Note: Descriptions are shown in the official language in which they were submitted.
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689-092-0
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TITLE OF THE INVENTION
METHOD OF SEPARATING NAP~THOQUINONE
FROM PHTHALIC ACID ADORED
BACKGROUND OF THE INVENTION
Field of the Invention
The resent invention relates to a process for
separating naphthoquinone from phthalic acid android.
Description of the Background
In the production of phthalic android by air-
oxidation of naphthalene and naphthalene-containing
mixtures in the gas phase, the raw phthalic android
product is contaminated with naphthoquinone. Most of
the byproducts, such as resinous compounds, malefic
android and sulfur, can be readily removed by
distillation. However, naphthoquinone with a boiling
point in the range of that of phthalic android
remains in the phthalic android through the
distillation, thereby detracting from its color and
purity. Therefore, it is important to remove as much
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of the naphthoquinone as possible before the
distillation of the raw ~hthalic android product. It
would be desirable to attain S Pam or less of
naphthoquinone in the refined raw product, and 1 Pam or
less in the distilled phthalic android.
At present, using conventional techniques,
naphthoquinone is removed from phthalic android by
converting it into higher condensed products which are
then retained in the residue in the subsequent
distillation of the raw phthalic android. The
preferred catalyst often used for the conversion is
sulfuric acid with the use of high temperature. For
example "Ullmann's Encyclopedia don Technician
Chemise", Ed, Ed., V. 13, p. 723), or, e.g., a mixture
of sulfuric acid and boric acid, US. Pat. 2,850,440.
However, sulfuric acid leads to corrosion problems and,
moreover, the acid off gases generated, as well as the
salts produced by the neutralization of sulfuric acid,
and boric acid where present, cause major problems
during the distillation of the raw phthalic android.
Other catalysts which have been suggested for such
use are alkaline catalysts e.g., alkali hydroxides,
see, e.g., US. Pats. 2,670,325 and 4,165,324, and
sodium carbonate with stuns chloride, see US. Pat.
2,557,499. However, alkaline catalysts have the
disadvantage that they decarboxylate some of the
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phthalic android, and thus contribute to a lower
yield of phthalic android. Also, relatively large
amounts of alkali hydroxide can lead to an explosive
polymerization reaction of the malefic acid contained in
the raw phthalic android.
Other substances proposed for the refinement of
raw phthalic android include potassium bisulfite and
potassium pyrosulfate, see Jay. Pat. 10323tl970.
However, these compounds are disadvantageous in that
the residue in the distillation of the refined raw
phthalic android contains a fairly large amount of
sulfur, the removal of which, e.g., by burning off
presents environmental hazards.
Accordingly, a need continues to exist for a
process for removing naphthoquinone from phthalic
android without the use of either acid catalysts
which disadvantageously produce acid off gases and
salts, or alkaline catalysts which decarboxylate the
phthalic android, lowering the yield thereof, while
at the same time maintaining the level of napthoquinone
at 5 Pam or less in the raw phthalic android.
SUMMARY OF THE INVENTION
According to the present invention, a method is
provided for separating naphthoquinone from phthalic
android such that 5 Pam or less of naphthoquinone
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remains in the raw phthalic android and 1 Pam or less
remains in the distilled phthalic android.
It is also an object of this invention to attain
the above separation without the use of either acid
catalysts which disadvantageously produce acid off
gases and salts, or alkaline catalysts which
decarboxylate the phthalic android.
According to the present invention, the foregoing
and other objects are attained by a method for removing
naphthoquinone from phthalic android produced by the
air-oxidation of naphthalene or naphthalene-containing
mixtures, which entails mixing an effective amount of
1,5,9-cyclododecatriene or a distillation residue of
the same or a mixture thereof with the naphthoquinone-
containing phthalic android at an elevated
temperature.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
According to the present invention, a method of
refining raw phthalic android obtained from air-
oxidation of naphthalene or naphthalene-containing
mixtures is provided. This method facilitates a
reduction of naphthoquinone content in the raw ~hthalic
android from about 0.2 to 2 wit% to 5 Pam or less, and
in the distilled phthalic android to 1 Pam or less.
