Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF -THE INVENTION
This invention relates to an improved process for
the fluorination of polycyclic hydrocarbons. More particularly,
this invention relates to an improved method for the florination,
preferably perfluorination, of said hydrocarbons using a
three-stage reaction which effectively eliminates the
production of unwanted by-products.
U.S. Patent No. 3,6~1,167, as well as United
States Patent 4,041,086 disclosure a one-staga method for
making perfluoroalkyladamantanes. Recent data using new
analytical techniques now show that under the reaction
conditions employed therein, using CoF3 and high tempexature,
degradation of the non-florinated cyclic structure does result,
with the formation of ring-opened products.
SUM~RY OF THE INVENTION
In accordance with the present invention, it has
now been found that polycyclic hydrocarbons may be perfluorinated
with substantially no degradation o the cyclic structure by
~1) partially fluorinating the starting cyclic compound with
a mild fluorinating agent under moderate conditions in a
first stage, followed by (2) reacting said partially fluorinated
material in a second stage in the presence of a strong
fluorinating agent at temperatures just above the boiling
point of said material to provide a highly fluorinated
compound; and thereafter (3) recycling said highly fluorinated
compound into the same second stage reactor at considerably
higher temperatures to provide an essentially perfluorinated
polycyclic hydrocarbon free of any degradation ring-opened
products.
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There is thus provided, in accordance with the present
teachings, a process for the perfluorination of non-aromatizable
polycyclic hydrocar~ons which process comprises:
a) partially fluorinating a polycyclic hydrocarbon
or the carbonyl, hydroxyl, chlorinated, or
brominated derivative thereof, by contacting it in
a first reaction zone wi*h a fluorinating agent
selected from the group consisting of HF, HF-
pyridine, AgF2, MnF3, SF4, ~bF5, KCoF4 and
fluoroolefins, in the liquid phase under conditions
sufficient to provide not more than about 50%
fluorination corresponding to perfluorination; and
b) thereafter further fluorinating the partially
fluorinated polycyclic hydrocarbon in the vapor
phase in a second reaction zone with CoF3 at a
temperature of no greater than about 50 C~ above
the boiling point of the fluorinated material to
provide a highly fluorinated material having a
degree of fluorination corresponding to about 75-
95% of perfluorination.
As an optional step in the process, the highly
fluorinated material is recovered and recycled to the second
reaction zone for recontact with CoF3 in the vapor phase at a
temperature about 100 higher than was first employed in step
b) to provide a substantially perfluorinated polycyclic hydro-
carbon.
DESCRIPTION OF THE INVENTION
-
The starting materials for this improved perfluorina-
tion process comprise non-aromatizable polycyclic hydrocarbons
selected from the group consisting of alkyladamantanes, as des-
cribed in U.S. Patent 3,6~1,167, and having from 11-30 carbon
atoms, preferably 12-14 carbon atoms, such as 1~3-dimethylada-
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mantane, 1,3,5-trimethyladam~ntane, l-ethyladamantane, l-methyl-
adamantane, l-ethyl-3-methyladamantane, l-ethyl,
3,5-dimethyladamantane, or the like; endo-and exo-tetrahydro-
dicyclopentadiene; methanodecalins such as 1, 4-methanodecalin
or 1,4,5,8-dimethanodecalin; hydrogenated pinane; camphane;
bi-cyclooctanes; bicyclononanes; and the like. When these
compounds are treated in accordance with the process of this
invention, there are obtained the corresponding perfluorinated
polycyclic materials in high yield and purity, wherein at least
95% of the hydrogen atoms, and more preferably 97% to
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100%, are replaced by fluorine atoms. Generally, with this
improved process, the conversion of the starting material to
the corresponding perfluorinted compound is at least 50%,
and most usually about 90% or more.
These perfluorin~ted materials are useful in a
variety of industrial and pharmaceutical applications. The
fluorinated alkyladamantanes, for example, are useful as gas
turbine engine coolants, dielectric coolants for transformers,
generators, and the like, as well as components in synthetic
blood compositions, perfusion media, and like bi~logical
applications. The perfluorinated cyclic materials are also
useful as working fluids in heat pipes and Rankill cycle
engines.
