Note: Descriptions are shown in the official language in which they were submitted.
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PREPARATION OF SUBSTITUTED AROMATIC AMINES
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods for the production
phenyl-p-phenylenediamine (PPDA) and higher amines of structural
formula (I) below from the starting material of structural formula(//) below.
More particularly it relates to a method for preparing PPDA wherein aniline
is oxidized in the presence of trisodium pentacyano ferrate(II)complexes
containing various water soluble ligands, such as ammonia, mono alkyl
amine, dialkyl amines, and trialkyl amines, and utilizing oxygen or
hydrogen peroxide as the oxidizing agents. The complex is then reduced
by hydrogenation using suitable heterogeneous metal catalysts.
Ri
H N --\ ~- H C
H
R ., n
wherein n equals 2 to 5, and R~ and R2 are as set forth below
R~
\i
'-1~
R2
R, and R2 may be the same or different, must be ortho or meta to the
amino group, and may be hydrogen, C,-C4 alkyl, C,-C4 alkoxy, halogen,
cyano, carboxylate salts and amides of carboxylic acids or mixtures
thereof.
The invention relates to the production of PPDA with the ability to
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recycle the transition-metal complex, high selectivity and yield. The
conversion of aniline to N-phenyl-p-phenylenediamine is in the range of
40-85%. The yield of PPDA ranges from 91 to 97%. The method of this
invention is also cost effective and produces no environmentally
undesirable byproducts.
2. Background of the Related Art
The production of p-phenylenediamine and its derivatives is
widespread and its uses are widely known. In U.S. Patent No.
5,1 17,063, Stern et al., disclose various methods of preparing N-phenyl-
p-phenylenediamine wherein aniline and nitrobenzene are reacted under
specific conditions.
In other publications, the oxidative dimerization of aniline to
produce N-phenyl-p-phenylenediamine is disclosed. British patent No.
1,400,767 and European patent 0-261096 utilize an alkali metal
ferricyanide whereas European patent 0-272-238 utilizes a hypohalite
oxidizing agent. None of these processes are very selective, nor do they
give good conversions.
J. Bacon and R. N. Adams in J. Am. Chem. Soc.,90 p 6596 (1968)
report the anodic oxidation of aniline to N-phenyl-p-quinonediimine but no
conversions or yields are given. E. Herrington, in J.Chem.Soc. p4683
(1958) reports the oxidative dimerization of aniline with disodium
pentacyanoamminoferrate (III) to form a complex containing N-phenyl-p-
phenylenediamine which is then reduced chemically with reducing agents
such as hydrazine hydrate, sodium dithionate, sodium hydrogen sulfite
and hydrogen sulfide. The use of the trisodium pentacyanoamminoferrate
(II) complex and catalytic reduction with hydrogen of this invention
distinguish over this publication and the differences result in a
significantly improved process. The stoichiometry of the instant invention
is much improved over Herrington since higher ratios of aniline to complex
can be used in the process disclosed herein.
It is therefore an object of this invention to provide a method for
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the production of N-phenyl-p-phenylenediamine and related compounds.
It is a further object of this invention to disclose a method for the
production of such compounds via an aqueous process that allows the
easy removal of unreacted aniline and subsequent separation of the
reconstituted starting complex from the desired end product [formula (I)]
after reduction giving a process which is commercially viable, involving
both low cost and recyclability.
It is still a further object of this invention to provide a process that
favors the p-phenylenediamine product, with both high yield and good
selectivity. It is yet a further object of this invention to furnish a process
with produces less waste and effluent streams. A still further objective is
the production of phenylenediamine derivatives which may be used
industrially as antidegradants made from the high purity products of the
process of this invention.
