeolite material, for example with a halide, a nitrate or an oxide of the 
metals described above, in aqueous, alcoholic or ammoniacal solution. Both 
ion exchange and impregnation are followed by at least one drying step or 
a further calcination. 
In a possible embodiment, for example, Cu(NO.sub.3).sub.2.3H.sub.2 O or 
Ni(NO.sub.3).sub.2.6H.sub.2 O or Ce(NO.sub.3).sub.3.6H.sub.2 O or 
La(NO.sub.3).sub.2. 6H.sub.2 O or Cs.sub.2 CO.sub.3 is dissolved in water. 
The molded or unmolded zeolite is impregnated with this solution for a 
certain time, about 30 minutes. Any supernatant solution is freed from 
water in a rotary evaporator. 
The impregnated zeolite is then dried at about 150.degree. C. and calcined 
at 550.degree. C. This impregnation process can be carried out several 
times in succession in order to obtain the desired metal content. 
It is also possible, for example, to prepare an aqueous Ni(NO.sub.3 ).sub.2 
solution or ammoniacal Pd(NO.sub.3).sub.2 solution and to suspend the pure 
zeolite in powder form therein at from 40.degree. to 100.degree. C. while 
stirring for about 24 hours. After the resulting zeolite material is 
filtered off, dried at about 150.degree. C. and calcined at about 
500.degree. C., it can be further processed with or without a binder to 
give extrudates, pellets or fluidizable material. 
Ion exchange of the zeolite in the H form or ammonium form or alkali form 
can be carried out by a procedure in which the zeolite, in the form of 
extrudates or pellets, is initially taken in a column and, for example, an 
aqueous Ni(NO.sub.3).sub.2 solution or ammoniacal Pd(NO.sub.3).sub.2 
solution is circulated over it at slightly elevated temperatures of from 
30.degree. to 80.degree. C. for from 15 to 20 hours. Thereafter, thorough 
washing with water, drying at about 50.degree. C. and calcination at about 
550.degree. C. are carried out. In the case of some metal-doped zeolites, 
for example Pd-, Cu- and Ni-doped zeolites, an aftertreatment with 
hydrogen is advantageous. 
In another possible method of modification, the molded or unmolded zeolite 
material is subjected to a treatment with acids, such as hydrochloric 
acid, hydrofluoric acid and phosphoric acid, and/or steam. In an 
advantageous procedure of this type, for example, zeolites in powder form 
are treated with 1 N phosphoric acid for 1 hour at 80.degree. C. After the 
treatment, they are washed with water, dried at 110.degree. C. for 16 
hours and calcined at 500.degree. C. for 20 hours. In another procedure, 
zeolites are treated, before or after they have been molded with binders, 
with a 3-25, in particular 12-20, % strength by weight aqueous 
hydrochloric acid, for example for from 1 to 3 hours at from 60.degree. to 
80.degree. C. The zeolite treated in this manner is then washed with 
water, dried, and calcined at from 400.degree. to 500.degree. C. 
In a particular embodiment of the acid treatment, the zeolite material, 
before it has been molded, is treated at elevated temperatures with 
hydrofluoric acid, which is generally used as 0.001 to 2 N, preferably 
0.05 to 0.5 N, hydrofluoric acid, for example by refluxing for in general 
from 0.5 to 5, preferably from 1 to 3, hours. After the zeolite material 
has been isolated, for example by filtering off and washing thoroughly, it 
is advantageously dried, for example at from 100.degree. to 160.degree. 
C., and calcined at in general from 450.degree. to 600.degree. C. In 
another preferred embodiment of the acid treatment, the zeolite material 
is molded with the binder and then treated preferably with from 12 to 20% 
strength by weight hydrochloric acid at elevated temperatures, 
advantageously at from 50.degree. to 90.degree. C., preferably from 
60.degree. to 80.degree. C., for from 0.5 to 5 hours. The zeolite material 
is then generally washed thoroughly and advantageously dried, for example 
at from 100.degree. to 160.degree. C., and calcined at in general from 
450.degree. to 600.degree. C. An HF treatment may also be followed by an 
HCl treatment. 
