U.S. patent application number 09/480481 was filed with the patent office on 2002-06-06 for apparatus for the purification of commercially available diphenyl-p-phenylenediamine (dppd).
Invention is credited to Frings, Albert-Johannes, Horn, Michael, Jenker, Peter, Monkiewicz, Jaroslaw, Srebny, Hans-Guenther, Standke, Burkhard, Trautvetter, Bertram.
Application Number | 20020066662 09/480481 |
Document ID | / |
Family ID | 27438256 |
Filed Date | 2002-06-06 |
United States Patent
Application |
20020066662 |
Kind Code |
A1 |
Frings, Albert-Johannes ; et
al. |
June 6, 2002 |
APPARATUS FOR THE PURIFICATION OF COMMERCIALLY AVAILABLE
DIPHENYL-P-PHENYLENEDIAMINE (DPPD)
Abstract
A process for the purification of crude
N,N'-diphenyl-p-phenylenediamine (DPPD), which comprises extracting
crude DPPD with a hydrocarbon or hydrocarbon mixtures thereby
forming an extract solution containing DPPD, passing the extract
solution over an adsorption layer, and recovering purified DPPD
from the solution.
Inventors: |
Frings, Albert-Johannes;
(Rheinfelden, DE) ; Horn, Michael; (Rheinfelden,
DE) ; Jenker, Peter; (Rheinfelden, DE) ;
Monkiewicz, Jaroslaw; (Rheinfelden, DE) ; Srebny,
Hans-Guenther; (Duelmen, DE) ; Standke, Burkhard;
(Loerrach, DE) ; Trautvetter, Bertram;
(Rheinfelden, DE) |
Correspondence
Address: |
Oblon Spivak McClelland Maier & Neustadt PC
1755 Jefferson Davis Highway Fourth Floor
Arlington
VA
22202
US
|
Family ID: |
27438256 |
Appl. No.: |
09/480481 |
Filed: |
January 11, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09480481 |
Jan 11, 2000 |
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09301601 |
Apr 29, 1999 |
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09301601 |
Apr 29, 1999 |
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09004851 |
Jan 9, 1998 |
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09004851 |
Jan 9, 1998 |
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08777702 |
Dec 20, 1996 |
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Current U.S.
Class: |
202/168 ;
202/169; 202/170; 202/183; 202/184; 202/200 |
Current CPC
Class: |
C07C 209/84 20130101;
Y10S 203/17 20130101; C07C 211/55 20130101; B01D 11/0288 20130101;
B01D 11/028 20130101; B01D 11/028 20130101; B01D 11/0288
20130101 |
Class at
Publication: |
202/168 ;
202/169; 202/170; 202/183; 202/184; 202/200 |
International
Class: |
B01D 011/00; B01D
015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 1995 |
DE |
195 49 032.0 |
Claims
What is claimed as new and desired to be secured by letters patent
of the United States is:
1. A process for the purification of crude
N,N'-diphenyl-p-phenylenediamin- e (DPPD), which comprises:
extracting crude DPPD with a hydrocarbon or hydrocarbon mixture
thereby forming an extract solution containing DPPD; passing the
extract solution over an adsorption layer; and recovering purified
DPPD from the solution.
2. The process as claimed in claim 1, wherein the purification is
conducted under an inert atmosphere.
3. The process as claimed in claim 1, wherein said crude DPPD is
technical-grade DPPD.
4. The process as claimed in claim 1, wherein the extraction is
conducted at a temperature in the range of 40 to 100.degree. C.
5. The process as claimed in claim 1, wherein the extractant is
hexane.
6. The process as claimed in claim 1, wherein the adsorbent is
silica gel.
7. The process as claimed in claim 6, wherein said silica gel has a
BET surface area of from 450 to 550 m.sup.2/g.
8. The process as claimed in claim 6, wherein said silica gel has a
mean grain size of from 0.063 to 0.5 mm.
9. The process as claimed in claim 1, wherein the adsorption is
conducted at a temperature in the range of 40 to 100.degree. C.
10. The process as claimed in claim 1, wherein the mean residue
time of the product in the purification process is from 20 to 60
hours.
11. The process as claimed in claim 1, wherein the purification of
crude DPPD is conducted continuously.
12. The process as claimed in claim 1, wherein the purified DPPD
has a purity of >90%.
13. The process as claimed in claim 12, wherein the purified DPPD
has a purity of >95%.
14. The process as claimed in claim 1, wherein the purified DPPD
melts at a temperature range over 142 to 148.degree. C.
