Note: Descriptions are shown in the official language in which they were submitted.
` ~Z~8S~
Mo-2526
LeA 22,007
` DIISOCYANATES, DIISOCYANATE MIXTURES
AND A PROCESS FOR THEIR PRODUCTION
,
BACKGROUND OF THE INVENTION
__
This invention relates to isocyanatobenzyl-
5 cyclohexylisocyanates which may be present as isomer
~ mixtures and are alkyl-substituted at ~he aromatic ring.
J The present invention also relates to a process for the
production of such isocyanates.
Asymmetric diisocyanates which have one aro-
l0 matically and one cycloaliphatically bound isocyanate
~ group would be particularly suitable for the production
,~ of polyurethane plastics by the prepolymer process due
to the significantly different reactivity of the iso-
cyanate groups. The more highly reactive, aromatically
~; 15 bound isocyanate group would react to form the NCO
prepolymer which would then be converted into a high
molecular weight polyurethane in a second reaction
stage.
Such asymmetric diisocyanates would also be
20 suitable for the production of modified diisocyanates
such as uretdione diisocyanates. The more highly
reactive isocyanate group would be reacted off with
dimerization in a first reaction stage and a diisocya-
nate containing uretdione groups would be obtained.
25 This uretdione diisocyanate could then be further
reacted with compounds having groups reactive to iso-
cyanate groups.
U.S. Patent 3,663,514 describes one such diiso-
cyanate, namely 4-(4-isocyanatobenzyl)-cyclohexyliso-
30 cyanate. However, use of this disclosed diisocyanate
to any great extent has been limited due to the fact
that the diamine on which the diisocyanate is based
can only be obtained in yields of less than 35% of the
theoretical yield. These poor yields are attributable
35 to asy~metric nuclear hydrogenation. The pure asymmetric
Mo-2526
LeA 22 007-US ~æ
~168S~
.
-2-
diisocyanate can therefore only be obtained at consider-
'~ able purification cost .
SUMMARY OF THE INVENTION
It is an object of the present inVention to
provide new diisocyanates having aromatically and cyclo-
aliphatically bound isocyanate groups.
It is also an object of the present invention
~ to provide liquid diisocyanates having aromatically and
i~ cycloaliphatically bound isocyanate groups which have a
~ 10 low viscosity at room temperature.
,~ It is another object of the present invention
to provide diisocyanates having aromatically and cyclo-
',~ aliphatically bound isocyanate groups which are soluble
~ and compatible with hydroxyl group-containing compounds.
,~ 15 It is a further object of the present invention
to provide diisocyanates having aromatically and cyclo-
aliphatically bound isocyanate groups with a low content
of unhydrogenated or perhydrogenated diisocyanates.
It is yet another object of the present inven-
tion to provide a process for the production of diiso-
cyanates having aromatically and cycloaliphatically
bound isocyanate groups in high yield.
These and other objectswhich will be apparent
to those skilled in the art are accomplished by phos-
25 genating diamines or isomer mixtures of diamines cor-
responding to the formula
/R
(H2N)m ~ 2 ~ NH2
(NH2)n R
in which Rl, R , m and n are as defined below at a
temperature of from -20 to 250C.
: Mo-2526
s~
; `! - 3-
-~ DETAILED DESCRIPTION OF THE INVENTION
"
l, The present invention provides diisocyanates
'"J, which correspond to the formula: 1
'~3 ~F~
}~ (OCN)m ~ 2 ~ NCO
~ 2
';A~ (NCO)n R
-. 5 in which
l and R2 which may be the same or diferent each
represent hydrogen or (optionally branched)
, alkyl groups having from 1 to 12 carbon atoms,
~, provided that at least one of the radicals
i 10 Rl and R2 represents an alkyl radical, and
.l m and n each represent 0 or 1, provided that the
total of m + n - 1 and when m or n = 0,
the remaining free valency is saturated by
hydrogen~
t~ ~ 15 These diisocyanates may be in the form of isomer mix-
~ ~ tures and may be present in admixture with minor amounts
}~` : of the corresponding perhydrogenated diisocyanates and/or
~: corresponding unhydrogenated aromatic diisocyanates.
This invention also provides a process for
~; 20 the production of such diisocyanates or diisocyanate
mixtures, in which the aminobenzyl-cyclohexylamines
,~ on which the product diisocyanates are based and which
t~ are optionally present as a position and/or stereo
isomer mixture and optionally in admixture with minor
quantities of the corresponding perhydrogenated diamines
and/or the corresponding unhydrogenated aromatic diamines
are phosgenated in a known manner at from -20 to +250C.
