Process for preparing polyfluorooxetanes

This invention concerns a process for the preparation of polyfluorooxetanes by the reaction of fluoroketones or fluoroepoxides with haloethylenes in the presence of a Lewis acid catalyst. Polyfluorooxetanes are useful as solvents and plasticizers having high thermal stability.

FIELD OF THE INVENTION 
This invention concerns a process for the preparation of polyfluorooxetanes 
by the reaction of fluoroketones or fluoroepoxides with haloethylenes. 
Polyfluorooxetanes are useful as solvents and plasticizers having high 
thermal stability. 
TECHNICAL BACKGROUND 
French patent No. 1,391,493 discloses polyfluorooxetanes of the formula 
##STR1## 
where R.sub.1 and R.sub.2 is hydrogen, chlorine or fluorine. The utility 
of said compounds is as chemical intermediates, solvents and plasticizers 
characterized by a high degree of thermal stability and inertness. The 
polyfluorooxetanes are prepared by the photochemical reaction between 
fluoroketones and fluoroolefins. 
J. F. Harris, D. D. Coffman, J. Am. Chem. Soc., 84, 1553 (1962) and E. W. 
Cook, B. F. Landrum, J. Heterocycl. Chem., 2, 327 (1965) disclose similar 
processes and tabulate a large number of polyfluorooxetanes prepared by 
this route. Such processes proceed only under UV irradiation, which 
significantly limits productivity and makes it difficult to use them for 
preparation of the compounds on a commercial scale. 
U.S. Pat. No. 3,164,610 discloses the preparation of partially fluorinated 
oxetanes by the non-catalyzed reaction of fluorinated ketones with 
non-fluorinated vinyl ethers. Only highly reactive non-fluorinated vinyl 
ethers may be involved in the reaction. 
G. G. Belen'kii, G. I. Savicheva, E. P. Lur'e, L. S. German, Bull. Acad. of 
Science USSR. Chem. Div., 1248 (1978) disclose the reaction of 
trifluorotrichloro-acetone with tetrafluoroethylene in the presence of 
antimony pentafluoride to give a 45% yield of a mixture comprising an open 
chain ketone, 1,1,4,4,5,5,5-hepta-fluoro-1,3,3-trichloro-2-pentanone (36%) 
and an oxetane, 
2-difluorochloromethyl-2-dichlorofluoromethyltetra-fluorooxetane (64%). 
Also disclosed is the reaction of the same substituted acetone with 
trifluoroethylene in the presence of antimony pentafluoride to give a 27% 
yield of a three component mixture comprising an open chain ketone (22%) 
and two different oxetanes (67% and 11%, respectively). 
U.S. Pat. No. 2,992,884 discloses the formation of oxetane containing 
mixtures. 
V. Weinmayr, J. Org. Chem. 28, 492(1963) discloses the reaction of 
tetrafluoroethylene with bis (fluoro-methyl) ether (formed in situ from 
formaldehyde and HF) to give fluoromethyl-2,2,3,3,3-pentafluoropropyl 
ether and/or 2,2,3, 3, 3-pentafluoro-1-propanol depending on temperature 
in addition to 4 small quantity by-products one of which is 
2,2,3,3-tetrafluorooxetane. 
SUMMARY OF THE INVENTION 
This invention provides a process for the preparation of polyfluorooxetanes 
which process comprises the reaction of fluoroketones or fluoro-epoxides 
with haloolefins in the presence of a Lewis acid catalyst. Suitable 
catalysts are selected from aluminum chlorofluoride (AlF.sub.n 
Cl.sub.3-n), wherein n is from 0 to 2.95, or metal fluorides which do not 
possess oxidative properties, such as NbF.sub.5 or TaF.sub.5. The process 
can be carried out in the optional presence of an inert solvent. 