15. An apparatus for the purification of
N,N'-diphenyl-p-phenylenediamine (DPPD), which comprises: a solvent
evaporator (1); a condenser (3) downstream of said evaporator which
is connected via a solvent line (5) to an extraction unit (7), said
extraction unit provided with an interior and liquid-permeable
container (8) in which DPPD is extracted from crude DPPD (9) placed
therein and a downstream absorption layer (11) therein; an extract
line (13) which connects the extraction unit (7) to solvent
evaporator (1) which in turn is coupled at its base via a lock (15)
to a filter unit 17; and a filtrate line (19) which leads via pump
(21) to solvent evaporator (1).
16. The apparatus as claimed in claim 15, which has at least one
blanketing gas line (23) and (25) which provides the system with an
inert atmosphere.
17. The apparatus as claimed in claim 15, wherein the extraction
unit consists of a liquid-permeable extraction vessel (41) in which
DPPD is extracted from crude DPPD, and a vessel (43) which is
connected thereto via a line (45) and which contains an
adsorbent.
18. The apparatus as claimed in claim 15, wherein the extraction
vessel (41) further comprises a crude product feeder (47) and/or a
residue outlet (45).
19. A method of manufacturing tires, comprising: molding a rubber
latex containing the purified DPPD product prepared by the process
of claim 1 into the shape of a tire.
20. A method of stabilizing organosilanes, comprising: blending an
effective stabilizing amount of an organosilane containing
methacryloxy or acryloxy groups, of the formula I: 2wherein R is a
hydrogen atom or a methyl group, R.sup.1 and R.sup.2 are identical
or different alkyl groups having 1 to 4 carbon atoms or phenyl
groups, and m is equal to 0, 1 or 2.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention:
[0002] The present invention relates to a process and to an
apparatus for the purification of crude diphenyl-p-phenylenediamine
(DPPD) and to the use of purified DPPD.
[0003] 2. DESCRIPTION OF THE BACKGROUND
[0004] DPPD is used on a large industrial scale as a stabilizer,
inter alia, in the reaction of potassium methacrylate with
3-chloropropyltrimethoxysilane. In this application, the use of
commercially available DPPD can impair product quality, in
particular the color number of the product. Unfortunately, in the
past, industrial quantities of DPPD have only been available on the
market in a technical quality.
[0005] Crude DPPD, that is, commercially available DPPD or
technically pure DPPD, has, as a rule, a purity in the range around
85% by weight, the remainder of about 15% by weight essentially
consisting of unconverted or incompletely converted starting
materials such as, for example, diphenylamine, and of inorganic
components such as iron and chlorine, for example in the form of
iron chloride. The commercial material is gray and is often in the
form of a powder or in the form of flakes. In contrast thereto,
pure DPPD is white and crystalline.
[0006] Several methods for the purification of DPPD are described
in the literature. It is possible to crystallize DPPD from
chlorinated hydrocarbons or carbon tetrachloride (Beilstein 13, IV,
116). The disadvantage of these processes is, however, the use of
chlorinated solvents which are toxic and pollute the
environment.
[0007] Another purification method is solids distillation. This
method can be applied successfully in the laboratory. For the
purification of crude DPPD on an industrial scale, however, solids
distillation is not a suitable process, since it is too expensive
in engineering terms. A need therefore continues to exist for a
method of inexpensively and effectively purifying DPPD.
SUMMARY OF THE INVENTION
[0008] Accordingly, one object of the present invention is to
provide a process which allows crude DPPD to be purified in a
simple and economical manner, thereby making a purified DPPD
product available for application on an industrial scale.
[0009] Briefly, this object and other objects of the present
invention as hereinafter will become more readily apparent can be
attained in a process for purifying crude
N,N'-diphenyl-p-phenylenediamine (DPPD), comprising extracting
crude DPPD with a hydrocarbon or hydrocarbon mixture, passing the
extract over an adsorption layer and recovering purified DPPD from
this solution. Preferably, the purification is carried out under a
blanketing gas.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0011] FIG. 1 is a flow diagram showing apparatus components of a
preferred embodiment of the invention for purifying DPPD; and
[0012] FIG. 2 is a flow diagram of a preferred embodiment of the
apparatus arrangement of the extraction unit of the flow process
shown in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] Surprisingly, it has now been found that, by extracting
crude DPPD with a hydrocarbon or a mixture of hydrocarbons and
passing the extract over an adsorption layer, pure DPPD, preferably
white and in crystalline form, is obtained in a simple and
economical manner from the solution which has been prepared. In the
present process, industrial DPPD can also be used as the crude
DPPD.