In another procedure, the zeolites can be modified by applying phosphorus 
compounds, such as trimethyl phosphate, trimethoxyphosphine or primary, 
secondary or tertiary sodium phosphate. The treatment with primary sodium 
phosphate has proven particularly advantageous. Here, the zeolites in the 
form of extrudates, pellets or fluidizable material are impregnated with 
aqueous NaH.sub.2 PO.sub.4 solution, dried at 110.degree. C. and calcined 
at 500.degree. C. 
Further catalysts for the preparation of bifunctional building blocks from 
dialkoxyalkanoates are phosphates, in particular aluminum phosphates, 
silicon aluminum phosphates, cerium phosphate, zirconium phosphates, boron 
phosphate, iron phosphate and mixtures thereof. 
In particular, substituted and unsubstituted aluminum phosphates and 
silicon aluminum phosphates synthesized under hydrothermal conditions are 
used as aluminum phosphate and silicon aluminum phosphate catalysts for 
the novel process. 
The aluminum phosphate catalysts structurally related to the zeolites are 
synthesized for the novel process, in particular under hydrothermal 
conditions. In particular they are silicon aluminophosphates (acronym 
SAPO) or aluminophosphates (acronym AlPO.sub.4). These crystalline solids 
have defined void and pore structures and are structurally related to the 
zeolites. 
The preparation, properties and classification of these solids on the basis 
of structure and chemical composition are described in detail by R. M. 
Barrer, Pure and App. Chem., Vol. 58, No. 10, (1986) pages 1317 to 1322, 
by E. M. Flanigen et al., Pure and Appl. Chem., Vol. 58, No. 10, (1986) 
pages 1351 to 1358 or by N. B. Milestone et al., Stud. Surf. Sci. Catal. 
(1988), 36 (Methane Convers.), pages 553 to 562. 
About 700 different combinations of the currently known crystal structures 
and of the many element modifications are now possible. The 
aluminophosphates are designated by the following acronyms: AlPO.sub.4, 
SAPO, MeAPO, MeAPSO, ElAPO or ElAPSO. A or Al is aluminum, S is silicon, P 
is phosphorus and 0 is oxygen. Me is a metal, such as Fe, Mg, Mn, Co or 
Zn, and El is an element, such as Be, Ga, Ge, Ti, As, B or Li. A number 
added together with a hyphen serves to define the crystal structure of the 
relevant phase. 
The aluminum phosphates prepared under hydrothermal conditions are, for 
example, AlPO-5, AlPO-9, AlPO-11, AlPO-12, AlPO-14, AlPO-21, AlPO-25, 
AlPO-31, AlPO-33, AlPO-34, AlPO-37 and AlPO-54. Syntheses of these 
compounds are described in EP-A-132 708, US-A-4,310,440 and 
US-A-4,473,663. An overview of this class of compounds is given in Pure 
and Applied Chemistry 58, 10 (1986), 1351-1358. 
For example, AlPO.sub.4 -5 (APO-5) is synthesized by homogeneously mixing 
orthophosphoric acid with pseudoboehmite (Catapal.RTM. SB) in water, 
adding tetrapropylammonium hydroxide to this mixture and then carrying out 
the reaction in an autoclave at about 150.degree. C. for from 20 to 60 
hours under autogenous pressure. The AlPO.sub.4 filtered off is dried at 
from 100.degree. to 160.degree. C. and calcined at from 450.degree. to 
550.degree. C. 
AlPO.sub.4 -9 (APO-9) is likewise synthesized from orthophosphoric acid and 
pseudoboehmite, but in aqueous D.ABCO solution 
(1,4-diazabicyclo[2.2.2]octane) at about 200.degree. C. under autogenous 
pressure in the course of from 200 to 400 hours. 
AlPO.sub.4 -21 (APO-21) is synthesized from orthophosphoric acid and 
pseudoboehmite in aqueous pyrrolidone solution at from 150 to 200.degree. 
C under autogenous pressure in the course of from 50 to 200 hours. 
The syntheses for MeAPOs are described in US-A-4,544,143, EP-A-132 708 and 
US-A-4,567,029 and those for ElAPO in US-A-4,500,651 and EP-A-158 976. 
