Title of Invention

"SPEARATION OF AROMATIC AMINE FROM A PHENOLIC COMPOUND"

Abstract A process comprises contacting a product mixture with a base, optionally in the presence of a polyhydric alcohol, lo produce a base-lreated mixture and distilling the base-treated mixture in which the product mixture comprises an aromatic amine and a phenolic compound.
Full Text SEPARATION OF AMINE FROM A PHENOLIC COMPOUND
FIELD OF THE INVENTION
The invention relates to a process for separation of an aromatic amine
from a phenolic compound in a mixture comprising the aromatic amine and
phenolic compound.
BACKGROUND OF THE INVENTION
Aromatic amines are important industrial chemicals. They can be used to
produce a very important class of industrial compounds such as azo dyes.
Aromatic amines can be produced by chemical reduction of nitro compounds with
a metal and acid such as, for example, iron or tin and hydrochloric acid or by
catalytic hydrogenation using molecular hydrogen and a hydrogenation catalyst
such as nickel or platinum. Nitro compounds can be readily made by direct
nitration of aromatic compounds.
The product mixture produced by catalytic hydrogenation of an aromatic
nitro compound generally comprises the desired amine, a corresponding phenolic
compound, and unreacted aromatic nitro compound. These by-products, because
of their color and deleterious effects on product properties, are undesirable and are
difficult to separate from the amines by distillation. Therefore, there is an
increasing need for the reduction of impurities to increase the amine purity.
SUMMARY OF THE INVENTION
A process comprises contacting a product mixture with a base, optionally
in the presence of a polyhydric alcohol, to produce a base-treated mixture and
distilling the base-treated mixture in which the product mixture comprises an
aromatic amine and a phenolic compound.
DETAILED DESCRIPTION OF THE INVENTION
An aromatic amine can be produced by catalytic reduction or
hydrogenation of an aromatic nitro compound, either under liquid phase or gas
phase. The reduction or hydrogenation can be carried out under any suitable
conditions known to one skilled in the art, continuously, semi-continuously, or
batch-wise. A suitable condition can include a temperature in the range of from
about 30°C to about 300°C, preferably about 80°C to about 250°C; a pressure that
can accommodate the temperature such as about 1 atm (103 kPa) to about 20 arm
(300 psig, 2000 kPa), preferably about 150 kPa to about 800 kPa; and for a
sufficient period of time such as from about one to about 100 minutes.
Any hydrogenation catalysts known to one skilled in the art such as, for
example, nickel, iron, platinum, copper, cobalt, palladium, iridium, and
combinations of two or more thereof can be used in the production of aromatic
amiue. Generally, a catalyst can be present in a catalytic amount effective to
catalyze the hydrogenation or reduction and can be in the range of from about 1 to
about 10,000 ppm (mg per kg) aromatic nitro compound.
The hydrogenation or reduction process produces a product mixture or
crude product, which comprises desired amine and impurities. A desired amine
can have the formula of RAr(CH2)pNR1 where Ar is an arylene group; R and each
R1 can be the same or different; each R1 is independently selected from the group
consisting of hydrogen, halogen, alkyl group, aryl group, and combinations of two
or more thereof; and p is a number from 0 to 3. Examples of amine products
include, but are not limited to, aniline, toluidines, chloroanilines, bromoanilines,
iodoanilines, chlorotoluidines, bromotoluidines, iodotoluidines, benzylamine, Nbenzylamine,
ethylanilines, fluoromethylanilines, chloromethylanilines,
bromomethylanilines, and combinations of two or more thereof. These disclosed
examples include all possible isomers.
For example, aniline can be produced by the reduction of nitrobenzene
with hydrogen either in the liquid phase using a supported hydrogenation catalyst
such as nickel or precious metal, or in the gas phase using supported catalysts.
Phenol is a byproduct, in trace amounts ranging from about 50 to about 1000 mg
per kg amine product (ppm). Aniline can also be produced by conversion of
phenol in the Halcon process.
Also for example, toluidine can be produced by reduction of nitrotoluene.
Nitrotoluene can be vaporized at a temperature in the range of from about 150°C
to about 400°C to obtain a vapor or gas phase of nitrotoluene. The vapor phase
nitrotoluene is then introduced or fed to suitable equipment such as a gas phase
vessel or reactor, preferably a fixed bed reactor containing a hydrogenation catalyst.
Hydrogen can be introduced into the equipment, preferably contemporaneously with
Hie vapor phase nitrotoluene.
Impurities or by-products associated with the production of aromatic amines
