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Patented Jan. 7, 1947
Frederick B. Downing, Carneys Point, and'
Anthony F. Benning and ‘Robert C. McHarness,
Woodstown. N. J ., assignors to Kinetic Chemi
cals, Inc., Wilmington, DeL, a corporation of
No Drawing. Application June 29, 1944,
Serial No. 542,820
1 Claim. (01. 260—653)
This invention relates to the preparation of
organic ?uorine compounds by pyrolysis. In the
applications identi?ed as Benning et al., Serial
No. 344,666, ?led July 10, 1940, issued as U. _S.
Patent 2,365,516, dated December 19, 1944, and
Banning Serial No. 379,473, ?led February 18,
dium for the quick freezing of foods as described
in U. S. Patent 2,059,970. It is also useful as a
solvent, as a reaction medium and as an inter
mediate in chemical syntheses.
Although for the production of particular com
pounds the reaction will be carried out under
well-controlled conditions of time, temperature
1941, issued as U. S. Patent‘ 2,343,252, dated
and pressure, complex mixtures of compounds of
March ‘7, 1944, are, disclosed two processes in
various molecular weights can be produced by
~volving a reaction between a ?uorohydrocarbon
subjecting the compounds to reaction conditions
and HCl in the presence of a catalyst. Those 10 for extended periods of time. Pressures may
reactions may be described as additive, since
also be used to vary the results, although for the
their apparent course is the addition of HCl
purposes of economy and safety each particular
to the ole?ne in the place of double bonds. Those
reaction should be carried out with the lowest
reactions were carried out at comparatively low
pressure consistent with optimum results. For
temperatures, in most cases below 350° C., be
example, pressures of four atmospheres absolute
cause those temperatures were satisfactory and
have been found satisfactory in many cases. In
because observations of a limited number of ex
general, operations may be carried out at pres
periments at higher temperatures showed the
sures between .1 and 10 atmospheres absolute.
existence of what were thought to be undesirable
but other pressures are useful and may be em
side reactions. We have now discovered that the
ployed when an increase in efficiency will re
side reactions are of a fundamentally different
nature than 1101 addition and that they can be
put to valuable use. ,
produced essentially by heat. It is,.therefore.
It is an object of this invention to produce
,_ This is a pyrolytic process.
The reaction is
important to select a temperature Which will ef
organic compounds by pyrolysis. Another object 25 ficiently produce the reaction. The temperature
‘of the invention is to produce compounds which
should be selected to give optimum production
are useful, by methods which are economically
and technically satisfactory.
Another object of
the invention is to produce new ?uoro hydrocar
bons. A particular object of the invention is to
synthesize organic compounds having ?uoralkyl '
chains by the pyrolysis of ?uorohalogen'o carbon
compounds. Another object of the invention is
to produce the compound CsFsHz.
According to our vinvention ?uo-ro-chloro or
bromo alkanes, fluoro-chloro or bromo alkenes,
and ?uoro alkenes, which may otherwise be called‘
?uoro-chloro or bromo
of the desired product. We have found that, ex
cellent pyrolytic results have been produced at
temperatures between 600° and 1000" C., but
that particular reactants have pyrolyzed at tem
peratul‘es as low as 400° C. and above‘ 1000” C.
under appropriate conditions of time and pres
sure. Electrical heating is efficient, but any
method of heating may be applied.
The tem
peratures which are used must be chosen in view
of the materials that. compose the reaction ap
The time of exposure of the reactants to the
pyrolytic conditions is a matter of considerable
and fluoro unsaturated aliphatic compounds, are 40 importance where a particular product is desired.
made into other compounds by pyrolysis. As a
Extending the period of exposure frequently
starting material, we prefer to 'use CHFzBr which,
produces compounds of increased molecular
?uoro-chloro or bromo unsaturated aliphatic,
when pyrolyzed under suitable conditions, will
yield a reaction mixture containing CsFsHz.
The compound C3F6H2 is a new chemical com
pound which can be separated from the reaction
mixture by fractional distillation. The com
pound CaFsHz is particularly adapted for use as '
a refrigerant in an absorptive or adsorptive sys
In general, the reaction proceeds eiliciently
in the absence of catalysts.
