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Патент USA US3100808

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3,lj?0,803>
United States Patent 0 MICC
Patented Aug. 13, 1963
2
l
?uoride and :tri?uoromethyl hypo?uorite. When both of
these products are present in a reacting mixture, one may
3,1tl0,803
expect to obtain per?uorodimethyl peroxide. Per?uoro
dimethyl peroxide can be produced by reacting carbon
monoxide, carbon dioxide or carbonyl ?uoride with either
?uorine or' tri?uorornethyl hypo?uorite.
In order that a high yield of per?uorodimethyl
PREPARATIQN 0F E’ERFLUGRSDWETHYL
Roger 5. Porter, @rinda, Calit., and George H. Cady,
Seattle, Wash, assignors, by mesne assignments, to the
United States of America as represented by the Secre
‘ tary of the Navy
‘
peroxide may be obtained by the reaction of ?uorine
with carbonyl ?uoride or carbon monoxide, or by the re
No Drawing. Filed Sept. 8, 1959, Ser. No. 833,389
1 Claim. (Cl. 265-610)
>
10
empirical formula, CZFGOZ. The structural formula prob
ably is
action of carbonyl ?uoride with tri?ucromethyl hypo?uo
rite, it is necessary that the temperature and the relative
proportions of the reactants be held within certain limits.
The yield ‘also is dependent upon the length of time al
This invention relates to the preparation and produc
tion ‘of per?uorodimethyl peroxide a compound of the
lowed for the reaction and upon the presence or absence
15 of a catalyst.
Four different reaction vessels have been used by the in
ventors to prepare per?uorodimethyl peroxide. Vessel A
The object of the invention is to provide a good method
was a cylindrical container made of nickel. 'It had a
volume of 1.71 liters and it could be heated to any de
for producing the compound.
It has heretofore been known that per?uorodimethyl 20 sired temperature by electrical heaters. Its temperature
peroxide is produced in small yield by the electrolysis of
an aqueous solution containing tri?uoroacetate ion ['F.
was measured by thermocouples. The reactants were
added separately to this vessel and their pressures were
Swarts, Bull. soc. chim. Belg. 42, 102 (1933)] but only
measured.
very small amounts have been obtained.
action involving a pressure change was followed by meas
The method
is costly because of the low e?ciency in utilization of
As the vessel was heated, the course of a re
uring the total pressure of the mixture of gases. Samples
materials. The present invention uses materials ef?ciently
of gas were sometimes removed from the vessel for identi
and is capable of producing large amounts of per?uoro
?cation and anaylsis.
dimethyl peroxide at \a much lower cost than was formerly
The second reaction vessel (vessel B) was constructed
of copper tubing. It was used to study reactions under
conditions of continuous ?ow. The two gaseous reactants
entered (by separate inlets) a cylindrical ‘mixing chamber '
having an internal diameter of 4.1 cm. and a length of 9.0
possible.
,
Per?uorodimethyl peroxide is an oxidizing agent capa
ble of supporting the combustion of hydrocarbons and
other fuels. It is of potential value as an oxidant for
fuels in rocket propulsion. Since it is a peroxide, it may
be expected to be {of value for causing polymerization re
cm. They passed through this chamber and then through
an electrically heated tube of 89 cm. length and 1.7 cm.
internal diameter.
actions to occur.
When carbon monoxide and ?uorine
The inventors now disclose that per?uorodimethyl
were used as the reactants much heat was liberated in the
peroxide is formed by combining carbonyl ?uoride with
tri?uoromethyl hypo?uorite. The reaction may be repre
sented by the equation:
mixing chamber. If rapid flows of these gases were to
be used in a large scale plant, it would be desirable to
cool the reactor near the inlets for reactants.
40
A third reaction vessel (vessel C) was also constructed
from copper tubing. It was packed with a tangled mass
Theyv also disclose that the peroxide may be prepared by
combining ?uorine with carbon monoxide or with car
of copper ribbon of 0.035 cm. Width and 0.008 cm. thick
ness. This ribbon weighed 4500 g. and before use it was
bonyl ?uoride. Fluorinating catalysts such as the higher
?uorides of metals belonging to the class including AgF2,
plated with 100 g. of silver. As the result of use, the
silver metal became converted to ?uorides of silver. The
CuFz, CoF3, CeF4, HgF2, SbF5, Feb}, and NiFZ induce
reaction vessel had a length of 90 cm. and an internal
diameter of 7.5 cm. It could be heated bypassing elec
tricity through coils of resistance wire wound over a
the reaction. In the case of carbonyl ?uoride, it is prob
able that ?uorine reacts to give tri?uoromethyl hypo
?uorite as shown in Equation 2
COF2+F2—> craon
' (2)
layer of ‘asbestos paper surrounding the reactor. There
50 were two heating coils.
and that the hypo?uorite combines with unchanged car
bonyl ?uoride as shown in Equation 1.' When carbon
monoxide is used as the starting material, it ?rst reacts
with ?uorine to give carbonyl ?uoride as shown in Equa 55
' tion 3:
CO+F2->COF2
(3)
This made it possible to con
trol the temperature separately in each end of the re
actor. At one end of the reactor the two gaseous reactants
entered, each by its own inlet, and at the other end the
products departed through an outlet.