The silicon-containing aluminophosphates (SAPO, MeAPSO or ElAPSO), such as 
SAPO-11, SAPO-5, SAPO-20, SAPO-34, SAPO-37, SAPO-41 or SAPO-46, are 
particularly preferred for the novel process. 
Syntheses of the silicon aluminophosphates are described, inter alia, for 
SAPO in US-A-4,440,871 and EP-A-103 117, for MeAPSO in EP-A-158 348, 
EP-A-158 975 and EP-A-161 491 and for ElAPSO in EP-A-159 624. 
SAPOs are prepared by crystallization from an aqueous mixture at from 
100.degree. to 250.degree. C. and under autogenous pressure in the course 
of from 2 hours to 2 weeks, the reaction mixture comprising a silicon, 
aluminum and phosphorus component being reacted in aqueous solutions of 
organic amines. 
Examples of suitable silicon aluminophosphates are ZYT-5, ZYT-6, ZYT-7, 
ZYT-9, ZYTl-11 and ZYT-12 (JP 59/217-619). 
For example, SAPO-5 is obtained by mixing SiO.sub.2, suspended in aqueous 
tetrapropylammonium hydroxide solution, with an aqueous suspension of 
pseudoboehmite and orthophosphoric acid and subsequently carrying out the 
reaction at from 150.degree. to 200.degree. C. in the course of from 20 to 
200 hours under autogenous pressure in a stirred autoclave. Drying of the 
filtered-off powder is effected at from 110.degree. to 160.degree. C. and 
calcination at from 450.degree. to 550.degree. C. 
Precipitated aluminum phosphates may also be used as phosphate catalysts in 
the process. For example, an aluminum phosphate of this type is prepared 
by dissolving 92 g of diammonium hydrogen phosphate in 700 ml of water. 
260 g of Al(NO.sub.3).sub.3.H.sub.2 O in 700 ml of water are added 
dropwise to this solution in the course of 2 hours. The pH is kept at 8 by 
the simultaneous addition of 25% strength NH.sub.3 solution. The 
precipitate formed is stirred for a further 12 hours and then filtered off 
under suction and washed thoroughly. It is dried at 60.degree. C. for 16 
hours. 
Boron phosphates of the novel process can be prepared, for example, by 
mixing and kneading concentrated boric acid and phosphoric acid and by 
subsequent drying and calcination in an inert gas, air or steam atmosphere 
at from 250.degree. to 650.degree. C., preferably from 300.degree. to 
500.degree. C. 
CePO.sub.4 is obtained by precipitation from 52 g of 
Ce(NO.sub.3).sub.3.6H.sub.2 O and 56 g of NaH.sub.2 PO.sub.4.2H.sub.2 O. 
After filtration, the material is molded to give extrudates, which are 
dried at 120.degree. C. and calcined at 450.degree. C. The catalyst 
contains 47.1% by weight of Ce and 12.7% by weight of P. 
Suitable zirconium phosphates are commercial zirconium phosphates, for 
example CSZ 100, zirconium phosphate silicates and zirconium phosphates 
which adsorb or which have adsorbed NH.sub.3. 
These phosphates or phosphates having a zeolite structure can be modified 
by doping with metals, acid treatment, steaming, etc., as described above 
for the zeolites. 
The catalysts described here can be used alternatively as 2 to 4 mm 
extrudates or as pellets having a diameter of from 3 to 5 mm or as chips 
having particle sizes of from 0.1 to 0.5 mm or as a fluidizable catalyst. 