Moreover, according to this method, the subsequent
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distillation is not burdened by the presence of sulfur
compounds which present environmental hazards.
According to the present method, the raw phthalic
android from the air-oxidation of naphthalene or
naphthalene-containing mixtures is treated for a number
of hours with l,5,9-cyclododecatriene and or the
distillation residue of same, at elevated
temperatures. This refining technique results in the
reduction of the content of the naphthoquinone in the
raw phthalic android from as high as 2 wt.% to 5 Pam
or less, whereby in the subsequent distillation a
purified ~hthalic android is obtained with a
naphthoquinone content of 1 Pam or less.
The present invention entails a method of removing
naphthoquinone from phthalic android produced by air-
oxidation of naphthalene or naphthalene-containing
mixtures wherein the raw phthalic android is treated
with l,5,9-cyclododecatriene and/or the distillation
residue of same at elevated temperatures.
The 1,5,9-cyclododecatriene is produced
industrially by cyclotrimerization of butadiene, and is
purified by vacuum distillation. The distillation
residue contains, in addition to 1,5,9-
cyclododecatriene, chiefly oligomers of butadiene,
namely (C4H6)n atoms.
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The present method is quite advantageous in that
the refining process is very effective, so that the
desired high purity requirements for the product can be
met. Moreover, pure hydrocarbons are used as the
refining agent, so that problems do not occur in the
distillation of the raw phthalic android. Further,
these hydrocarbons are not present in the purified
phthalic android, and, accordingly, a distillation
residue is obtained which can be removed without
problems and without environmental hazards.
In the present method, the naphthoquinone-
containing raw ~hthalic android is heated with a
small amount of l,5,9-cyclododecatriene and/or the
distillation residue of same, with the possible
addition of a small amount of alkali ions. The
concentration of naphthoquinone in raw phthalic
android thus treated is reduced to such an extent
that, in general, the purified ~hthalic android
obtained after distillation of the raw phthalic
android has a melting point of 131.2C, a
naphthoquinone content of 1 Pam or less, and an ALPHA
color index of <10. With the present method, the
concentration of the naphthoquinone in the raw phthalic
android produced by gas phase oxidation of
naphthalene or naphthalene-containing mixtures, e.g.
mixtures of naphthalene and o-xylene, is not
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critical. any of the usual raw product compositions
from the Production of ~hthalic android by the gas
phase method are suitable. The naphthoquinone content
of such raw products depends on the catalyst used and
the conditions employed. As a rule, it is between
about 0.2 and 2 wt. %, and the content of malefic
android is between about 0.01 and 2 wt.%
The 1,5,9-cyclododecatriene used for binding the
naphthoquinone is commercially available, and the
distillation residue is produced in the purification of
the l,5,9-cyclododecatriene. The amounts of 1,5,9-
cyclododecatriene or of the distillation residue of
same, or of mixtures of l,5,9-cyclododecatriene and its
distillation residue, which amounts are required for
the refinement of the raw phthalic android, are about
0.01-1 wt. % of the amount of raw phthalic android.
While larger or smaller amounts are possible, they do
not furnish any advantage. The preferred amount,
however, is in the range OOZE wt. However, where
the naphthoquinone content in the raw phthalic
android is substantially higher than 1.5%, the amount
of refining agent must be increased correspondingly.
The effectiveness of the refining process can be
surprisingly improved by the addition of alkali ions
along with the l,5,9-cyclododecatriene and/or the
distillation residue of l,5,9-cyclododecatriene.
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Preferred ions used are sodium, potassium, and lithium
ions. The amounts of alkali ions required for optimum
results are about 1 to 40 Pam, preferably 2-20 Pam.
The treatment temperature for the treatment of raw
phthalic android with l,5,9-cyclododecatriene and/or
the distillation residue of the same, with optional
alkali ions is about 180-280C, preferably 220-270C.
