Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DEHYDRATION PIItOCESS
Field of the Invention
This invention relates to a process for removing water from hydrous
substrates.
Backgroundl
Many materials, including chemical materials and compositions, and articles
of manufacture, are water-sensitive or for other :reasons are desirably free
or
substantially free of water. Examples of chemic~~ls used in water-sensitive
chemical
systems include surfactants such as fluorinated surfactants, urethanes,
pharmaceutical compounds, and many chemicals and chemical systems useful in
energy storage systems and devices (e.g., batteries, capacitors, etc.).
Some of these arid other chemicals used iin water-sensitive chemical systems
may be manufactured in aqueous systems, but are then desirably employed in
substantially anhydrous systems. Much effort is made to dehydrate, i.e.,
remove
water from, chemical components in such chemical systems, and thereafter to
keep
such systems dry.
To provide chemicals and chemical systems having appropriately low water
content, tedious drying procedures are often used. Chemicals can be
commercially
sold as spray-dried or tray-dried, giving them a water content of less than
about
5000 parts per million (ppm). Having such a relatively high water content can
cause these materials to require additional drying by the purchaser, often
achieved
by rotary vacuum drying or vacuum oven drying, followed by special handling in
dry rooms.
Known methods of removing water from chemical compositions can be
tedious, relatively slow, costly, and can involve the use of flammable or
hazardous
solvents. A need exists to identify new processes for drying hydrous materials
such
as chemicals and articles of manufacture.
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Summary of the Invention
The invention provides a method for removing water from a hydrous
substrate by contacting the hydrous substrate with a hydrofluorocarbon (HFC).
Water of the hydrous substrate can be transferred to the hydrofluorocarbon (to
become contained, e.g., dissolved or dispersed in the hydrofluorocarbon), and
thereafter optionally and preferably removed from the HFC in any convenient
and
effective manner, the net effect being a reduction in the concentration of
water
associated with the hydrous substrate. Water can be removed from the HFC
mechanically, by volatilization (e.g., distillation, a~zeotropic distillation,
boiling,
etc.), or by any other useful method. Preferred hydrofluorocarbons include
hydrofluoroethers (HFEs).
For purposes of the present description, a. chemical composition, e.g., a
mixture or solution, containing hydrous substrate and hydrofluorocarbon (i.e.,
containing substrate, water, and Hl~ C), will be rejPerred to as a "hydrous
HFC
ZS composition." Water can be removed from the hydrous HFC composition,
generally with HFC also being removed, to result in a dehydrated HFC
composition
containing substrate, hydrofluorocarbon, and a reduced amount of water,
preferably
no more than a residual amount of water, and most preferably substantially no
water.
The method can be used to dehydrate a variety of different substrates, and is
particularly useful for dehydrating chemical compositions including an aqueous
solution of an electrolyte salt. Optionally, an organic solvent can also be
present in
the aqueous salt solution.
An HFC (such as an HFE) as a solvent medium in a dehydration process can
exhibit low ozone depletion and reduced global v~~arming effects. Moreover,
the
dehydration process can be more efficient than dehydration processes that use
other
solvents such as perfluorocarbons. Additionally, the use of HFCs to dehydrate
chemical compositions has been found to provide a dehydration product with an
appearance that is more aesthetically pleasing than such products dehydrated
using
other common organic solvents (PFCs or CFCs), or other dehydration techniques
(spray drying or oven drying). Specifically, some chemical substrates
dehydrated
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using an HFE solvent have been found to exhibit: relatively improved
appearance,
including an attractive pearlescent appearance (a,s a solid or in the form of
a solution
or slurry), and as a solid have the attractive appearance of a flaky, flowable
solid
with uniform consistency. In contrast, like substrates dehydrated by methods
such
as oven or spray drying can be of a less attractive, less flowable, less
uniform
consistency (e.g., coalesced, chunky, non-uniformly textured), of a relatively
higher
density, and not flaky but typically of a chunky o~r cube-like or agglomerated
cube-
like structure.
An aspect of the invention relates to a mE;thod of dehydrating a hydrous
substrate. The method includes the steps of combining the hydrous substrate
with a
hydrofluorocarbon to form a hydrous hydrofluorocarbon composition, and
volatilizing the hydrous hydrofluorocarbon composition.
A further aspect of the invention relates to a method of dehydrating a water-
containing substrate. The method comprises the steps of providing a water-
containing substrate comprising substrate and water, and adding
hydrofluorocarbon
to the water-containing substrate to provide a hydrous hydrofluorocarbon
composition comprising substrate, water, and hydrofluorocarbon. Optionally,
water
can be removed from the hydrous hydrofluorocarbon composition, by any desired
method, to provide a dehydrated hydrofluorocarl>on composition comprising
hydrofluorocarbon, substrate, and a reduced amount of water, preferably no
more
than a residual amount of water.
Yet a further aspect of the invention relates to a method of dehydrating a
hydrous substrate comprising a fluorinated chemiical salt and optionally an
organic
solvent. The method includes the steps of combining the hydrous substrate with
hydrofluoroether to form a hydrous hydrofluoroe~ther composition,
azeotropically
distilling the hydrous hydrofluoroether composition to volatilize water and
the
hydrofluoroether therein. This removes water from the hydrous hydrofluoroether
composition and produces a dehydrated hydrofluoroether composition having a
reduced water content. A polar organic solvent can optionally be added to the
dehydrated hydrofluoroether composition, and th.e hydrofluoroether can
optionally
be separated from the polar organic solvent.
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As used within the present description, the prefix "perfluoro-," and the term
"perfluorinated," refer to organic carbon backbone-based molecules typically
containing carbon-bonded hydrogen atoms, but wherein substantially all (e.g.,
at
least 90%, preferably at least 95%) of the carbor,~-bonded hydrogen atoms have
been replaced by fluorine atoms.
Brief Description of the Drawings
Figure 1 illustrates an embodiment of the present invention wherein a
hydrous substrate is contacted with an HFC to fc>rm a hydrous HFC composition,
and HFC and water are removed from the hydrous HFC composition by azeotropic
distillation.
Detailed Description
According to the method of the invention., a hydrous substrate can be
combined with a hydrofluorocarbon to form a hydrous hydrofluorocarbon
composition ("hydrous HFC composition"). For purposes of the present
description the term "hydrous substrate" means a,ny solution, mixture,
suspension,
emulsion, or other material or combination of materials containing water and a
substrate, with the water contacting, containing, or being contacted by or
contained
by, or on the surface of, the substrate. The term "water-containing substrate"
means a particular type of hydrous substrate wherein water is contained within
the
substrate, as opposed to water contacting an exposed surface of the substrate
in a
manner that would allow removal or drying of the surface water by solvent
displacement. A water-containing substrate can include solid or liquid
materials in
the form of a solution, suspension, mixture, emulsion, etc., and can contain
water,
e.g., in the form of dissolved, dispersed, or absoribed water, water of
hydration, or
any other form of water present other than on an exposed surface of the
substrate.
The substrate can in general be any material at all, and can be organic or
inorganic, natural or synthetic, and ca,n be in the i:orm of a solid, a
liquid, or an
article of manufacture. Preferably the substrate can be substantially non-
reactive
with the hydrofluorocarbon chosen for use with t:he dehydration method, and
can be
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substantially thermally stable (e.g., will not degrade to an unacceptable
degree) at
the volatilization temperature. The substrate can include a liquid chernical
such as a
polar organic solvent, an alcohol, or polyol; another type of liquid such as a
liquid
fluorochemical; a solid such as a solid article of manufacture or a solid
chemical
5 composition which can be, e.g., in a granular form or the form of a powder,
a
polymer or polymeric material, or a synthetic or natural material like a plant
or a
natural or synthetic fiber; or mixtures of these or other forms of materials.
More
specifically, the substrate can comprise a liquid, a solid, a dispersed or
dissolved
chemical composition (e.g., an alkali metal hydroxide such as lithium
hydroxide
10 monohydrate, an alkali metal halide, e.g., potassium fluoride or cesium
fluoride, or
an alkali metal imide), a wet or damp solid, (e.g., a powder such as a
cosmetic or a
magnetic powder), an aqueous slurry, an aqueous solution, a water-contaminated
polar organic solvent, or a water-containing emulsion.
The process can be useful to remove water from a single hydrous substrate,
IS or a mixture or combination of substrates. For Example, the process can be
useful
for removing water from a chemical composition that contains water, but is
otherwise relatively pure. Alternatively, the pro~~ess can be useful for
removing
water from a mixture of a hydrous chemical corr~position contained, e.g.,
dissolved,
suspended, or in admixture with, an organic solvent. The organic solvent may
or
20 may not be water-miscible or water-soluble, and may or may not be miscible
or
soluble in a chosen HFC.
