Chemistry of inorganic compounds – Oxygen or compound thereof
Reexamination Certificate
2001-12-15
2003-09-23
Silverman, Stanley S. (Department: 1754)
Chemistry of inorganic compounds
Oxygen or compound thereof
Reexamination Certificate
active
06623718
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improved method of chemically generating singlet delta oxygen. It particularly relates to a gas-solid reaction involving a hydrogen halide gas or deuterium halide gas and a solid alkali metal peroxide or solid alkaline earth peroxide.
2. Related Art
The singlet delta (
1
&Dgr;g) state of oxygen, its first electronically excited state, lies 7874 cm
−1
(1.27 microns) above the triplet sigma ground state. Singlet delta oxygen was first discovered in 1924 and has found wide application as an oxidizer
1,2
and energy transfer agent
3,4
. Its role in biological processes
5
(cell/tissue destruction, aging and cancer inducing processes), synthetic organic chemistry
1,2
, airborne environmental and waste treatment chemistry, and the chemical oxygen iodine laser (COIL)
3,4,6
is well documented. A variety of methods have been used to produce singlet delta oxygen either from oxygen containing reagents or directly from oxygen. The documented reaction
6
used to produce singlet delta oxygen for the COIL is exemplified in equation (1):
2MOH+H
2
O
2(aq)
+Cl
2
→O
2
(
1
&Dgr;g)+2MCl+2H
2
O (1)
M in equation (1) is an alkali metal or mixture
7
thereof The aqueous environment represented by equation (1) is known to deactivate the singlet delta oxygen by collisional quenching and methods for very rapid and efficient oxygen extraction are required for COIL applications
8
. The hazards associated with concentrated basic hydrogen peroxide are also a disadvantage common to all coil embodiments based upon equation (1) and these hazards necessitate considerations for reaction zone cooling and maximum peroxide utilization and regeneration
7,9-12
.
A variety of chemical sources of singlet delta oxygen has been reported
13
. These are typically solution based reactions that include analogs of equation (1). The reaction between gaseous ozone and certain organic substrates in the gas phase leads to singlet delta oxygen formation
14
. However, this approach is of no practical value in view of the hazards and difficulties associated with producing and handling ozone. Preparative oxidation chemistry methods which utilize singlet delta oxygen are generally limited to substrates soluble in water or in a suitably modified solvent system.
Direct photophysical techniques
15
that generate singlet delta oxygen from ground state oxygen require high powered light sources and inconvenient, dangerous pressures (100 atm) in purely gaseous or gas-liquid systems. Microwave or rf discharge of oxygen-gas mixtures are reliable techniques
16,17
for producing singlet delta oxygen at low total pressures of ca. 5 torr. A number of possibly undesirable species, including oxygen atoms, are also formed in the discharge process.
References Cited
1. A. A. Frimer and L. M. Stephenson. The singlet oxygen ene reaction, in Singlet O
2
, Vol. 2, A. A. Frimer, ed., CRC Press, Boca Raton, Fla., 1984. Ch. 3.
2. R. F. Gould, ed., Oxidation of organic compounds, Vol. 3, Ozone chemistry, photo and singlet oxygen and biochemical oxidations, Advances in Chemistry, Vol. 77 (American Chemical Society, Washington, D.C., 1969.
3. W. E. McDermott, N. R. Pchelkin, D. J. Benard, and R. R. Bousek, An electronic transition chemical laser., Appl. Phys. Lett. 32, 469 (1978).
4. D. J. Benard, W. E. McDermott, N. R. Pchelkin, and R. R. Bousek, Efficient operation of a 100-W transverse-flow oxygen-iodine laser., Appl. Phys. Lett. 34, 40 (1979).
5. A. U. Khan, The discovery of the chemical evolution of singlet oxygen., Int. J. of Quantum Chem. 39, 251 (1991).
6. R. I. Wagner, Singlet delta oxygen generator and process., U.S. Pat. No. 4,310,502, Jan. 12, 1982.
7. C. W. Clendening, W. D. English, M. H. Mach, and T. D. Dreiling, Gas generating system for chemical lasers., U.S. Pat. No. 5,624,654, Apr. 29, 1997.
