A Fundamental Study Aimed at Providing the Foundation for the Development of A Novel Benign Technology for the Direct Fixation and Subsequent Re-Utilization of Nitrogen Oxides (NO₂ and N₂O₄) from Effluent Gas Streams Generated Upon Pyrolysis of Nitrogenous Containing Solids

Ramiro Sanchez, Ph.D., Associate Professor, UHCL
Donald Henninger, Ph.D., JSC
Graciela Lubertino, Ph.D., Post-Doctoral Fellow, UHCL

THE BENIGN REMOVAL OF Nitrogen Oxides (NO₂ and N₂O₄) from effluent gas streams generated during pyrolytic (high temperature) degradation of nitrogenous solid waste materials would remove one of the key barriers to continued development by NASA-JSC researchers of closed loop life support systems. Under partial support from the ISSO Post-Doctoral Aerospace Fellowship program, we have been carrying out research on several novel reactions that we have discovered in an attempt to lay down the foundation for various new technologies that can be developed as closed loop systems to support life during long-duration manned space activities. This past year, we have been quite fortunate in having discovered a heretofore unknown chemical process which allows for the direct fixation and reutilization of NO₂ and N₂O₄. This finding we consider to have direct and very positive relevance to NASA-JSC efforts which use pyrolysis or other high temperature degradation for the degradation of nitrogenous solid wastes. These wastes result from the necessary destruction of non-edible higher plant life support systems as well as from all sources onboard a platform inhabited by a crew during a long-duration space mission. In addition to this application, we feel that our discovery of this new chemical reaction process may also be developed into an even more "general use technology."

Dr. Graciela Lubertino, Post-Doctoral Fellow, conducts ALSS research at JSC and UHCL.

This new process holds the potential for being the foundation of novel technologies that can be employed for the removal and re-use of Nitrogen Oxides from any effluent stream generated either by design or by unexpected contamination during long-duration manned space activities. This technology can be applied to a gamut of activities on Earth. The major near term relevance of the proposed study is probably best directed to the endeavors of the NASA-JSC Advanced Life Support Systems Group (ALSSG) which is developing a higher plant based life support system for long-duration manned space activities. In addition to use of the developed technology for the removal of nitrogen oxides from the waste gas streams generated after pyrolytic degradation of nitrogenous solid wastes, we propose that the ALSSG at NASA-JSC may also use the final technology for: (1) removal of nitrogen oxides inadvertently put in the general life support atmosphere of the humans carrying out long-duration manned activities (2) increased plant growth and food production (for example, the conversion of azo and/or nitroso compounds to nitrates), and (3) the generation of high energy fuel (e.g., N-nitroso and substituted hydrazine derivatives) for activities where re-dox based energy generation would be required.

Theoretical Background
Current research is predicated on a two-part theory which states: (1) that the evaluation of the mechanisms involving organometallic reagents can better be discerned if the observed dynamic structure-reactivity relationship is correlated to the innate residual bonding capacity (RBC) of the reagent under study and (2) that the mechanism for a general structural family of organometallic reagents will vary along a mechanistic continuum as the innate RBC of the reagent goes from a maximum to a minimum. The residual bonding capacity is defined here as a function of available low-lying electronic orbitals (pure or hybridized) present on the metal which are, in turn, influenced by the ligands appended to the metal, the volume in space occupied by the ligands around the metal, external electron donors (such as donor solvents, ligands or other organometallic compounds), etc. This theory would predict that mechanistic studies on a given organometallic family of reagents should be undertaken with the most representative structural member (with respect to maximum RBC) and that the observed structure-reactivity relationships would be different than for any other member of the family of reagents which would have their RBC either internally or externally decreased.

A review of the scientific literature yields a multitude of examples in which investigators have not used this approach but have rather assumed that the structure of a given organometallic reagent with minimal RBC-for example the so-called Grignard Reagent-was representative of the true structure for all organomagnesium compounds. They carried out structure-reactivity relationship studies where correlations to single factors such as electronic and steric effects and the use of absolute transition state theory have led to a mechanism involving a polar transition state in which anomalous S.E.T. behavior was invoked for those systems which did not yield the expected polar transition state results.

To test the tenets of our theory, we have embarked on both the design and synthesis of metal-containing reagents which, we propose, possess the maximum innate RBC. In parallel, we are carrying out physical studies and the development of novel synthetic methods which would not be available via the analogous classical reagents possessing low RBC.

Some fundamental results are known at this relatively early date in the research: (1) physical studies concerning the reaction between unsolvated diorganomagnesium compounds and the analogous externally unsolvated organomagnesium amides (not the minimum RBC-containing so-called Grignard Reagents or Hauser bases which have been used in the past) and carbon monoxide have indicated to us that the fundamental tenets of our theory are valid.

