Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
This invention relates to a process for the production
of ~-methyl piperidine by the catalytic hydrogena-tion o~
2-methyl glutaric acid dinitrile (1~3 butane dicarbonitrile)
in the liquid phase9 according to the following reaction soheme:
IH3~ 4H2 i ~ C~
NG--CE--CE2~ CH2--C~J ~ l l
3 ~ ~ ~ (I) -
(II) H
3-Methyl piperidine (I) may be obtained by the hydro-
genation of~ -picoline (J. Amer. Chem9 Soc, 49, (1927)t
(2837). Howevers 3-methyl piperidine may also be obtained from
2-methyl glutaric acid dinitrile (II), which can be formed
~rom 2-me-thylene glutaxic acLd dinltrile b~ hydro~enating the
double bond, the 2-methylene glutar:lc acid clinltri:Le helng ln
turn obtainable from acrylonitrile by dimerisa-tion. One method
by which 3-methyl piperidine has been obtained from 2-me-thyl
glutaric acid dinitrile is by reduction wi-th sodium in ethanol
(Monatshefte fur Chemie 23, (1902) 878, 883) or in butanol (Zhur.
Obshchei Khim 24, tl954) 291-298; C.A 49 (1955) 4643, 8109).
In the latter case, 3 methyl plperidine was obtained in a yield
of 21~ together wi-th 68~o o~ 2-methyl-1~5-dlaminopentane.
In another synthesi~, 2-methyl glutarlc acid dinitrile
was initially cyclised with sodium amide to form the glutari-
midine derivative in a yield of 70%. The glu-tarimidine deriva-
tive thus ~ormed was then reduced with sodium in alcohol to
form 3-methyl piperidine (~ull. Chemu Soc. Japan 35, (1962)
1438-1443; Japanese patent No~ 14 140/65)o
~he above syntheses are unsuitable for the production o~
3-methyl piperidine on a commercial scale bo-th on account of the
poor yield and on account of the high consumption of 30dium or
sodium amide~
9~ :
Conventionally, a cobalt ca-talyst has been used in the
hydrogenation of 2-methyl glutaric acid dinitrile to produce
2-methyl-1,5-diaminopen-tane in high yields. Additives ~uch
as ammonia or tertiary aliphatic amines containlng from 3 to 5
carbon atoms per molecule, or these compounds together with al~
cohols containing from 1 to 12 carbon atoms per molecule have : -
been found to be ef~ective as solvents in increasing the yield
of 2-me-thyl-1,5-diamino pentane in the catalytic hydrogenation
process using cobalt catalysts.
Contrary to expectations, we made the surprising disco-
very tha-t -the use of a nickel catalyst, such as finely divided
nickel, for example Raney nickelt or nickel on a support, pro-
motes the formation of 3-methyl piperidine and suppresse~ for-
mation of the 2-methyl-1, 5-diaminopentane which would normally
be e~pected.
Accordingly1 the present invention provides a process
for the production of 3-methyl piperidine9 which process com-
prises hydrogenating 2-meth.yl glutaric acid dinitrile in the
presence o~ a nickel catalyst.
According to -the process of the invention, 3-methyl
piperidine is produced in a yield of over 50 mol ~, based on
the theoretical yield9 and yields of over 80 mol % are possible~
'~he hydrogenation gas i5 preferably hydrogen alone.
I-t has been found that the addition of considerable
quantities of such substances as, for example, ammonia, which
generally promote the formation of the linear diamine, do not . -
prevent the formation of 3-methyl piperidine.
Experimental inves-tigations produced the following sur-
prising results.
30i As indicated in Example 1, reported herei.naf-ter there ; :
wa~ obtained 2-methyl-1,5--diaminopentane in yields of up to 90~
of the theoretical in the h~drogenation of 2-methyl glutaric
2-
, ; , , ~ :;, -. , , : .
~os~
acid dinitrile in li~uid ammonia using commercial coball ca-
taly3ts such as RCI-I 45/20* (a product of ~Ioechst A~G), or 0121
(a produc-t of ~Iarshaw Chem. ~V, de Meern/holland). After
changing the cobalt catalyst for nickel-con~aining supported
catalysts, such as RCH 55/10*(1Ioechst AG) or 3250 ~ (~Iarshaw),
there was ob-tained 3-methyl piperidine as main product in a
yield of up to 90% following exactly -the same procedure. ~e
production of 3-methyl piperidine is not confined to the US8
uf supported catalysts or continuous workingO It can also
be produced by carrying out hydrogenation in ~L-tches, for ex-
ample in the presence of Raney nickel catalyst.