DETAILED DESCRIPTION OF THE INVENTION 
Polyfluorooxetanes are prepared by the reaction of hexafluoroacetone (HFA) 
and other fluoroketones or fluoroepoxides with fluoro, chloro, or 
bromoethylenes within a temperature range 100.degree.-150.degree. C. The 
reaction is catalyzed by strong Lewis acids, such as aluminum 
chlorofluoride AlF.sub.n Cl.sub.3-n wherein n is 0 to 2.95, or metal 
fluorides which do not posses oxidative properties. Examples of such metal 
fluorides are NbF.sub.5, and TaF.sub.5. In most cases, oxetane product is 
obtained as a single regioisomer. 
Ketones useful herein are of the formula 
##STR2## 
wherein X is F or Cl and Y is selected from the group consisting of F, Cl, 
and R.sub.f (C.sub.1 -C.sub.5), where R.sub.f is a perfluoroalkyl radical 
and C.sub.1 to C.sub.5 indicates that it has one to five carbon atoms, 
optionally containing ether oxygen and terminal functional groups such as 
--CN, C.sub.6 F.sub.5 O--, --C(O)F, SO.sub.2 F and C(O)R', wherein R' is 
C.sub.1 to C.sub.5 alkyl or phenyl. 
Epoxides useful herein are of the formula CF.sub.2 OCFCFXY, wherein X is F 
or Cl and Y is selected from the group consisting of F, Cl, and R.sub.f 
(C.sub.1 -C.sub.5), where R.sub.f is a perfluoroalkyl radical and C.sub.1 
to C.sub.5 indicates that it has one to five carbon atoms, optionally 
containing ether oxygen and terminal functional groups such as --CN, 
C.sub.6 F.sub.5 O--, --C(O)F, SO.sub.2 F and C(O) R', wherein R' is 
C.sub.1 to C.sub.5 alkyl or phenyl. The most preferred epoxide is 
hexafluoropropylene oxide (HFPO). 
Olefins useful herein are of the formula CX'.sub.2 =CY'Z', wherein X' is F 
or Cl and Y' and Z' are independently H, Cl, Br, F, R.sub.f 
(C.sub.1-C.sub.3), OR(C.sub.1 -C.sub.3), where R is C.sub.1 to C.sub.3 
alkyl, provided that only one of Y' and Z' is R.sub.f (C.sub.1 -C.sub.3), 
Br or Cl. Preferred olefins herein include CHBr=CF.sub.2, CHCl=CF.sub.2, 
CFH=CF.sub.2, CF.sub.2 =CF.sub.2, CF.sub.2 =CFCl , CH.sub.2 =CCl.sub.2, 
CH.sub.2 =CF.sub.2, CF.sub.2 =CFBr. Most preferred are CF.sub.2 =CFH, 
CF.sub.2 =CF.sub.2, CClH=CF.sub.2 and CBrH=CF.sub.2. 
The reaction is carried out in the presence of strong Lewis acid catalysts, 
such as aluminum halides, wherein the halide is one or more of F, Cl, Br 
or I, with a proviso that the halide cannot be entirely F. Active 
catalysts can be preformed, as in most examples below, or can be formed in 
situ by partial halogen-F exchange. Preferred catalysts are of the 
structure AlF.sub.n Cl.sub.3-n, where n is from 0 to 2.95. Fluorinated 
AlCl.sub.3 catalyst can be prepared by the reaction of AlCl.sub.3 and 
CFCl.sub.3, as described in U.S. Pat. No. 5,162,594, column 4, lines 
35-57, which is incorporated herein by reference, in its entirety. 
The proportion of catalyst to olefin or ketone is 0.1-0.2 mol per mol of 
olefin or ketone; the proportion of ketone to olefin is 1:1. 
The reaction temperature is about 50.degree. C. to about 200.degree. C., 
preferably about 100.degree. C. to about 150.degree. C. Reaction times can 
vary from about one hour to several hours, depending upon such variables 
as catalyst concentration, pressure and temperature. 