In one preferred embodiment of the process, the substrate can comprises a
hydrous, ionizable, hygroscopic, light metal salt that can be in the form of a
solid, or
that can be dissolved, suspended, or in admixture with an organic solvent.
25 Examples of such light metal salts include alkali :metal, alkaline earth
metal,
ammonium, and Group IIiB metal (e.g., aluminum) salts of anions such as BF4 ;
PF6 , AsFs , C 104 , SbFs , RfS03', where Rf is a p~erfluoroalkyl group
preferably of
one to about 12 carbon atoms, more preferably 1 to about 4 carbon atoms; the
bis(perfluoroalkanesulfonyl)imide anion, (ReSOz;IN(SOzR'f), where Rf and R'f
are
30 independently selected from perfluoroalkyl groups preferably of 1 to about
12
carbon atoms, more preferably 1 to about 8 carbon atoms;
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bis(perfluoroalkylsulfonyl)methide anion, (RfSOz)C'(R)(S02R'f), where Rf and
R'f
are independently selected from perfluorinated alkyl groups preferably of 1 to
about
12 carbon atoms, more preferably 1 to about 4 carbon atoms, and R is H, Br,
C1, I,
alkyl of 1 to about 20 carbon atoms, alkenyl of 3 to 4 carbon atoms, aryl, or
alkaryl;
and the tris{perfluoroalkanesuIfonyl)methide anion, (RfSOz)C'(SOZRf')(SOzRf"),
where Rf, Rf" and Rf' are independently selected from perfluorinated alkyl
groups
preferably of 1 to about 12 carbon atoms, more ;preferably one to about 4
carbon
atoms. Such salts also include cyclic perfluoroaliphaticdisulfonimide salts
such as
those described in U.S. Pat. No. 4,387,222 (Kos~har), and metal salts of acids
such
as those described by DesMarteau et al. in J. Fluor. Chem. 45 24 ( 1989).
Representative examples of light metal sat substrates include LiOH~H20,
CF3S03Li, C2FsS03Li, C8F1~S03Li, CloFz,SO3L~, (CF3SO3)zBa, (CF3SOz)zNNa,
(C2FSSOz)zNLi, (C4F9SOz)(CF3SOz)NLi, [(CF3SOz)zNJ3Al, (CF3SOz~C(H)Lj,
(CF3SOz)zNLi, cyclo(CF2SOz)zNLi, cyclo-(CF2S~Oz)zC(H)Li, (CF3SOz)3CL1,
(CF3)zNCzF4S03Li, [(CF3)zNC2FaSOzJzNLi, (CsIEmSOz)(CF3SOz)NLi,
CF3SOz(C6HsS02)NLi, (CF3SOz)(NC)zCLi, phosphorus salts, and mixtures thereof.
Representative solvent substrates, e.g., those that can be useful in battery
electrolytes, include aprotic solvents which are dry, i.e., solvents which
have a
water content less than about 100 ppm, preferably less than about 50 ppm.
20 Examples of suitable aprotic electrolyte solvents include linear ethers
such as diethyl
ether, diethylene glycol dimethyl ether, and 1,2-dlimethoxyethane; cyclic
ethers such
as tetrahydrofuran, 2-methyltetrahydrofuran, dio:xane, dioxolane, and 4-
methyldioxolane; esters such as methyl formate, ethyl formate, methyl acetate,
dimethyl carbonate, diethyl carbonate, propylene carbonate, ethylene
carbonate, and
butyrolactones (e.g. gamma butyrolactone); nitrites such as acetonitrile and
benzonitrile; vitro compounds such as nitromethane or nitrobenzene; amides
such as
N,N-dimethylformamide, N,N-diethylformamide, and N-rnethylpyrrolidinone;
sulfoxides such as dimethyl sulfoxide; sulfones such as dimethylsulfone;
tetramethylene sulfone, and other sulfolanes; oxazolidinones such as N-methyl-
2-
oxazolidinone; and mixtures thereof.
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Preferably, the electrolyte solvent is selected from the group consisting of
propylene carbonate, ethylene carbonate, dimetlhyl carbonate, diethylene
glycol
dimethyl ether and 1,2-dimethoxyethane.
The hydrous substrate can contain any amount of water, generally from
5 about SO parts per million (ppm) up to about 99~ percent by weight water,
often
from about 100 ppm to about 50 weight percent water. The water can be in the
form of free water, dispersed water, surface water, water as a solvent or
solute, or
water of hydration. Preferably, for the sake of Efficiency, the method can
include
the step of removing as much water as is feasible from the substrate, e.g., by
i0 mechanical methods, prior to combining the hydlrous substrate with
hydrofluoroca~rbon to form a hydrous HFC composition. Suitable mechanical
methods can include centrifugal methods, filtering methods, etc., or chemical
methods such as desiccants, phase separations, extractions, etc.
The term "hydrofluorocarbon" means an organic chemical compound
15 minimally containing a carbon backbone substituted with carbon-bonded
hydrogen
and carbon-bonded fluorine atoms, and optionally containing one or more
skeletal
heteroatoms such as divalent oxygen, trivalent nitrogen, or hexavalent sulfur.
The
carbon backbone can be straight, branched, cyclic, or mixtures of these, but
preferably includes no functional or unsaturated groups. This definition
includes
20 compounds having more than approximately 5 nnolar percent fluorine
substitution,
or less than 95 molar percent fluorine substitution, based on the total number
of
hydrogen and fluorine atoms bonded to carbon, and specifically excludes
organic
compounds generally referred to as perhalogenated compounds, perfluorinated
compounds, and hydrocarbon (non-fluorinated) compounds.
25 Preferred hydrofluorocarbons can be capable of volatilization along with
water, at a desired temperature and pressure, yet have neither so high a
boiling
point as to require large heat input to effect volatilization, nor so low a
boiling point
that unacceptable losses of the HFC occur due t~o its volatilization. Most
preferably, the HFC, when it contains water {e.g;., dispersed or dissolved
water), has
30 a vapor pressure that will provide a vapor evolviing from the hydrous F~FC
composition (i.e., a hydrous F~FC vapor}, wherein the vapor has a
concentration of
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water, whether considered on a molar or weight basis, that is relatively
higher than
the concentration of water in the hydrous HFC composition. The particular
hydrofluorocarbon chosen for use with a specific hydrous substrate in a
particular
dehydration process can be based on these properties of the hydrofluorocarbon
at a
particular range of temperature and pressure. Preferred hydrofluorocarbons can
have a boiling point in the range from about 30°C to about
275°C, preferably from
about 50°C to about 200°C, most preferably from about
50°C to about 110°C.
It can be especially desirable that the hyd.rofluorocarbon be non-flammable.
This can mean that the HFC can have a flashpoint above 100 degrees Fahrenheit:
To be non-flammable, the relationship between the number of fluorine,
hydrogen,
and carbon atoms can preferably be related in th<~t the number of fluorine
atoms per
the number of combined hydrogen atoms and carbon-carbon bonds be less than or
equal to about 0.8:
# of F atoms / (# H atoms + # C=C bonds) _> 0.8
In general, increasing the number of fluorine atoans, decreasing the number of
hydrogen atoms, or decreasing the number of carbon-carbon bonds, each increase
the flashpoint of the HFC.
Preferred hydrofluorocarbons include hydrofluoroether compounds (also
sometimes referred to as simply hydrofluoroethers, highly fluorinated ethers,
or
HFEs) which are chemical compounds minimally containing carbon, fluorine,
hydrogen, one or more ether oxygen atoms, and optionally one or more
additional
heteroatoms within the carbon backbone, such a;> sulfur or nitrogen. The
hydrofluoroether can be straight-chained, branched-chained, or cyclic, or a
combination thereof, such as alkylcycloaliphatic, and is preferably free of
unsaturation. The hydrofluoroether can preferably have from about 2 to about
20
carbon atoms. Preferred HFEs can be relatively :low in toxicity, can have low
ozone
depletion potentials, e.g., zero, short atmospheric: lifetimes, and a low
global
warming potential, e.g., relative to chlorofluorocarbons and many
chlorofluorocarbon substitutes.
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Preferred hydrofluoroethers include two identifiable varieties: segregated
hydrofluoroethers, wherein ether-bonded alkyl or alkylene, etc., segments of
the
HFE are either perfluorinated {e.g., perfluoroca~tion) or non-fluorinated
(e.g.,
hydrocarbon), but not partially fluorinated; and omega-hydrofluoroalkylethers,
wherein ether-bonded segments can be non-fluorinated (e.g., hydrocarbon),
perfluorinated (e.g., perfluorocarbon), or partially fluorinated (e.g.,
fluorocarbon or
hydrofluorocarbon).