include, but are not limited to, unreacted nitro compounds, cyclohexanones, phenolic
compounds, ketones, and combinations of two or more thereof. Examples of phenolic
compounds include, but are not limited to, phenol, cresols, chlorophenols,
bromophenols, iodophenols, oholortDluidinoa chlorotoluidines. bomiotoluidinco
bromotoluidines, iodotoluidines, benzylamine, N-benzylamine, ethylphenols,
fluoromethylphenols, chloromethylphenols, bromomethylphenols and combinations
of two or more thereof. These disclosed examples include all possible isomers.
Any unreacted nitro compound can be present in the product mixture in
the range of from 0 to about 1000 ppm and can be readily removed from the
crude product by any means known to one skilled in the art such as, for example,
distillation. Because such means are well known, the description of which is
omitted herein for the interest of brevity.
Ideally, a desired amine compound contains lower than 500, preferably
lower than 100, and more preferably lower than 50 parts per million (mg/kg) of
such phenolic compound.
According to the invention, the product mixture (or crude product) can be
contacted with a base before it is distilled. Any base, organic or inorganic, can be
used. For example, suitable bases can include, without limitation, lithium hydroxide,
sodium hydroxide, sodium hydrosulfide, sodium bisulfide, potassium hydroxide,
potassium hydrosulfide, potassium bisulfide, calcium hydroxide, magnesium
hydroxide, sodium bicarbonate, sodium carbonate, sodium sulfide, sodium oxide,
magnesium oxide, calcium oxide, calcium carbonate, sodium phenoxide, barium
phenoxide, calcium phenoxide, tetramethylammonium hydroxide,
tetraethylammonium hydroxide, tetrapropylammonium hydroxide,
tetramethylammonium bisulfide, tetraethylammonium bisulfide, and combinations of
any two or more thereof. Potassium hydroxide and sodium hydroxide are preferred
for they are readily available and inexpensive.
A base can be combined with the crude product at any concentration
effective to reduce the phenolic compound contamination to the desired level
disclosed above. Generally, the molar ratio of base to phenolic compound
can be in the range of from about 0.5:1 to about 10:1, preferably about 1:1 to
about 3:1 or about 1:1 to about 2:1. The contacting of the crude product with
a base can be carried out under any suitable conditions. For example, such
condition can include a temperature in the range of from about 0°C to about
200°C, preferably about 20°C to about 50°C, a pressure that can
accommodate the temperature such as about 1 IcPa to about 300 kPa,
preferably about 10 kPa to about 110 kPa, and for a sufficient period of time
such as from about 0.01 to about 10,000 minutes.
Combining a base and an amine can also be carried out in the presence of
a polyhydric alcohol. Examples of polyhydric alcohol include, but are not limited
to trimethylene glycol, triethylene glycol, glycerols, etiiylene glycol, diethylene
glycol, 1,2-propane diol, 1,3-propane diol, tripropylene glycol, polyethylene
glycols, polyprop3dene glycols, and combinations of two or more thereof. The
polyhydric alcohol can be present in the base-amine combination in the range of
from about 1 to about 10,000 mg per kg of the total combination.
Thereafter, a desired amine can be recovered from the base-treated
crude product (or product mixture) by, for example, distillation. Suitable
apparatus for the distillation is any customary apparatus as described for
example in Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Ed.
Vol. 7, John Wiley & Sons, New York, 1979, pages 870-881, such as sieve
plate columns, bubble cap columns or columns packed with arranged or
dumped packing. The distillation can be carried out in a single column or a
plurality of columns, such as 2 or more columns. Any distillation techniques
known to one skilled in the art can be used. A suitable distillation can
include a temperature in the range of from about 100 to about 400, preferably
about 100 to about 250°C, a pressure that can accommodate the temperature
such as about 0.1 kPa to about 200 IcPa, preferably about 5 kPa to about
30 kPa, and for a sufficient period of time such as from about 1 to about 1500
minutes.
EXAMPLES
Example 1; This example illustrates reduction of phenol in aniline us|ng
KOH.
To a distillation flask was added 100 ml of commercial aniline containing
122 ppm (rng/kg) phenol (a final product produced from a DuPont commercial
plant at Beaumont, Texas, USA) and potassium hydroxide (53.5 mg) dissolved in
64.4 mg of water. This was connected to a distillation head containing a short
vigreux column. Reduced pressure (42 mmHg (5.6 kPa)) distillation was
continued until 75 ml of aniline was in the receiver. GC analysis of the distillate