The fourth reaction vessel (vessel D) was a steel cylin-‘
der of the type commonly used to store gases. its capac
ity was approximately ?ve liters. Its inner surface was
conditioned by long exposure to ?uorine; :then the cylinder
The carbonyl ?uoride may then give per?uorodimethyl
peroxide by Reactions 2 and 1. ‘These equations and
Was used in the laboratory as a storage tank for tri?uoro
7 clear the nature of the invention and to show that the
di?’erent methods may be regarded as one invention.
When using each type of apparatus it was possible to
collect samples ‘of the products by condensing them in
traps cooled by liquid oxygen. Such samples were
the theoretical discussion ‘are given at this point to make 60
'lhe theory permits one to predict that many substances
may react with ?uorine to give per?uorodimethyl peroxide.
Thus, one would expect any substance capable of re
acting with ?uorine to give carbonyl ?uoride to also be
capable of giving per?uorodimethyl peroxide. 'It should
be possible to prepare per?uonodimethyl peroxide by the
methyl hypo?u‘orite, CFQOF.
analyzed by distillation, the substances being recognized
by their boiling points and other‘properties.
Example 1.-—Equimolar amounts ot tri?uoromethyl
hypo?uorite and carbonyl ?uoride were placed in vessel
A at 27 ° C. giving :a total pressure of |1\6.l cm. of mercury.
The vessel was heated slowly to 287° C. Up to 225° C.
ethanol, dimethyl ether, formaldehyde and many other 70 {the pressure increased in proportion to the absolute tem
peratune, thereby indicating not more than a little corn
compounds containing carbon and oxygen atoms. Many
combinations of reactants should give both carbonyl ‘ bination of the two gases. Above about 235° C. the
reaction of ?uorine with such substances as methanol,
3,100,803
,
3
pressure decreased with rising temperature, thereby in
7 (3) When the ratio of Fz'ito CO was ‘greater than
to 1, ,
dicating that the gases were combining. When the ves
much CF3OF was torrncd :but little C2F6O2 (see‘runs 3
sel was returned to 27° C. the total pressure of gas was
1.1 cm. of mercury. The remaining gas was found to
‘less, nearly all of the product probably would be COF2
and 7). (4) If the ratio of F2 to CO were to be 1 to 11 or
contain .per?ucrodimethyl peroxide together with un
(see run 8).
.
"
reacted tri?uoromethyl hypo?uorite and carbonyl ?uo
The greatest yield "of per?uorodimcthyl peroxide ob
ride. The decrease in pressure corresponded to the con
tained from continuous ‘gas streams through vesselB .
version of 62% of the reactants to per?uorodirnethyl
was about 21% of that theoretically possible. The yield
' peroxide. This experiment showed that the rate of reac
was independent of temperature from 307° C. up to ‘the
‘tiontof Ih‘i?uoromethyl hypo?uorite with carbonyl ?uoride 10 highest temperature used, 405° C. Since Example il in
became appreciable at about 230° C. it also showed
dicated thatthe peroxide should not have been obtained
‘that'th‘e rate‘increased with rising temperature above‘
above about 325° C., it is likely thatt‘ne per?uorodirnethyl 5
230° C. (as indicated by an increase in the rate of pres
sure change). Since the reaction was slow in the neigh
borhood of 230° C. to 250° C., it follows that the dura
peroxide [obtained with vessel B at its higher temperatures ~
was formed as the gas became cooler while passing
15 through the outlet tube leading from the reactor. '
tion of contact or the reactants in a continuous flow re
Runs 11 ‘and 12 of Table 1 showed'thiat carbonyl
actor at this temperature is important in determining the
?uoride was formed from ?uorine and carbon monoxide
_ yieldoi’ per?uorodimethyl peroxide.
whenthe temperature of the reactor was'held below about
Vessel A was also used to study the decomposition of
200° C. ‘but that the formation of pcr?uorodimcthyl
per?uorcdirnethyl peroxide. A sample of the gas was 20 peroxide must have been very slow. Unreacted ?uorine
heated slowly to 420° C. All: about 225° C. the substance
remained mixed with the carbonyl ?uoride. When no
started to decompose, as shown by an abnormally great
increase in pressure with temperature. At approximate
electrical heating of the reactor was used, it was possible
to tell that the reaction to dorm carbonyl ?uoride oc
ly 325° C. the decomposition was substantially complete.
