Stable chlorine trifluoride dioxide

Chlorine trifluoride dioxide is disclosed for use as an oxidizer in formulating energetic compositions, such as propellants. The stable ClF.sub.3 O.sub.2 is produced by reacting a ClO.sub.2 F.sub.2 .sup.+ salt with a strong Lewis base at -78.degree. C.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to compositions of matter and is particularly 
directed to chlorine trifluoride dioxide and a method of producing the 
same. 
2. Prior Art 
Energetic compositions of matter are useful in providing energy sources for 
rocket engines, guided missiles, auxiliary power units for aircraft, 
ordnance, demolition and the like. Such compositions conventionally are 
produced by mixing a fuel with an oxidizer. Obviously, the energy of such 
compositions results primarily from the oxidation of the fuel. Hence, it 
is desirable to provide a highly energetic oxidizing agent. On the other 
hand, it is equally desirable that the oxidizing agent be a stable 
material, so as to prevent accidental or unintentional ignition or 
explosive decomposition of the composition. Numerous organic and inorganic 
compounds have been proposed heretofore for use as such oxidizing agents. 
However, it has been found that, as a general rule, stable compounds are 
low energy oxidizers and high energy oxidizers are unstable. Thus, 
although some useful oxidizing agents have been disclosed by the prior 
art, the search for a stable, high-energy, oxidizing material has 
continued. In recent years, studies have indicated that halogen 
oxyfluoride materials might provide a satisfactory oxidizing material. 
However, although empirical formulas may be stated for such materials and 
some of the properties of such materials may be predicted, the synthesis 
of these materials has proven to be extremely difficult and it is 
sometimes found that several materials, each having distinct structures 
and properties, are defined by a single empirical formula. Thus, U.S. Pat. 
No. 3,285,842 discloses a process for producing a material which was 
believed to have the empirical formula chlorine trifluoride dioxide, 
ClF.sub.3 O.sub.2, which the patent states to be a violet liquid which is 
unstable at temperatures above -72.degree. C. It was subsequently shown, 
however, that this composition does not contain the chemical compound 
ClF.sub.3 O.sub.2, but consists of a mixture of chlorine fluorides and 
oxygen fluorides (K. O. Christe, R. D. Wilson, and I. B. Goldberg, J. 
Fluor-Chem., 7,543 (1976). This fact readily explains the great difference 
in physical and chemical properties between the composition and the novel 
composition disclosed in this invention. While it would be expected that 
the previously claimed composition would also be a highly energetic 
oxidizing agent, the lack of stability renders it unsafe for use in the 
production of propellants and the like. 
Brief Summary and Objects of Invention 
These disadvantages of the prior art are overcome with the present 
invention and a composition of matter is disclosed which based on its 
chemical structure truly is chlorine trifluoride dioxide. It is 
sufficiently stable at +25.degree. C. and, hence, can be safely employed 
for manufacturing propellants and the like. In addition, a method is 
disclosed for producing chlorine trifluoride dioxide by reacting ClF.sub.2 
O.sub.2.sup.+ PtF.sub.6.sup.- with a strong Lewis base at a temperature of 
about -78.degree. C. and separating the products of the reaction by 
distillation. 
Accordingly, it is an object of the present invention to provide a new 
composition of matter having the chemical composition ClF.sub.3 O.sub.2. 
An additional object of the present invention is to provide a method of 
producing chlorine trifluoride dioxide. 
A specific object of the present invention is to provide chlorine 
trifluoride dioxide by reacting ClF.sub.2 O.sub.2.sup.+ salts with nitryl 
fluoride at a temperature of about -78.degree. C. and separating the 
products of the reaction by distillation. 
These and other objects and features of the present invention will be 
apparent from the following detailed description.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
In that form of the present invention chosen for purposes of illustration, 
chlorine trifluoride dioxide has been produced by reacting a ClF.sub.2 
O.sub.2 .sup.+ salt, such as ClF.sub.2 O.sub.2 .sup.+PtF.sub.6 .sup.-, 
with a strong Lewis base at -78.degree. C. 
EXAMPLE I 
A sample of ClO.sub.2 .sup.+PtF.sub.6 .sup.- containing about 10% of 
ClF.sub.2 O.sub. 2 .sup.+PtF.sub.6 .sup.- was treated at -78.degree. C. in 
a sapphire reactor with a large excess of FNO for several days. No 
material noncondensible at -196.degree. C. (i.e., F.sub.2) was observed. 
The products, volatile at 25.degree. C. were removed and separated by 
fractional condensation through a series of traps kept at -126.degree. C., 
-142.degree. C., and -196.degree. C. The -142.degree. C. fraction 
contained a novel compound which was identified by its infrared spectrum 
as ClF.sub.3 O.sub.2. The observed frequencies are listed in Table I and 
are in excellent agreement with those expected for a trigonal bypyramidal 
structure of symmetry C.sub.2v. 