This invention further provides a process for
the production of polyurethane plastics by the isocya~
nate-polyaddition process from the diisocyanates of the
present invention.
''` .
~: Mo-2526
~, ',`
.
i858
-4-
Startiny materials for the production of the
diisocyanates of the present invention are diamines or
~ mixtures of position and/or stereoisomers of diamines
I corresponding to the formula: R1
(H2N)m ~ CH2 ~ 2NH2
~NH2)n R
in which
Rll R2, m and n are as defined above. Preferred diamines
are those in which Rl and/or R2 represents alkyl groups
having from 1 to 4 ~arbon atoms and especially methyl
groups.
The diamines or diamine mixtures which are used
in the present invention are often mixtures in which
minor quantities of the corresponding perhydrogenated
diamines and/or with minor quantities of the correspond-
ing unhydrogenated aromatic diamines are present. Theexpression "minor quantities" as used herein means that
the proportion of perhydrogenated or unhydrogenated
diamines is in each case a maximum of 15, preferably a
maximum of S wt. %, based on total diamine mixture.
According to NMR spectroscopic findings, the main compo-
nent or the main components of the diamines or diamine
mixtures of the present invention (i.e., the amino-
benzyl-cyclohexylamines) are almost exclusively asym-
metric diamines of the specified structure in which the
alkyl substituents are bonded to the aromatic ring.
The composition of the diisocyana~es or of the diiso-
cyanate mixtures of this invention ~orresponds to the
composition of the diamines or diamine mixtures used as
starting material in the process of the present inven-
tion.
The diamines to be used in the present inven-
tion are preferably produced by partial nuclear hydro-
genation of the alkyl-substituted diaminodiphenyl
Mo-2526
~2J1 6858
--5--
methanes on which they are based. These asymmetrically
substituted diaminodiphenyl methanes may be obtained,
for example by condensation of _- and/or ~~nikrobenzyl
halides (particularly chlorides) with substituted
anilines corresponding to the formula
1 NH2 2
in which Rl and R2 are as defined above, and reduction
of the nitro group to produce the primary amine and by
subsequent transposition. Such a procedure is disclosed
in Belgian Patent 864,533 and British Patent 1,567,114.
Depending upon whether pure _-nitrobenzyl halide or pure
p-nitrobenzyl halide or mixtures of these isomers are
used during the condensation reaction, the ratio of the
4,4'-diamino-3(,5)-(di)-alkyldiphenylmethanes to the
4,2'-diamino~3(,5)-(di)-alkyldiphenylmethanes corresponds
substantially to the isomer ratio of _-nitrobenzyl
halide to o-nitrobenzyl halide used in the condensation
reaction. Only when monosubstituted anilines (R2 = H)
are used are minor quantities (up to 5 wt. %, based on
the total mixture) of 2,4'-diamino-3-alkyldiphenyl-
methanes and/or of the corresponding 2,2'-isomers pro-
duced.
The nuclear hydrogenation of the aromatic
diamines may be carried out by methods known to those
in the art (see U.S. Patent 2,511,028). In one such
method, aromatic diamines are hydrogenated catalytical-
ly with the addition of 3 mols of hydrogen per mol of
diamine. The hydrogenation reaction is preferably
interrupted after the consumption of 3 mols of hydrogen
per mol of starting compound.
Mo-2526
-' ~2~6~S~
--6--
Hydrogenation is carri0d out at from 20 ~o 300~,
preferably from 70 to 300C and most preerably from 120
to 250C under a pressure o~ from 20 to 300 ~ars, pre-
ferably from 70 to 300 bars and mosk preferably rom 120
to 250 bars.
The hydrogenation reaction is generally carried
out in the presence of from 0.1 to lO wt.%, preferably
from 0.1 to l wt. % of a hydrogenation catalyst, based
on catalytically active metal and on diamino compounds.
