Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to organo-metallic polymers used
to scavenge oxidants and Lewis acids from inert fluids (both
liquids and gases), and their use.
In numerous products and processes the purity of fluids
is of critical importance Often, the presence of even small
amounts of Lewis acid or oxidant impurities will dramatically
reduce the utility of a fluid.
Among the known methods for purification of inert fluids
is the use of scavengers. With this method, a fluid is
passed over a scavenger that reacts with and removes
impurities without affecting the fluid itself. For example,
the fluid may be passed through a bed or column containing
the scavenger.
US. Patents 3,079,428 and 3,316,223 disclose processes
for scavenging acidic impurities from organic liquids by
contacting the liquids with an insoluble polymeric anionic
material.
However, there is a continuing need for new and better
ways of purifying such fluids. Among the properties that are
desired in a good scavenger are the ability to remove a wide
variety of impurities and to insure that the remaining level
of impurities is low, and the capacity to remove high levels
of impurities. Furthermore, it is desirable that a scavenger
should be effective not only when swollen by the liquid to be
purified, but also that it should be effective with liquids
and gases that cannot swell the scavenger. For many
applications, it is also desirable that the scavenger should
have "uniform loading", that is, some of its reactive sites
should not be more reactive than others. If a scavenger does
not have uniform loading, it will not behave consistently
throughout its lifetime, thereby making it difficult to
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predict how the scavenger will perform at any particular
time. It is also desirable that the scavenger should have
good thermal stability, and that it should change color as it
becomes exhausted, so that the need for replacement is
readily determinable.
Cross-linked polymers that remain porous even in the
absence of swelling solvents are known, for instance, from
Chemical and Engineering News, November 15, 1982, p. 15,
which discloses that "functionalized" polystyrene divinely-
Bunsen, including lithiated polystyrene divinylbenzene, maybe used as a catalyst support. Taylor, macromolecules, 14,
(1981), pp. 135 138, discloses also the treatment of swollen
polystyrene divinylbenzene with n-butyl lithium to form an
intermediate in the preparation and halogenation of silylated
polystyrene. Bates et at., Macromolecules, 14, (1981), pp.
881-883 discloses the treatment of a divinylbenzene gel with
n-butyl lithium to detect the presence of vinyl groups in the
gel. None of these references discloses means for removing
acidic and oxidant impurities from fluids through the use of
porous or "macro reticulate" polymers.
According to the invention, all of the desirable
properties for a scavenger, discussed above, are found in
macro reticulate polymers containing mutilated functional
groups, that are characterized in that the functional groups
correspond to the general formula:
-Ar-lCH-CH2-R
M
where An is an aromatic hydrocarbon radical containing from
one to three rings, R is selected from the group consisting
of alkyd hydrocarbon radicals containing from 1 to 12 carbon
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atoms, benzophenone radicals, alkali or alkaline earth metal
salts of benzophenone, fluorenone radicals and alkali or at-
Kline earth metal salts of fluorenone; and M it selected
from the group consisting of lithium, potassium, sodium, at-
Kyle magnesium, and alkyd zinc, where the alkyd groups are at-
Kyle hydrocarbon radicals containing from 1 to 12 carbon
atoms.
Also according to the invention, a process for the
purification of inert fluids containing Lewis acid and
oxidant impurities by contacting the liquids with an
insoluble polymeric anionic material is characterized in that
it comprises contacting the fluid with the macro reticulate
polymer according to the invention, and then separating the
fluid from the scavenger.
In the preferred polymers according to the invention,
the aromatic hydrocarbon radical containing from one to three
rings, which may be phenylene, naphthylene, fluorethylene and
the like, is preferably phenylene.
R can be an alkyd hydrocarbon radical containing from 1
to 12 carbon atoms. Typical alkyd hydrocarbon radicals in-
elude methyl, ethyl, and the various isomers of propel,
bottle, ponytail, Huxley, octal, decal and dodecyl. The prefer-
red alkyd hydrocarbon radicals are bottle radicals.