[0014] FIG. 1 shows the flow diagram of a preferred embodiment of
the equipment in which the process of the invention can be carried
out.
[0015] The apparatus for the purification of
N,N'-diphenyl-p-phenylenediam- ine (DPPD) comprises a solvent
evaporator (1) to which is attached a downstream condenser (3)
which is connected via a solvent line (5) to an extraction unit (7)
which in turn is equipped with an interior and liquid-permeable
container (8) in which DPPD is extracted from crude DPPD (9) and
with a downstream adsorption layer (11). Layer (11) is connected
via an extract line (13) to the solvent evaporator (1) which in
turn is coupled at the bottom via a lock (15) to a filter unit
(17). A filtrate line (19) leads via, a pump (21) to the solvent
evaporator (1). Suitably, one or more blanketing gas line(s) (23)
and/or (25) are also provided in the apparatus.
[0016] The apparatus embodiment, shown in FIG. 2, is a preferred
embodiment of the extraction unit and employs extraction vessel
(41) in which DPPD is extracted from crude DPPD (9) and a vessel
(43) which is connected thereto via a line system (45) and which
contains an adsorbent layer 44. Suitably, the extraction unit is
equipped with a crude product feeder (47) and/or a residue outlet
(49). Furthermore, however, the solvent evaporator (1), the
extraction unit (7) and the filtration unit (17) can also be
equipped with a material feeder lock or a material removal
lock.
[0017] In order to achieve more thorough mixing in the relevant
solid/liquid phases or also better heat transfer in the liquid
phases, the apparatus of the invention can also be equipped, with
respect to units (9), (41) and (1), with a stirrer or mixer
unit.
[0018] For the recovery of purified DPPD, the present apparatus can
also be equipped, in place of filtration unit (17), with other
separation devices, known per se for the separation of solid/liquid
systems, such as a centrifuge or a decanter.
[0019] In general, the process of the invention is carried out as
follows:
[0020] Hydrocarbons or hydrocarbon mixtures can initially be
introduced into the solvent evaporator (1). The quantity of
extractant introduced here depends as a rule on the size of the
apparatus or unit available.
[0021] In general, all cyclic, aliphatic or aromatic, but also
acyclic branched or unbranched hydrocarbons having 3 to 10 carbon
atoms are suitable as extracting solvents. For carrying out the
extraction, preferably pentane, cyclopentane, hexane, cyclohexane,
benzene, toluene, heptane, cycloheptane and many others are used.
In the process of the invention, the extraction is carried out with
particular preference for hexane, which includes all of its isomers
and isomer mixtures. However, unsaturated cyclic or acyclic
hydrocarbons such as cyclopentene, pentene, cyclohexene,
cyclohexadiene, hexene and many others, can also be used as
extractants in the process. Likewise, mixtures of aliphatically
saturated, aliphatically unsaturated, cyclic. acyclic and aromatic
hydrocarbons can also be used.
[0022] As a rule, the solvent evaporator (1) is operated under
normal pressure at a temperature in the range from 40 to
110.degree. C. The solvent fraction thus transferred into the gas
phase is suitably passed through a condenser (3) and the condensate
which forms is fed via a solvent line to the extraction vessel
(7).
[0023] The extraction containers (8) and (41), which are permeable
to liquids, of the extraction unit can consist of a textile fabric
which can be made of a polyester, polyamide or another polymer,
and/or can consist of a metal fabric. The mesh width of such
fabrics is usually in the range from 0.01 to 0.2 mm. The extraction
vessel, which is permeable to liquids, and/or the bottom for taking
up an adsorbent can, however, also consist of ceramic materials,
for example of G 1-G 4 fritted glass.
[0024] The part of each absorption layer (11) and (44), which is
suitably equipped with a liquid-permeable bottom, can be covered by
a layer of adsorbent. The adsorbent used in the process of the
invention is preferably silica gel, for example a silica gel made
by MERCK. For such adsorption layers, layer thicknesses in the
range of from 2 cm to 30 cm are preferred, but the layers can also
be thicker. Thus, for example a silica gel having a mean grain size
of from 0.063 to 3.00 mm can be used here, and the silica gel
preferably used has a mean grain size from 0.063 to 0.5 mm. A
particularly preferred silica gel is a silica gel having a mean
grain size from 0.20 mm to 0.5 mm. In particular a silica gel
having a BET surface area of from 450 to 550 m.sup.2/g. A
liquid-permeable extraction vessel (8) filled with commercially
available DPPD can be located above the adsorption layer (11). The
extraction unit (7) prepared in this way is in general sealed
gas-tight and charged via the condensate line (5) with solvent.