~he hydrogenation of 2-methyl glutaric acid dinitrile
is preferably carried out in the presence of hydrophilic subs-
tances as solvents or dlluents.
The proces~ may be carried out wit;h advantag~ the
presence of liquid ammonia as diluent. However, the formation
of 3-me-thyl piperidine is not confined to the presence of
ammonia. Comparable quanti-ties are also obtained with admix-
tures comprising ammonia and aliphatic or cycloaliphatic al-
cohols, preferably having from 1 to about 8 carbon a-toms, such
as methanol, ethanolt propanol, isopropanol, bu-tanol, hexanol
or cyclohexanol. The hydrogenation o~ 2-methyl glutaric acid
dinitrile to ~`orm 3 me-thyl piperidlne in the process o~ the in-
vention may also be carried out in non-alcoholic solvents, such
as dicyclohexane, dioxane, tetrahydrofuran and ether~ In ge-
neral, the diluent ~enerally has to satisfy the requirement of
at least acting a~ a solvent for the 3-me-thyl piperidene which
is formed. }Iydrogenation may even be carried out in 3-methyl
piperidine itself as reaction medium~
Although the presence of~ for example 9 ammonia, tertiary
aliphatic amines and, op-tionally~ alkali hydroxide and/or al-
kaline earth hydroxide is not absolutely essential9 it i~ of
* Trademarks
,~s,
advantage insofar as it reduces or eliminates the undesirable
formation of relatively high boiling secondary products~ for
example condensed secondar~ and tertiary amines
'~he quantity o~ diluent, where presen-t, is not cri-tical.
It is preferable to use ratios by volume of ammonia or other
diluents to nitrile in the range from 1:0.01 to 1:109 prefe-
rably from 1:0.1 to 1: 10
The catalysts used for hydrogena-tion may be commercial
nickel catalyst, for example, RC}I 55/10 ~rS~ a product of ~arb-
werke E1oechst, G49A* a product of Girdler-Sudchemi Kat. GmbH,
Ni 0104 P*or 3250 T* products of Harshaw ~hemie BoVo These
cata]ysts are supported cataLyts based on kieselguhr or aLumi-
nlum oxlde with Ypecial activators aclded. ~t ls also possible
to use puxe metal catalysts such as raney nickel. The quantity
in which the catalyst is usecl is not crucial to the rsaction,
~`he only requirement in this respect is that the catalyst should
be present ~ a sufficie~tly larg~ quantity to keep reduction in
process. ~his quan-tity is in the same order of magnitude as
the quantities normally used in the hydrogenation of nitrile
compounds, that i5, genèrally betwecn 0.5 and 10~ by weight,
based on th0 dini-trile.
The process may be carried out in batches or continu-
ously.
In cases where hydrogenation is carried out in a batch
manner, the ~atalyst is preferably used ln powdered form. After
the reaction solution has been filtered off, the catalyst may
be used for further hydrogenation cycles~
For continuous liquid-phase hydrogena-tion in the sump
phase or by the trickle process9 -the suitably shaped ca-talyst
is arranged as a fixed bed in the reactor,
It is preferred tha-t the process according to the in-
ventlon takes place at a temperature in the range from 80 to
* Trademarks
,~c,
098~
200C and pre~erably at a temperature in the range from 75 to
150C. It is preferred that the gas comprising molecular hy-
drogen is used at a pressure of up to 500 atms preferably un-
der a pressure of from 50 to 200 atms
The continuous process may be worked for prolonged
periods with high yields of 3-methyl pipeIidine. Ammonia may
be distilled o~f from the reaction produc-t and recycled into
the process irrespective o~ small quantities of 3-methyl pi-
peridine present therein~
3-Methyl piperidine is used as a vulcanisation acce-
lerator and as an additive for lubricating oils. It is also
~n intermediate product for the production of nicotinic acid
which is of significance as a medicament and animal feed sup-
plement.
'~he inventlon is illustrated by the following Examples.