SUMMARY OF THE INVENTION
The present invention is directed to an improved method for
preparation of substituted aromatic amines of formula (1) comprising the
steps of: a) oxidizing an aromatic amine of formula (II) in the presence of
a metal pentacyano ferrate (II) complex to form an
arylenediaminopentacyanoferrate complex, said metal being selected from
the group consisting of potassium and sodium; and b) catalytically
reducing said arylenediamino-pentacyanoferrate complex with hydrogen
using a heterogeneous metal catalyst, producing the corresponding
substituted aromatic amine of formula (I).
R~
H ~N --~~,~i H C I
H
R
wherein n equals 2 to 5, and R, and RZ are as set forth below
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R~
HzN~/-\% ~ I I )
R2
R, and R2 may be the same or different, must be ortho or meta to the
amino group, and may be hydrogen, C,-C4 alkyl, C,-C4 alkoxy, halogen,
cyano, carboxylate salts and amides of carboxylic acids or mixtures
thereof.
The most preferred embodiment is directed to a process which
oxidizes aniline in the presence of trisodium pentacyano ferrate (II)
complexes containing various water soluble ligands, such as ammonia,
mono alkyl amine, dialkyl amines, trialkyl amines and the tike. Oxidizing
agents may be oxygen or hydrogen peroxide. The N-phenyl-p-
phenylenediamino pentacyano ferrate complex is then reduced with
hydrogen using a heterogeneous metal catalyst, which may be supported
or not supported. Suitable supports could include those known to the art
such as, for example, carbon or alumina. The mixture of aniline and N-
phenyl-p-phenylenediamine is then extracted with a suitable solvent after
filtration of the heterogenous catalyst. Preferred solvents are
environmentally friendly, water-immiscible, and easily recyclable. The
aqueous layer containing the pentacyano ferrate (If) complex is then
recycled.
DETAILED DESCRIPTION OF THE INVENTION
A preferred method of the present invention for producing N-
phenyl-p-phenyfenediamine (PPDA) involves the steps of a) the oxidation
of aniline in the presence of trisodium pentacyano ferrate (Il) complexes
with the optional use of a heterogeneous metal catalyst; followed by b)
reduction of the N-phenyl-p-phenylenediamino-pentacyano ferrate
complex with hydrogen using a heterogeneous metal catalyst.
In most cases, both steps (a) and (b) will use the same
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heterogeneous catalyst. In the first step, any suitable oxidant including
either oxygen or hydrogen peroxide may be used as the oxidizing agent.
Oxygen is the preferred oxidizing agent. Still more preferred is the use of
oxygen under pressure and at elevated temperatures which will increase
the rate of oxidation and facilitate the completion of step a.
The metal pentacyano ferrate (II) complexes useful in this invention
must be of a water soluble type having water soluble ligands as a part of
the complex. Preferred metals are the alkali metals such as sodium or
potassium. The most preferred, trisodium pentacyano ferrate (II) complex
containing various water soluble ligands, is illustrative of the class of
complexes useful. These figands may be ammonia, monoalkyl amines,
dialkyl amines, or trialkyl amines. A preferred structure for this preferred
complex is Na3[Fe(CN)5NH3xH20], or its dimer.
In the second step of the preferred reaction, the N-phenyl-p-
phenylenediamino-pentacyano ferrate complex is reduced with hydrogen
using a heterogeneous metal catalyst. This catalyst is selected from the
heterogeneous metals of Group Vlll such as palladium, platinum,
ruthenium, rhodium, or nickel. The catalyst may or may not be
supported. If supported, the supports may be carbon, alumina, and the
like, many of which are known to those familiar with the art.
The mixture of aniline and PPDA that is the product of the reaction
is extracted with a suitable solvent. Then the heterogeneous catalyst is
filtered off. Suitable solvents include those that are water-immiscible and
easily recyclable. The aqueous layer containing the pentacyano ferrate (II)
complex is then recycled.
The compounds of this invention can be synthesized
advantageously by the following general method. The preferred method
for the preparation of PPDA is contained in the examples that follow.