revealed the phenol content was 7.4 ppm. The phenol content of the material still
in the distilling flask was 321 ppm based on 25 ml aniline remaining in the flask.
Similarly, 100 ml of commercial aniline and potassium hydroxide (52 mg)
in 66 mg of water was added to a distillation flask. This was vacuum distilled at
40 mmHg (5.33 kPa) and three cuts taken, 79.4g, 8.1g and 8.4g. The phenol
content of these cuts were respectively 4 ppm, 3 ppm, and The phenol content of the distillation residue was 2391 ppm.
Example 2. This example shows reduction in phenol content in aniline using
NaOH.
To a distillation flask was added 100 ml of commercial aniline (phenol
122 ppm) and sodium hydroxide (35.7 mg) dissolved in 93 mg of water. The
same procedure as Example 1 was followed. The distillate (75 ml) had a phenol
content of 19 ppm. The phenol content of the material remaining in the distilling
was 374 ppm.
Example 3. This example shows using KOH and unrectified crude aniline.
A series of runs was conducted using a sample of crude, unrectified,
aniline obtained from a commercial plant, which had a phenol content of 107 ppm
to determine the efficiency of removing phenol with various doses of potassium
hydroxide. An unrectified aniline was a crude plant aniline which had been
dewatered but not detared in the final (rectifying) distillation column.
To a distillation flask was added 50 ml of crude aniline and 35 ul of 50%
potassium hydroxide in water. Distillation was performed at 90 mm Hg (12 kPa)
pressure using a five plate Oldershaw column and vacuum distillation head.
Distillation was stopped on obtaining 48.9 g of aniline distillate. This had a
phenol content of 2.7 ppm. The results are shown in the following table.
Example 4. This example illustrates using a polyhydric alcohol.
To a distilling flask was added 50 ml of crude aniline, 40 ul of 50%
potassium hydroxide and 100 ul of polyethylene glycol (avg. Mn ca. 400, "PEG
400", Aldrich Chemical Company, Milwaukee, Wisconsin). The resulting
mixture was vacuum distilled at 90 mm giving 46.6 g of aniline distillate
containing 1.1 ppm of phenol.
Example 5. This example shows treating o-toluidine with KOH.
Aqueous potassium hydroxide solution (45%; 0.1055 g) was charged
into a three neck round bottom flask (500 ml) followed by 123.5g of otoluidine
(OTOL) containing 489.1 ppm of o-cresol. OTOL was a
commercial product commercially available from First Chemical Corp.,
Pascagoula, Mississippi. An Aldrich Oldershaw column (ten stages) with a
short path distillation head on top of the column was attached to the flask.
The mixture in the flask was agitated with a magnetic spin bar while vacuum
was gradually pulled down to 90 mmHg (12 IcPa). The pot temperature was
raised using a heating mantle to distill OTOL. The typical distillation
conditions were: pot temperature 130°C, overhead temperature 125°C,
vacuum 90 mmHg (12 kPa). The distillation was stopped when boil up
slowed down and the overhead temperature started falling. Distillate
(108.5 g) was collected and was analyzed with GC to find o-cresol nondetectable.
In separate runs, a plant distilled OTOL sample, obtained from a
storage tank, having 133.3 ppm of o-cresol was used. A different amount of
o-cresol was added to the sample to make OTOL with different
concentrations of o-cresol. The OTOL was then mixed with aqueous KOH
solution (45%) at different KOH/o-cresol mole ratios and distilled through a
ten-stage Oldershaw column under vacuum. The distillation conditions
were similar to the plant OTOL distillation conditions disclosed above. The
results summarized in the following table (ND denotes non-detectable)
demonstrate that the invention process substantially reduced the o-cresol
content in OTOL.
Run No.
1
2
3
4
5
6
7
8
9
10
Initial o-Cresol
Content (ppm)
489.1
489.1
489.1
489.1
286.5
286.5
286.5
133.3
133.3
133.3
KOH/o-Cresol
mole ratio
1.51/1
1.20/1
1.08/1
0.99/1
2.00/1
1.60/1
0.99/1
1.22/1
1.07/1
0.99/1
o-Cresol in
Distillate (ppm)
ND
ND
31.7
220.9
ND
ND
68
ND
29.6
38.4
Example 6. This example shows using a potyhydric alcohol to stabilize
excess KOH.
In another separate run, o-cresol was added to OTOL to raise the ocresol
concentratiqn to 8.8%. About 1.6 equivalent of KOH (45%) was
charged. The pot temperature was raised under vacuum to strip water and
then to reflux OTOL for 8 hours. At the end of the reflux, OTOL (20% of
the charge) was distilled through the ten-stage column. The overhead
sample showed 10.1 ppm of o-cresol. The potassium o-cresolate
concentration was about 14% in the pot. It was noted that some white salt
(excess KOH) coated on the flask bottom. Poly(ethylene glycol) was then
added to the pot. The amount of PEG charged was the same as the KOH
(45%) charge. After being agitated at 120°C for 20 minutes, all the salts
went into the solution.