In the compounds of the general formulae I, II and III, 
R.sup.1 and R.sup.2 independently of one another are each C.sub.1 -C.sub.20 
-alkyl, preferably C.sub.1 -C.sub.12 -alkyl, such as methyl, ethyl, 
n-propyl, isopropyl, n-butyl, isobutyl, sec butyl, tert-butyl, n-pentyl, 
isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, n-hexyl, isohexyl, 
sec-hexyl, n-heptyl, isoheptyl, n-octyl, isooctyl, n-nonyl, isononyl, 
n-decyl, isodecyl, n-undecyl, isoundecyl, n-dodecyl or isododecyl, 
particularly preferably C.sub.1 -C.sub.4 -alkyl, such as methyl, ethyl, 
n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl, C.sub.1 
-C.sub.20 -cycloalkyl, preferably C.sub.3 -C.sub.8 -cycloalkyl, such as 
cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl or 
cyclooctyl, particularly preferably cyclopentyl, cyclohexyl or cyclooctyl, 
C.sub.4 -C.sub.20 -alkylcycloalkyl, preferably C.sub.6 -C.sub.20 
-alkylcycloalkyl, such as 2-methylcyclopentyl, 3-methylcyclohexyl or 
4-methylcyclohexyl, C.sub.4 -C.sub.20 -cycloalkylalkyl, preferably C.sub.6 
-C.sub.20 -cycloalkylalkyl, such as cyclopentylmethyl, cyclohexylmethyl or 
cyclohexylethyl, aryl, such as phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 
2-anthryl or 9-anthryl, preferably phenyl, 1-naphthyl or 2-naphthyl, 
particularly preferably phenyl, C.sub.7 -C.sub.20 -alkylaryl, preferably 
C.sub.7 -C.sub.12 -alkylphenyl, such as 2-methylphenyl, 3-methylphenyl, 
4-methylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 
2,6-dimethylphenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, 
2,3,4-trimethylphenyl, 2,3,5-trimethylphenyl, 2,3,6-trimethylphenyl, 
2,4,6-trimethylphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 
2-n-propylphenyl, 3-n-propylphenyl or 4-n-propylphenyl, C.sub.7 -C.sub.20 
-aralkyl, preferably C.sub.7 -C.sub.12 -phenylalkyl, such as benzyl, 
1-phenethyl, 2-phenethyl, 1-phenylpropyl, 2-phenylpropyl, 3-phenylpropyl, 
1-phenylbutyl, 2-phenylbutyl, 3-phenylbutyl or 4-phenylbutyl, particularly 
preferably benzyl, 1-phenethyl or 2-phenethyl, or a heterocyclic radical, 
such as an aromatic or a nonaromatic heterocyclic structure having from 
one to three hetero atoms, such as nitrogen, oxygen and/or sulfur, 
preferably nitrogen and oxygen, and n is an integer of from 3 to 7, such 
as 3, 4, 5, 6 or 7, preferably 4 or 5. 
Examples of preferred ketones II are: acetophenone, benzophenone, 
phenylacetone, methyl isopropyl ketone, 2-butanone, 2-pentanone, 
3-pentanone, hexanone, cyclohexanone and cyclopentanone. 
Examples of preferred cyclic amines III are: pyrrolidine, morpholine and 
piperidine. 
The preparation of such starting materials of the formulae II and III is 
sufficiently well known from standard works (Beilstein, Gmelin). 
The amines I are, as a rule, useful building blocks in organic synthesis. 
Such compounds are of particular interest as intermediates for drugs and 
active ingredients in herbicides, fungicides and insecticides and as 
catalysts for organic synthesis or in polymerizations.

The Examples which follow illustrate the invention. 
Gas-phase reaction 
The reactions in the gas phase are carried out under isothermal conditions 
in a tubular reactor (coil, 0.6 cm internal diameter, 90 cm length) over a 
fixed-bed catalyst. The amount of catalyst was varied from 1 to 20 g, 
corresponding to a space velocity WHSV of from 0.1 to 10 h.sup.-1. The 
reaction products are isolated by conventional methods and characterized 
by GC/MS. The quantitative determination of the reaction products and of 
the starting materials was carried out by gas chromatography or by 
weighing the fractions obtained by distillation or extraction. 
The catalysts used for the novel process are: 
Catalyst A 
The borosilicate zeolite of the pentasil type is prepared in a hydrothermal 
synthesis from. 640 g of finely divided SiO.sub.2, 122g of H.sub.3 
BO.sub.3, 8,000 g of an aqueous 1,6-hexanediamine solution (weight ratio 
of the mixture 50 : 50 ) at 170.degree. C. under autogenous pressure in a 
stirred autoclave. The crystalline reaction product is filtered off, 
washed thoroughly and then dried at 100.degree. C. for 24 hours and 
calcined at 500.degree. C. for 24 hours. 
This borosilicate zeolite is composed of 94.2% by weight of SiO.sub.2 and 
2.3% by weight of B.sub.2 O.sub.3. 