Treatment times are about 4-20 hr. Longer times are
possible, but, in general, they do not afford
additional advantages. In general, the treatment time
is correlated with the time required for the subsequent
distillation.
The present invention will be further illustrated
by certain examples and references which are provided
for purposes of illustration only and are not intended
to limit the present invention.
Example 1
Raw phthalic android in the amount of 500 g,
produced by gas phase oxidation of naphthalene and
having a naphthoquinone I content of 0.04 wt.% and a
malefic android (MA) content of 0.03 White was treated
with 0.3 wt.% 1,5,9-cyclododecatriene (CDT) i.e.,
sufficient CDT to give a concentration of 0.3 wit % and
30 Pam anydrous sodium carbonate, i.e., sufficient
an hydrous sodium carbonate to yield 13 Pam No+, at
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270C fur 7 hr. After this refinement, the
naphthoquinone content in the product was 1 Pam, and
after subsequent vacuum distillation, it was 0.1 Pam.
Example 2
A product containing 0.5 White NO and 0.04 wt.% MA
was treated as in Example 1. After the treatment with
the CDT, the NO content was 1 Pam, and after the
distillation it was 0.1 pm.
example 3
A product containing lo wt.% NO and 0.03 wt.% MA
was treated as in Example 1. After the refining, the
NO content was 1 Pam, and after the distillation it was
0.5 Pam.
Example 4
Raw phthalic android in the amount of 500 q,
having an NO content of 0.2 wt.% and an MA content of
White.% was stirred intensively with 0.4 wt.% CDT and
10 Pam an hydrous sodium carbonate (4.3 Pam No ) at
270C for 7 hr. This reduced the NO concentration to 1
Pam. After the subsequent distillation, the purified
product contained only 0.1 Pam NO.
Example 5
Raw phthalic android having an NO content of 0.2
wt.% and an MA content of 0.08 wt.% was stirred
intensively with White.% CDT and 15 Pam potassium
hydroxide tlO.4 Pam K+) at 260C for 7 hr. This
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reduced the NO concentration to 4 Pam. After the
subsequent distillation, the purified product contained
a residual 1 Pam of NO.
Example 6
To a raw phthalic android having an NO content
of 0.9 wt.% and an MA content of 0.4 wit% there was
added 0.6 wt.% CDT, i.e., sufficient CDT to comprise
0.6 wt.%, and 40 Pam sodium hydroxide, i.e., sufficient
Noah to yield 23 Pam No+, and the mixture war heated
to 250C for 6 hr., under intensive stirring. This
reduced the NO concentration to 2 Pam. The product of
a subsequent precision distillation had 0.5 Pam NO.
Example 7
To a raw phthalic android having an NO content
of 1.5 wt.% and an MA content of 0.03 wt.% there was
added 0.4 wit% CDT and 10 Pam anh~drous sodium carbonate
(providing 4.3 Pam No+), and the mixture was heated at
270C for 7 hr., under string. This reduced the NO
concentration to 4 Pam. The NO concentration in the
produce of the distillation of the phthalic android
was reduced further, to 0.5 Pam.
Example 8
To a raw phthalic android having an NO content
of 0.04 wt.% and an MA content of 0.3 wt.% there was
added 0.01 wit% CDT and 25 Pam anydrous sodium carbonate
(providing 11 Pam No+), and the mixture was heated at
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270C for 7 ho, under stirring. This reduced the NO
concentration to I Pam. The precision distillation
yielded a purified phthalic android with 1.0 Pam NO.
Example 9
Raw phthalic android in the amount of 500 g,
having an NO content of 2 wt.% and an MA content of
2 wt.% was refined with 0.1 wt.% CDT and 30 Pam
an hydrous sodium carbonate, providing 13 Pam Nay , at
270C for 7 hr. This reduced the NO content to 5
Pam. After the subsequent distillation, the purified
product contained 0.5 Pam NO.
Example 10
A raw phthalic android of the same composition
as in Example 9 was treated with 1.0 wt.% CDT and 5 Pam
potassium hydroxide, providing 3.5 Pam K+, at 280DC for
7 ho, under stirring. This enabled the NO content to
be reduced to 5 Pam. After distillation of the raw
phthalic android, the NO concentration was 0.5 Pam.