Solvents are generally not essential to the reaction but may, optionally, 
be used if they are relatively inert to the reaction conditions. By 
"relatively inert" is meant substantially unreactive toward the catalyst 
at reaction temperatures. Relatively inert materials that can be used as 
solvents include perhalogenated or highly fluorinated linear and cyclic 
alkanes and ethers. 
Products of this process have the following structure: 
##STR3## 
X' is F or Cl and Y' and Z' are independently H, Cl, Br, F, R.sub.f 
(C.sub.1-C.sub.3), OR(C.sub.1 -C.sub.3), where R is C.sub.1 to C.sub.3 
alkyl, provided that only one of Y' and Z' is R.sub.f (C.sub.1 to 
C.sub.3), Br or Cl; and wherein X is F or Cl and Y is selected from the 
group consisting of F, Cl, and R.sub.f (C.sub.1 -C.sub.5) , optionally 
containing ether oxygen and terminal functional groups such as --CN, 
C.sub.6 F.sub.5 O--, --C(O)F, --SO.sub.2 F and C(O)R', wherein R' is 
C.sub.1 to C.sub.5 alkyl or phenyl.

EXAMPLES 
Catalyst preparation, AlCl.sub.3 +CFCl.sub.3 
500 g (3.75 mol) of AlCl.sub.3 (Aldrich-99% pure) was stirred mechanically 
under N.sub.2 in a r.b. flask fitted with a -80.degree. C. condenser while 
1750 mL (about 2625 g, 19 mol) of CFCl.sub.3 was added over a 1.5 hr 
period. Reaction is very exothermic in the early stages, so addition of 
CFCl.sub.3 was slow at first in order to keep the temperature below 
65.degree. C., then rapid The resulting suspension was stirred an 
additional 3 hrs while volatiles (CF.sub.2 Cl.sub.2) were allowed to 
escape through the warmed condenser. The condenser was then replaced with 
a simple stillhead, and most of the CCl.sub.4 was distilled under reduced 
pressure [mainly bp 38.degree. C. (200 mm)]. Finally, the last traces of 
volatiles were removed by warming the residual solid to 
30.degree.-35.degree. C. at 0.05 mm. 
The sealed round bottom flask was transferred to a dry box and unloaded 
into a Teflon.RTM.FEP bottle; 340 g of rather finely divided yellow-green 
solid. Portions of the catalyst were weighed out in the dry box as needed 
and taken out in plastic bottles with pressure-seal caps. 
Analysis for fluorine of the products from preparation of this type 
indicated the composition to be AlF.sub.2.9 Cl.sub.0.1, AlF.sub.n 
Cl.sub.(3-n) ; n=2.9. 
EXAMPLE 1 
A 400 ml Hastelloy shaker tube was loaded with 2 g of aluminum 
chlorofluoride (ACF--prepared by reaction of CFCl.sub.3 and AlCl.sub.3), 
cooled to -78.degree. C., evacuated and charged with 51 g (0.31 mol) of 
hexafluoroacetone (HFA) and 24 g (0.3 mol) of trifluoroethylene. The 
reaction vessel was shaken at 100.degree. C. for 18 h. The mixture of 
starting materials and products was bled out of the reactor at 
40.degree.-50.degree. C. and collected in a cold trap (-78.degree. C.). 
Starting materials were distilled out on a low temperature distillation 
column, and the residue was washed with cold water to remove residual HFA, 
dried over P.sub.2 O.sub.5 and distilled to give 47 g (64% isolated yield, 
100% yield on converted HFA and trifluoro-ethylene ) of F-2,2 -dimethyl -3 
-H-oxetane with b.p. 44.degree.-45.degree. C . 
