PROCESS FOR THE PREPARATION OF DIAMINOMALEONITRILE

PROCEDE POUR LA PREPARATION DU DIAMINOMALEONITRILE

English Abstract

PROCESS FOR THE PREPARATION OF DIAMINOMALEONITRILE
ABSTRACT OF THE DISCLOSURE
A process for the preparation of diaminomaleonitrile
in high purity comprising polymerizing hydrogen cyanide in the
presence of an alkyl aluminum compound having the general
formula
<IMG>
wherein R1 is alkyl containing 1 to 10 carbon atoms, and R2
and R3 are hydrogen, halogen having 17 to 53 of atomic number
or alkyl containing 1 to 10 carbon atoms.
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Claims

WHAT IS CLAIMED IS:
1. A process for the preparation of diaminomaleonitrile
comprising polymerizing hydrogen cyanide in the presence of
an alkyl aluminum compound having the general formula
<IMG>
wherein R1 is alkyl containing 1 to 10 carbon atoms,
and R2 and R3 are hydrogen, halogen having 17 to 53 of atomic
number or alkyl containing 1 to 10 carbon atoms.
2. A process according to claim 1, wherein the alkyl
aluminum compound is used in amounts of the molar ratio to
hydrogen cyanide of from 0.001 to 1.
3. A process according to claim 1, wherein the alkyl
aluminum compound is used in amounts of the molar ratio to
hydrogen cyanide of from 0.005 to 0.1.
4. A process according to claim 1, wherein the reaction
is carried out at a temperature of -20° to + 150°C.
5. A process according to claim 1, wherein the reaction
is carried out at a temperature of -10° to + 50°C.
6. A process according to claim 1, wherein the alkyl
aluminum compound has the following general formula
11

<IMG>
wherein R1 is alkyl containing 1 to 5 carbon atoms,
and R2 and R3 are one member selected from the group
consisting of hydrogen, chlorine, bromine, iodine and
alkyl containing 1 to 5 carbon atoms.
7. A process according to claim 1, wherein the
alkyl aluminum compound has the following general
formula
<IMG>
wherein R1 is alkyl containing 1 to 5 carbon atoms,
and R2 and R3 are one member selected from the group
consisting of chlorine, bromine and alkyl containing
1 to 5 carbon atoms.
8. A process according to claim 1, wherein the
alkyl aluminum compound is a trialkyl aluminum having
general formula
<IMG>
wherein R1, R2 and R3 are alkyl containing 1 to 10
carbon atoms.
9. A process according to claim 2, wherein the
alkyl aluminum compound is a trialkyl aluminum having
general formula
<IMG>
wherein R1, R2 and R3 are alkyl containing 1 to 5
carbon atoms.
12

10. A process according to claim 2, wherein the reaction
is carried out in a solvent.
11. A process according to claim 10, wherein the solvent
is at least one member selected from the group consisting of
aromatic, aliphatic and alicyclic hydrocarbons.
12. A process according to claim 10, wherein the solvent
is aromatic hydrocarbons.
13. A process according to claim 9, wherein the trialkyl
aluminum is triethyl aluminum.
14. A process according to claim 9, wherein the trialkyl
aluminum is tri-n-propyl aluminum.
15. A process according to claim 9, wherein the trialkyl
aluminum is triisobutyl aluminum.
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Description

1057305
The present invention relates to a process for the
preparation of diaminomaleonitrile and, more particularly,
to a~l improved process for the preparation of diaminomaleo-
nitrile by polymerizing hydrogen cyanide in the presence of
alkyl aluminum and its derivatives.
Diaminomaleonitrile is known as a tetramer of hydrogen
cyanide, having the structural formula:
H2N - C - CN
.' 11
H2N - C - CN
and is of great value as a starting compound for the synthesis
of various heterocyclic compounds, especially as a raw material
for the manufacture of intermediates and medicinal compounds,
such ~s dicyanopyrazine, ade~ine and dicyanoimidazole~ various
chemicals~ agricultural chemicals and additives for foodstuffs.
However, it has been of a very high price because there has not
been developed any favorable process for the synthesis thereof.
In a prior process, diaminomaleonitrile has been prepared
by polymerizing hydrogen cyanide in a presence of a basic compound
such as alkali cyanides, trialkylamines or organic quaternary
ammonium hydroxid~s as a catalyst and separating and purlfying
diaminomaleonitrile from the resulting polymerizate. This
prior process, however, is low in reaction rate and in yield.
Pecently, great advance and improvement have been ac-
complished and more than 50/O of yield can be obtained as dis-
closed in Japanese Patent Open No. 2917/1971 and Japanese Patent
Publication No. 5925/1972. In the former process diaminomaleo-