Segregated hydrofluoroethers include hydrofluoroethers which comprise at
least one mono-, di-, or trialkoxy-substituted peWuoroalkane,
perfluorocycloalkane,
IO perfluorocycloalkyl-containing perfluoroalkane, ~or perfluorocycloalkyIene-
containing perfluoroalkane compound. These HFEs are described, for example, in
WO 96/22356, and can be represented below in :Formula I:
(Formula )~
wherein:
x is from 1 to about 3, and Rf is a perfluorinated hydrocarbon group having
a valency x, which can be straight, branched, or cyclic, etc., and preferably
contains
from about 2 to 15 carbon atoms, more preferablly from about 3 to 12 carbon
atoms, and even more preferably from about 3 to~ 10 carbon atoms;
in all cases, Rf can optionally comprise a terminal FSS- group;
each R~, is independently a linear or branched alkyl group having from 1 to
about 8 carbon atoms, a cycloalkyl-containing alkyl group having from 4 to
about 8
carbon atoms, or a cycloalkyl group having from 3 to about 8 carbon atoms;
wherein either or both of the groups R~ and Rh can optionally contain one or
more catenary heteroatoms;
wherein the sum of the number of carbon atoms in the Rf group and the
number of carbon atoms in the Rh group(s) is preferably greater that or equal
to 4.
Preferably, x is 1; Rf is a pertluoroalkyl comprising from about 3 to 10
carbons, optionally containing one or more heteroatoms; and R,, is an alkyl
group
having from 1 to about 6 carbon atoms. Most preferably, x is 1; Rf is a linear
or
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branched perfluoroalkyl groups having from 3 to about 8 carbon atoms; a
perfluorocycloalkyl-containing perfluoroalkyl group having from 5 to about 8
carbon atoms; or a perfluarocycloalkyl group having from about 5 to 6 carbon
atoms; R,, is an alkyl group having from 1 to about 3 carbon atoms; and Rf but
not
R,, can contain one or more heteroatoms.
Representative hydrofluoroether compounds described by Formula I include
the following:
F CF20CH3 F CF20C2H5
F N(CF2)3OCzH5 CF3 F CF20CH3
F N(CF2)30CH3 F N(CF2~OCH3
O N(CF2}30CH3 n-C4F9pCH3
CF3CFCF2OCH3 CF3CFCF20C2H5
CF3 CF3
OCH3
F
n-C4F9OC2H5
CgF 170CH3 CH30 (CF2}~O CH3
CF3 F CF20CH3 C3F70CH3
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CF3
CsF110C2Hs CsF110C3H7 F .
OCH3
CF3OC2F4OC2Hs C3F70CFCl?20CH3 (CF3~CFOCH3
CF3
(CF3)3C-OCH3 C4F~OC2F4OCF2CF2OC2Hs C4F9O(CF2~OCH3
~5Ff3~3H7 O~F NCFZCFZOCI-~ O F~NCF2CF20C.lHs
(C2Fs)zNCF2CFzOCH3 (CzFs)2N~Fba~ F N(CF~30C~
CF3CFCF20C2Hs
F (CF2)30C2Hs F
(CFs~zN(CF2)3~DCH3
(CF3hN(CF2~OC2Hs
(C2Fs~NCF2ClF20CH3
C2FSNCF2CF2CF20C2Hs
CF3
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(C3F7)2NCF2CFzCFzOCH3
(C3F7)2NCF2CF~zCFzOC2Hs
{C3F7~NCF2CF2CF20C3H7
O NCFCF'ZCF20CH3
CF3
O F N(CFz~,OCH3 rt=1-4
O~N(CF2~,OC2H5 r~l-4
F N(CFz)nOCH3 ~1-4
F N(CFz)nOC2Hs n=1-4
F -N(CFz)nOCH3
.n=1-4
F -N(CFz)nOC2Hs
(C4F9)2N(CF2)3«CH3
(CzFs~N(CFz)s~)CH3
O F N-{CF2)3OCH2CHzOCH3
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CF3
O F N-(CF'2~OCH3
CF3
CFA F ~(CF;Z~OC2Hs
CF3-T F~I(CF'2~OCH~
CZFs F C:F20CZHs
C7K3OF2C
F CF20CH3
F CF20CH3
CF2OCH3
CFZOCH3
cF3 cF2oc3H7
F CF20 C2Hs F F
IO
CF20CH3 CF20C2Hs
F
F F
CF3
CF20CH3
F
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C3F~CF(OCzHs)CF(CF3~,
C2FSCF{OC2H5)CF(CF3~
CZFSCF(OCH~)CF(C'.F3~, and
CF3CF(OCH3)CF(CF3~,
wherein cyclic structures designated with an intE;rior "F" are perfluorinated.
These
HFE compounds can be used alone or in admixture with another HFE.
Particularly preferred segregated hydrofluoroethers of Formula I include
n-C3F,OCH3, (CF3)ZCFOCH3, n-C4F9OCH3, (Cl?3)2CFCFZOCH3, n-C4F90C2Hs,
(CF3)zCFCFZOC2Hs, (CF3)3COCH3, CH30(CF2;IaOCH3, CH30(CFZ)60CH3, and
mixtures thereof.
Segregated hydrofluoroethers can be prepared by alkylation of
10 perfluorinated alkoxides prepared by the reaction of a corresponding
perfluorinated
acyl fluoride or perfluorinated ketone with an anhydrous alkali metal fluoride
(e.g.,
potassium fluoride or cesium fluoride) or anhydrous silver fluoride in an
anhydrous
polar aprotic solvent. (See, e.g., the preparative methods described in French
Patent Publication No. 2,287,432 and German Patent Publication No. 1,294,949).
Alternatively, a fluorinated tertiary alcohol can be allowed to react with a
base (e.g.,
potassium hydroxide or sodium hydroxide) to produce a perfluorinated tertiary
alkoxide which can then be alkylated by reaction with alkylating agent, such
as
described in U.S. Pat. No. 5,750,797, which is herein incorporated by
reference.
Suitable alkylating agents far use in the preparation of segregated
20 hydrofluoroethers include dialkyl sulfates (e.g., climethyl sulfate), alkyl
halides (e.g.,
methyl iodide), alkyl p-toluenesulfonates (e.g., rrtethyl p-toluenesulfonate),
alkyl
perfluoroalkanesulfonates (e.g., methyl perfluoromethanesulfonate), and the
like.
Suitable polar aprotic solvents include acyclic ethers such as diethyl ether,
ethylene
glycol dimethyl ether, and diethylene glycol dime,thyl ether; carboxylic acid
esters
25 such as methyl formate, ethyl formate, methyl acetate, diethyl carbonate,
propylene
carbonate, and ethylene carbonate; alkyl nitrites ;>uch as acetonitrile; alkyl
amides
such as N,N-dimethylformamide, N,N-diethylformamide, and N-methylpyrrolidone;
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alkyl sulfoxides such as dimethyl sulfox:ide; alkyl sulfones such as
dimethylsulfone,
tetramethylene sulfone, and other sulfolanes; ox:azolidones such as N-methyl-2-
oxazolidone; and mixtures thereof.
Suitable perfluorinated acyl fluorides can be prepared by electrochemical
5 fluorination (ECF) of the corresponding hydrocarbon carboxylic acid (or a
derivative thereofj, using either anhydrous hydrogen fluoride (Simons ECF) or
KF2IdF (Phillips ECF) as the electrolyte. Perfluorinated acyl fluorides and
perfluorinated ketones can also be prepared by dissociation of perfluorinated
carboxylic acid esters (which can be prepared from the corresponding
hydrocarbon
or partially-fluorinated carboxylic acid esters by direct fluorination with
fluorine
gas). Dissociation can be achieved by contacting the perfluorinated ester-with
a
source of fluoride ion under reacting conditions (see the method described in
U. S.
Pat. No. 3,900,372 (Chills), the description of 'which is incorporated herein
by
reference) or by combining the ester with at least one initiating reagent
selected
1 S from the group consisting of gaseous, nonhydroxylic nucleophiles; liquid,
non-
hydroxylic nucleophiles; and mixtures of at least one non-hydroxylic
nucleophile
(gaseous, liquid, or solid) and at least one solvent which is inert to
acylating agents.
Initiating reagents which can be employed in the dissociation are those
gaseous or liquid, non-hydroxylic nucleophiles and mixtures of gaseous,
liquid, or
solid, nonhydroxylic nucleophile(s) and solvent /;hereinafter termed "solvent
mixtures") which are capable of nucleophilic reaction with perfluarinated
esters.
The presence of small amounts of hydroxylic nucleophiles can be tolerated.