The first step of a preferred process of this invention involves
dissolving sodium pentacyanoammino ferrate (II) in water. The synthesis
of sodium pentacyanoammino ferrate (II) is known. It was prepared
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according to the method of G. Brauer "Handbook of Preparative Inorganic
Chemistry", 2nd ed. Vol Il, academic Press, New York, N.Y. 19fi5 p
1511.
Novel method for preparation of Trisodium aentacyano ammino ferrate III)
An alternate method for preparation of trisodium pentacyano
ammino ferrate(II) is the concurrent addition of aqueous solution of
ferrous chloride tetrahydrate, stabilized with hypophosphorous acid, and
sodium cyanide in the ratio of 1 to 5 equivalents to an aqueous solution
of ammonium hydroxide. The aqueous solution of ammonium hydroxide
may contain anywhere from one equivalent based on the ferrous chloride
to a large excess. The preferred range is two to ten equivalents and the
most preferred is three to six equivalents of ammonium hydroxide.
The concurrent additions are done over one to three hours and the
solution is then filtered if necessary to remove small amounts of iron
hydroxides and the complex is precipitated by adding isopropanol or any
convenient water soluble organic solvent. The complex may be dried or
redissolved in water without drying and used directly. The excess
ammonia and isopropanol are recovered.
For the addition of aniline, a water miscible organic solvent may be
added to help solubifize the aniline. In the instant invention, this reaction
may be run without organic solvent. Examples of such solvents are
ethylene glycol, propylene glycol, diethylene glycol, and triethylene glycol.
Two equivalents of aniline are added and the mixture is then oxidized.
Oxygen or hydrogen peroxide are two possible oxidizing agents that can
be used. A heterogeneous metal catalyst may be added prior to the
oxidation.
fn the second step of the process of this invention, the oxidized
complex containing the N-phenyl-p-phenylenediamino ligand is subjected
to hydrogenation in the presence of a heterogeneous metal catalyst. This
may be carried out without added solvent, or in the presence of a suitable
water immiscible solvent. Possible solvents in this category include butyl
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acetate, hexanol, 2-ethyl-1-butanol, hexyl acetate, ethyl butyl acetate,
amyl acetate, methyl isobutyl ketone or aniline and the like. After
hydrogenation, the heterogeneous catalyst is removed by filtration and
the organic layer separated. The solvent, aniline, and N-phenyl-p-
phenylenediamine are recovered by distillation. The sodium
pentacyanoammino ferrate(II) is then recycled.
The reaction is best carried out at a pH equivalent to the pH of the
solution containing the dissolved complex in water. The pH is adjusted,
when necessary, after each recycle of the complex by adding ammonia to
the solution in order to maintain a pH equivalent to the initial pH of the
solution at the start of the process. This adjustment of pH is achieved by
the addition of an appropriate base, for example, ammonium hydroxide or
ammonia, the ligand used in the complex. A more preferred range of pH
is from 10 to 12. A pH equivalent to the pH of the dissolved complex,
which is dependant on concentration of the solution is preferred.
Oxygen and hydrogen pressures may be in the range of from about
I atmosphere to 100 atmospheres. A preferred range of these pressures
would be from about 2 to about 75 atmospheres. A preferred range of
these pressures would be from about 50 to about 75 atmospheres, or
about 5.0 x 106 to about 7.5 x 106 Nm-2. Similar pressures are used for
the reduction reaction with hydrogen..
Temperatures may range up to the point where the complex looses
stability which currently is believed to be from about 5°C to about
65°C in
a closed system. Although the reaction can be carried out at lower
temperatures, the rate of reaction of the oxidation step is significatnly
lower. The preferred operation temperature for the oxidation reaction is
between 30°C and 55°C, and most preferred range is between
45°C and
55°C. The temperature used will require a balance of factors to
maximize
the reaction rate and yeild of the process. Higher temperatures than
specified here will slowly degrade the complex. Low temperatures reduce
the solubility of the complex and decrease the rate of reaction.