EXAMPLE 1 (Comparison Example~
After the air present in it had been displaced by ni-
trogen, a vertically arranged 0,5 litre capaci-ty pressure tube,
filled with 0.3 litres (280 g) of cobalt catalyst of the
RCH 45/20 * type in the form of tablets measuring 5 x 6 mm
(~ product of ~arbwerke Hoechst) was filled with hydrogen gas
to a pressure of 400 atms, 70 ml/h of 2-methyl glutaric acid
dinitrile and 720 ml/h of li~uid ammonia were the~ introduced
into the tube $rom the bottom at a temperature maintained at
110~. A pressure of 400 atms. was maintained by continuously
replacing the hydrogen consumed, the hydrogen being recycled
in order to dissipate the heat of reaction. ~he reaction mix-
ture i~suing from the reactor passed through a cooling coil -
into a receiver from which it was continuously removed, The
removal o~ ammom a by distilla~ion g~70ml/h of a ~ixture which,
according to analysis by gas chromatography, contai~ed 90~9
o~ 2-methyl-1,5-diamino pen-taneS 8.2% o~ 3-methyl plperidine
* Trademark~
~ -5-
. ~ , .
87
and 1 to 2~ of more highly condensed secondary and tertiary
aminesO
EXAMPLE 2
~ he procedure was as in Example 1, except that -the ca-
talyst used in that Example was replaced by the same volume
t240 g) of a nickel catalys-t of the RC~I 55/10*type in the form
of -tablets measuring 5 x 6 mm ( a product of Hoechst AG), Work-
ing up in the same way produced a reaction mixture con-taining
3.9~ of 2~methyl-175-diaminopentane, 90.1% of 3~methyl piperi-
dine and from 6 to 8% of more highl~ condensed polyamines.
Wiith this catalyst, it was found that the hydrogenpressure could be lowered to 130 atmosphere3 without any adverse
effects upon the reaction,
~.
The procedure was as in the preceding Example3, except
that the pressure tube was filled with 0.33 litres ~330 g) of
~ickel catalyst 32 50 T*in the fol~ of tablets measuring 3 x ~ mm,
~nd 100 ml/h of 2-methyl glutaric acid dinitr$1e and 720 ml/h
of liquid ammonia were introduced -into it at 155~/400 atmos-
pheres hydrogen pres3ure. Working up in -the same way as in
Example 1 ga~e 100 ml/h of a mixture which, according -to ana-
lysis by gas chromatography, consisted of 90.7~ of 3-mcthyl pi-
peridine and 3.7~0 of 2-me-thyl-1,5-diaminopentane.
Examples 4 to 7, which illustra-te the batch-type process9
yielded results which axe set out in the following Table. ~he
general procedure adopted for -these Examples was as follows:
A high-pressure autoclave was filled, under nitrogen,
with -the quantities indicated of 2-methyl glutaric acid dinitrile
(MGN) and sol~ent other than ammonia~ i~ any. After the auto-
clave had been closed and purged wi-th hydrogen, the quan-tity of
liquid ammonla indicated was in-troduced into i-t under pressure
* Trademarks
,, ;,
from a measuring ~es~el~ Hydrogen was introduced while stirring
in the same way as before, and the reaction was initiated by
heating. After reduction had commeneed, recognisable from the
drop in the hydrogen pressure and the increase in reaction tem
perature, the pressure was kept constant by the continuous in-
troduction of hydrogen~ whilst the -temperature was kept 20
degrees C above the initiation temperature by controlling the
stirring periods
After the hydrogen ~ad been absorbed~ followed by cool-
ing to 40 to 50C, the excess hydrogen was blown of~ with the
free ammonia. The catalyst was then separated off through a
pressure filter, washed with solven-t (where one was used) and
the filtrate was ~ractionated under normal pressure through
a 50 cm Vigreux column. ~he removal of dlssolved ammonia
and solvent left a crude d-ist~lla-te~ boiling at a maximum o~
185C, which was separated by fractina-tion through a 1 20 m
packed column into the components 3-methyl piperidine (MP) hav-
ing a boiling point of 125 to 126~9 and 2-methyl-1,5-diami- -
nopentane (MD) having a boiling point of 192C. ~he crude dis-
tillation residue was a viscous product consisting of secon-
dary and tertiary amines9 of which the quan-ti-ty corresponded
-to the di~ference in yield in the Table.
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