Suitable gaseous or liquid, nonhydroxylic nucleophiles include dialkylamines,
trialkylamines, carboxamides, alkyl sulfoxides, amine oxides, oxazolidones,
pyridines, and the like, and mixtures thereof. Suitable non-hydroxylic
nucleophiles
for use in solvent mixtures include such gaseous or liquid, non-hydroxylic
nucleophiles, as well as solid, non-hydroxylic nucleophiles, e.g., fluoride,
cyanide,
cyanate, iodide, chloride, bromide, acetate, mercaptide, alkox:ide,
thiocyanate,
azide, trimethylsilyl difluoride, bisulfite, and bifluoride anions, which can
be used in
30 the form of alkali metal, ammonium, alkyl-substituted ammonium (mono-, di-,
tri-,
or tetra-substituted), or quaternary phosphonium salts, and mixtures thereof.
Such
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salts are in general commercially available but, if desired, can be prepared
by known
methods, e.g., those described by M. C. Speed and R. C. Brasted in
Comprehensive
Inorganic Chemistrv Volume Six (The Alkali Ivfetals), pages 61-64, D. Van
Nostrand Company, Inc., New York (1957), and by H. Kobler et al. in Justus
Liebigs Ann. Chem. 1978, 1937. 1,4-diazabicy<;lo[2.2.2]octane and the like are
also
suitable solid nucleophiles.
Other useful hydrofluoroethers include omega-hydrofluoroalkyl ethers such
as those described in U.S. Patent No. 5,658,962 (Moore et al.), incorporated
herein
by reference, which can be described by the general structure shown in Formula
II:
X-R~-(O-R~'h,-O-R"-H
(Formula II)
wherein:
X is either F or H;
R~ is a divalent perfluorinated organic radical having from 1 to about 12
carbon atoms;
Rf' is a divalent perfluorinated organic radical having from 1 to about 6
carbon atoms;
R" is a divalent organic radical having from 1 to 6 carbon atoms, and is
preferably perfluorinated; and
y is an integer from 0 to 4;
wherein when X is F and y is 0, R" contains at lE;ast one F atom.
Representative compounds described by :Formula II which are suitable for
use in the processes of the invention include the Following compounds:
C4FgOC2F4H,
HC3F60C3F6H,
HC3F6OCH3
CSF 11 OC2F4~
C6F130CF2H,
C6F13OC2F40C2F4H,
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c-C6F 11 CF20CF2H,
C3F70CH2F,
HCF20(C2F40)n(CF20)mCF2H, wherein m = 0 to 2 and n = 0 to 3,
C3F70[C(CF3)CF20]pCFHCF3, wherein p = 0 to 5,
C4F90CF2C(CF3 )2CF2H,
HCF2CF20CF2C(CF3)2CF20C2F4H,
C7F 150CFHCF3
,
C8F170CF20(CF2)$H, and
C8F 170C2F40C2F40C2F40CF2H.
Preferred omega-hydrofluoroalkyl ethers, include C4F9OC2F4H,
C4F9OC2F~.H, CsF~30CF2H, HC3F60C3F~I, C3F~OCH2F,
HCF2O(C2F40)n(CF20),"CF2H wherein m is from 0 to 2 and m is from 0 to 3, and
mixtures thereof.
Omega-hydrofluoroalkyl ethers described by Formula II can be prepared by
15 decarboxylation of the corresponding precursor :Eluoroalkyl ether
carboxylic acids
and salts thereof or, preferably, the saponifiable alkyl esters thereof, as
described in
U.S. Pat. No. 5,658,962, which is incorporated herein by reference.
Alternatively,
omega-hydrofluoroallcyl ethers can be prepared by reduction of a corresponding
omega-chlorofluoroalkyl ether (e.g., those omega-chlorofluoroalkyl ethers
20 described in WO 93/11868 published application.), which is also described
in U.S.
Pat. No. 5,658,962.
Other hydrofluorocarbons can include non-ether HFCs selected from the
following groups:
(1) linear or branched compounds ofthe formula:
C4~Fio.~ where n < S;
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representative examples of this class are:
CHF2(CF2}2CFZI~ CF3CFZC:HZCH2F,
CF3CH2CF2CH2F, CH3CHFCF2CF3,
CF3CH2CH2CF3, CH2FCF,2CF2CHzF2
CHF2CH(CF3}CF3, CHF(CF,3}CF2CF3;
(2} linear or branched compounds of the empirical formula:
CsH"Flzfi where rr < 6;
representative examples of this class are:
CF3CH2CF2CH2CF3, CF3CHZCH2CF2CF3,
CH3CHFCF2CFZCF3, C)HI3CFZCF2CF2CF3,
CHzFCF2CFZCF2CF3, CI~3fFzCF2CF2CFZCF3,
CH3CH(CFZCF3)CF3, CF3~zCH(CHFz)CF2CF~,
CHF2CF(CHFz}CFZCF3, Cl~lF2CF2CF(CF3)z;
(3) linear or branched compounds of the empirical formula:
CsH"Fn." where n < 7;
representative examples of this class are:
CHFz(CFz)4CFzH, (Cf3CHz)2CHCF3,
CFzHCHFCF2CFZCHFCF2H, CHZFCF2CF2CFZCF2CFzH,
CHF2CFzCFzCFZCF2CHFz, CH:3CF(CF3)CHFCHFCF3,
CH3CF(CF3)CFZCF2CF3, CHF2CF2CH(CF3)CFZCF3,
CHFzCFzCF(CF3}CF2CF3;
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(4) linear or branched compounds of the empirical formula:
C~H"F~s." where n < 8;
representative examples of this class are:
CH3(CF2)sCH3, ChI3CH2(CF2}4CF3,
CF3CHzCHz(CF2)3CF3, C332FCFZCHF(CF2~CF3,
CF3CFZCF2CCHFCHFCF2CF3, Cl~3CF2CFZCHFCF2CF2CF3,
CH3CF(CF3)CH2CFHCFxCF3, C133CF(CFZCF3}CHFCF2CF3,
CH3CH2CH(CF3)CFZCFZCF3, CI~2CF(CF3)(CF2)3CH2F, and
CHF2CF(CF3)(CF2)3CF3,
(5) linear or branched compounds of"the empirical formula
CsH"Fi&" where n < 9;
representative examples of this class are:
CH3(CFz)6C~i3, CHFZCF(CF3}(CFZ)4CHF2,
CH3CH2CH(CF3)CF2CF2CF2CF3, CFi3CF(CFZCF3)CHFCF2CF2CF3,
CH3C(CF3}ZCFZCFZCF2CH3, and Cfi2FCF2CF2CHF(CF2)3CF3.
The hydrofluorocarbon can be used alone, as a mixture of two or more
hydrofluorocarbons, or in admixture with one or more other ingredients such as
another volatile co-solvent. A surfactant (other than a surfactant which may
be
present as substrate} can be included in the hydr~ofluorocarbon, but is not
necessary
for many applications of the method, and may preferably be absent for many
applications; especially where high purity of the dehydrated substrate is
desired.
According to the method of the invention a hydrofluorocarbon can be
combined, mixed, or otherwise contacted with a hydrous substrate to provide a
hydrous HFC composition; e.g., a hydrofluoroether can be contacted with a
hydrous substrate to provide a hydrous hydroflu~oroether composition (hydrous
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HFE composition). Upon combining the hydrous substrate with the HFC, water is
removed from the hydrous substrate and transfers to and is thereafter
contained
(e.g., dispersed, dissolved, or otherwise present;) in the HFC.
The hydrous substrate and the hydrofluorocarbon can combine to form
various forms of hydrous HFC compositions. If the substrate is completely
miscible
in the HFC, the hydrous HFC composition can be a single phase of the HFC and
dissolved substrate. If the substrate comprises either an immiscible solvent
or an
insoluble solid, the hydrous I3FC composition can contain the HFC phase and
one
phase for each of the immiscible solvent and insoluble solid, establishing two
or
three phases. Additionally, given a sufficient amount of water in the hydrous
substrate, there can be a separate aqueous phase which may exist initially and
subside as the dehydration process progresses. A typical hydrous HFC
composition
can comprise at least two phases: 1) an aqueous phase containing water,
substrate,
and if present and if water soluble, organic solvent; and 2) an HFC phase
containing
hydrofluorocarbon and water. If the substrate includes a water-insoluble
organic
solvent, the hydrous HFC composition may comprise a ternary system with
organic
solvent being an additional phase. The phases may be present in the form of an
emulsion, although this may be unpreferred because in practice an emulsion may
be
dif'flcult to handle or process. Also, the hydrous HFC composition may be
susceptible to foaming, hut foaming will preferably be minimized.
The amounts of each phase in the hydrous HFC composition can be
controlled and optimized to provide an efficient process. Typically, water
will be
contained, e.g., dissolved or dispersed, in each oiFthe phases.