EXAMPLE 2 
Following the procedure of Example 1, 70 g (0.42 mol) HFA, 5 g of ACF and 
40 g (0.4 mol) tetra-fluoroethylene (TFE) was shaken at 60.degree. C. for 
a total reaction time of 48 h (TFE was loaded in two portions: 20 g 
initially and 20 g after 24 h) . After isolation as in Example 1, there 
was obtained 70 g (100% yield based on the HFA that was converted) of 
F-2,2-dimethyloxetane, b.p. 27.degree.-28.degree. C. and 10 g of 
polytetrafluoroethylene, identified by IR. F-2,2-dimethyloxetane: .sup.19 
F: -78.88 (6F, t), -79.53 (2F, br.s.) -118.70 (2F, hept), J=9Hz, MS 
(m/z): 265.9785 (M.sup.+, C.sub.5 F.sub.10 O.sup.+, calc. 265.9789). 
Coversion of HFA was 66%. 
EXAMPLE 3 
In the procedure of Example 1, 40 g (0.24 mol) HFA, 29 g (0.2 mol) of 
CHBr=CF.sub.2 and 0.5 g ACF were allowed to react. The reaction vessel was 
shaken 18 h at 100.degree. C. The reaction mixture was worked up as in 
Example 1. There was isolated 20.4 g (100% yield) of 
F-2,2-dimethyl-3H-3Br-oxetane, b.p. 77.degree.-78.degree. C. .sup.1 H NMR: 
5.25 (t). Conversion of HFA and olefin was 30%. 
EXAMPLE 4 
In the procedure of Example 1, 50 g (0.3 mol) of HFA, 35 g (0.28 mol) of 
chlorotrifluoroethylene (CTFE) and 3 g of ACF were allowed to react. The 
reactor was shaken 18 h at 100.degree. C. The reaction mixture was worked 
up as in Example 1. There was isolated 37 g of liquid, b.p. 55.degree. C. 
According to GC and .sup.19 F data the product was 42% of 
F-2,2-dimethyl-3-chlorooxetane, 48% of F-2,2-dimethyl-4-chlorooxetane and 
10% of 1,2-dichloro-hexa-fluorocyclobutane. Calculated yield of oxetanes 
was 82% based on coverted CTFE, conversion of HFA was 43%. Conversion of 
CTFE was 48%. 
EXAMPLE 5 
As in Example 1, 50 g (0.3 mol) of HFA, 45 g (0.28 mol) of 
bromotrifluoroethylene and 0.5 g of ACF were allowed to react. The reactor 
was shaken 18 h at 100.degree. C. The reaction mixture was worked up as 
above. There was isolated 12 g of liquid, b.p. 67.degree.-68.degree. C. 
According to .sup.19 F NMR the product was a mixture of 54% of 
F-2,2-dimethyl-3-bromorooxetane and 46% of F-2,2-dimethyl-4-bromooxetane. 
The yield of oxetanes was 70% based on converted HFA, conversion of HFA 
and olefin was 18%. 
EXAMPLE 6 
As in Example 1, 50 g (0.3 mol) of HFA, 25 g (0.39 mol) of 
1,1-difluoroethylene and 5 g of ACF were allowed to react. The reactor was 
shaken 18 h at 100.degree. C. The reaction mixture was worked up as above. 
There was isolated 25 g of liquid, which was according to GC and .sup.19 F 
was a mixture of 75% of F-2,2-dimethyl-3,3-dihydro-oxetane, 20% of 
F-2-hydro-3-hydroxy-3-trifluoromethyl-butene-1 and 5% of 
F-2,2-dihydro-3-hydroxy-3-trifluoro-methyl-butane. Washing this mixture 
with a 10% aqueous solution of NaOH gave pure oxetane, b.p. 
55.degree.-55.5.degree. C. .sup.19 F NMR (CDCl.sub.3): -60.23 (6F, m), 
-78.29 (2F, t); .sup.1 H NMR: 3.46 (t) . Calculated yield of oxetane was 
82% based on converted HFA, conversion of HFA and olefin was 33%. 