8. R. A. Dickerson, Singlet delta oxygen generator., U.S. Pat. No. 5,516,502, May 14, 1996.
9. J. D. Rockenfeller, Singlet delta oxygen generator., U.S. Pat. No. 4,461,756, Jul. 24, 1984.
10. W. L. Dinges, Formation of basic hydrogen peroxide., U.S. Pat. No. 5,378,449, Jan. 3, 1995.
11. W. E. McDermott, Singlet delta oxygen generator and process., U.S. Pat. No. 5,417,928, May 23, 1995.
12. D. G. Beshore and D. Stelman, Salt free lithium hydroxide base for chemical oxygen iodine laser., European Patent EP 0 819 647 A2, Jan. 21, 1998.
13. R. W. Murray, Chemical sources of singlet oxygen, in Singlet Oxygen H. H. Wasserman and R. W. Murray, ed., Academic Press, New York, N.Y., 1979, Ch. 3.
14. W. C. Eisenberg, K. Taylor, and R. W. Murray, Gas-phase generation of singlet oxygen by reaction of ozone with organic substances., J. Am. Chem. Soc. 107 8299 (1985).
15. W. C. Eisenberg, Atmospheric gas phase generation of singlet delta oxygen., in Advances in Oxygenated Processes, Vol. 3, pages 71-113, A. L. Baumstark, ed., JAI Press Inc., 1991.
16. S. M. Anderson, J. Morton, K. Mauersberger, Y. L. Yung, and W. B. DeMore, A study of atom exchange between O
2
(
1
&Dgr;) and ozone, Chem. Phys. Lett. 189 581 (1992).
17. J. Schmiedberger and H. Fujii, Radio-frequency plasma jet generator of singlet delta oxygen with high yield, Appl. Phys. Lett. 78, 2649 (2001).
OBJECTS OF THE INVENTION
It is, therefore, an object of this invention to provide a technique that produces singlet delta oxygen in high yield from readily available starting materials in a minimally quenching environment without the need for external electrical, optical, or thermal energy.
Another object is to provide a safe method that avoids the use of dangerous, explosive chemicals such as basic hydrogen peroxide.
Yet another object is to provide a process that avoids the need for separating gases from a liquid phase thus rendering it suitable for zero gravity conditions.
A further object is to provide a lightweight, readily scalable, and mechanically simple method that avoids the use of heavy complex machinery, such as vortex mixers, centrifuges, and vacuum pumps to extract excited state oxygen from solution.
SUMMARY OF THE INVENTION
To implement the objects stated above, the method of the present invention was devised in which singlet delta oxygen is generated by a chemical reaction at ambient temperature of a solid peroxide with a hydrogen halide gas or a deuterium halide gas, without using external energy sources.
Singlet delta oxygen was produced from an alkali metal peroxide (such as lithium peroxide or sodium peroxide) or an alkaline earth peroxide (such as barium peroxide) in a reaction with a non-radioactive-hydrogen-isotope halide gas (such as hydrogen chloride, hydrogen bromide, deuterium chloride, or deuterium bromide). A static gas fill system was used and the results were observed by emission spectroscopy. Comparable results can be obtained in a flow system, and further, the reaction may take place in a chemical oxygen-iodine laser.
Accordingly, the present invention provides a safe, compact, lightweight, readily scalable, and highly efficient method for producing singlet delta oxygen from commercially available starting materials by directly reacting a solid peroxide with a non-radioactive-hydrogen-isotope halide gas. It avoids the use of unstable starting materials, such as basic hydrogen peroxide that can explode, and liquid phase quenching that can rapidly destroy most of the desired singlet delta oxygen. Furthermore, it avoids the need for a gas-liquid phase separation, thus making it ideal for space-based applications under zero gravity conditions.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is the chemical generation of singlet delta oxygen by a gas-solid reaction at ambient temperature without external energy sources. A dry, solid alkali metal peroxide or solid alkaline earth peroxide is reacted with a dry hydrogen halide gas or a dry deuterium halide gas to form singlet delta oxygen. Alkali metal peroxides include lithium peroxide, Li
2
O
2
, and sodium peroxide, Na
2
O
2
; alkaline earth peroxides include barium peroxide, BaO
2
. Non-radio
Alfano Angelo J.
Christe Karl O.
ERC Incorporated
Medina Maribel
Silverman Stanley S.
Unterberg Walter
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