The water will typically be contained in the HFC as a dissolved solute or as
a dispersed phase. Generally, whether or not a dispersed phase of water is
present,
water will be in equilibrium with the HFC and di:;solved in the HFC up to a
saturation level. The amount of water dissolved or dispersed in the HFC will
depend on various factors such as the solubility c~f water in the HFC at the
processing temperature. Water can be dissolved in HFCs, at equilibrium, at
various
levels, depending on temperature and the HFC (its affinity to dissolve water).
Typical saturation concentrations of water in an l:3FE, for example, can be
less than
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about 100 parts per million (ppm) water by weight, e.g., less than 60 ppm or
15
ppm. The HFC may contain dissolved or dispersed water when introduced to the
hydrous substrate, or, as can be preferred, the F1FC can be substantially free
of
water when introduced to the hydrous substrate.. In either case, water will
transfer
from the hydrous substrate to the HFC, and can be removed from the aqueous HFC
composition system as desired.
The amount of hydrofluorocarbon relative to the hydrous substrate in the
hydrous HFC composition can be chosen based on factors such as the solubility
of
water in the hydrofluorocarbon, the amount of water understood to be
associated
10 with the hydrous substrate, desired or actual process conditions (e.g.,
process
parameters such as temperature, pressure, and vvhether the process is a batch
or a
continuous process), the amount of water desired to be removed from the
hydrous
substrate, and the amount of water acceptably contacting, associated with, or
present in the substrate after performing the dehydration process. The hydrous
i5 I3FC composition should contain enough hydrofluorocarbon to remove, through
a
batch or continuous process, a significant portion of, and preferably,
substantially all
of the water initially associated with the hydrous substrate. Although the
following
ranges are not intended to be limiting, and these ranges can change or be
adjusted
according to factors such as those listed above, the hydrous HFC composition
can
20 preferably contain from about 30 to about 90 parts by weight
hydrofluorocarbon
per 100 parts by weight of the hydrous HFC composition, (i.e., the combined
parts
by weight of hydrous substrate (substrate and water) and hydrofluorocarbon),
more
preferably from about 50 to about 80 parts by weight hydrofluorocarbon based
on
100 parts hydrous I3FC composition.
25 With removal of HFC during the removal step, as detailed below, additional
HFC can be introduced to the hydrous HFC composition, with the additional HFC
containing water, or, preferably, being free or substantially free of water.
The hydrous HFC composition can be prepared by combining the hydrous
substrate and hydrofluorocarbon in any manner, such as in a kettle or other
vessel
30 adapted to facilitate the dehydration process. (T'he kettle or other vessel
will be
referred to herein for convenience as the "vessel.") The process can be
practiced in
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a continuous, a batch, or a semi-batch method, inn vessels properly adapted
for any
of these. Preferably the hydrous substrate and the hydrofluorocarbon can be
intimately contacted to facilitate removal of water from the hydrous substrate
by
dissolution or dispersion of the water in the hydrofluorocarbon. The vessel
can
preferably be equipped with a stirrer to enable aF~tation of the contents and
uniform
mixing. Preferred vessels can also preferably be equipped with an inert gas
inlet and
outlet to enable blanketing of the contents of the vessel with a dry; inert
gas, and
can additionally be equipped to allow a continuous dehydration process by
being
fitted with a condenser arranged so that condensate can be directed to a
receiver or
preferably a decanter. The vessel can also preferably be fitted with a heating
or a
cooling jacket, internal heating or cooling coils, or other means to transfer
heat
energy into or out of the hydrous HFC composition.
Once prepared, water can be removed from the hydrous HFC composition
by any convenient, effective, or otherwise desires3 or suitable method.
Because the
hydrous HFC composition contains water (e.g., <~ water phase of the hydrous
HFC
composition, or water dispersed in the HFC) in contact with an HFC phase, some
generally small amount ofwater will typically dissolve in the HFC phase to a
level
of saturation. This being true, the process allows for removal of water from
the
hydrous substrate by transfer of water from the hydrous substrate to the HFC,
and
optionally and preferably the additional step of removing water from the HFC,
or
removing water-containing HFC (i.e., the HFC phase) from the hydrous HFC
composition. in a continuous or semi-continuous process, the water-containing
HFC phase can be removed; and can optionally and preferably be replaced with
relatively drier IEiFC to maintain a concentration gradient between the
hydrous
substrate and the HFC phase, resulting in mass transfer of water from the
hydrous
substrate to the HFC phase for removal.
By "removed" it is meant that water, and generally HFC, can be taken away
or otherwise allowed, forced, or encouraged to depart from the hydrous HFC
composition, for example by mechanical or chemical separation methods,
volatilization, refluxing, azeotroping, evaporation, distillation (e.g.,
azeotropic
distillation), etc. of the HFC and water (e.g., the IE~C phase of the hydrous
HFC
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composition). Because water is contained in the HFC phase, any type of
mechanical or chemical method of removing the. HFC phase will accomplish the
water-removal step. As is evident, the water-removal step will typically be
accomplished by removal of a portion of HFC, meaning simultaneous removal of
both HFC and water from the hydrous HFC connposition.
As a preferred method of removing water from a hydrous HFC composition,
water, in the form of water dissolved in the HFC; phase, can be removed as a
vapor
(e.g., volatilized, evaporated, azeotroped, distilled, etc.), under desired
conditions
of reduced or elevated temperature and reduced or elevated pressure. The
pressure
within the vessel can be reduced, and/or the temperature can be increased to
effect
volatilization of HFC and water ,in the HFC phase. .Alternatively, the
temperature
of the hydrous HFC composition can be reducecl by cooling, and the pressure
reduced to effect volatilization. Reduced tempe7rature can be desired in
situations
where a component of the hydrous HFC composition (e.g., the substrate or the
HFC) is temperature sensitive. Often, the hydrous HFC composition can be
heated
to a temperature suflF~cient to initiate volatilization of water and
hyrofluorocarbon
by distillation at atmospheric pressure, under vacuum, or under greater than
atmospheric pressure. The actual temperature and pressure employed in any
particular dehydration process may vary, and may be chosen based on factors
such
as the particular hydrous substrate to be dried and the chosen
hydrofluorocarbon.
While either elevated or reduced pressures or temperatures may be useful,
preferred
volatilization temperatures can be in the range from about 50 to 150°C,
or from
about 50 to 110°C. It is possible for the hydrous: HFC composition to
reach a bail,
although this is not generally preferred, and voIa~tilization can be effected
without
boiling.
During volatilization, HFC and water from the hydrous HFC composition
evolve to form a hydrous HFC vapor phase comprising gaseous HFC and water
vapor: The relative amounts of water and I-iFC vapor contained in the vapor
phase
will depend an the amounts of each component in the hydrous HFC composition,
and the relative volatility of each component. In general, because of the
azeotropic
nature of a composition containing water and l:iF'C, it has been found to be
possible
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and preferable for the hydrous HFC vapor phase to have a higher concentration
of
water vapor than the concentration of water in the liquid HFC phase (when
considered either on a weight ar molar basis). 'this can be preferable because
it
enables, e.g., in a continuous process, condensation of the vapor phase to a
two-
s phase liquid system. (If the concentration of water in the vapor phase were
less
than in the liquid phase, where water is dissalve;d in the HFC, the condensate
would
also be a single phase of water dissolved in HF(:.) Separation of the organic
HFC
and aqueous phases of the condensate allows th.e HFC phase to be returned as a
recycle stream to the hydrous HFC compositioru.
10 In such a continuous system, because the aqueous and the HFC phases of
the condensate will be in equilibrium, the recycle HFC stream will typically
contain
dissolved water, possibly to a level of saturatior,~. An optional and
preferred, but
not required, step of the process can be included, if desired, e.g., to
accelerate
removal of water from the substrate. This step :includes further treating the
HFC
15 recycle stream to remove some or alI of the water in the recycled HFC
phase.
When the treated recycled HFC is returned to the hydrous HFC composition, the
concentration of water in the HFC phase of the hydrous HFC composition is
further
reduced, thereby allowing more water from the :hydrous substrate to transfer
into
the HEC of the hydrous HFC composition, and ;further reducing the
concentration
20 of water associated with the hydrous substrate. This optional HFC drying
step can
be accomplished by known methods of drying liquid chemicals, for example by
contacting the recycled HFC phase with a conve;ntionai solid drying agent such
as a
molecular sieve, anhydrous magnesium sulfate, anhydrous calcium chloride or
Drierite~ drying agent (available from W. A. Hammond Drierite Co., Xenia,
Ohio),
25 or the Like.