Alternatively, R can be either a radical of benzophenone, one
of its alkali or alkaline earth metal salts, a radical of
fluorenone or one of its alkali or alkaline earth metal salts.
M is a metal or organometal chosen from the group con-
sitting of lithium, sodium, potassium, alkyd magnesium or at-
Kyle zinc, where the alkyd group is an alkyd hydrocarbon fad-
teal containing from about 1 to 12 carbon atoms. The nature of the metal-functional group bond varies depending on the
choice of M. where M is potassium, the bond is highly ionic,
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whereas where M is an alkyd zinc the bond is much more cove-
lent. The other possible M's fall somewhere between these
two extremes. The greater the ionic nature of the bond, the
greater the carbanion character of the functionality. It has
been found that the greater the carbanion character, the more
reactive the functionality and the more intense the color of
the scavenger. Only where M is alkyd zinc is the scavenger
not intensely colored.
The polymeric backbone may be any polymer which is both
macro reticulate and inert to the mutilated functional
groups. The baclcbone must be macro reticulate, i.e., it must
possess a porous reticulate structure in the absence of a
solvent. generally, the pore size will be in the range of
500 to 1000 nanometers. Such a structure ensures that the
scavenger is not adversely effected by the inert fluid, for
when the backbone is macro reticulate, the scavenger will not
dissolve or swell to an appreciable extent in the fluid.
moreover, because the backbone is macro reticulate r the sun-
face area of the scavenger is sufficiently large so that the
scavenger is effective in purifying gases and liquids which
do not swell the scavenger. The polymeric backbone must not
react with the mutilated functional groups for a functional
group which reacts with the backbone is not available to
scavenge impurities.
The preferred polymer backbone is macro reticulate
polystyrene).
In some embodiments it is the most reactive and most in-
tensely colored scavenger that will be desired. There are
other embodiments, however, where less reactivity is sought
and in these situations less reactive mutilated functional
groups or mixtures of mutilated functional groups will be
employed. The particular mutilated functional group or mix-
lure of mutilated functional group best suited for a specie
lie application will be readily ascertained by one skilled in
the art without undue experimentation following the teachings
of their specification.
The loading of the polymer backbone is an indication of
the number of functional groups present and is expressed in
milli-equivalents of functional groups per milliliter of
scavenger. The greater the loading, the greater the capacity
of the scavenger. The optimal loading for a particular scat-
enter will depend on the polymer backbone, the mutilated
functional group, the impurities to be removed and the par-
titular application. The proper loading for a particular
scavenger will be readily ascertained by one skilled in the
art. In general, the loading will be from about 0.01 to
about 3.0 and preferably from about 0.05 to about 2.5 Millie
equivalents of functional group per milliliter of scavenger.
The scavengers of this invention are stable at tempera-
lures as high as 72C for prolonged periods of time and
stable at temperatures as high as 135C for short periods of
time.
The scavenger of this invention is preferably Cynthia-
sized by mutilating macro reticulate polymers having pendant
aromatic vinyl groups. The preferred macro reticulate polymer
is commercially available macro reticulate polystyrene-
divinylbenzene) (hereinafter referred to as PSDVB). This
material has the requisite pendant groups.
The terminal double bonds of the macro reticulate polymer
are mutilated with an organometallic compound such as an
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alkyd lithium, alkyd sodium, alkyd potassium, dialkyl magnet
slum, alkyd magnesium halide or dialkyl zinc, where the alkyd
group is an alkyd hydrocarbon radical containing from about 1
to 12 carbon atoms; or with a salt of a benzophenone radical-
anion or dianion or a salt of a fluorenone radical-anion or
dianion. The preferred organometallic compounds are left-
bottle lithium, dibutyl magnesium and sodium/potassium salts
of the benzophenone radical-anion or dianion.