This material is molded with boehmite as a binder (weight ratio 60 : 40) to 
give 2 mm extrudates, which are dried at 110.degree. C. for 166 hours and 
calcined at 500.degree. C. for 24 hours. 
Catalyst A is obtained by subjecting these extrudates to ion exchange with 
ammoniacal palladium nitrate solution and then carrying out drying at 
110.degree. C. for 16 hours and calcination at 500.degree. C. for 5 hours. 
The Pd content is 3.3% by weight. 
Catalyst B 
The borosilicate zeolite of the pentasil type molded with boehmite (cf. 
catalyst A) is impregnated with an aqueous AgNO.sub.3 solution. 
Thereafter, drying is carried out at 130.degree. C. for 2 hours and 
calcination at 540.degree. C. for 2 hours. 
Catalyst C 
The borosilicate zeolite of the pentasil type molded with boehmite (cf. 
catalyst A) is treated with a 20% strength aqueous NH.sub.4 Cl solution at 
80.degree. C. for 2 hours. It is then washed Cl-free. Treatment is then 
carried out with an ammoniacal Pd nitrate solution at 50.degree. C. for 16 
hours in a circulation apparatus. After drying at 110.degree. C. for 2 
hours and calcination at 500.degree. C. for 5 hours, the Pd content is 
0.34% by weight. 
Catalyst D 
Borosilicate zeolite powder is prepared as described for catalyst A and 
subjected to ion exchange at 50.degree. C. for 4 hours with an ammoniacal 
Pd nitrate solution and an NaNO.sub.3 solution. Thereafter, drying is 
carried out at 110.degree. C. for 2 hours and calcination at 500.degree. 
C. for 5 hours. The Pd content of the zeolite after ion exchange is 0.45% 
by weight and the Na content is 0.12% by weight. This powder is molded 
with molding assistants at a molding pressure of 110 bar to give 2.5 mm 
extrudates. The extrudates are dried at 100.degree. C. for 2 hours and 
calcined at 500.degree. C. for 16 hours. 
Catalyst E 
The borosilicate zeolite of the pentasil type molded with boehmite (cf. 
catalyst A) is impregnated with an ammoniacal Pt chloride solution. 
Thereafter, drying is carried out at 130.degree. C. for 2 hours and 
calcination at 540.degree. C. for 2 hours. The Pd content is then 2.49% by 
weight. 
Catalyst F 
Borosilicate zeolite powder is prepared as described for catalyst A and 
subjected to ion exchange at 50.degree. C. for 4 hours with an ammoniacal 
Pt chloride solution. The product is filtered off and washed thoroughly 
with H.sub.2 O and then dried at 110.degree. C. for 2 hours and calcined 
at 500.degree. C. for 5 hours. The Pt content is then 2.11% by weight. 
Catalyst G 
An aluminosilicate zeolite of the pentasil type is prepared under 
hydrothermal conditions, at autogenous pressure and 150.degree. C., from 
65 g of finely divided SiO.sub.2, and 20.3 g of Al.sub.2 
(SO.sub.4).sub.3.18H.sub.2 O in 1 kg of an aqueous 1,6-hexanediamine 
solution (weight ratio of the mixture 50 : 50 ) in a stirred autoclave. 
The crystalline reaction product is filtered off, washed thoroughly and 
dried at 110.degree. C. for 24 hours and calcined at 500.degree. C. for 24 
hours. This aluminosilicate zeolite contains 91.6% by weight of SiO.sub.2 
and 4.6% by weight of Al.sub.2 O.sub.3. The catalyst is molded with a 
molding assistant to give 2 mm extrudates, which are dried at 110.degree. 
C. for 16 hours and calcined at 500.degree. C. for 24 hours. 
These extrudates are impregnated with an aqueous solution of Cu nitrate, Ni 
nitrate and Pd chloride. After drying at 130.degree. C. for 2 hours and 
calcination at 540.degree. C. for 2 hours, the Cu content is 2.6% by 
weight, the Ni content is 0.57% by weight, the Pd content is 0.05% by 
weight and the Cl content is 0.06% by weight. 