Suitable catalysts include, for example, elements of the
VIII Secondary Group of the Periodic System of Elements
which are optionally present on inert carriers (such as
active carbon, silica gel and in particular aluminum
oxide) or catalytically active inorganic compounds of
these elements. Specific examples of appropriate cata-
lysts are ruthenium, platinum, rhodium, nickel and/or
cobalt in elementary or chemically bound form. Ruthen-
ium or catalytically active ruthenium compounds are
preferred. Examples of suitable ruthenium compounds
include ruthenium dioxide, ruthenium tetroxide; barium
perruthenite; sodium, potassium, silver, calcium or
magnesium ruthenate; sodium perruthenate; ruthenium
pentafluoride; ruthenium tetrafluoride hydrate and
ruthenium trichloride. If a material is used as both
carrier and catalyst, the metal content of the carrier
catalyst is generally from l to lO wt. ~, preferably
from l to 5 wt. %. The type and quantity of catalyst
to be used is not essential to the present invention.
It is often appropriate to carry out the
hydrogenation reaction in the presence of ammonia
because a~monia suppresses undesired deamination reac-
tions and the formation o~ secondary amines as ky-
products. If ammonia i5 used, it may be used in quan-
tities of from 0.1 to 30 wt. %, preferably from 5 to lO
wt. ~ (based on the starting materials to be hydrogen-
ated).
Mo-25~6
~6~S~
--7--
The hydrogenation reaction may be carried out
without a solvent or in the presence of an inert sol-
vent. Low-melting or liqu~d diamines are generally
hydrogenated without using a solvent. High-melting
diamines are generally hydrogenated in dissolved form.
Organic compounds which are inert under the reaction
conditions and which have a low boiling point are suit-
able as solvents. Bxamples of suitable solvents are
alcohols such as methanol, ethanol, n-propanol and i_
propanol; ethers such as dioxane, tetrahydrofuran and
diethyl ether; and hydrocarbons such as cyclohexane.
Hydrogenation may be carried out continuously in a
reaction $ube or in a pressure boiler cascade. It is
preferable, however, that hydrogenation be carried out
discontinuously in a stirrer-equipped autoclave by
charging the autoclave with catalyst, the substance to
be hydrogenated and optionally with a solvent and
repeatedly flushing with inert gas and optionally meter-
ing in ammonia. Hydrogenation is then injected undPr
pressure, the mixture is brought to reaction temperature
and hydrogenation is carried out until the theoretically
necessary quantity of hydrogen has been absorbed.
After the reaction mixture has been cooled and the
catalyst has been separated, the hydrogenation product
may be worked up by distillation.
The hydrogenation products are obtained in
high yields. Mono-alkyl-substituted diamines may be
produced in amounts which are more than 70% of the
theoretical yield. Dialkyl-substituted diamines may be
obtained in amounts of more than 90~ of the theoretical
yield. Further, the hydrogenation products may be
almost completely separated by distillation from
unreacted aromatic diamines or from the perhydrogenated
diamines which are produced as by-products. The hydro-
genation products are generally stereoisomeric mixtures,optionally also position isomer mixtures which corres-
Mo-2526
685~
--8--
pond substantially to the starting materials with
respect to position isomerism. It is generally not
necessary to separate the products into individual
position and/or stereoisomers before using them as
starting materials in the process of the present inven-
tion because in this process isomer purity is not
necessary. In fact, isomer mixtures are often desirable
because they improve the properties of the product
diisocyanates.
Materials which may be produced by the above-
described hydrogenation process which are preferred
starting materials in the process of the present inven-
tion include: 4-(4-amino-3,5-dimethylbenzyl)-cyclo-
hexylamine, 4-(4-amino-3,5-diethylbenzyl)-cyclohexyl-
amine, 4-(4-amino-3,5-diisopropylbenzyl)-cyclohexyl-
amine, 4-(4-amino-3-ethyl-5-methylbenzyl)-cyclohexyl-
amine and isomer mixtures containing these diamines as
essential components; 2-(4-amino-3,5-dimethylbenzyl)-
cyclohexylamine, 2-(4-amino-3/5-diethylbenzyl)-cyclo-
hexylamine, 2-(4-amino-3,5-diisopropylbenzyl)-cyclo-
hexylamine, 2-(4-amino-3-ethyl-5-methylbenzyl)-cyclo-
hexylamine and isomer mixtures containing these diamines
as essential components; 4-(4-amino-3-methylbenzyl)-
cyclohexylamine, 4-t4-amino-3-ethylbenzyl)-cyclohexyl-
amine, 4-(4-amino-3-isopropylbenzene)-cyclohexylamine
and mixtures thereof with other position isomers (for
example the corresponding 2-(4-amino-3-alkylbenzyl)-
cyclohexylamines and/or 4-(2-amino-3-alkylbenzyl)cyclo-
hexylamines); 2-(4-amino-3-methylbenzyl)-cyclvhexyl-
amine, 2-(4-amino-3-ethylbenzyl)-cyclohexylamine,
2-(4-amino-3-isopropylbenzyl)-cyclohexylamine and
mixtures thereof with the corresponding 4-(4-amino-3-
alkylbenzyl)- or 4-(2-amino-3-al~ylbenzyl)-cyclohexyl-
amines.