Mutilation reactions are well known in the art. The
mutilation can be achieved simply by contacting the macro-
reticulate polymer starting material with a solution contain-
in the organometallic compound. Typical solvents for the
organometallic compound include aliphatic hydrocarbons, art-
matte hydrocarbons and ethers. The contacting is carried out
at ambient temperature and pressure. The time for the con-
tatting is typically in the range of from 10 minutes to 10
hours. Other methods of synthesis of the scavenger will be
known to those skilled in the art.
The mutilated polymer scavenger of this invention is
used to purify any material which is a gas or liquid at the
conditions under which it is contacted with the scavenger and
which is inert to the scavenger's mutilated functionalities.
Representative of the fluids which may be treated are elf-
phatic hydrocarbons, including methane, ethanes propane,
butane, pontoon, hexane, Hutton, octane, decant, dodecane
and the like; olefins including ethylene, propylene, l-butene
and the like, (but not those olefins which would react with
the mutilated functionalities such as, those having an adja-
cent aromatic group including styrenes those having a coinage-
grated double bond, including 1, 3-butadiene and those con-
twining acidic protons including allele and cyclopentadiene);
and inert gases including nitrogen, argon, helium, xenon,
hydrogen and carbon tetrafluoride.
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The mutilated polymers effectively scavenge a wide
variety of impurities such as oxidants and Lewis acids. A
Lewis acid is a compound which can accept a pair of elect
irons. Representative impurities include oxygen, water,
alcohols, phenols, aldehydes, kittens, carboxylic acids, car-
bun dioxide, carbon monoxide; alpha-acetylenes, allele, con-
jugated dines, peroxides, sulfur compounds and the like.
Apparently the mutilated functional group is capable of no
moving impurities by at least three mechanisms: oxidation,
deprotonation and mutilation.
The macro reticulate polymer can be contained in any de-
vice comprising a chamber which is impermeable to the fluid
to be purified and having an inlet port and an outlet port to
allow the impure fluid to enter mid chamber and the purified
fluid to exit respectively. Preferably, the device is trays-
lucent so that any loss of color of the scavenger can be ox-
served. Such devices are known in the art. Typical devices
include beds and columns. The precise configuration of a de-
vice will depend upon the scavenger, the fluid and the impure
flies. The optimal size and configuration for a particulars will be readily determinable by one skilled in the art
without undue experimentation. In some embodiments it will
be desirable to initially pack the device with unmetallated
PSDVB and then carry out the above described mutilation react
lion using the device as the reaction vessel. because the scavengers are largely insensitive to swelling in the inert
fluids, columns can be packed to full volume without concern
for large volume changes.
The impurities are removed in accordance with the pro-
cuss of this invention by passing the fluid containing impure
flies over the macro reticulate polymer, for example, by past
sing the impure fluid through a bed or column containing the
mutilated polymer. The time required will depend on the
scavenger, the inert fluid and the composition and concentra-
lion of the impurities. The -time required for a particular
situation will be readily ascertained by one skilled in the
art.
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To determine if the proper conditions have been chosen
for a particular situation, one need only to take an Alcott
of the fluid after it has been passed through the scavenger
and test for the presence of impurities using any appropriate
analytic method. A particularly useful method is simply to
pass the fluid though an indicator solution after the fluid
has been passed through the scavenger.
There is an additional benefit in using a scavenger
where the metal-functional group bond has ionic character.
Such scavengers are intensely colored. As the mutilated
functional group reacts with impurities, the metal-functional
group bond is destroyed and consequently the scavenger loses
- its intense color and turns white. When the color is gone,
the scavenging power has been depleted, so that the absence
of color serves as an indication that the scavenger needs to
be replaced.
This also means that scavengers which have a metal-
functional group bond having sufficient ionic character may
be used as indicator for the various Lewis acid and oxidant
impurities with which they react. A color change indicates
that these impurities are present, whereas when there is no
change in color, the fluid is free from the impurities
The following examples are to further illustrate the
invention and not to limit it.