Catalyst H 
Commercial Na Y zeolite is molded with boehmite in a weight ratio of 60 : 
40 at a molding pressure of 100 bar to give 2 mm extrudates, which are 
dried at 110.degree. C. for 2 hours and calcined at 500.degree. C. for 16 
hours. These extrudates are subjected to ion exchange with an ammoniacal 
Pd nitrate solution at 50.degree. C. After drying at 110.degree. C. for 2 
hours and calcination at 500.degree. C. for 5 hours, the Pd content is 
2.33% by weight and the Na content is 3.6% by weight. 
Catalyst I 
Na Y zeolite extrudates are subjected to ion exchange with a 20% NH Cl 
solution at 80.degree. C. for 2 hours, as described for catalyst H. This 
exchange is repeated 3 times. After drying at 110.degree. C. for 2 hours 
and calcination at 500.degree. C. for 5 hours, the Na content is 0.2% by 
weight. Ion exchange is now effected with an aqueous Co nitrate solution 
at 80.degree. C. for 2 hours. Thorough washing with H.sub.2 O is followed 
by drying at 130.degree. C. for 2 hours and calcination at 540.degree. C. 
for 2 hours. 
Catalyst J 
The HY-zeolite prepared as catalyst J by ion exchange (but without molding 
with boehmite) is treated with an aqueous Cu nitrate solution and molded 
with a molding assistant to give 2 mm extrudates, which are dried at 
130.degree. C. for 2 hours and calcined at 540.degree. C. for 2 hours. The 
Cu content is 5% by weight. 
Catalyst K 
13X molecular sieve available commercially from Union Carbide and having an 
SiO.sub.2 content of 46.5% by weight, an Al.sub.2 O.sub.3 content of 27.9% 
by weight and an Na content of 11.3% by weight is subjected to ion 
exchange in a column with 20% strength aqueous Cu nitrate solution at 
80.degree. C. for 2 hours. Thereafter, it is washed NO.sub.3 -free, dried 
at 110.degree. C. for 2 hours and calcined at 500.degree. C. for 5 hours. 
The Cu content is 13.9% by weight and the Na content 1.3% by weight. 
Catalyst L 
Beta-zeolite available commercially from PQ Corporation and having an 
SiO.sub.2 content of 87.0% by weight and an Al.sub.2 O.sub.3 content of 
4.9% by weight is subjected to ion exchange with an ammoniacal Pd nitrate 
solution at 50.degree. C. for 4 hours. The product is filtered off and 
then dried at 110.degree. C. for 2 hours and calcined at 500.degree. C. 
for 5 hours. The Pd content is 2.73% by weight. This powder is molded with 
molding assistants to give 2 mm extrudates, dried at 110.degree. C. and 
calcined at 500.degree. C. for 16 hours. 
Catalyst M 
AlPO.sub.4 -5 (APO-5) is synthesized by dissolving or suspending 200 g of 
98% strength phosphoric acid and 136 g of boehmite in 335 g of water, 
adding 678 g of a 30% strength aqueous tetrapropylammonium hydroxide 
solution and reacting this mixture at 150.degree. C. under autogenous 
pressure for 43 hours in a stirred autoclave. The crystalline material is 
filtered off and then dried at 120.degree. C. and calcined at 500.degree. 
C. for 16 hours. The AlPO.sub.4 -5 synthesized in this manner contains 
45.5% by weight of Al.sub.2 O.sub.3 and 46.5% by weight of P.sub.2 
O.sub.5. This material is treated with an aqueous Rh nitrate solution and 
molded with molding assistants to give 2 mm extrudates, which are dried at 
120.degree. C. and calcined at 500.degree. C. for 16 hours. The Rh content 
is 2% by weight. 
Catalyst N 
Silicon aluminophosphate-5 (SAPO-5) is prepared from a mixture of 200 g of 
98% strength phosphoric acid, 136 g of boehmite, 60 g of 30% strength 
silica sol, 287 g of tripropylamine and 587 g of H.sub.2 O. This mixture 
is reacted at 150.degree. C. under autogenous pressure for 168 hours. The 
crystalline product is filtered off and then dried at 120.degree. C. and 
calcined at 500.degree. C. SAPO-5 contains 49.8% by weight of P.sub.2 
O.sub.5, 33.0% by weight of Al.sub.2 O.sub.3 and 6.2% by weight of 
SiO.sub.2. SAPO-5 is molded with finely divided silica gel in a weight 
ratio of 80 : 20 to give 2 mm extrudates, which are dried at 110.degree. 