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A number of ligands can be used instead of ammonia in the sodium
pentacyano ferrate (11) complex. Ligands may be mono alkyl amines such
as methyl, ethyl, propyl, or butyl amines, dialkyl amines such as dimethyl
or diethyl amine and trialkyl amines such as trimethyl amine or triethyl
amine. Other amines that can be used are N,N-dimethyfaminoethanol,
N,N,N',N'-tetramethylethylenediamine, and substituted or unsubstituted
pyridine. A variety of other iigands can be used, limited only by their
solubility, and their ability to be displaced by aniline and by their
stability.
In this invention, sodium pentacyano ferrates (II) containing figands
other than ammonia were prepared by substitution of the ammonia
complex with an excess of the appropriate ligand.
Among the heterogeneous metal catalysts that may be used are
palladium-on-carbon, platinum on-carbon, ruthenium-on-carbon, rhodium-
on-carbon, and Raney nickel. Supports other than carbon, such as
alumina, Kieselguhr, silica, and th.e like can be used as well.Preferred
among the catalysts that may be used are the noble metals. Still more
preferred are supported noble metal catalysts. An even more preferred
catalyst is platinum or palladium supported on carbon.
The recyclabitity of the pentacyanoammino ferrate complex is
demonstrated in various examples of this invention. The recycling
procedure may be carried out at temperatures ranging from 25°C to
60°C,
and most preferably between 45°C and 55°C. The recyclability is
useful
with ligands other than ammonia in the pentacyano ferrate (ll) complex,
such as pentacyanotrimethylamino ferrate (II) or
pentacyanoisopropylamino ferrate (II) complexes. Experimental details of
the recyclability, including conversion and yield data, are presented in the
examples.
Reductive alkyiation of PPDA to produce antidegradants can be
conducted by any one of various known methods known to those skilled
in the art: See, for example, U.S. Patent No. 3,336,386.
Preferably, PPDA and a suitable ketone or
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aldehyde are reacted in the presence of hydrogen and a catalyst such as
platinum sulfide with or without a support. Suitable ketones include
methylisobutyl ketone, acetone, methylisoamyl ketone, and 2-octanone.
The following examples are intended to further illustrate the
invention and are not intended to limit the scope of the invention in any
manner whatsoever.
EXAMPLES
Example 1: The Oxidation of Aniline using Hydrogen Peroxide as the
Oxidizing Agent(step a); and Hydrogen (with 5% Palladium/Carbon) as the
Reducing Agent (step b) in the Preparation of PPDA
The reaction of step a was run using 3.0 g of aniline, 6.0 g sodium
pentacyanoammino ferrate (II), 300 ml of distilled water and I.0 g of 5%
palladium on charcoal(Pd/C) (50% wet) in a three-neck flask equipped
with mechanical stirrer and addition funnel. Eight ml of 30% hydrogen
peroxide (oxidizing agent) was added in 0.5 hours.
The heterogeneous catalyst was removed by filtration and the
reaction mixture was transferred to a I-I Magne-drive autoclave. 1.0 g of
fresh Pd/C catalyst (50% water) was then added. The vessel was sealed,
purged first with nitrogen and then with hydrogen and pressurized with
hydrogen to about 1000 psig [69 atm or 6.9 x 1 O6 Nm~z J. The vessel
was agitated at room temperature for 2.0 hours. Isopropyl acetate was
added to the reaction mixture after venting and purging with nitrogen.
The catalyst was removed by filtration and the organic solution was
analyzed by gas chromatography using a Varian 3400 instrument
equipped with a DB-I capillary column. The product N-phenyl-p-
phe~nyfenediamine (PPDA)was found in 74.3% conversion, and aniline
was measured at 18.4%. The yield based on conversion of aniline was
91 %.