~057305 :`
nitrile is prepared by polymerizing hydrogen cyanide using
cyanogen together with hydrogen cyanide in a solvent in the
pr0sence of a basic compound such as trialkylamines. Accord-
ing to this process, although about 7~,h of yield can be attained,
a large amount of cyanogen should be elnployed. Therefore,
cyanogen should be previously prepared, so a special apparatus
and process are necessary.
In the latter process, it ls prepared by dissolving
hydrogen cyanide into dissolving dimethylsulfoxide, adding
sodium cyanide as a catalyst and heating it in an autoclave.
~lowever, thi~ process has some disadvantages that separation
and further recovering purificatio~ process of dimethylstllfoxide
is necessary.
Further, polymerizate of hydrogen cyanide obtained by
the above mentioned any known methods contains a large amount
o~ perpolymerizate, diaminomaleonitrile has low purity, thus
diaminomaleonitrile should be obtained by complicated purific-
atlon processe~.
Accordingly, an object of the present inventlon is to
provide a novel process for the preparation of diaminomaleo-
nitrile.
~ nother object of the present inv0ntion is to provide
a process for the preparation of diaminomaleonitrile in high
purity,
~ still another object of the present invention is to
provide a process for the preparation of highly pure diamino-
maleonitril0 by a simple process in high yieldO
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~057305
The aforesaid objects are accomplished by a process
for the preparation of diaminomaleonitrile comprisi.ng poly-
meri.zin~ hydrogen cyanide in the presence of an allcyl aluminum .;
compound. l~ccording to the present in~ntion, considerably
highly pure diaminomaleonitrile can be obtained in consi.der-
; ably high yield,
The alkyl aluminum compound ùsed in the present invention
i9 one having at least one alkyl group in a molecule and has
the following general formula:
1 1 R3
wherein Rl is alkyl containing 1 to 10 carbon atoms, and R2
and n3 are hyclrogen, halogen having 17 to 53 of atomic number
or alkyl containing 1 to 10 carbon atoms,
In the above mentioned formula~ ~1 is preferably alkyl
containing 1 to 5 carbon atom~, and R2 and ~3 are one member
selected from the group consisting of hydrogen, chlorine,
bromine~ iodin~ and allcyl containing 1 to 5 carbon atoms.
Rl, R2 and R3 are more preferably alkyl containing 1 to 10
carbon atoms and most preferably alkyl containing 1 to 5 carbon
atoms.
Typical alkyl aluminum compound~ are trimethyl aluminum,
triethyl aluminum~ tri-n-propyl aluminum~ triisopropyl alumin~lm,
tri-n-butyl aluminum, triisobutyl aluminum~ tri-tert-butyl
aluminum~ tripentyl aluminum, trihexyl aluminum, triheptyl
aluminum, trioctyl aluminum, trinonyl aluminum, tridecyl alumi-