##STR1## 
This structure was confirmed by .sup.19 F nuclear magnetic resonance 
spectroscopy. The observed signal consisted of a typical AB.sub.2 pattern 
centered at -413 ppm relative to the external standard CFCl.sub. 3. The 
F-F coupling constant was measured to be 443 Hz. The B.sub.2 part of the 
AB.sub.2 pattern occurs downfield from the A part, proving that the 
B.sub.2 fluorine atoms occupy the two axial positions. Additional 
structural proof was obtained from the Raman spectrum of the gas and the 
liquid showing strong absorptions at 1096, 684, 548, 527, 493, 290, and 
229 cm.sup..sup.-1. The molecular weight of the compound was confirmed by 
vapor density measurements (measured, 122; calculated, 124). These data 
establish beyond doubt (see K. O. Christe and R. D. Wilson, Inorg. Chem, 
12, 1356 (1973) and K. O. Christe and E. C. Curtis, Inorg. Chem. 12, 2245 
(1973) that contrary to the previous claim (U.S.P. 3,285,842) our novel 
composition has indeed the chemical composition ClF.sub.3 O.sub.2. 
Table I 
______________________________________ 
Infrared Spectrum of ClF.sub.3 O.sub.2 and its Tentative Assignment 
Frequency Assignment for Point 
(cm.sup.-.sup.1) 
Intensity Group C.sub.2v 
______________________________________ 
1334 s .nu..sub.10 (B.sub.2), .nu.asCl0.sub.2 
1096 s .nu..sub.1 (A.sub.1), .nu.symCl0.sub.2 
699 vs .nu..sub.7 (B.sub.1), .nu.asClF.sub.2 Ax 
687 vs v.sub.2 (A.sub.1), .nu.ClF 
598 ms .nu..sub.11 (B.sub.2), .delta.rock ClO.sub.2 
543) 
532) mw .nu..sub.3 (A.sub.1) and .nu..sub.8 
______________________________________ 
(B.sub.1) 
The solid residue obtained from the FNO displacement reaction showed the 
correct weight change expected for conversion into NO.sup.+PtF.sub.6 
.sup.-. Its identity as NO.sup.+PtF.sub.6 .sup.- was confirmed by infrared 
spectroscopy. 
The chlorine trifluoride dioxide is white as a solid having a melting point 
of about -81.2.degree. C. and colorless as a liquid having a boiling point 
of about -21.degree. C. It is marginally stable at 25.degree. C. The 
observed stability and lack of color furthermore demonstrate that our 
product cannot be identical with the previously reported deeply violet and 
unstable ClF.O.sub.2 F.sub.2 and ClF.sub.3.O.sub. 2 addition compounds 
supposedly having the empirical composition ClF.sub.3 O.sub.2. 
EXAMPLE II 
A sample ClO.sub.2 .sup.+PtF.sub.6 .sup.- containing about 10% of ClO.sub.2 
F.sub.2 .sup.+PtF.sub.6 .sup.- was treated with a sufficient quantity of 
FNO.sub.2 to maintain a liquid phase at -78.degree. C. in a stainless 
steel reactor for up to 12 hours. This reaction yielded solid NO.sub.2 
.sup.+PtF.sub.6.sup.- and gaseous ClF.sub.3 O.sub.2 plus FClO.sub.2. If 
desired, the chlorine trifluoride dioxide may then be separated by 
conventional distillation techniques, as in a multi-plate distillation 
tower. 
Small amounts of material were purified by combining the ClF.sub.3 O.sub.2 
and FClO.sub.2 at -196.degree. C. with a small excess of BF.sub.3. These 
materials were allowed to mix and warm to ambient temperature. This 
results in ClF.sub.2 O.sub.2 .sup.+BF.sub.4 .sup.-, which is stable, plus 
ClO.sub.2 .sup.+BF.sub.4 .sup.-, which has a dissociation pressure of 182 
millimeters at 22.degree. C. and which can be removed by pumping. The 
ClF.sub.2 O.sub.2 .sup.+BF.sub.4 .sup.- is then reacted with sufficient 
FNO.sub.2 to maintain a liquid phase at -78.degree. C. for up to 12 hours. 
This reaction produced solid NO.sub.2 .sup.+BF.sub.4 .sup.- plus gaseous 
ClF.sub.3 O.sub.2 and FNO.sub.2. The two gases may be pumped off and 
separated by passing the gases through a pair of traps maintained at 
-126.degree. C. and -196.degree. C., respectively. The chlorine 
trifluoride dioxide will be caught in the -126.degree. C. trap. 
Obviously, numerous variations and modifications may be made without 
departing from the present invention. Accordingly, it should be clearly 
understood that the forms of the present invention described above are 
illustrative only and are not intended to limit the scope of the present 
invention.