C. and calcined at 500.degree. C. for 16 hours. These extrudates are 
subjected to ion exchange with ammoniacal Pd nitrate solution at 
50.degree. C. After drying at 110.degree. C. for 2 hours and calcination 
at 500.degree. C. for 16 hours, the Pd content is 0.5% by weight. 
Catalyst O 
An SAPO-11 is synthesized by homogeneously mixing 200 g of orthophosphoric 
acid (98% by weight) with 417 g of aluminum triisopropylate and 60 g of 
silica sol (30% by weight of SiO.sub.2) in 927 g of water and adding 91.5 
g of di-n-propylamine to this mixture. The reaction is then carried out at 
200.degree. C. under autogenous pressure for 96 hours in a stirred 
autoclave. The silicon aluminophosphate is filtered off, washed, dried at 
110.degree. C. and calcined at 500.degree. C. The SAPO-11 is composed of 
40.4% by weight of Al.sub.2 O.sub.3, 49.5% by weight of P.sub.2 O.sub.5 
and 1.87% by weight of SiO.sub.2. This material is molded with a molding 
assistant to give 2 mm extrudates which are dried at 110.degree. C. for 16 
hours and calcined at 500.degree. C. for 16 hours. These extrudates are 
subjected to ion exchange with an ammoniacal Pd nitrate solution at 
50.degree. C. After drying at 110.degree. C. for 2 hours and calcination 
at 500.degree. C. for 16 hours, the Pd content is 0.5% by weight. 
Catalyst P 
SAPO-34 commercially available from Union Carbide Corporation is molded 
with pyrogenic silica gel in a weight ratio of 80 : 20 to give 2 mm 
extrudates, which are dried at 110.degree. C. and calcined at 500.degree. 
C. for 16 hours. These extrudates are subjected to ion exchange with an 
ammoniacal Pd nitrate solution at 50.degree. C. After filtration, drying 
is carried out at 110.degree. C. for 2 hours and calcination at 
500.degree. C. for 16 hours. The Pd content is 0.5% by weight. 
The experimental results obtained with these catalysts are listed in the 
Tables below. 
Reaction A: Benzophenone + pyrrolidine .fwdarw. 
Reaction B: Methyl isopropyl ketone + morpholine .fwdarw. 
Reaction C: Methyl isopropyl ketone + piperidine .fwdarw. 
Reaction D: Methyl isopropyl ketone + pyrrolidine .fwdarw. 
Reaction E: 2-Pentanone + morpholine .fwdarw. 
Reaction F: 2-Pentanone + piperidine .fwdarw. 
Reaction G: 2-Pentanone + pyrrolidine .fwdarw. 
Reaction H: 2-Pentanone + 2,6-dimethylpiperidine .fwdarw. 
Reaction I: 2-Pentanone + 4-methylpiperidine .fwdarw. 
TABLE 1 
______________________________________ 
Catalyst screening for reactions A-G 
Conver- 
Selec- 
Ex- Re- H.sub.2 
sion % tivity % 
am- Cata- ac- Temp. WHSV ml/ based on 
based on 
ple lyst tion .degree.C. 