In a preferred embodiment of the methoci, water can be removed from a
hydrous HFC composition by continuous azeotropic distillation; with the
hydrous
HFC vapor phase being condensed and allowed to separate into a two-phase
condensate, and with the HFC portion of the condensate being separated and
30 redirected back to the hydrous HFC composition as recycle. An example of
such a
preferred method is illustrated in Figure 1. In the Figure, vessel 2 includes
hydrous
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WO 00138813 PCT/US98127777
HFC composition 4, comprising HFC, substrate, and water. Hydrous HFC
composition 4 is typically a mufti-phase composition comprising an aqueous
phase
and an HFC phase. Hydrous HFC composition 4 is volatilized at desired
conditions
of temperature and pressure to produce hydrous HFC vapor 8, comprising HFC and
water. Hydrous HFC vapor 8 can be condensedf in condenser I O to form
condensate 12 having HFC phase 14 and aqueous phase 16. Preferably, the
concentration of water in vapor phase 8 and con;densate 12 is higher than the
concentration of water in hydrous HFC composition 4. HFC phase 14 can be
separated from condensate 12, optionally processed further to partially or
fully
remove any dissolved or dispersed water (the optional processing step is not
shown
in Figure 1), and then returned to hydrous HFC compositiow4.
The water removal step can proceed until the water content of the hydrous
substrate is desirably low for a particular substrate being dehydrated. Water
content of the substrate can be measured directly by removing a sample of the
15 substrate and using standard analytical methods ouch as spectroscopy, Karl
Fischer
titration, or a melting point measurement. Altennatively, water content of the
substrate can be measured indirectly by monitoring the water content of the
HFC
phase.
When the water content of the hydrofluo:rocarbon has been reduced to an
20 acceptable level, any water phase of the hydrous HFC composition has
substantially
subsided and departed, leaving a dehydrated HFC composition. The dehydrated
HFC composition will comprise an HFC phase, substrate which may be dissolved
in, dispersed in, or in admixture with the HFC phase, and may constitute or
comprise a separate phase (the "substrate phase"), and will further typically
contain
25 a residual amount of water dissolved in one or more of the HFC phase, the
substrate, and the substrate phase (if present). The residual water can be a
relatively minor amount up to the saturation point of the HFC, and preferably
is
below an amount of water that would result in th.e presence of an aqueous
phase.
The amount of water present in the dehydrated ~~C composition can depend on
30 factors such as the duration and effectiveness of the water removal step,
the identity
of the substrate and its amity to associate with water, the particular
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hydrofluorocarbon used in the dehydration process and its ability to dissolve
water
at the given temperature and pressure, and the desired end application of the
substrate and its tolerance for the presence of water, etc. For many
applications the
amount of water remaining in a dehydrated HFC: composition will desirably be
5 minimized and the dehydrated HFC composition will be essentially free of
water,
meaning that the dehydrated HFC composition contains substrate, HFC, and only
a
residual amount of water, e.g., less than 100 ppm.
After substantially complete removal of water from the hydrous HFC
composition, what remains will be referred to as'. the dehydrated ~iFC
composition.
The dehydrated HFC composition will contain ~~C, substrate, and substantially
no
water (as stated, each component or phase of the dehydrated FiFC composition
may
contain a residual amount of water absorbed or .dissolved therein). The
dehydrated
HFC composition will take the same form and have similar phases as the
hydrated
HFC composition, except that if an aqueous phase was present in the hydrated
HFC
1S composition, an aqueous phase will preferably not be present in the
dehydrated
H1:C composition. Ifthe substrate comprises an insoluble solid, a soluble
solid, or a
solvent that is miscible with the HFC, the dehydrated HFC composition will
typically similarly contain the solid substrate, the. dissolved solid, or the
miscible
solvent, respectively. If the substrate comprises a chemical (e.g., a salt)
dissolved in
an organic solvent imnuscible with the HFC, the dehydrated HFC composition
will
typically contain two phases including an HFC phase and a separate
solvent/dissolved salt phase.
The dehydrated HFC composition can preferably be brought to ambient
temperature under a dry, inert gas atmosphere, fir example, nitrogen or air,
and the
HFC can be separated from the dehydrated HFC composition to leave behind a
dehydrated substrate. The dehydrated substrate will comprise the substrate,
possibly a residual amount of water, and any other component not removed in
the
volatilization step, such as additives or impurities; that were initially
present in the.
hydrous substrate. The dehydrated substrate will typically take the form of
the
original substrate, e.g., a solid such as a powder, a liquid such as an
organic solvent,
or a combination of these.
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The separation step, i.e., separation of the HFC from the dehydrated
substrate, can be accomplished by separation methods that are well known and
understood in the chemical art, including the uses of liquid separation
equipment and
techniques, and mechanical separation equipment and techniques such as
filtration,
centrifuging, etc. The particular method chosen. to accomplish the separation
step
can depend on factors such as the form of the substrate within the dehydrated
HFC
composition, e.g., whether the substrate is a soIi.d or solvent, and whether
the
substrate is dissolved or dispersed in the composition.
Solid substrates can be separated from the HFC by mechanical methods
such as filtration to leave a dry solid substrate. Again, dry means that the
dehydrated substrate may contain a residual amount of absorbed or adsorbed
water.
According to one embodiment of the method, a solid substrate (e.g., an
electrolyte salt) dispersed in the dehydrated HFC; composition may be
separated
from the HFC phase by adding an organic solvent to the dehydrated HFC
composition to form a solvent solution of the salt dissolved or dispersed in a
phase
of the organic solvent, which can then be separated from the dehydrated HFC,
e.g.,
by draining offthe HFC phase. This embodiment of the process allows a solid
dehydrated substrate to be directly transferred from the dehydrated
hydrofluoroether composition to an organic solvent or other chemical treatment
phase without transforming the substrate to the state of a dried solid. This
embodiment can preferably be used for preparing a water sensitive or
hygroscopic
substrate, e.g., an electrolyte salt solution; because both the dehydration
and the
preparation of the salt solution are carried out within the environment of a
dry
liquid, perhaps under an inerting atmosphere, preventing contamination of the
solid
with water or undesirable gases.
The amount of water present in the dehydrated substrate is preferably
minimized, and should be no more than a residual. amount of water, i.e., an
amount
of water attracted to the substrate when in equililbrium with the HFC, with
the HFC
containing no more than a residual amount of water. The actual amount of water
remaining any dehydrated substrate will depend on the amount ofwater remaining
in the dehydrated HFC composition, and the affli~ity for the substrate to
attract
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w0 00/38813 PCTIUS98/27777
water dissolved in the dehydrated HFC composition. As exemplary amounts of
water preferably remaining in a dehydrated substrate, for applications of
dehydrating electrolytes useful in electrical storage cells, the water content
of the
dehydrated electrolyte (optionally in solvent) can generally be Iess than
about 100
ppm, preferably less than about 50 ppm.
In a preferred embodiment of the invention, the hydrated substrate and the
dehydrated substrate both comprise an organic solvent with a salt dispersed or
dissolved therein. An advantage to this method is that, as opposed to other
drying
processes (e.g., tray drying with heat), water can be removed from the salt
without
i0 any process step wherein the salt has to be transformed into the state of a
solid, but
can be dissolved or dispersed in a solvent, preferably a dry solvent,
throughout the
dehydration process, with the dried substrate beiing dissolved in a dry
solvent. A
further advantage of this embodiment is that it provides an aesthetically
pleasing
dehydrated substrate, and does not cause caking or hardening of the substrate;
thus
eliminating the need for grinding or pulverization the otherwise dried,
dehydrated
solid.
This invention is further illustrated by the; following examples, but the
particular materials and amounts thereof recited in these examples, as well as
other
conditions and details, should not be construed to limit this invention. All
parts are
ZO by weight unless otherwise stated. Ail determinations of water content in
the
examples were performed by Karl Fischer titration using a 652 KF Coulometer
instrument made by Metrohm of Switzerland and distributed by Brinkmann
Instruments in the U.S.A.
EXAMPLESi
Preparation of Perfluorobutyl Methyl :Ether (C4F90CH3} - a 20 gallon
(3.8 L) Hastalloy C reactor, equipped with stirrer and a cooling system, was
charged with 6.0 kg {103.1 mol) of spray-dried potassium fluoride. The reactor
was sealed, and the pressure inside the reactor was reduced to less than 100
ton.
30 25.1 kg of anhydrous dimethyl formamide was then added to the reactor, and
the
reactor was cooled to below 0°C with constant agitation. 25.1 kg {67.3
mol) of
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WO 00/38813 PCTIUS98127777
heptafluorobutyryl fluoride (58% purity) was adlded to the reactor. When the
temperature of the contents of the reactor reached -20°C, I2 kg (95.1
mol) of
dirnethyl sulfate was added to the reactor over a. period of approximately 2
hours.