When carrying out the process of the present
invention for the production of the new diisocyanates,
Mo-2526
~6~S~
phosgenation of ~he abo~e-mentioned diamines or o the
salts thereof may be carried out in accordance with
known methods in the presence oF an inert organic sol-
vent (see Houben-Weyl, Methoden der OrganiRchen Chemie,
Georg Thieme Verlag, Stuttgart (1952), Volume 8, 4th
edition, pages 120 et se~).
The hydrochlorides or ammonium carbamates which
may be produced by saturation of the diamine solutions
with gaseous hydrogen chloride or carbon dioxide are
examples of preferred salts which may be phosgenated
to produce the diisocyanates of the present invention.
In principle, other salts which are produced, for example
by neutralization of the diamines with proton-releasing
acids may also be phosgenated.
The selectivity of the phosgenation reaction
is dependent upon the amine concentration and the phos-
gene excess. The phosgene is preferably used in a high
molar excess which generally amounts to from 100 to
2000%, preferably from 100 to 1000%. The diamine to be
phosgenated is used in a considerably dilute form. The
amine concentration (based on the total quantity of
amine and solvent) generally amounts to 0.1 to 15 wt. %,
preferably from 5 to 10 wt. %.
Any inert organic liquids or mixtures thereof
which have a boiling point of from 60 to 250C may be
used as solvent in the phosgenation process. Examples
of appropriate solvents include halogenated hydrocarbons,
aromatic compounds, hydroaromatic compounds and chlorine
compounds thereof. The following are mentioned as
specific examples of suitable solvents: xylene, mesi-
tylene, chlorobenzene, dichlorobenzenei trichlorobenzene,
chlvronaphthalene and dichloroethane.
The reaction may be carried out either in one
stage by hot phosgenation at a temperature of from 100
to 25~C, or in two stages by cold/hot phosgenation at
Mo-2526
3S8
--10--
a temperature of from -20 to 250C under normal pressure,
When free amines are used as the starting compound (base
phosgenation), ammonium carbamic acid chloride i8 ~irst
produced at a temperature of from -20 to ~60C. This
ammonium carbamic acid chloride further reacts with phos-
gene to produce the diisocyanate at a temperature o~
from 20 to 250C. The products are generally purified
after de-phosgenation by evaporating the solvent and
by subsequent distillation under reduced pressure.
The products of the process of the present
invention, i.e., the new diisocyanates of this invention
are produced in high yields as colorless, low viscosity
liquids. These diisocyanates are valuable synthesis
components in the production of polyurethane plastics
by the isocyanate-polyaddition process. The position
and/or stereoisomerism of the new diisocyanates corres-
ponds to the isomerism of the diamines which are used
as starting materials for the phosgenation process.
It is not generally necessary to separate the mixtures
produced by the process of the present invention into
individual position and/or stereoisomers because the
products may be used directly in the production of poly-
urethanes. The new diisocyanates of this invention are
particularly advantageous for the production of poly-
urethane lacquers, polyurethane elastomers and polyure-
thane foams. Such polyurethanes may be produced by
processes known to those skilled in the art by using
the diisocyanates of the present invention instead of
or together with the polyisocyanates which have been
used by those in the art. The new diisocyanates or
diisocyanate mixtures of the present invention are
particularly advantageous in the production of poly-
urethane plastics by the prepolymer process.
The following examples illu~.trate the present
invention. All percentages relate to percent by weight,
Mo-2526
~3 6~S~
unless otherwise indicated. The analysis of the isomer
distribution of the intermediate and end products was
carried out by yas chromatography.
EXAMPLES
Example 1
la) 250 g (1.04 mols) of 4,4'-diamino-3-ethyl-
5-methyl-diphenylmethane and 25 g of ruthenium-aluminum
oxide carrier catalyst (5~ of Ru on A12O3) were intro-
duced into a 0.7 liter stirrer-equipped autoclave.