h.sup.-1 
min ketone product 
______________________________________ 
1 A A 170 1 64 49.5 62.7 
2 A B 180 1.4 64 40.8 79.7 
3 A C 150 0.7 32 14.2 71.1 
4 A C 180 0.7 32 50.1 78.3 
5 A C 180 1.4 64 46.1 74.1 
6 A C 200 2.3 128 30.4 60.1 
7 A E 160 1.5 64 36.7 86.0 
8 A E 170 1.4 64 85.8 97.0 
9 A E 180 1.5 64 83.5 97.2 
10 A E 190 1.5 64 75.1 93.6 
11 B E 170 1.4 64 18.4 69.2 
12 B E 200 1.4 64 14.4 63.6 
13 C E 170 1.5 64 73.2 98.2 
14 D B 170 1.2 64 10.4 71.0 
15 D C 170 1.3 64 14.3 79.2 
16 D E 170 1.6 64 45.2 93.6 
17 D F 170 1.3 64 66.7 96.8 
18 E E 170 1.5 64 70.0 99.0 
19 F E 170 1.0 64 55.8 98.3 
20 G E 170 1.7 64 17.0 89.2 
21 H E 170 0.8 32 62.7 94.8 
22 H E 170 1.4 64 75.7 96.2 
23 H B 180 1.4 64 33.0 90.2 
24 J E 170 1.5 64 6.5 37.5 
25 I E 170 1.5 64 15.3 82.8 
26 J E 170 1.5 64 23.0 94.7 
27 K E 220 1.4 64 13.6 87.6 
28 K H 170 1.2 64 7.4 41.3 
29 L I 170 1.4 64 71.3 98.4 
30 L A 170 0.9 64 44.9 58.8 
31 L B 170 1.5 64 33.5 95.7 
32 L C 170 1.4 64 55.0 93.8 
33 L D 170 1.5 64 41.1 95.4 
34 M E 170 1.3 64 46.0 97.6 
35 N E 170 1.4 64 42.5 97.7 
36 O E 170 1.4 64 63.6 98.8 
37 P E 170 1.5 64 50.4 97.4 
______________________________________ 
TABLE 2 
______________________________________ 
Catalyst L, reaction F, 170.degree. C., WHSV = 1.4 h.sup.-1, 
64 ml/min H.sub.2 
EXAMPLE 38 
Selectivities 
Time Conversion 
[h] Educt 1 Product 
______________________________________ 
1.25 88.42 97.88 
2.25 89.77 99.63 
4.25 89.01 99.50 
8.25 86.18 98.80 
12.25 85.31 98.22 
16.25 84.35 98.73 
20.25 83.85 98.57 
24.25 83.53 99.00 
28.25 82.07 98.70 
32.25 81.88 98.11 
36.25 81.46 98.09 
40.25 81.72 97.95 
44.25 81.58 98.24 
48.25 81.29 97.94 
52.25 80.12 98.03 
56.25 79.98 98.18 
60.25 79.83 98.02 
48.25 81.29 98.08 
60.50 -- -- 
83.43 98.43 
______________________________________ 
TABLE 3 
______________________________________ 
Catalyst L, reaction G, 170.degree. C., WHSV = 1.2 h.sup.-1, 
64 ml/min H.sub.2 
EXAMPLE 39 
Selectivities 
Time Conversion 
[h] Educt 1 Product 
______________________________________ 
0.25 
1.25 79.51 91.27 
2.25 86.76 96.92 
4.25 88.58 96.78 
8.25 89.81 96.95 
12.25 90.43 97.48 
16.25 90.66 97.01 
20.25 90.54 97.36 
24.25 90.38 97.58 
28.25 89.18 96.32 
32.25 88.68 96.03 
36.25 88.67 95.91 
40.25 88.77 95.91 
44.25 88.63 95.64 
48.25 88.51 95.51 
52.25 86.96 96.03 
56.25 86.70 96.80 
60.25 86.68 96.54 
48.25 88.38 95.49 
60.25 -- -- 
88.73 96.49 
______________________________________ 
TABLE 4 
______________________________________ 
Catalyst L, reaction G, 170.degree. C., WHSV = 1.4 h.sup.-1, 
64 ml/min H.sub.2 
EXAMPLE 40 
Selectivities 
Time Conversion 
[h] Educt 1 Product 
______________________________________ 
0.25 
1.25 90.39 98.87 
2.25 92.30 97.00 
4.25 88.75 99.30 
8.25 87.64 97.63 
12.25 86.81 99.52 
16.25 84.92 99.25 
20.25 85.79 99.75 
24.25 85.38 100.00 
28.25 84.80 98.52 
32.25 84.68 98.51 
36.25 67.90 81.82 
40.25 84.42 98.50 
44.25 84.18 97.99 
48.25 83.76 98.49 
52.25 83.72 98.60 
56.25 83.76 98.47 
60.25 83.40 98.33 
48.25 83.65 98.49 
60.25 -- -- 
85.49 98.62 
______________________________________