EXAMPLES 2 - 6: The Oxidation of Aniline using Oxygen as the Oxidizing
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Agent(step al; and Hydrogen with Several Metal Catalysts as the
Reducing Agent (step b) in the Preparation of PPDA
Using the basic procedure depicted in Example 1, several
reactions were run in a I-liter Magne-Drive autoclave using 38.0 g. sodium
pentacyanoammino ferrate (II), 18.6 g aniline, 2.0 g. metal catalyst 50.0
g. ethylene glycol and 150 g distilled water. The metal catalysts used in
Examples 2-6 are supported Pd, Ru, Pt, Rh and Ni, respectively. In
Examples 2-5, the heterogeneous catalysts are present at 5% by weight
on carbon and they are used at 4.0 g and 50% water. In Example 6, the
nickel is used as 50% Ni/Kieselguhr 2.0 grams dry.
The vessel was sealed, purged first with oxygen and pressurized to
400 psig [28 atm or 2.8 x 106 Nm-2 ]. The vessel was agitated at room
temperature for 2.5 hrs. After this agitation, the vessel was purged with
nitrogen and then 100 ml of butyl acetate was pumped into the autoclave.
The vessel was purged with hydrogen and then pressurized with
hydrogen to 400 psig [28 atm or 2.8 x 106 Nm-2 ]. The vessel was then
agitated at room temperature for I.0 hr. The ester solution was isolated
and analyzed by HPLC. The nickel catalyst on Kieselguhr (Example 6)was
found to be inactive.
. Results of these Examples are presented in Table 1.
TABLE 1
EXAMPLE CATALYST G CONVERSION YIELD
a) (b)
2 5% Pd/C 4.0 g 50% 89 93
Hz0
3 5 % Ru/C 4.0 g 50% 30 87
H20
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4 5% Pt/C 4.0 g 50% 72 95
HZO
5% Rh/C 4.0 g 50% 51 96
H20
6 50% Ni/Kieselguhr 3 88
2.0
g Dry
Notes for Table 1:
5 (a) N-Phenyl-p-phenylenediamine analyses by reverse phase HPLC
using water-acetonitrile gradient with a Perkin-Elmer series 410 LC
pump, a LC 235 Diode Array detector using a 3.3 cu. pecosphereT""
3C 18 column.
(b) N-Phenyl-p-phenylenediamine yield based on converted aniline.
Example 7: Oxidation of Aniline using Oxygen and no Metal Catalyst
(step a); and Reduction with Hydrazine (step b) in the preparation of
PPDA.
In a manner similar to the previous examples, step (a) of the
reaction was run in a I-liter Magne-Drive autoclave using 24 g of sodium
pentacyanoammino ferrate (II), 12.8 g of aniline, 100 ml of ethylene
glycol and 300 ml of distilled water. The vessel was sealed, purged with
nitrogen, then oxygen and pressurized with oxygen to 400 psig [28 atm
or 2.8 x 106 Nm-21. The vessel was agitated at 15-20°C with cooling to
control the temperature for six hours.
Following oxidation, a one ml sample was removed from the
autoclave. Isopropyl acetate was then added to the sample, and the
synthesis of PPDA was continued with the reduction, step (b), with
hydrazine. The remaining mixture in the autoclave was purged with
nitrogen, then hydrogen and pressurized with hydrogen to 400 psig [28
atm or 2.8 x 106 Nm-2 ]. The reaction was agitated at 15-25°C for one
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hour. The reaction was vented, purged with nitrogen and isopropyl
acetate added.
Following this, the organic layer separated. Analyses were by gas
chromatography using a Varian 3400 G.C. equipped with a DB-I
megabore column. Conversion to N-phenyl-p-phenylenediamine (PPDA)
by hydrogenation was 6%. Conversion by hydrazine reduction was 66%.
As a result of this example, it was concluded that the
hydrogenolysis does require a metal catalyst, whereas the oxidation can
be done without one. However, it should be noted that it may be
convenient to add the heterogeneous catalyst before the oxidation. The
small amount of N-phenyl-p-phenylenediamine that was found may be due
to electron transfer reactions during the oxidation.