The first stage~of the aforedescribed process to
provide a partially fluorinated intermediate is conveniently
carried out by contacting the polycyclic hydrocarbon or
their hydroxylated or carboxylated derivatives depending on
the fluorinating agent used, in the liquid phase with a
fluorinatin~ a~ent selected from the group consisting of HF,
HF-pyridine complex, AgF2~ MnF3, SF4, SbF5, KCoF4, and
fluoroolefins, under vary^ing conditions of temperature~
pressure, and the like, depending upon the nature of the
starting material and fluorinating agent employed. These
fluorinating agents are much milder in their action than
CoF3 on hydrocarbons. Consequently, the degree of fluorination
can be controlled by the proper selection of agent and
starting material. Generally, the incorporation of from
about 3 to 6 fluorine atoms into the hydrocarbon is found to
stabilize the material for the more severe conditions employed
in exhaustive fluorination with e.g. CoF3.
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In general, in this first ~artial-fluorination
stage the above-mentioned fluorinating agents may be reac-ted
directly with the polycyclic hydrocarbons per se, or their
partly chlorinated or brominated derivatives, if desired.
However, one exception to this is the reaction of these
compounds with SF4 or dialkylaminosulfur fluorides,
in which case the cyclic starting material must first be
carbonylated before it can satisfactorily react with SF4 or
dialkylaminosulfur fluoride. Thus, for example, in the case
of the alkyladamantanes these compounds must first be converted
to their corresponding ketones, aldehydes, acids, or hydroxy
derivatives before they will properly react with the SF4 or
dialkylaminosulfur reagent.
Illustrations of the methods for forminy these
adamantyl carbonyl derivatives can be found, for example, in
the teachings of U.S. Patents 3,356,740 and 3,356,741 (adamantyl
ketone and diketone derivatives); U.S. Patent 3,2S0,805
(adamantyl dicarboxylic acids); U.S. Patents 3,383,424,
3,356,718, and 3,356,709 (adamantyl dihydro~ides and di-
carboxylic acids). Other similar reactions will be xecognizedand understood by those skilled in the art.
Similarly, other such carbonylated pol~cyclic
starting materials can be prepared in accordance with like
known techniques.
It will thus be understood from the foregoing that
a general recitation of the partial (i.e. first stage)
fluorination of the polycyclic starting materials is in all
cases intended to include their carbonyl derivatives when
SF4 or dialkylaminosulfur fluorides is used as the fluorinating
agent.
597
In addition to the use of carbonyl derivatives of
cyclic materials to be perfluorinated when SF4 is used, is
the use of analogous known alcohol derivatives of these
compounds when HF or HF-pyridine complex is the partial
fluorinating agent; and chlorinated or brominated derivatives
where SbF5 is employed.
Also, cyclic dienes such as 1,3-cyclohexadiene may
be reacted with fluoroolefins such as hexafluoro-propene in
a Diels-Adler type reaction, to obtain partially fluorinated
polycyclic hydrocarbons, as described in more detail below.
These materials may then also be perfluorinated in accordance
wi~h this invention.
Thus, these aforedescribed Diels-Adler reaction
products are also intended to be included in the general
definition of the partially fluorinated polycyclic hydrocarbons
which may then be perfluorinated with, e.g. CoF3 as described
above.
It will thus be evident from the foregoing description
that it is within the scope of this invention to exhaustively
fluorinate a partially fluorinated, and thus stabilized, cyclic
hydrocarbon regardless of how it is prepared.
The amount of fluorination necessary to impart
ring structure stability to the polycyclic materials prior
to their reaction with strong fluorinating agents such as
CoF3 in the second and third stages of this process is not
critical but desirably should comprise the replacement of
from about 3-6 hydrogen atoms by fluorine atoms up to as
much as a 50% replacement of such hydrogen by fluorine. The
location of these fluorine atoms may be either in the nucleus
or in the side chain of the hydrocarbon molecule, or both.
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Accordingly, it will be understood that the product of the
first stage fluorination may comprise either a single product
or a mixture of partially fluorinated materials depending
upon the fluorinating agent employed. This product, prior
to contact with CoF3 or the like, in the next stage, should
first be separated from the first fluorinating agent, preferably
by distillation.