1057305
num~ dimethyl aluminum hydride~ diethyl aluminum hydride,di-n-p~pyl aluminum hydride, diisopropyl aluminum hydride,
di-n~butyl aluminum hydride~ diisobutyl aluminum hydride,
di-t~rt-butyl aluminum hydride, dimethyl aluminum chloride,
diethyl aluminum chloride, di-n-propyl aluminum chloride,
diisopropyl aluminum chloride, di-n-butyl aluminum chloride,
diisobutyl aluminum chloride~ di-tert-butyl aluminum chloride,
dihexyl aluminum chloride, dioctyl aluminum chloride, dimethyl
aluminum bromide, diethyl aluminum bromide, di-n-propyl
aluminum bromide, diisopropyl aluminum bromide, di-n-butyl
aluminum bromide~ di-tert-butyl aluminum bromide, dihexyl
aluminum bromide~ dioctyl aluminum-bromide, dimethyl aluminum
iodide, diethyl aluminum iodide~ di-n-propyl aluminum iodide,
dil~opropyl aluminum iodide~ di-n-butyl aluminum iodide~
diisobutyl aluminum iodide~ di-tert-butyl aluminum iodide,
dihexyl aluminum iodide, dioctyl aluminum iodide, methyl
aluminum dichloride, ethyl aluminum dichloride, n-propyl
aluminum dichloride, isopropyl aluminum dichloride, n-butyl
aluminum dichloride, isobutyl aluminum dichloride, tert-butyl
aluminum dichloride~ hexyl aluminum dichloride~ octyl aluminum
dichloride~ methyl aluminum dibromide~ ethyl aluminum dibromide,
n-propyl aluminum dibromide, isopropyl aluminum dibromide, n-
butyl a].uminum dibromide, isobutyl aluminum dibromide~ -tert-
butyl aluminum dibromide, hexyl aluminum dibromide, octyl
aluminum dibromide, methyl aluminum diiodide~ ethyl aluminum
diiodide~ n-butyl aluminum diiodide, isobutyl aluminum diiodide,
tertbutyl aluminum diiodide~ hexyl aluminum di.iodide and octyl
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alumLnum diiodide The alkyl aluminum compound may be used
in aTnounts of the molar ratio to hydrogen cyanide of from
0,OO:L to 1~ preferably from 0 005 to 0.1.
According to the present invention~ although poly-
merization of hydrogen cyanide may be carried out in the
ab~ence of a solvent~ it is preferably treated and sub~ected
to reaction under an inert gas and/or a solvent Any solvent
which can be dissolved the alkyl aluminum compound and does not
decompose it may be used. Typical solvents are an aromatic
hydrocarbon such as benzene~ toluene, xylene, pseudocumene,
durene~ etc " an aliphatic or alicyclic hydrocarbon such as
hexane~ heptane, octane, decane~ dodecane, cyclohexane, cyclo-
heptane~ cyclododecane~ etc. The solvent may be used in
amounts of the weight ratio to hydrogen cyanide of generally
from 1 to ~0~ preferably 10 to 30.
l~eaction temperature in the pre~ent invention is
generally -20 to + 150~C~ preferably -lO~ to ~ 50 C~ most
preferably 0 to ~ 20 C. Although reaction time depends upon
the amounts of the catalyst~ it i5 generally 1 hour to 7 days,
preferably 24 to 96 hours. If alkyl aluminum halide is u~ed
as a catalyst~ reaction rate is increased by adding a basic
compound such as trimethylamine, triethylamine, tripropylamine,
tributylamine and the like in an about equivalent. Reaction
pressure is automatically decided based on used amount of the
catalyst~ amount of the solvent and the reaction temperature,
but high pressure is not necessary~ and good results in yield
and purity can be obtained by carrying out the reaction for a
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1057305
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long time in a dilute solution.
When the solvent is use~, reaction product is precipi-
tated~ 80 white needle crystals of highly pure dia~inomaleo-
0 nitrile can be obtained only by filtrating the precipitate
by a screen or a filter after completion of reaction and
drying it. ~urther, the catalyst is still remained in the
solvent after removing the reaction product, so it can be
repeatedly used in the subsequent reaction by filtrating the
solvent by means of usual fiter paper or cloth.
As mentioned above, condiderably highly pure diamino-
maleonitrile can be obtained in high yield by employing the
. .~ .
alkyl aluminum compound as a polymerization catalyst for