After repeated flushing with nitrogen and hydrogen,
25 g of ammonia were introduced with mixing. The mixture
was heated with stirring to 150-155C and hydrogenated
under 200 bars until 3.12 mols of hydrogen had been
absorbed. Thereafter, the mixture was allowed to cool,
the autoclave pressure was relaxed and the crude product
dissolved in methanol. The catalyst was filtered and
washed with methanol. The organic solutions were com-
bined. After evaporation of the solvent, the product
was subjected to a flash-distillation and then distilled
by fractionation. 220 g of diamine having a boiling
point of from 125 to 130C/0.05 mbar were obtained.
According to gas chromatographic findings, this diamine
was 97.2% 4-(4-amino-3-ethyl-5-methylbenzyl)-cyclo-
hexylamine, 0.8% 4,4'-diamino-3-ethyl-5-methyldicyclo-
hexylmethane and 2.0~ unreacted starting material andunknown diamine.
lb) 250 g of phosgene were dissolved in 700 ml
of chlorobenzene at from -5 to 8C. A solution of 123 g
of the diamine produced in Example la) in 700 ml of
chlorobenzene was added to the phosgene solution drop-
wise with stirring. A suspension was produced which
heated to 20C. The mixture was heated to 130C as
100 g/h of phosgene was introduced. The solids dis-
solved and the solution was boi~ed for an additional 2
Mo-2526
~l~1tii8S~3
-12-
hours under reflux. Thereafter, the addition o phos-
gene was completed. Excess phosgene was blown out with
nitrogen and the crude product was purified by di~til-
lation. 139 g (96% of the theoretical yield) of 4-(4-
isocyanato-3-ethyl~5-methylbenzyl)-cyclohexyl isocyanate
were produced. The product had the following properties:
Boiling point: 133 to 135~C/0.05 mbar;
NCO value: 28.3%;
Viscosity. 110 mPa.s~25C;
Content of hydrolyzable chlorine: 0.02~.
Example 2
2a) 250 g (1.11 mols) of 4,4'-diamino-3,5-
dimethyldiphenylmethane were hydrogenated in the presence
of 25 g of ruthenium-aluminum oxide carrier catalyst and
25 g of ammonia at 140C and under 200 bars by the same
procedure described in Example la). This hydrogenation
continued until 3.3 mols of hydrogen had reacted off.
After purifying by flash distillation and fine distilla-
tion at from 150 to 155C/0.1 to 0.2 mbar, 200 g of pro-
duct were obtained. According to gas chromatographicanalysis, the product was 97.4% 4-(4-amino-3,5-dimethyl-
benzyl~-cyclohexylamine, 2.1% 4,4'-diamino-3,5-dimethyl-
dicyclohexylmethane and 0.5% unreacted starting material.
2b) 116 g of the diamine mixture produced in
Example 2a~ dissolved in 700 ml of chlorobenzene were
added dropwise with intensive stirring into a solution
of 200 g of phosgene in 700 ml of anhydrous chloro-
benzene at from 0 to 8C. The resulting suspension
was heated to 120C with the introduction of 100 g/h
of phosgene. During this procedure, the solids slowly
dissolved and a clear solution resulted at 65C.
After phosgenating for two hours at 120C, the solution
was de-phosgenated and the crude product was purified
by distillation. 121 g (87.5% of the theoretical
yield) of 4-(4-isocyanato-3,5-dimethylbenzyl)-cyclo-
Mo-2526
~6~
-13-
hexyl isocyanate having a boiling point of from 138 to
141C/0.1 mbar, an NCO content of 29.5% and a viscosity
oE 140 mPa.s/25C were obtained.
~xample 3
3a) A 0.7 liter stirrer-equipped autcclave
was charged with 250 g (0.98 mols) of 4,4'-diamino 3,5-
diethyldiphenylmethane and 25 g of ruthenium-aluminum
oxide carrier catalyst (5% of Ru on A12O3). The auto-
clave was then flushed with nitrogen and 25 g of
ammonia were metered in. Thereafter, the mixture was
hydrogenated at 140C and under 200 bars until 3 mols
of hydrogen had been consumed. The autoclave was
allowed to cool, the pressure therein was relaxed,
the product was taken up in methanol and the catalyst
was filtered. The solvent was then drawn off and the
hydrogenated diamine was purified by flash and fine
distillation at from 136 to 140C/0.1 mbar. 170 g of
diamine having a content of 95.8% 4-~4-amino-3,5-di-
ethylbenzyl)-cyclohexylamine, 3,3% of perhydrogenated
starting diamine and 0.9~ of unreacted starting
material were obtained (according to gas chromato-
graphic analysis).