In the second stage of this process, the object is
to achieve as high a degree of 1uorination as`possible
short of degrading the ring structure of the compound. The
effect of this fluorination step is to impart a much greater
stability to the partially fluorinated polycyclic material
in order that, in the last stage, virtually 100% perfluorination
can be achieved under much more stringent reaction conditions
without orming ring degradation by-products. This high
degree of fluorination, in the second stage, which generally
falls short of perfluorination by not more than S-25%, is
readily accomplished by contacting the partially fluorinated
hydrocarbon mixture with CoF3 in the vapor phase (by preheating)
~o at a moderate charge rate at temperatures ranging from just
above the boiling point of the charge materials to about
50C above its boiling point. Preferably, a mul-ti-zone
reactor with temperatures graduated from just above boiling
point to 50 above should be used. Since the reaction is an
exothermic one, care should be taken to control the temperature
within about these ranges in order to avoid degrading the
molecules.
The final stage, which likewise is in the vapor
phase, comprises recycling the highly 1uorinated product of
the CoF3 reaction back into the same reactor, which this
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time is heated to a considerably higher temperature, preferably
about 100C greater across the thermally graded reactor, to
achieve substantially complete perfluorination, and provide
yields of about 50-95%, based on the amount of original
charge stock.
The perfluorinated product is then desirably
cooled to temperatures of-from about 0C to-80C by passing
it through several cooling traps as it is removed from the
reactor in order to collect not only the product, but also
HF and any other gaseous products.
The invention will now be illustrated by the
following examples.
The following four examples demonstrate the
preparation of partially fluorinated adamantanes which may
then be perfluorinated in accordance with the process of this
invention.
EXAMPLE 1
Adamantane dicarboxylic acid (22.4g-0.1 mole) and
SF4 (27.Og-25% excess) were heated in a hoke bomb for 24
hours at 110C. The contents of the pressure vessel were
cooled, extracted with CC14, filtered and the CC14 evaporated
off. The residue consisted of 21.8g of bistrifluorome~
adamantane (80% yield).
ExAMæLE 2
2-adamantanone (15.0g-9.1 mole) and SF4 (13~g-25%
excess) were heated as in Example 1. The product was worked
up as described in Example 1 to give 12.9g of 2,2-difluoro
adamantane (75% yield).
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EXAMPLE 3
5,7-dimethyl-1,3-adamantane dicarboxylic acid
(25.2g-0.1 mole) and SF4 (27.0g-25% excess) were heated and
worked up as in Example 1 to give 18g of 3,5-dimethyl-5,7-
bis(trifluoromethyl) adamantane (60%).
EX~MPLE 4
.
1,3-dimethyl adamantane (42g) is added slowly to a
slurry of MnF3 (1 lb) in perfluoro l-methyl decalin. After
all the hydrocarbon has been added the mixture is heated
with rapid stirring to 200C for 24 hours, and the Product
extracted with Freon~ 113 and distilled to remove both the
Freon~ 113 and perfluoro l-methyl decalin. The distillation
residue consists of partially fluorinated 1,3-dimethyl
adamantane in which the average molecule contains approximately
8 fluorine atoms; e.g. C12H12F8
EXAMPLE 5
Bistrifluoromethyl adamantane (~4cc; 33.67g;
0.123 moles) rom Example I was charged into a preheater at
0.247cc/min. The preheater temperature was 250C, and the
CoF3 reactor temperature was graduated ~rom 250C in Zone 1
to 300C in Zone 4. The product line was kept at 225C.
After all the hydrocarbon had been charged to the reactor,
the reactor was purged with nitrogen for 3.25 hours. The
crude product weighed 46.0g. This material was water washed
~ntil the pH of the water was 5.
This material from the second stage was dried
over mole sieves overnight and then 45.84g was recharged at
a rate of 0.764 cc/min. to the reactor which was graduated
from 275C in Zone 1 to 380C in Zone 4 for the final stage.
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The reactor was purged with nitrogen for 4 hours before
removing the product receiver containing 47.8g. fluorocarbon;
75% material balance G.C. analysis showed the product contained
90~ perfluoro 1,3-dimethyl adamantane, confirmed by mass
spectrography and FNMR.
A similar run was made with 1,3-bis(trifluoromethyl)-5,
7-dimethyl adamantane to give a 55% yield of perfluoro
tetramethyl adamantane.
In a similar fashion 2,2-difluoro adamantane and 3,5-
dimethyl-5,7-bis(trifluoromethyl) adamantane of Examples 2 and 3
were reacted with CoF3 in accordance with the procedures of
Example 5 to give the corresponding perfluoroadamantanes in
high purity and yield.