EXAMPLE 7 
As in Example 1, 50 g (0.3 mol) of HFA, 29 g (0.3 mol) of 
1,1-dichloroethylene (freshly distilled, without a stabilizer) and 5 g of 
ACF were allowed to react. The reactor was shaken 18 h at 100.degree. C. 
The reaction mixture was worked up as above. There was isolated 16 g of 
liquid with b.p. 100.degree.-103.degree. C. which was according to GC/MS 
and .sup.19 F NMR a mixture of 90% of 
F-2,2-dimethyl-3,3-dihydro-4,4-dichloro-oxetane and 10% of 
2-hydro-3-hydroxy-3-trifluoromethyl-1, 1-dichloro-butene-1. Calculated 
yield of oxetane was 80% based on converted HFA, conversion of HFA was 
20%. 
EXAMPLE 8 
As in Example 1, 70 g (0.42 mol) of HFA, 40 g (0.41 mol) of 
1-hydro-1-chloro-2,2-difluoroethylene, (containing 10% of isomeric 
1-hydro-2-chloro-1,2-difluoroethylene), and 5 g of ACF were allowed to 
react. The reactor was shaken 18 h at 100.degree. C. The reaction mixture 
was worked up as above. There was isolated 2.6 g of liquid, b.p. 
62.degree.-64.degree. C. According to GC/MS and .sup.19 F NMR the product 
was a mixture of 90% of F-2,2-dimethyl-3-chloro-3-hydro-oxetane and 10% of 
F-2,2-dimethyl-3-hydro-4-chlorooxetane (mixture of diastereomers). 
Calculated yield (GC) of oxetanes was 91% based on converted HFA; 
conversion of HFA was 22%. 
EXAMPLE 9 
As in Example 1, 37 g (0.2 mol) of chloropenta-fluoroacetone, 3 g of ACF 
and 20 g (0.2 mol) of TFE were allowed to react. The reaction vessel was 
shaken 18 h at 60.degree. C. There was isolated 5.8 g of 
F-2-chloromethyl-2-methyloxetane. Yield was 9.8%. 
EXAMPLE 10 
As in Example 1, 18 g (0.1 mol) of chloropenta-fluoroacetone, 5 g of ACF 
and 7 g (0.11 mol) of CH.sub.2 =CF.sub.2 were allowed to react. The 
reaction vessel was shaken 18 h at 100.degree. C. There was isolated 8 g 
of a mixture of 75% of F-2-chloromethyl-2-methyloxetane and 25% of 
unidentified material. Calculated yield of oxetane (GC) was 24.4%. 
EXAMPLE 11 
As in Example 1, 20 g (0.12 mol) of HFA, 3 g of AlCl.sub.3 and 9 g (0.11 
mol) of trifluoroethylene were allowed to react. The reaction vessel was 
shaken 18 h at 100.degree. C. There was isolated 3 g of 
F-2-dimethyl-3-H-oxetane, 80% purity. The yield of oxetane was 8.3 %. 
EXAMPLE 12 
As in Example 1, 50 g (0.3 mol) HFPO, 5 g ACF and 25 g (0.25 mol) TFE was 
allowed to react at 60.degree. C. for 48 h. (TFE was loaded in two 
portions: 15 g initially and 10 g after 24 h.) There was isolated 15 g 
(100% on converted HFPO) of F-2,2-dimethyloxetane, and 4 g 
polytetrafluoroethylene. Conversion of TFE was 38%. 
EXAMPLE 13 
As in Example 1, 51 g (0.31 mol) HFPO, 5 ACF and 24 g (0.375 mol) CH.sub.2 
=CF.sub.2 was allowed to react at 100.degree. C. for 18 h. There was 
isolated 20.4 g of a mixture, containing 73% of 
F-2,2-dimethyl-3,3-dihydrooxetane, 18% of 
F-2-hydro-3-hydroxy-3-trifluoromethyl-butene-1 and 9% of 
F-2,2-dihydro-3-hydroxy-3-trifluoromethylbutane. The yield of oxetane was 
73%, based on converted HFPO.