EXAMPLES 8 - 10: The Performance of the Oxidation (step a) and
Reduction (step b) Reactions to Yield PPDA Under a Range of Pressures
The reactions of these Examples were run in a similar fashion to
those previously described. In a I liter Magne-Drive autoclave using 76.0
g of three different batches of sodium pentacyanoammino ferrate (II),
37.2 g aniline, 4.0 g 5% Pd/C catalyst, 100 g ethylene glycol and 300 g
distilled water were combined. The vessel was sealed, purged first with
oxygen, then pressurized with oxygen to the desired pressure. The
vessel was agitated at room temperature for 2.5 hours.
Following this oxidation, the vessel was purged first with nitrogen.
Butyl acetate (200 ml) was pumped into the autoclave, which was then
purged with hydrogen, and then pressurized with hydrogen to the desired
pressure. The vessel was agitated at room temperature for I.0 hr. After
work up of the organic layer in the normal way, analyses by HPLC gave
the conversions as presented in Table 2.
TABLE 2
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EXAMPLE 02 and H2 CONVERSION % YIELD (a)
PRESSURE,
psig [atm]
8 400 [28] 69 93
9 800 [56] 63 88
100 [8] 55 94
5 Notes for Table 2:
In column 2, the pressures shown are for both oxygen and hydrogen
(a) Yield based on aniline used.
EXAMPLES 11 and '12: Demonstration of the ability to recycle the
sodium pentacyanoammino ferrate (II) complex
10 In accordance with the previous examples, the reaction was run in
a I-liter Magne-Drive autoclave using 76.0 g sodium pentacyanoammino
ferrate (II), 37.2 g aniline, 8.0 g. 5% Pd/C catalyst, 100 g ethylene glycol
and 300 g distilled water. The vessel was sealed, purged first with
oxygen and pressurized to 400 psig [28 atm or 2.8 x 1 O6 Nm-2 ] with
oxygen. The vessel was then agitated at room temperature for 2.5 hours.
Following the oxidation, The vessel was purged first with nitrogen
followed by the addition of 200 ml of butyl acetate pumped into the
autoclave. Then the autoclave was pressurized with hydrogen to 400
psig [28 atm or 2.8 x 106 Nm-2 ]. The autoclave was agitated at room
temperature for I.0 hour. The clave was opened, the solution filtered to
remove the metal catalyst, and the layers were separated.
The ester layer was analyzed by gas chromatography, and the
aqueous layer was returned to the autoclave. At this point, 37.2 g of
aniline, and 8.0 g 5% Pd/C catalyst were added. The vessel was then
seated, purged first with oxygen and pressurized with oxygen to 400 psig
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[28 atm or 2.8 x 1 O6 Nm-2 ]. The mixture was agitated at room
temperature for 2.5 hours, then purged with nitrogen. This was followed
by the pumping of 200 ml butyl acetate into the autoclave. The vessel
was then purged with hydrogen and pressurized with hydrogen to 400
psig (28 atm or 2.8 x 106 Nm-2 ]. The mixture was agitated at room
temperature for I.0 hour.
The ester solution was analyzed by gas chromatography. The
results of the analyses of both the fresh (example 1 1 ) and the recycled
material (example 12) are shown in Table 3 in terms of both conversion
and yield.
TABLE 3
EXAMPLE COMPLEX CONVERSION % YIELD (b)
REL. AREA (a)
1 1 FRESH 69 95.6
12 RECYCLE 66 96.3
(a) GC analyses using a Perkin Elmer Model 8310 gas chromatograph
with a one meter SP 2100 column.
(b) Based on aniline converted.