EXAMPLE 6
The following example illustrates the results
obtained when the first (partial) fluorination stage of this
invention is not employed:
Exo-tetrahydrodicyclopentadiene (25cc:24.15 g;
0.1776 moles) was charged into a preheater at 0.494 cc/min.
The preheater temperature was 225C, and the CoF3 reactor
temperature was graduated from 200C in Zone 1 to 250 in
Zone 4. The product line was kept at 225C. After all ~he
hydrocarbon had been charged to the reactor, the reactor was
purged with nitrogen for 3.25 hours. The crude product
weighed 63.6 g. This material was water washed until the
pH of the water was 5.
The material from the second stage was dried over
mole sieves overnight and then 55.84 g was recharged at a
rate of 0.764 cc/min. to the reactor which was graduated
from 300C in Zone 1 to 375C in Zone 4 for the final stage.
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The reactor was purged with nitrogen for 4 hours beore
removing the product receiver containing 60.8 g fluorocarbon;
87~ material balance based on the 24.15 g of THDCP charged.
G.C. analysis showed the product contained 40% of endo-and
exo-perfluoro-tetrahydrodicyclopentadiene, 45% of perfluoro
bicyclo [3,5,0] decane and ~ 15% unknown fluorocarbons.
EXAMPLE 7
Exo-tetrahydrodicyclopentadiene (35 g) is added
slowly to a slurry of MnF3 (1 lb) in perfluoro(l-methyl)
decalin solvent. After all the hydrocarbon has been added,
the mixture is heated to 200C and stirred rapidly for 24
hours. The product is extracted with Freo ~ 113 and distilled
to remove both the Freon~ 113 and perfluoro (l-methyl) decalin.
The distillation residue consists of partially fluorinated
tetrahydrodicyclopentadiene in which the average molecule
contains approximately 7 fluorine atoms: CloH9~7.
When the thus obtained partially fluorinated
te~rahydrodicyclopentadiene is then perfluroinated with
CoF3 in accordance with the procedures of Example 5, there
is obtained substantially pure exo-and endo-perfluorotetra-
hydrodicyclopentadiene in high yield, which is essentially
free of any of the by-products enumerated in Example 6.
E~AMPLE 8
In accordance with the procedures of Example 7,
but substituting partially fluorinated camphane, hydrogenated
pinane, 1,4-methanodecalin or 1,4,5,8-dimethanodecalin for
partially fluorinated tetrahydrodicyclopentadiene, there is
obtained the corresponding perfluorinated cyclocarbon in
high yield, and substantially free of any deyradation
ring-opened by-products.
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EXAMPLE 9
As indicated above, fluoroolefins and acetylenes,
for example, readily undergo Diels-Alder type reactions to
function as dienophiles in 1,4-cyclo-addition reactions;
their reactivity towards dienes is generally higher than
that of their hydrocarbon analogues. The following examples
demonstrate the preparation of partially fluorinated cyclocarbons
which may then be exhaustively fluorinated in accordance
with the procedures of Example 5 to provide perfluoro-
cyclocarbons in high yield and essentially free of
ring-opened by-products:
A. 1,3-Cyclohexadiene (1 mole) is reacted with a
25% molar excess of hexafluoropropene for 24 hours at about
150C to give 2-(trifluoromethyl) 2,3,3-trifluoro-bicyclo
~2.2.2] octane. Hydrogenation over rhodium gives 2-(tri-
fluoromethyl) 2,3,3-trifluoro-bicyclo [2.2.2] octane.
B. Similarly, reaction of cyclopentadiene with
hexafluoro-but-2-yne at 100C for 24 hours gives 2,3-bis (tri~
fluoromethyl) bicyclo [2.2.1] heptadiene which, upon hydro-
genation over platinum, gives 2,3-bis(trifluoromethyl)bicyclo
[2.2.1] heptane.
C. Also, in a like manner, octafluoro-but-2-ene
and cyclopentadiene react to give 2,3-difluoro-2,3-bis(tri-
fluoromethyl) bicyclo [2.2.1] heptane which, af-ter hydrogenation
over ruthenium gives 2,3-bis(trifluoromethyl)bicyclo ~2.2.1
heptane.
EX~PLE 10
Norbornadiene (1 mole) and a 25% molar
excess of hexafluorocyclopentadiene are heated for 24 hours
at 100C to give
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~ FFP ~
which, after treatment with CoF3 in accordance with the
procedures of Example 5 yields highly pure ~erfluoro
1,4,5,8-dimethanodecalin.
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