The resulting mixture was then allowed to react for i6 hours with continuous
agitation, the temperature was raised to 50°C for an additional 4 hours
to facilitate
complete reaction, and the temperature was cooled to 20°C. After
cooling, volatile
material (primarily perfluorooxacyclopentane present in the starting
heptafluorobutyryl fluoride reactant} was ventedl from the reactor over a 3-
hour
period. The reactor was then resealed and water (6.0 kg) was added slowly to
the
reactor. After the exothermic reaction of the water with unreacted
heptafluorobutyryl fluoride had subsided, the reactor was cooled to
25°C and the
reactor contents were stirred for 30 minutes. The reactor pressure was
carefully
vented, and the lower organic phase was removed, affording 22.6 kg of material
which was 63.2% by weight C4F90CH3 {b.p. of 58-60°C, product identity
confirmed by GC/MS and by 1H and '9F NMR}.
Preparation of Pertiuorobutyl Ethyl Ether (CaF90CZHs) - a 20 gallon
(3.8 L} Hastalloy C reactor, equipped with stirrer and a cooling system, was
charged with 7.0 kg ( / 20.3 mol) of spray-dried potassium fluoride. The
reactor
was sealed, and the pressure inside the reactor was reduced to less than 100
ton.
22.5 kg of anhydrous dimethyl formamide was then added to the reactor, and the
reactor was cooled to below 0°C with constant avgitation. 22.5 kg {60.6
mol) of
heptafluorobutyryl fluoride (58% purity) was added to the reactor. When the
temperature of the contents of the reactor reached -20°C, I8.6 kg
(120.8 mol) of
diethyl sulfate was added to the reactor over a pE;riod of approximately 2
hours.
The resulting mixture was allowed to react for 1 ti hours with continuous
agitation
The temperature was raised to 50°C for an additiional 4 hours to
facilitate complete
reaction, and then the temperature was cooled to~ 20°C. After cooling,
volatile
material {primarily perfluorooxacyclopentane preaent in the starting
heptafluorobutyryl fluoride reactant) was vented from the reactor over a 3-
hour
period: The reactor was resealed and water (6.0 kg) was added slowly to the
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reactor. After the exothermic reaction of the water with unrea.cted
heptafluorobutyryl fluoride had subsided, the reactor was cooled to
25°C and the
reactor contents were stirred for 30 minutes. Tlhe reactor pressure was
carefully
vented, and the lower organic phase was removed, affording I7.3 kg of material
which was 73% by weight C4F90CH3 (b.p. of 7:5°C, product identity
confirmed by
GC/MS and by 'H and '9F NMR).
Preparation of PerEIuoropropyl Methyl Ether (C3F'~OCH3) - a jacketed
1-L round bottom flask was equipped with an overhead stirrer, a solid carbon
10 dioxide/acetone condenser and an addition funnel. The flask was charged
with 85 g
(1.46 mol) of spray-dried potassium fluoride and 375 g of anhydrous diethylene
glycol and was then cooled to about -20°C using; a recirculating
refrigeration
system. i96 g (1.18 mol) of CZFSCOF was added to the flask over a one hour
period. The flask and its contents were warmed to about 24°C, and 184.3
g (1.46
mol) of dimethyl sulfate was added dropwise via, the addition funnel over a 45
minute period. The resulting mixture was stirred overnight at room
temperature.
Water (a total of 318 mL) was added dropwise to the mixture. The mixture was
transferred to a 1-L round bottom flask, and the resulting ether product was
azeotropically distilled. The lower product phase of the resulting distillate
was
separated from the upper aqueous phase, was w<~shed once with cold water, and
was subsequently distilled to give I80 g of C3F~()CH3 product (b.p.
36°C, >99.9%
purity by GLC). The product identity was confirmed by GCMS and by 1H and '9F
NMR.
Examote 1
This example describes a laboratory scale; dehydration of an aqueous
solution of lithium bis(trifluoromethanesulfonyl) imide using perfluorobutyl
methyl
ether.
80 g ofFluoradTM HQ-115 Lithium Trifluoromethanesulfonimide (available
from 3M Co., St. Paul, Minnesota) was dissolved in 20.5 g of distilled water.
This
solution and 120 g of C4F90CH3 were placed in a 250 mL round bottom flask
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equipped with a Dean-Stark distillation head, thermometer, condenser, heating
mantle, magnetic stirrer, and stirnng bar.
Temperature was adjusted to allow sufffcient heat flow to give a reffux rate
of about 10 L/min. The resulting C4F90CH3/water azeotrope was observed to boil
at about 60°C, and the condensate was collecte<i in the Dean-Stark
trap. Water was
separated from the condensate according to the elapsed time schedule shown in
Table 1.
TABLE 1
Elapsed Incremental Total Water
Time Water Removed General Comments
_Removed
0.25 1 1
0.5 1 2 _
0.75 1 3
1.0 1 4
1.25 1 5
1.5 1 6
1.75 1 7
2.0 0.4 7.4
2.5 1.6 9 _.
3 0.7 9.7
3.25 1 10.7
3.5 0.6 11.3
6.0 1 12.3
7.5 0.6 12.9 water removal rate slowed
considerably, 50 g ofHFE
added,
reflex rate ad'u
sted to 20 mL/min
7.8 _
apparent fornvation of
solid
10.4 3.9 16.8 slurry formed, 41 g of
HFE added to
maintain stirrin
11.8 2.4 19.2 20 g of HFE added to maintain
stirrin
12.7 0.9 20.1 free-flowing slurry observed,
clear
HFE layer in receiver
(formerly
cloud
13.4 0 20.1 distillation ex eriment
terminated
After stopping the distillation experiment after 13.4 hours, the slurry of
HFE/HQ-115 was vacuum filtered through a sizE; C fritted glass filter, drawing
nitrogen through the filter cake to dry the product. A free-flowing,
iridescent
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powder with plate-like crystal structure resulted. Through this process, 20.1
g of
water (98% of the 20.4 g theoretical) was recovered.
Eaamole 2
5 This example describes a pilot scale deh;~rdration of an aqueous solution of
lithium bis(trifluoromethanesulfonyl)imide using; pertluorobutyl methyl ether,
and
reports the results of a water analysis on the dehydrated irnide salt.
1000 g of an 83% (wt) aqueous solution of HQ-115 and 2500 g of
perfluorobutyl methyl ether were charged to a pilot scale reactor. The mixture
was
refluxed continually, returning to the distillation vessel the perfluorobutyl
methyl
ether captured in the trap. 183.2 g of water was recovered, representing
nearly the
theoretical amount for quantitative dehydration. The resulting white slurry of
imide
salt and the perfluorobutyl methyl ether was filtered in the -76°C dew
point dry
room, producing a white, free-flowing, iridescent powder. A 1M (1 molar)
solution
15 of this powder was prepared in propylene carbonate. Karl Fisher titrations
run on
both the 1M solution (240 ppm) and propylene carbonate alone (175 ppm) showed
that the dehydrated imide salt contained about 65 ppm residual moisture.
ExamuEe 3
20 Essentially the same experiment was run as described in Example 1, except
that 101 g of a 73% (wt) aqueous solution of lithium triflate (FluoradTM FC-
122
Lithium TrifluoromethanesuIfonate, available from 3M Co.) and 200 g of
perfluorobutyl methyl ether were used. The process proceeded in a similar
fashion
as was described in Example 1, with the recovery of 27.0 g of water,
representing
25 an essentially quantitative removal of water.
Example 4
Essentially the same experiment was run as described in Example 1, except
that 10 g of a 82% (wt) aqueous solution of lithnum
bis(pentafluoroethanesulfonyl)
30 imide (prepared as described in Example 3 ofU.;S. Pat. No. 5,652,072) and
200 g
of perfluorobutyl methyl ether were used. The process proceeded in a similar
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fashion as was described in Example 1, with the apparent quantitative removal
of
water. Analysis of the sample the sample purity to be 99.91% of the desired
dehydrated imide salt, with traces of hydrofluoroethers as the only deteetable-
impurity.
Examine 5
This example describes a laboratory scale preparation and subsequent
dehydration of an antistatic phosphonium triflate; compound,
{CsHs)3{CH3)P+ ~03SCF3 {described in U.S. Pat. No. 5,051;330, Table 3,
compound
2a), using perfluorobutyl methyl ether as the azeotroping solvent.