3b) 200 g of phosgene were dissolved in 700 ml
of anhydrous chlorobenzene. A solution of 130 g of
diamine from ~xample 3a) in 700 ml of dry chlorobenzene
was added dropwise to the phosgene solution with stir-
ring and cooling. A dispersion which was difficult to
stir and which changed into a clear solution during
heating with the introduction of phosgene at 80C
formed. The solution was boiled for 2 hours under
reflux, the addition of phosgene was completed, the
solution was de-phosgenated and the crude product was
distilled at 135C/O.9S mbar. 134 g (90% of the
theoretical yield) of 4-(4 isocyanato-3,5-diethyl-
benzyl)-cyclohexylisocyanate, were obtained having an
NCO content of 27.0% and a viscosity of 90 mPa.s/2SC.
Mo-2526
~l~216~
-14-
Example 4
4a) 250 g (0.89 mols) of 4,4'-diamino-3,5-
diisopropyl-diphenylmethane were hydrogena~ed in the
presence of 25 g of xuthenium-aluminum oxide carrier
catalyst (5% of Ru on A12O3) and 25 g of ammonia at
140C/200 bars by the same procedure as that used in
Example la), until 2.7 mols of hydrogen had been
absorbed. After flash distillation, the product was
subjected to fractional distillation. During this
procedure, 214 g of 4-(4-amino-3,5-diisopropylbenzyl)-
cyclohexylamine were produced in the main fraction.
According to gas chromatographic analysis, 0.5% of
perhydrogenated diamine and 0.5~ of starting diamine
were present in the product diamine.
4b) A solution of 200 g of phosgene in 700 ml
of dry chlorobenzene wasmixed with a solution of 144 g
(0.5 mols) of 4-(4-amino-3,5-diisopropylbenzyl)-cyclo-
hexylamine in the same manner as described in Example
la). The mixture was brought to reflux temperature with
phosgene and was boiled for 2 hours. De-phosgenation
was carried out and the product was purified by dis-
tillation under reduced pressure. The yield of 4-(4-
isocyanato-3,5-diisopropylbenzyl)-cyclohexylisocyanate
amounted to 154 g. The product had the following
properties:
NCO content: 24.6%;
Boiling point: 170-190C/0.1 mbar;
Hydrolyzable chlorine: 0.05%;
Viscosity: 500 mPa.s/25C.
Example 5
5a) 250 g (l.L8 mols) of 4t4'-diamino-3-
methyldiphenylmethane were hydrogenated in the pre-
sence of 25 g of a ruthenium catalyst (5 wt. ~
ruthenium on A12O3) and 25 g of ammonia by the same
procedure as was used in Example la). The crude product
was taken up in methanol, the catalyst was filtered and
Mo-2526
5~
-15-
washed, and the combined solutions were subjected to
fractional distillation under reduced pressur~. In the
main fraction, 210 g of diamine having a boiling point
of 125-135C/0.1 mbar were obtained. This diamine was
85.0% 4-~-amino-3-methylbenzyl)-cyclohexylamine,
13~ 4,4'~diaminodicyclohexylmethane and 2~ 4,4'-
diaminodiphenylmethane.
Sb) A s~lution of 400 g of phosgene in 1300 ml
of dry chlorobenzene was introduced into an autoclave
at -5 to 8C. 210 g of ~he diamine of Example 5a)
dissolved in 1300 ml of chlorobenzene were added drop-
wise with cooling and stirring. The resulting suspen-
sion was heated to 130~C with the introduction of 100
g/h of phosgene. The solids melted at from 50 to 60C.
An emulsion formed but it changed into a clear solution
at 75C. Phosgenation was carried out for 1.5 hours at
130C, followed by de-phosgenation. The resulting
4-(4-isocyana-to-3-methylbenzyl)-cyclohexylisocyanate
was purified by distillation. 188 g (85~ of the theor-
etical yield) of diisocyanate which boiled at from 130to 133C/0.05 mbar were obtained. According to gas
chromatographLc analysis, the diisocyanate had a
purity o~ 98%, an NCO content of 30.8~. The viscosity
of the product was 50 mPa.s/25C.