hydrogen cyanide in the present invention, so purification
thereof is not substantially necessary, it is very eaonomical
on account of high yield. Further, in case of solution poly-
merization the reaction product 18 precipitated during the
reaction, 80 diaminomaleonitrile can be obtained a~ a highly
pure white crystals merely by filtration after completing
the reaction, Thus not only the separation process of the
reaction product is simple, but also allcyl aluminum compound
used as the catalyst can be easily removed by filter paper or
cloth after completing the reaction. Therefore~ there are
advantages that special recovering purification process for
the solvent is not necessary and it can be repeatedly used
as it is for the subsequent raaction.
The present invention will be more illustrated by
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:~057305
the following Lxamples, All of yields of diaminomaleonitrile
in the following ~xamples are percent by weight.
~XA~IPL~ 1
In a round-bottomed flask of a capacity of 200 ml
having a stopper~ there was charged 140 ml of toluene, then
added thereto 2 ml of triethyl aluminum and 5.0 g of hydrogen
cyanide. The flask was then put in a thermostat and maintained
at 5 C. After 72 hours, the reaction mixture was filtered by
a screen (80 meshes) to obtain 4.8 g of white needle crystals
of diaminomaleonitrile (yield 96~/o)~ This diaminomaleonitrile
was sub~ected to purity analysis~ That i9 to say, a spot of
diaminomaleonitrile was ~eparated by a thin layer chromato-
graphy~ and it wa~ desorbed by water~ and then it was analysed
by an ultraviolet spectrophotometer using a wave length of
295 m~. Purity of diaminomaleonitrile thus obtained was 98~/o~
EXA~IPLE 2
In a round-bottomed flask of a capacity of 200 ml
ha~ing a stopper~ there was charged 120 ml of xylene, then
added thereto 2 ml of tri-n-propyl aluminum and 5.0 g of
hydrogen cyanide. The flask was then put in a thermostat and
maintained at 10 C. After 48 hours~ the reaction mixture wa~
filtered by a screen (80 meshes~ to obtain 3~6 g of white
needle crystals of diaminomaleonitrile (yield 74.0~). This
diaminomaleonitrile was sub~ected to purity analysis by a
similar method as in Example 1 to obtain 97 ~ 3% of puritv,
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1057305
EXAMPLE 3
In a round-bottomed flaslc of a capacity of 200 ml
havillg a stopper, there was charged 140 ml of toluene, then
added thereto 2 ml of triisobutyl aluminum and 5.0 g of
hydrogen cyanide. The flask was then putin a thermostat and
maintained at 5~C. After 72 hours, the reaction mixture was
filtered by ascreen (80 meshes) to obtain 3.2 g of white
needle crystals of diaminomaleonitrile (yield 64.o~). This
diaminomaleonitrile was sub~ected to purity analysis by a
similar method as in Example 1 to obtain 97.5~ of purity.
~XAMPLE 4
In a round-bottomed flask of a capacity of 200 ml
having a stopper, there was charged 140 ml of toluene, then
added thereto 2 ml of diethyl aluminum chloride~ 2.3 ml of
; triethylamine and 5,0 g of hydrogen cyanide. The flask was
then put in a thermo~tat and maintained at 5C. After 72
hours~ the reaction mixture was filtered by a screen (80 meshes)
to obtain 3,0 g of white needle crystals of diaminomaleonitrile
(yield 60~/o)~ This diaminomaleonitrile was sub~ected to purity
analysis by a slmilar method as in Example 1 to obtain 91~3~o
of purity.
EXAMPLE 5
In a method of Example 1, toluene after removing di-
aminomaleonitrile was filtered by a filter paper to remove the
catalyst. Then 2 ml of triethyl aluminum and 5.0 g of hydrogen
cyanide were charged into it and maintained at 5C. ~fter 72
hours, the reaction mixture was filtered by a screen (80 meshes)
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1057305
; to obtain 4.8 g of white needle crystals of diaminomaleonitrile. This diamonomaleonitrile was sub~ected to purity analysis by
a ~imilar method as in Example 1 to obtain 96, 2% purity.
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Al:
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