In a 3-necked flask equipped with stirrer., cooler, and condenser; and under
a nitrogen blanket was charged 26.2 g (0.1 mol) of triphenylphosphine
(available
from Aldrich Chem. Co., lVfiIwaukee, Wisconsin) and 400 mL of anhydrous
diethyl
ether. Then, at room temperature, I6.4 g (0.1 moI) of methyl
trifluorornethanesulfonate was added slowly over about a 30 minute time
period. A
white precipitate slowly formed while reacting fc>r 24 hours at room
temperature
under nitrogen. The white precipitate was filtered, washed with deionized
water,
and fettered again, leaving a water-damp precipitate. 100 g of CaF90CH3,
perfluorobutyl methyl ether, was added to the water-damp precipitate, and the
precipitate was dried by azeotropic distillation using a Dean-Stark trap.
After no
further water was coming over with the CaF90ClEi3, the C4F90CHa was evaporated
off. A white solid resulted, which contained 40 ppm of water according to Karl-
Fisher analysis.
Comparative Example CI
The same experiment was run in the same; manner as described in Example
5, except that C6F14, perfluorohexane, was substituted for C4F9OCH3. During
the
early stages of the azeotropic distillation step, foaming started to such an
extent that
the distillation could not be continued. The C6Fl,s was then allowed to
evaporate,
leaving a white solids which, through Karl Fisher analysis, was found to
contain
about 1000 ppm of water.
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Example 6
This example describes a laboratory scale dehydration of an aqueous
solution of lithium perfluorooctanesulfonate using perfluorobutyI methyl
ether.
200 g fluorochemical surfactant (26% lithium perfluorooctanesulfonate in
water) and 450 g of C4F90CH3 were added to a 500 mL round-bottom flask
equipped with a Dean-Stark distillation head, thermometer, condenser, heating
mantle, magnetic stirrer, and stirring bar. Approximately 50 g of C4F~OCH3 was
placed in the azeotrope receiver. The resulting 3mixture was heated, but too
much
foam was produced to boil off the C,,F9OCH3. Addition of up to 40 drops of
isopropyl alcohol temporarily reduced foaming I>ut only for a short duration.
To gain more reaction reactor space, the mixture was transferred to a 1-L
round-bottom flask equipped the same way as the 500 mI, flask. The flask and
its
contents were heated to boiling, and 100 mL of C~.F90CH3 was distilled through
the
Dean-Stark head. 100 mL of C4F'90CH3 was added back to the reaction, and the
15 C4F90CH3 was distilled off at a rate of about 10 ml/hour. After
approximately 6
hours, the salt began phasing out of solution; forming large amounts of white,
voluminous solid. Over time, the lumps graduallly broke up into a powdery
slurry.
After about 16 hours of distillation time, less than 2 ml/hour of water was
collecting
in the Dean-Stark trap, so the distillation was stopped.
The resulting slurry was filtered through Whatman #1 filter paper, and the
precipitate was oven dried to recover 52.6 g of a~ slightly ofl;-white powder.
Eaamule 7
Essentially the same laboratory scale dehydration experiment of lithium
25 perfluorooctanesulfonate was run as described in Example 6 except that
instead of
pure C4F9OCH3, an azeotropic solvent mixture consisting of a 50/50 (w/w)
C4F90CH3/trans-dichloroethylene was used. Also, no solvent was initially
placed in
the receiver. The head temperature was maintained at 39°C.
After heating the mixture for about 5 hours, 4.8 g of water was collected in
30 the Dean-Stark distillation head. 300 g more of t:he azeotropic solvent
mixture was
then added to the flask to reduce foaming. After an additional 2 hours, 6.0 mL
of
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water had been collected. The apparatus was shut down for the night, and next
morning 200 mL more of the azeotropic solvent mixture was added. After 1 hour,
the total collection of water had reached 10.1 g. After 6 hours from the
morning
restart, 200 mL more of the azeotropic solvent mixture was added. After 45
more
minutes, the: procedure was terminated for the day.
Next morning, a gel formed which was no longer stirrable. .The flask and its
contents were heated to reflex with stirring for an additional 8 hours. Over
this
time, the contents in the flask began turning white. The azeotroping was then
stopped, and the contents of the flask were filtered to recover 47.4 g of
slightly off
I0 white powder (original FC-94 contained 52 g th~eoreticaI solids).
Ezamule 8
This example describes a laboratory scale dehydration of wet desiccant
using perfluorobutyl methyl ether, C4F9OCH3.
15 148.77 g of "theTM" desiccant (available from EMScience, Gibbstown, N)
was conditioned from the moisture of a wet sponge for a period of 3 days. The
desiccant turned pink and became virtually wet, :indicating a large amount of
water
absorption. The wet desiccant was then transferred to a round-bottom flask
equipped with a Dean-Stark distillation head, thermometer, condenser, heating
20 mantle, magnetic stirrer and stirring bar. To the flask was then added
928.7 g of
perfluorobutyl methyl ether. The flask and its contents were heated to reflex
with
stirring. After'h hour, 10.3 g of water was collected in the Dean-Stark
distillation
head, though the desiccant remained pink. After 1 hour, many blue desiccant
spheres were evident, indicating the beginning of desiccant dehydration. After
2.75
25 hours, 26.8 g of v~rater had been collected and the desiccant was bright
blue,
indicating a high level of dehydration. The flask and its contents were heated
for an
additional 8 hours, after which the total amount of collected water was 35.8
g.
Example 9
30 In Example 9, essentially the same dehydration procedure was followed as
described in Example 1 except that 100 g of a 75% (wlw) aqueous solution of FC-
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122 (lithium triflate) was dehydrated using an a~:eotropic solvent consisting
of SS 1 g
of pertluoropropyl methyl ether (C3F~OCH3). T'he dehydration process was run
at
34°C; the boiling point of the mixture. After 43 hours, 23.4 g of water
(94% of the
theoretical amount) had been captured by the Dean-Stark distillation head.
S
Example 10
in Example 10, essentially the same dehydration procedure was followed as
described in Example 1, except that 100 g of a TS% (w/w) aqueous solution of
FC-
I22 (lithium triflate) was dehydrated using an az;eotropic solvent consisting
of 82S g
i0 of perfluorobutyl ethyl ether {C4F90Ca~is). The dehydration process was run
at
77°C, the boiling point of the mixture. After 8.S hours, 26.3 g of
water (I00% of
the theoretical amount) had been captured by thE: Dean-Stark distillation
head.
Examule 11
I S In Example 11, essentially the same dehydration procedure was followed as
described in Example l, except that 13S g of a 75% (w/w) aqueous solution of
lithium bis(perfluoroethylsulfonyl)imide (prepared using the procedure
described in
Example 3 ofU.S. Pat. No. S,6S2,072) was dehydrated using an azeotropic
solvent
consisting of 692 g of C,4F90C2H3. The dehydration process was run at
77°C, the
20 boiling point of the mixture. After S.S hours, 33.7 g of water (100% of the
theoretical amount) had been captured by the Dean-Stark distillation head.
Example 12
This example shows the dehydration of an electrolyte solution consisting of
2S lithium triflate, water and propylene carbonate.
An electrolyte solution was made consistiing of 75.4 g of FC-122 (lithium
triflate), 25.2 g of deionized water and 7S g of 9!?% propylene carbonate
(available
from Aldrich Chemical Co., Milwaukee, WI). To a round-bottom flask equipped
with a Dean-Stark distillation head, thermometer, condenser, heating mantle,
30 magnetic stirrer, and stirring bar was added 62S g of C4F90C2H5 and the
above-
made electrolyte solution. The resulting mixture was heated to 77°C
with stirring.
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After 3.3 hours ofheating time, 25.fi g ofwater (100% oftheoretical) had
collected
in the distillation head, leaving in the flask a clear, colorless dehydrated
electrolyte
salt solution layer on top of a hydrofluoroether I;~yer.
Eaam~le 13
This example shows the dehydration of an electrolyte solution consisting of
lithium triflate and water using a non-ether hydrofluorocarbon.
The azeotroping process was run and completed as described in Example 1
except for the following modifications. 76.8 g oaf FC-122 {lithium triflate),
10 previously dried in a vacuum oven, was dissolved in 26 g of distilled
water. To this
aqueous solution was added 825 g of VertrelTM :~ (CF3CFHCFHCFZCF3, having a
boiling point of 55°C, available from E. I. duPont de Numours and Co.).
The
azeotroping process was run for a total of 8 hours, and the amount of water
removed as a function of time is shown in TABLE 2.
TABLE 2
Elapsed Time Incremental Tptal Water % of Theoretical
(hr) Water RE;moved Water Removed
Removed
1.0 6.3 6.3 __
24:2
2.0 4.2 10.5 40.4
3.0 4.7 15.2 _ 58.5
5.5 7.8 23.0 88.5
7.0 ~ 2.4 25.4 97.7
8.0 ~ 0.4 25.8 99.2
The data in TABLE 2 show that, using the hydrofluorocarbon for
azeotropic processing, over 99% of the water was removed after 8 hours.
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