curred in the mixing chamber. This became warm to
This experiment shows that it is desirable when preparing 25 the touch (perhaps ‘80° C.) but the tube of 89 cm. length
per?uorodimethylperoxide to keep the temperature of
remained at vabout 25° vC. Runs which produced per
the reactants as low as possible while still obtaining the
?uonodirnetheyl peroxide must have done so by [the reac
desired product. When a continuous ,tlo-w reactor is used
tion of carbonyl ?uoride with ?uorine in the heated tube ,
at temperatures ‘above 325° C., one may obtain per?ucro
of vessel B.’ This series of experiments showed that per
dimethyl peroxide, but it is probable that much of the 30 ?uorodirnethyl peroxide was produced by the reaction of
product is formed as the temperature of the gas halls,
?uorine with carbon monoxide or with carbonyl ?uoride.
upon leaving the reactor.
The best yields of per?uorodimethyl peroxide resulted
‘7
'
Example, .2‘.-—$everal runs were made using reaction
I fromusing COFZ and F2 in a. volume-ratio of 2 to 1 as '
vessel B to determine the effect of temperature and of the
required by the not equation
'
' > V
relative concentrations of the reactants upon the yield 35
of periluorodimcthyl peroxide. Carbon monoxide en-y
2COF2+F2=F3COOCF3
(5)
tered‘ one inlet and ?uorine the other. The total pressure
Example 13.—Vessel C was used, the region near the
within the system was substantially one atmosphere. The
gas inlets being at 76 ° C. and the region near the outlet
reaction conditions ‘and the yields of per?uorodimethyl
being at about 183° C. Fluorine was passed at a rate '
peroxide are vgiven in ‘liable 1. The yield of C2F6O2 40 of 3.25 liters per hour lmdcarbon monoxide at 2.20
shown in column '5 was calculated from the equation:
liters per hour (each measured at about 25° C. and one
wt. of carbon in C2F6O2 produced
wt. of carbon in CO used
TABLE 1
x 1007
the inlet was about v5 0° C. and near the outlet was about‘
727° C. Rates of ?ow of gases measured
liters per.
50 hour at about 25° C. and one atmospherewere: F2, 2.90;
N o.
temp,
and pressure
° 0
1
Yield .
Other products (111 =
014F502,
much, 1 = little)
percent
CO
Fr
CO, 2.15; N2 (diluent), 4.0.
When a sample of the
product was distilled, no per?uorodiincthyl peroxide was
found. A small amount probably was present. If so,
2- __
405
2. 20
3.05
21
8- __
~ 405
1. 00
3.05
Below 1
4- __
5- __
400
307
0.90
2.17
1. 55
3.10
21
17
6- __
7_ __
8_ a.
307
307
307
2.17
2.10
2.17
- 3. 90
4. 30
8
Trace
>4
2. 50 7
carbonylv ?uoride and tri?uor-omeinyl hypo-?uorite were
obtained as ‘by-products. In another run made in vessel
C no electrical heating was used. The temperature near
Rates of ?ow,
liters per hour
peroxide was about 58% of that theoretically possible
from ‘the lanrounfof carbon monoxide consumed. Both
45
_ Preparation of Per?uorodimethyl Peroxide in Vessel B
Run Reactor at room temp.
atmosphere pressure). The yield of per?uorodimethyl
however, it distilled with the carbonyl ?uoride. The gas
contained ?uorine and rnuch carbonyl fluoride. in the
H1—COF9, Elk-CF30]?
II1—OF3OF, m-—Fg
Ill-CF3OF, m-COF:
m-—CFaOF, m—COF2
case of this run the gas streams were shut off [and the mix
ture was allowed to stand in the apparatus at about 25°
C. for 23 hours. . A sample of the gas was then removed.
m-OFaOF, l-COFz
I11—CF3OF
II1~GOF2, l——OF3OF
9- __
307
2 20
3.30
21
10...
~ 240
2 17
3. 25
_ 10
m-GOFg, m—CF3OF
1l___
200
2.20
3. 25
Below 1
m—COF2,
121--
25
0
0
Below 1
m—-OOF2, m-F2
'
IBFOOFZ, 1-OF3OF, l-—
‘2
m—F2,
CF2OF
l
'
60
The product contmned CF3OF, COFZ and per?uorodi
methyl peroxide approximately in the volume ratio; 2
to 5 to :8 respectively.
'
The runs in Example 3 showed that the ?rst step in
‘the process was the production of carbonyl ?uoride as
1 In run 12 the reactor was ?lled at room temperature by
shown in Equation 3 and that this was followed by addi- ,
passing F2 and CO at rates of 3.20 L/hr. aud'2.15 1./hr.
respectively. The gases then stood for 28 hours, At the end 65 tional reactions involving ?uorine, to give tri?uoromethyl
of this time the gas contained COFe and F2. Neither (321F002
hypo?uoriteand per?uorodirnethyl peroxide. By using
nor CFsOF' were observed to be present in amounts as great
as 1% of the total product. '7
The tollowing conclusions were drawn- from the ex
vvessel C it was possible to produce per?uorodirnethyl
peroxide attemperatures as low as 25° C.