The process is preferably carried out‘continu
ously by passing the convertible material through
a tube heated to a pyrolytically e?ective temper
ature. The tube should be composed of a ma
tem because of its boiling point, volatility, low 50
toxicity and because it has two very active atoms
for hydrogen bonding. These properties render
‘ it especially suitable for use in a system using a
terial which is inert to the reaction and the re
action products. Carbon and thenoble metals
are su?iciently inert and have proved to be sat
isfactory materials for the construction of re
solvent having a donor atom such as polyglycol '
55 action chambers. The chamber need not be
ethers and the like, and as an immersion me
wholly-composed of the inert material, but may
' having-a boiling point of -a1° 0.; HCaFsBr boil-'
ing‘at 40°-41° C. and having a vapor density of
5.76 g. per liter at 28° C. and 452 mm.
‘be lined with it. Reaction chambers containing
a platinum lining are particularly satisfactory.
The‘ process may be carried ‘out in batches rather
than continuously, but continuity is preferred.
‘ The following example has been carried out and
Because of the wide differences in the boiling
points of the components of the reaction mass,
. they can be readily separated by fractional distil
has been selected for illustration. ~ The applicants
‘ present this example, not as constituting any lim
lationand the CaFcHa recovered. We believe that
the compound CJFQH: has the structural formula
itation of the work which has actually been done,
CHFFCFFCHFM, since, upon chlorination, it
but as su?iciently representative to enable per
yields the known compound CC?'FCFa-CCIFL
sons skilled in the art to practice the invention.
A suitable method of chlorinating CaFoHa is as
In this example, the terms "conversion" and " follows!’
_ “amount converted” include the assumption that
A 5-liter Pyrei: ?ask was evacuated and 25 cc.
the disappearance of one mol of the primary or
water was introduced, followed by 7.5 g. of
ganic material resulted in the liberation of one 15
CaF'sHz. Chlorine'was then passed in (in'absence
mol of halogen acid. ’ This assumption is war
of light) until the absolute pressure in the ?ask
ranted by the close agreement between the ?gures
reached 1.2 atmospheres. The ?ask was then ir
- for conversion obtained by acid analysis and the .
radiated with a Photo?ood lamp. The tempera
actual primary material which disappeared. The
ture. rose from 30° C .to 45° C. ‘and the pressure.
temperatures of the reactions were measured with 20
fell. ‘ After the pressure became steady, irradia
a thermocouple which was placed in contact with
tion was continued‘ for two hours. The liquid
the outer surface of the reaction tube near the
content of the ?ask was poured out and the lower
- center of the heated zone, so that the true average ,
layer separated, washed‘ successively
temperatures vof the gases ‘in the tube may have
been somewhat lower than the‘ values given.
Example XX
tically the entire product was found to boil at
34.6” C. at 760 mm. pressure.
CHFnBr was passed through a platinum-lined -'
' Inconel-jacketed nickel tube, 13.7 mm._i.-d. x 108
with water, ‘
and 10% NazSO'a, and dried over CaClz. 0n dis
25 _ tillation through a laboratory precision still,- prac
' .
' p
From all of the above, it‘willbe apparent that
cm, at a rate of about 42.6 g. per hour while the .30 by our invention, we have obtained a novel chem- '
ical compound which has novel properties render
pressure in the tube was kept at approximately
ing it valuable and useful for a variety of pur-_
onev atmosphere. The . tube temperature was ' , poses.
maintained at about 615° C. over an estimated
This is a continuation-in-part of our applica
length-of 200 mm. by electrical heating. Free
bromine was detected in the wash water. The re 35 tion Serial No. 435,064 for “Compositions of mat.
ter and pyrolytic methods of synthesizing them,"
action products were washed with water, .dried
filed March 17, 1942, issued as \U. 8. Patent
and condensed in receivers cooled to about —70° .
. C. A receiver cooled in liquid nitrogen was placed
2,387,247, dated October 23, 1945.
We claim:
‘after the receiver cooled to —7_0.° C. Acid analysis
' formula
showed a conversion of about 46%., A'total of 40 CsF'eH: which has a boiling pointbyof the
about 10-11‘
about 179 g. of crude organic products were colC. and a vapor density of about 6.97 g./1iter at
] lected. The following compounds have been
21° C. and 760mm.
-'found in the reaction mass: CaFfeHz having a
FREDERICK B. DOWNING. boiling point of about 10-11° C. and a vapor dens
ity of 6.97 g/liter at 21° C. and 760 mm.; CHE 45
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