[0025] The extraction vessel (8) and the vessel for the adsorbent
layer (11) can of course also be arranged separate from one
another, in which case the crude extract can be fed from the
extraction vessel (41) via a line (45) to the adsorbent vessel (43)
which contains adsorbent layer 44. A preferred embodiment for this
purpose is shown in FIG. 2.
[0026] Suitably, the crude DPPD first introduced into the
extraction vessel (8) or also into unit (41) is covered with
extractant. However, the extraction vessels (8) and (41) as a rule
are filled up to a level which corresponds to the highest point in
the extract discharge (13) or (45). When this level is reached, the
extract flows off because of the siphoning effect into the solvent
evaporator (1) or via the vessel (43) into the solvent evaporator
(1).
[0027] In the process of the invention, the extraction is generally
carried out at a temperature in the range of from 40 to 100.degree.
C. The adsorption is as a rule also carried out at a temperature in
the of range from 40 to 100.degree. C.
[0028] In a suitable manner, the adsorption layers (11) and (44)
then take up particles present in the extract and impurities which
cause turbidity, so that the solution flowing off into the solvent
evaporator (1) is clear. The process of the invention can be
carried out under normal pressure, at reduced pressure or even at
slightly elevated pressure.
[0029] It has been found that it can be expedient to insulate the
extraction unit (7), as well as units (41) and (43), including the
lines (45), as well as (13) and (15) against heat losses. It is
also possible to provide trace-heating for the extraction unit (7),
as well as units (41) and (43) including the lines (45), as well as
units (13) and (15).
[0030] Crude DPPD (9) can be charged to the extraction vessels (8)
and (41) discontinuously or continuously. Especially for carrying
out the process of the invention continuously, the extraction
vessels (8) and (41) can be equipped with a product-charging device
for crude DPPD, for example, (47), and a discharge device for the
extraction residue, for example, (49). The adsorbent vessels, for
example, (43) can also be equipped with suitable locks for the
removal of spent silica gel and for the charging of fresh silica
gel. Such an arrangement is advantageous for increasing the plant
capacity for the production of purified DPPD.
[0031] The equipment of the invention is advantageously blanketed
with inert gas, for example nitrogen (23) and (25), in order to
prevent the formation of ignitable mixtures.
[0032] After several extraction cycles, the purification of DPPD
can be observed by how it crystallizes as a white microcrystalline
powder from the supersaturated solution in the solvent evaporator
(1).
[0033] The process of the invention for the purification of crude
DPPD can be carried out discontinuously or continuously. In
discontinuous operation of the unit, the extraction vessel (8) or
(41) is suitably emptied and refilled with crude DPPD several times
before the extraction is stopped and the purified product is
isolated from the extractant. In this case, 2 or 3 emptying and
filling steps are preferred before the pure DPPD is isolated. The
adsorption layer (11) or (44) can be partially or completely
replaced. It is, however, also possible to run several extractions
through the same adsorption layer, without impurities passing into
the solvent evaporator (1). The extraction period is as a rule 20
to 60 hours, so that in general the mean residence time of the
product in the purification process is also 20 to 60 hours.
Experience shows that an extraction period of about 35 hours is to
be preferred from the viewpoint of space/time yields. In the
process of the invention, yields of 60 to 85%, relative to the
crude DPPD employed, are generally achieved, which is to say that
the process of the invention can also be operated without a loss of
valuable product.
[0034] After termination of the extraction, the suspension
consisting of extractant and purified crystalline DPPD is, for
example, drained onto a filter (17) and separated. The filtrate is
clear and can in general be used for further extractions, even
without further purification (compare 19 and 21). However, the
filtrate can also first be distilled before re-use.
[0035] The purified DPPD present can, for example, be dried in
vacuo or isolated, under a stream of nitrogen, as a white to
light-beige microcrystalline powder. The product purified by the
process of the invention has in general a purity of >90%,
preferably >95% and very particularly preferably 97 to 99%
(determination by NMR spectroscopy). The DPPD purified by the
invention preferably has a melting range in the temperature range
of from 142.degree. C. to 154.degree. C., and purified DPPD having
a melting range in the temperature range of from 144.degree. C. to
148.degree. C. is particularly preferred. In contrast thereto, the
commercially available crude DPPD, having a purity of about 85%,
has a melting range of from 124 to 126.degree. C.