EXAMPLES 13 -15: The Use of Ligands other than Ammonia for
Pentacyano Ferrate III) Complex and Recycle
In accordance with the previous examples, the reaction was run in
a I-liter Magne-Drive autoclave using 42.8g sodium
pentacyanotrimethylamino ferrate (II1, or the same amount of sodium
pentacyanoisopropylamino ferrate (II), 18.6 g aniline, 4.0 g. 5% Pd/C
catalyst, and 200.0 g distilled water. The vessel was sealed, purged first
with oxygen and pressurized to 250 psig [ 18 atm or 1.8 x 1 O6 Nm-2 ] with
oxygen. The vessel was then agitated at room temperature for 0.5 hours.
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Following the oxidation, The vessel was purged first with nitrogen
followed by the addition of 200 ml of butyl acetate pumped into the
autoclave. Then the autoclave was pressurized with hydrogen to 400
psig (28 atm or 2.8 x 1 O6 Nm-z ]. The autoclave was agitated at room
temperature for I.0 hour.
Following the agitation, the autoclave was opened and its contents
removed. The mixture was then filtered and the aqueous and organic
layers separated. The ester solution, contained in the organic layer, was
analyzed by gas chromatography using a Perkin-Elmer Model 8310 Gas
Chromatograph with a one meter SP2100 column, and the aqueous layer
was returned to the autoclave.
At this point, 18.6 g of aniline, 4.0 g of 5% Pd/C catalyst was
added. The vessel was then sealed, purged first with oxygen and
pressurized with oxygen to 250 psig (18 atm or 1.8 x 106 Nm~2 ]. The
vessel was agitated at room temperature for 3.0 hours, followed by the
pumping of 100 ml butyl acetate into the autoclave. The vessel was
purged first with nitrogen and then with hydrogen and pressurized with
hydrogen to 250 psig [18 atm or 1.8 x 106 Nm~2 ]. The vessel was
agitated at room temperature for 0.5 hour, after which time the autoclave
was opened and the contents removed.
The ester solution was analyzed by gas chromatography, using the
same equipment that has been specified in the earlier examples. The
results of the analyses are presented in Table 4.
TABLE 4
EXAMPLE Ligand CONVERSION % YIELD (a1
Used
13 trimethylamine 89.5 96.9
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14 trimethylamine 63 95.9
/ 1 st recycle)
15 isopropyiamine 55 98.7
Notes for Table 4: a) Yield based on aniline used
EXAMPLES 16-17: The Use of Non-Noble Metal Catalyst in Reduction
(Step b) in Preparation of PPDA
In accordance with the previous examples, the reaction was run in
a 1-liter Magna-Drive autoclave using 57 grams of sodium
pentacyanotrimethylamino ferrate 111), 27.9 g aniline, and 250 ml of
distilled water. The vessel was sealed, purged first with oxygen and
pressurized to 250 psig [ 18 atm or 1.8 x 1 O6 Nm-2 ] with oxygen. The
vessel was then agitated at room temperature for three hours.
Following this oxidation, the vessel was purged first with nitrogen,
then opened and the catalysts added. Then butyl acetate (200 ml) was
added. The vessel was sealed, then with pressurized with hydrogen to
the desired pressure of 400 psig [28 atm or.2.8 x 1 O6 Nm-2 ]. The
catalysts used for the reduction, step b, were as shown in Table 5. The
vessel was agitated at room temperature for I.0 hr.
The ester solution was analyzed by gas chromatography, using the
same equipment that has been specified in the earlier examples. The
results of the analyses are presented in Table 5.
TABLE 5
EXAMPLE CatalystCatalyst;Time CONVERSION YIELD (a)
Level
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16 6.5 g Raney Ni;2.5 48.1 92.0
h
(40%
Hz0)
17 6.1 g 5% Pd/C; 0.5 62.6 97.0
h
(50%
HZO)
(a) Yield based on moles of aniline used
In view of the many changes and modifications that may be made
without departing from principles underlying the invention, reference
should be made to the appended claims for an understanding of the scope
of the protection afforded the invention.
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