Example 11
Raw phthalic android in the amount of 500 q,
having an NO content of 0.6 wt.% and an MA content of
0.3 wt.%, was treated with 0.2 wt.% CDT and 30 pi
an hydrous sodium carbonate, providing 13 Pam Nay, at
270C for 4 hr. This reduced the NO concentration to 2
Pam. After the distillation of the treated material,
the NO concentration was 1 Pam.
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Example 12
A raw phthalic android of the same composition
in Example 11 was refined with 0.2 wt.% CDT and 30 Pam
an hydrous potassium carbonate, providing 16.9 Pam K+,
at 270C for 4 hr. The results were the same as in
Example 11.
Example 13
The raw phthalic android described in Example 11
was treated with 0.6 wt.% CDT alone, at 270C for 7
hr. This reduced the NO content to 2 Pam. Subsequent
precision distillation yielded a purified phthalic
android with residual NO content 1 Pam.
Example 14
Raw phthalic android in the amount of 500 g,
having an NO content of 1 White CDT and an MESA content of
0.5 White was treated with 0.2 White CDT and 30 Pam an hydrous
sodium carbonate, providing 13 Pam No+, at 220C for 7
hr. This reduced the NO concentration to 1 Pam. After
the subsequent distillation, the purified product still
contained 1 Pam NO.
Example 15
To a raw phthalic android having an NO content
of 0.8 wt.% and an MA content of 0.5 wt.% there was
added 0.2 wt.% CDT and 3 Pam an hydrous sodium
carbonate, providing 1.3 Pam No+, and the mixture was
heated at 240 C for 7 hr. This reduced the NO
concentrate to 3 Pam. In the product of a subsequent
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precision distillation there was an improvement and
decrease to 1 Pam NO.
Example 16
Raw phthalic android in the amount of 500 g,
having an NO content of 0.5 wt.% and an MA content of
0.04 wit% was treated with 0.1 wit% of distillation
residue from CDT distillation, at a treatment
temperature of 270C for 7 hr. The treating mixture
had the following composition:
CDT 18 wt.%
Butadiene oligomers as follows:
C16 38 wt.%
C20 31 wt.%
C24 8 wt.%
C28 4 wt.%
C32 1.5 wt.%
The refined product had an NO content of 1 Pam,
and the distilled product 0.5 pi
Example 17
The procedure used was as in Example 16, except
that in addition 30 Pam an hydrous sodium carbonate,
providing 13 Pam No+, was added to the raw phthalic
android product. The NO content in the distilled
product was ~0.5 Pam.
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Example 18
The procedure used was as in Example 16, except
that the material added to the raw phthalic android
was 0.2 White of the distillation residue of the
treatment product of Example 16 which treatment product
had the composition there stated, along with 25 Pam
lithium carbonate, providing 4.7 Pam H+. Following
the purifying distillation, an I content ox 0.5 Pam
was determined.
Example 19
The procedure used was as in Example 16, except
that a raw product was employed with an NO content of 2
wt.% and an MA content of 0.01 wt.%. To the refinement
medium there was added 0.3 wt.%. of the distillation
residue used in Example 16, and 30 Pam an hydrous sodium
carbonate, providing 13 Pam No . After the treatment the
NO content was 3 Pam, and after the distillation 1 Pam.
Example 20
The procedure used was as in Example 16, except
that a raw product was employed having 1.3 wt.% NO and
0.01 wt.% MA. The relining agent employed comprised
the distillation residue from CDT distillation
described in Example 16, in the amount of 0.7 wt.%, and
40 Pam of lithium hydroxide, providing 11.6 Pam H+.
After the distillation, a purified phthalic android
was obtained which had only 0.5 Pam NO.
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Having now fully described this invention, it will
be apparent to one of ordinary skill in the art that
many changes and modifications can be made thereto
without departing from the spirit or scope of the
invention as set forth herein.