Example 1
Lithiated polystyrenedivinylbenzene (Hereinafter revered
to as PSDVB) is prepared in the following manner. Macro-
reticulate PSDVB polymer (Amberlite~XAD4 manufactured by Room
& Hays) is washed with three bed volumes of water, then moth-
anon, then isopropanol and finally hexane. One bed volume is
equal to the volume of the unfilled bed. The polymer is
placed in a reaction vessel and for about two hours dried us-
don a stream of nitrogen at 120C. The reaction vessel is
then flooded with 2 molar tert-butyl lithium. The mixture is
agitated occasional for two hours.
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The resulting polymer reaction product is then washed with
hexane and dried with nitrogen at room temperature. The no-
suiting product is a lithiated polymer of this invention,
which is dark red and turns white upon reaction with
impurities.
The lithiated polymer is used to fill a 500 ml. glass
column. Nitrogen, containing the impurities listed below is
passed through the bed at a flow rate of 40 volumes of gas
per volume of bed per hour. In order to determine if any imp
purities remain in the nitrogen after it is passed therewith bed; the nitrogen is passed through an indicator soul-
lion. The indicator solution consists of 5 ml. of diglyme
which contains 2.5 micro moles of sodium anthracene. The
anthracene will decolonize if any impurities are left in the
nitrogen. It is found that the lithiated polymer scavenger
removes oxygen (41 micro moles), isopropanol (50 micro moles),
carbon dioxide (41 micro moles), and acetone (54 micro moles).
A 30 ml. serum vial containing about 3 ml. of the lithe-
axed polymer is pressurized to 10 prig with nitrogen. One
ml. of carbon monoxide is added. Within three minutes, there
is no detectable carbon monoxide present in the nitrogen gas.
Example 2
Butylmagnesium polystyrenedivinylbenzene is prepared in
the following manner. The procedure of Example 1 is followed
except that the clean PSDVB polymer is flooded with 0.7 M
Bu2Mg and reacted at room temperature for one hour. The
resulting product is a macro reticulate polymer of this invent
lion which is yellow and turns white upon reaction with
impurities.
Example 3
Potassium benzophenone polystyrenedivinylbenzene is pro-
pared in the following manner. Sixty ml. of PSDVB polymer is
placed in one side of a vessel having two 250-ml. round-
bottom flasks joined by a coarse Fritz 4~2 g. benzophenone
in 75 ml. tetrahydrofuran is added to the other side.
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Then sodium/potassium alloy is added to the benzophenone
solution. The solution immediately turns blue. When the
solution becomes purple, the thus formed potassium buoyancy
phenone dianion solution is transferred to the side contain-
in the polymer. The solution is then returned back to thesodium/potassium alloy side and an additional 75 ml. of
tetrahydrofuran is added. After one-half hour the solution
is transferred back to the side containing polymer and left
overnight. The product is washed with 400 ml. tetrahydro-
Furman, then 300 ml. hexane and finally nitrogen dried. The product a macro reticulate polymer of this invention, which is
black to reflected light and when crushed under an inert at-
misfire is blue-purple and turns white upon reaction with
impurities.
Example 4
In a crown capped vessel is placed 400 ml. of purified
hexane delineate and a Teflon covered magnetic stir bar. The
delineate is then sparred with purified nitrogen for about 50
minutes. The vessel is placed in a constant temperature bath
at 50C. Then, the vessel is attached to a propylene manic
fold and flushed with propylene for several minutes in order
to remove the nitrogen.
To the hexane delineate is added 1.2 ml. of a 1.36 M dip
ethyl aluminum chloride in hexane and then 0.3 moles of
Tokyo. The propylene is polymerized at a temperature of
65C under 30 prig propylene pressure for 2.5 hours.
The polymerization is repeated following the same prove-
dune except that the propylene gas is first purified by past
sing it through a 400 ml. column, packed with a lithiated
polystyrenedivinylbenzene prepared as outlined in Example 1.
Without purification, the yield of insoluble polymer is
4.0 g. and the percent insoluble yield is 97%. With purify-
cation, the yield of insoluble polymer is 5.0 g. and the per-
cent insoluble yield is 98%.