Example 6
6a~ 226 g (1 mol) of 4,2'-diamino-3,5-
dimethyldiphenylmethane and 22.6 g of ruthenium-aluminum
oxide carrier catalyst (5% of Ru) were introduced into
a 0.7 liter stirrer-equipped autoclave. After repeatedly
flushing with nitrogen and hydroyen, 22.6 g of ammonia
were metered in. The mixture was heated to 140C and
hydrogenated with stirring under 200 bars hydrogen
until 3 mols of hydrogen had been absorbed (reaction
time of four hours). The reaction was stopped by dis-
connecting the stirrer, the mixture was left to coolto room temperature, the pressure was removed~ The
product was taken up in methanol. The catalyst was then
Mo-2526
L68~;~
-16-
filtered, washed with methanol ar.d the combined solutions
were subjected to ~'lash distillation. Z28.6 g of diamine
distilled at a temperature of from 114 to 152C/0.015
mbar. The diamine was 93.0% 2-(4-amino-3,5-dimethyl-
benzyl)-cyclohexylamine, 6.3% 4 r 2'-diamino-3,5-dimethyl-
dicyclohexylmethane and 0.6~ of unreacted starting
materials.
6b) 200 g of phosgene were dissolved in 430 ml
of anhydrous chlorobenzene at from 0 to 8C. A solution
of 116 g of the diamine mixture of Example 6a) in 500 ml
of anhydrous chlorobenzene was added dropwise to the
phosgene solution with stirring and cooling such that
the temperature of the reaction mixture did not exceed
10C. The mixture was then heated to 120C with the
introduction of 120 g/h of phosgene, during which the
resulting suspension dissolved. The mixture was then
stirred for an additional 3 hours under the same condi-
tions. After de-phosgenating for two hours, the product
was purified by flash distillation and fine distillation
at 126C/0.06 mbar~
127.4 g (96% of the theoretical yield) of
2-(4-isocyanato-3,5-dimethylbenzyl)-cyclohexylisocyanate
which'had an NCO content of 29.6%, a content of hydrolyz-
abl'e chlorine of 0.01% and a viscosity of 110 mPa.s/
25C were obtained.
Example 7
7a) A 0.7 liter stirrer-equipped autoclave
was charged with 212 g (1 mol) of 4,2'-diamino-3-
methyldiphenylmethane and 21.2 g of ruthenium-aluminum
oxide carrier catalyst (Ru content 5%). After flushing
with nitrogen and hydrogen, 21.2 g of ammonia were
metered in. Hydrogenation was then carried out with
stirring at a temperature of 140C and under a ~ressure
of 200 bars until 3 mols of hydrogen had been absorbed.
Mo-2S26
6~35~
-17-
The autoclave was then left to cool to room temp~rature,
the pressure was removed and the crude product was
taken up in methanol. The catalyst was separated by
filtration, washed with methanol and the product was
purified by distillation. 153.4 g of 2-~4-amino-3-
methylbenzyl)-cyclohexylamine distilled at a temperature
of from 145 to 149C/0.018 mbar. According to gas
chromatographic analysis, the product had a purity of
98.4%.
7b) lO9 g of 2-(4-amino-3-methylbenzyl)-cyclo-
hexylamine from Example 7a), dissolved in 500 ml of
anhydrous chlorobenzene were added dropwise with stir-
ring and cooling into a solution of 200 g of phosgene
in 430 ml of anhydrous chlorobenzene. Thereafter, the
resulting suspension was heated to reflux temperature
with the introduction of phosgene and was boiled for
an additional 4 hours. De-phosgenation was carried out
for 2 hours, the solvent was distilled off under reduced
pressure and the crude product was purified by distil-
ling it twiceO 122.6 g (92% of the theoretical yield~of 2-(4~isocyanato-3-methylbenzyl)-cyclohexylisocyanate
were obtained. The product diisocyanate had the
following properties:
Boiling point: 135C/0.05 mbar;
NCO value: 31.0%;
Content of hydrolyzable chlorine: 0.03~;
Viscosity: 50 mPa.s/25C.
Although the invention has been described in
detail in the foregoing for the purpose of illustration,
it is to be understood that such detail is solely for
that purpose and that variations cah be made therein
by those skilled in the art without departing from the
spirit and scope of the invention except as it may be
limited by the claims.
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