[0036] When DPPD purified by the process of the invention is
employed, for example, for the stabilization of MEMO
3-methacryloxypropyltrimethoxysila- ne) (compare German Patent
Specification 3,832,621), the product thus obtained is
distinguished by a particularly outstanding color number.
[0037] Another aspect of the invention is the use of DPPD, purified
by the process of the invention, for the stabilization of
organosilanes, containing methacryloxy or acryloxy groups, of the
formula I 1
[0038] R is a hydrogen atom or a methyl group, R.sup.1 and R.sup.2
are identical or different alkyl groups having 1 to 4 C atoms or
phenyl groups and m is equal to 0, 1 or 2.
[0039] The purified DPPD of the invention can also be used in tire
manufacture.
[0040] A further advantage of the process of the invention is that,
because of the use of largely non-polluting hydrocarbons, methods
using chlorinated hydrocarbons as extractants do not have to be
employed.
[0041] Having generally described this invention, a further
understanding can be obtained by reference to certain specific
examples which are provided herein for purposes of illustration
only and are not intended to be limiting unless otherwise
specified.
EXAMPLE 1
[0042] An extraction vessel, fitted with a liquid-permeable bottom,
is filled with 5.5 kg of silica gel 60 (grain size 0.2 to 0.5 mm)
made by MERCK, which is mixed with 4 kg of ceramic saddle-type
packing having a diameter of 15 mm. Above this adsorption layer, a
liquid-permeable extraction vessel containing 10 kg of crude DPPD
made by GOBEL and PFRENGLE is suspended from the lid of the
extraction vessel.
[0043] 300 1 of hexane (an isomer mixture having a boiling point of
68.degree. C.), manufactured by OLFABRIK Lahr, is first introduced
into the solvent evaporator. The unit is permanently blanketed with
dry nitrogen, so that atmospheric oxygen and atmospheric humidity
can be excluded.
[0044] The extractant is heated to the boil. A temperature of
68.degree. C. is measured at the base of the extraction unit. The
condensate flows via the condensate line into the extraction vessel
and from there, depending on the filling level in the extraction
vessel, with dissolved DPPD back into the solvent evaporator. The
extraction cycles are repeated over a period of 60 hours. The
extraction unit is then opened to remove the extraction vessel. The
residue is removed from the extraction vessel. Weighing after
drying gives a quantity of 1.5 kg of residue. The silica gel is
replaced by 6 kg of fresh silica gel containing 4 kg of saddle-type
packing. The extraction vessel filled with 10 kg of crude DPPD is
reinserted into the extraction vessel. After an extraction period
of 36 hours, 1.5 kg of residue are obtained.
[0045] The content from the solvent evaporator is drained onto a
filter. The filter cake is washed twice with about 18 kg of hexane
and dried in vacuo with a little nitrogen being introduced
simultaneously. This procedure provides 16 kg of pure DPPD as a
light-beige microcrystalline powder. This corresponds to a yield of
80%, relative to the total quantity of crude DPPD employed.
EXAMPLE 2
[0046] Quantities employed for one extraction:
[0047] i) 4 kg of silica gel 60 (0.2 to 0.5 mm)=55 mm layer height,
ii) 1.5 kg of used silica gel (yellow)=25 mm layer height, iii) 4
kg of saddle-type packing: Total height of the adsorption layer=80
mm, iv) 400 1 of hexane (isomer mixture), v) 9 kg of crude DPPD
(flakes).
[0048] After an extraction period of 40.5 hours, the amount of
residue was 2.5 kg and the amount of extracted DPPD was 6.5 kg.
EXAMPLE 3
[0049] Quantities employed for the first extraction:
[0050] i) 4 kg of silica gel,
[0051] ii) 1.5 kg of used silica gel,
[0052] iii) 9 kg of crude DPPD (powder),
[0053] iv) 400 1 of hexane.
[0054] Quantities employed for the second extraction:
[0055] i) 3 kg of unused silica gel 60,
[0056] ii) 3 kg of used silica gel 60,
[0057] iii) 4 kg of saddle-type packing
[0058] iv) 10 kg of crude DPPD (flakes)
[0059] From 19 kg of crude DPPD, 12.5 kg=67% of pure DPPD were
isolated in the form of a white powder.
[0060] Having now fully described the 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.
* * * * *