With vessels
A ‘and B temperatures near 200° C. or more were re
periments described in Table 1: (1) To obtain per?uoro
dimethyl peroxide rapidly the temperature of the reactor 70 quired for the reaction vto proceed rapidly. It follows
that vessel C contained a ‘catalyst for the formation of‘
needed to be greater than 200° C. (2) The best yield of
per?uorodimethyl peroxide and that the catalyst was the
per?uorodimethyl peroxide was obtained with an F2 to CO
tangled mass of copper ribbon bearing a surface layer
ratio of 3 to 2. This corresponded to the equation:
formed by the ?uorination of silver. '
f
,
'
zco+srz=craoocr3
(4) 75 Example 4.—A two to one ratio by volume of ?uorine
3,100,803
5
(3) In the absence of a catalyst the reaction vessel
should preferably be held ‘at a temperature greater than
and carbon dioxide was heated in vessel A to about 325°
C. and was then cooled slowly to room temperature. The
resulting mixture of gas contained about ten percent per
-?uorodirnethyl peroxide.
Example 5.—Tri?uoromethy1 hypo?uorite was stored
at room temperature in vessel D for a period somewhat
over one year. At ?rst the gas contained some carbonyl
?uoride as an'impurity but little or no per?uorodimethyl
peroxide was present. At the end of the storage period
a part of the gas ‘was condensed and distilled.’ An appre
ciable amount of per?uorodirnethyl peroxide then was
‘ 200° C.
The reaction occurs at temperatures as low as
25° C. but it is slow. Even though per?uorodimethyl
per-oxide decomposes ‘at temperatures below 3-25 ° C.,‘ it
is possible to produce the substance with the reactor (at
least in part) at higher temperatures than this. Ap
parently the upper temperature limit is that at which the
rate of corrosion of the reactor by ?uorine becomes
10 large. For a nickel vessel this temperature is about
present. This example shows that tri?uonomethyl hypo
500° C.
(4) Copper, coated with silver ?uoride(s) serves as a
?uorite and carbonyl ?uoride react even at room tem
catalyst for the preparation of per?uorodimethyl per
perature to form per?uorodirnethyl peroxide. From Ex
amples 1 and 2 it is evident that the reaction at room tem
perature (about 25 ° C.) is very slow.
oxide.
tion in part of our prior copending application Serial
Number 655,948, ?led April 30, 1957, and now aban
Summary.—( 1) Per?uorodimethyl peroxide may be ob
tained in the following ways: (a) combining carbonyl
?uoride with tri?uoromethyl hypo?uorite, (b) combining
carbon monoxide with ?uorine, (c) combining carbonyl
?uoride with ?uorine, (d) reacting carbon dioxide with
When it is present, reaction temperatures as low
This application is a continua
15 as ‘25° C. rnay'be used.
doned.
'
What we claim is:
20
?uorine. Any combination of reactants which forms both
carbonyl ?uoride and tri?uoromethyl hypo?uorite should
also be capable of forming per?uorodimethyl peroxide.
(2) The preferred proportions of reactants are in 25
each case those required by the stoichiometry of the re
2actions. A range of concentrations may be used in each
case. For carbon monoxide and ?uorine it is best that
A process for producing per?uorodimethyl peroxide
which comprises contacting carbonyl ?uoride and tri?uoro~
methyl hypo?uorite within the temperature range 225° C.
to 325 ° C.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,689,254
Cady et al. __________ __ Sept. 14, 1954
OTHER REFERENCES
of CO to 2 of F2. For ?uorine and carbonyl ?uoride it 30 Kellogg et al.: 1 our. Amer. Chem. Soc., vol ‘70 (1948),
is desirable that the ratio of F2 to COFZ be less than 1. ‘
pages 3986-90 (?ve pages).
, the ratio by volume lie within the limits 1 to 1 up to 1
UNITED STATES PATENT OFFICE
CERTIFICATE OF CORRECTION
Patent No. 3, 100 , 803
August 13, 1963
Roger S. Porter et a1.
It is hereby certified that error appears in the above numbered pat
ent requiring correction and that the said Letters Patent should read as
corrected below .
Column 3,
column 4,
line 4, for "1.1 cm." read —— 11.1 cm.
—-;
line 25. for "8Oo C. " read —— '700 C. ——.
Signed and sealed this 14th day of April 1964.
(SEAL)
Attest:
EDWARD J. BRENNER
ERNEST W. SWIDER
Attesting Officer
Commissioner of Patents
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