We Claim:
1. A process for separation of an aromatic amine from a phenolic compound comprising contacting a product mixture with a base, optionally in the presence of a polyhydric alcohol, to produce a base-treated mixture, introducing said base-treated mixture to a distillation apparatus, and distilling said base-treated mixture wherein said product mixture comprises an aromatic amine and a phenolic compound, the molar ratio of base to phenolic compound is in the range of from 0.5:1 to 10:1.
2. A process as claimed in claim 1 wherein the molar ratio of said base to said phenolic compound is in the range of from 1:1 to 3:1 and said base is lithium hydroxide, sodium hydroxide, sodium hydrosulfide, sodium bisulfide, potassium hydroxide, potassium hydrosulfide, potassium bisulfide, calcium hydroxide, magnesium hydroxide, sodium bicarbonate, sodium carbonate, sodium sulfide, sodium oxide, magnesium oxide, calcium oxide, calcium carbonate, sodium phenoxide, barium phenoxide, calcium phenoxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetramethylammonium bisulfide, tetraethylammonium bisulfide, or combinations of any two or more thereof.
3. A process as claimed in claim 2 wherein the molar ratio of said base to said phenolic compound is in the range of from 1:1 to 2:1 and said base is potassium hydroxide, sodium hydroxide, or combinations thereof.

4. A process as claimed in claim 1, 2, or 3 wherein said contacting is carried out in the presence of said polyhydric alcohol, which is trimethylene glycol, triethylene glycol, glycerol, ethylene glycol, diethylene glycol, 1,2-propane diol, 1,3-propane diol, tripropylene glycol, polyethylene glycol, polypropylene glycol, or combinations of two or more thereof.
5. A process as claimed in claim 1 wherein
the molar ratio of said base to said phenolic compound is in the range of from 1:1 to 3:1;
said base is sodium hydroxide, potassium hydroxide or a combination thereof; and
said amine is aniline, toluidines, chloroanilines, bromoanilines, iodoanilines, chlorotoluidines, bromotoluidines, iodotoluidines, benzylamine, N-benzylamine, ethylanilines, fluoromethylanilines, chloromethylanilines, bromomethylanilines, or combinations of two or more thereof.
6. A process as claimed in claim 5 wherein said contacting is carried out in the presence of a
polyhydric alcohol, which is trimethylene glycol, triethylene glycol, glycerol, ethylene glycol,
diethylene glycol, 1,2-propane diol, 1,3-propane diol, tripropylene glycol, polyethylene
glycol, polypropylene glycol, or combinations of two or more thereof.

7. A process as claimed in claim 6 wherein the product mixture comprises o-toluidine as the
aromatic amine and o-cresol as a phenolic compound, comprising contacting said mixture
with potassium hydroxide to produce a base-treated mixture and distilling said base-treated
mixture.
8. A process as claimed in claim 7 wherein said polyhydric alcohol is polyethylene glycol.

Documents:

833-delnp-2006-abstract.pdf

833-delnp-2006-assignment.pdf

833-DELNP-2006-Claims-(01-08-2011).pdf

833-delnp-2006-claims.pdf

833-DELNP-2006-Correspodence Others-(01-08-2011).pdf

833-delnp-2006-Correspondence Others-(08-06-2011).pdf

833-delnp-2006-correspondence-others 1.pdf

833-delnp-2006-correspondence-others-1.pdf

833-delnp-2006-correspondence-others.pdf

833-delnp-2006-description (complete).pdf

833-delnp-2006-form-1.pdf

833-delnp-2006-form-18-1.pdf

833-delnp-2006-form-18.pdf

833-delnp-2006-form-2.pdf

833-delnp-2006-Form-3-(08-06-2011).pdf

833-delnp-2006-form-3.pdf

833-delnp-2006-form-5.pdf

833-DELNP-2006-GPA-(01-08-2011).pdf

833-delnp-2006-pct-101.pdf

833-delnp-2006-pct-210.pdf

833-delnp-2006-pct-220.pdf

833-delnp-2006-pct-237.pdf

833-delnp-2006-pct-304.pdf

833-delnp-2006-pct-409.pdf

833-delnp-2006-pct-416.pdf

833-DELNP-2006-Petition-137-(01-08-2011).pdf


Patent Number 252575
Indian Patent Application Number 833/DELNP/2006
PG Journal Number 21/2012
Publication Date 25-May-2012
Grant Date 23-May-2012
Date of Filing 17-Feb-2006
Name of Patentee E.I. DUPONT DE NEMOURS AND COMPANY
Applicant Address 1007 MARKET STREET, WILMINGTON, DELAWARE, 19898, USA.
Inventors:
# Inventor's Name Inventor's Address
1 RENNER CARL ANDREW 1408 IVY DRIVE, WILMINGTON, DE 19803, USA.
2 DUBNANSKY RICHARD FRANK 6277 IVANHOE LANE, BEAUMONT, TX 77706, USA
3 PARSONS FREDDISON A. 3834 COBBLESTONE LANE, PORT ARTHUR, TX 77642,USA.
4 STIMEK RICHARD T. 6255 WEST BEND, BEAUMONT, TX 77706, USA
5 WU ZHIHONG 9641 HAMPSHIRE COURT, MOBILE, AL 36695, USA
PCT International Classification Number C07C 209/00
PCT International Application Number PCT/US2004/033199
PCT International Filing date 2004-10-06
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10/798,083 2004-03-11 U.S.A.
2 60/510,690 2003-10-10 U.S.A.