A major new theory has resulted from these endeavors which we will communicate to the general scientific community in a manuscript submitted to the Journal of the American Chemical Society.[2] Using the unsolvated organomagnesium amides, which we first prepared and characterized,[3] we have been able to develop several new synthetic methods which are not available through the analogs of these reagents which have limited RBC (such as the so-called Hauser Bases). In addition to the new methods that we have described in the primary literature,[4] we have been able to bring about the fixation of carbon dioxide at room temperature and atmospheric pressure. We are continuing to develop this novel reaction for the removal and regeneration of carbon dioxide.[5] From these latter studies, we have also isolated a new family of reagents with a novel composition of matter and are exploring the use of this new family of reagents to further test our theory via physical techniques and the development of other new synthetic methods and unprecedented technologies. Because our fundamental interests require that we carry out concurrent research on multiple projects, we do not anticipate committing to just the pursuit of that one research endeavor alone.

However, we will use the new family of reagents to evaluate the possibility of bringing about chemical transformations of interest in synthetic organic chemistry. We also expect to use the reagents to develop novel technologies. Among these is a new reaction for the conjugate addition of organoaluminum compounds to a,b-unsaturated,[6] and the use of the fundamental reaction to develop a novel carbon dioxide removal and regeneration technology for use by humans establishing activities in space.

We have also achieved several scientific findings during the further testing of our fundamental premise: (1) a novel method for the formulation of olefins via a tandem carbometalation/carbonylation of a Main-Group bimetallic species; (2) a novel synthesis for formamidines via the direct carbonylation of unsolvated organomagnesium amides; (3) a novel method for the extension of the carbon framework of simple formamides to formamidines; (4) a novel reaction which allows for the direct conversion of nitriles to substituted imidazoles and pyrimidines; (5) a novel method for the cyclotrimerization of alkynes; (6) a novel method for the direct conversion of isocyanates to substituted guanidines; (7) a new reaction for the synthesis of alcohols from CO and ethylene; (8) a novel composition of matter for polymerization of olefins; (9) the preparation and preliminary structure-reactivity relationships studies as well as new synthetic method development, of unsolvated organomagnesium imides; and (10) a new synthesis for ureas from CO. Because of the potential of getting either composition-of-matter or process patent coverage, we have not, as yet, submitted our study for publication in the primary literature.

The novel reaction, which is the basis of this proposal, is our most recent discovery and is the subject of a formal invention disclosure submitted to the University of Houston System. The university of Houston Clear Lake has committed funds and has hired external legal counsel to carry out the first phase of a patent application process on this discovery.[7]

Research Activities
Preliminary Results
During the course of our studies dealing with the development of a novel technology for the removal and regeneration of carbon dioxide for use in long-duration manned space activities, we discovered that the reaction between donor-solvent free diorganomagnesium compounds and nitrogen dioxide proceeds smoothly at room temperature and atmospheric pressure in alkanes media. The basis of this proposal is the newly discovered reaction which depicted in general by Eqs. (1) and (2) below.

All of the preliminary data indicate that, indeed, the reaction proceeds for more than one specific type of structural unit, and gives the general products indicated above. While it is difficult to generalize based upon the cursory work completed to date, there does seem to be an indication that when the substituents (R and R') yield a secondary magnesium amide, the direct reaction of those reagents with NO₂ yields the N-Nitrosoamines upon work-up. On the other hand, if the substitution pattern on the magnesium amide is such that R and R' generate a primary magnesium amide, then, upon work-up, the products are an alcohol and a ketone derived from the substituent that was not hydrogen. Products obtained to date are in keeping with results published in the literature when secondary and primary amines were subjected to what is generally referred to as nitrosation under the very stringent, brutal classical methods commonly used for those types of transformations.[8]

The most general of these is depicted by the sequence given by Eqs. (3), (4), and (5) above.

Of course it is understood that those methods would not be even remotely useful for ALSSG endeavors. The benign removal of nitrogen oxides from off-gases would result from the pyrolytic degradation of nitrogenous waste solids. We are now in the process of conducting a systematic study on the generality of the novel reaction process and the optimization of reaction conditions.

Dr. Ramiro Sanchez, UHCL

References and Notes
[1]S. Sun, D. L. Henninger, J. Sager, and T. O. Trio. "NASA's Approach to Integrated System Testing of Regenerative Life Support Systems," Paper No. 951494 and references therein, Int'l Conf. on Environmental Systems (1995); D. L. Henninger, T. O. Trio, D. J. Barta, and R. S. Stahl. "Johnson Space Center's Regenerative Life Support Systems Test Bed," NASA Report--NASA-TM-107943 (1991); B. L. Robertson and C. S. Lemay. "Investigating Pyrolysis/Incineration as A Method of Resource Recovery From Solid Waste," NASA/ASEE Summer Faculty Fellowship Program 2(SEE-N94-2536706-99) (1993).
[2]R. Sanchez, E. Tsilingiridis, and M. Anderson. "A Residual Bonding Capacity Based Variable Transition States Theory For The Reactivity of The Carbon-Magnesium Bond Based Upon the Comparative Uncatalyzed Carbonylation of Unsolvated Diorganomagnesium Compounds," J. of the Am. Chem. Soc. (1997). (Submitted for publication.)
[3]R. Sanchez, T. Ratham, R. Morrison, and V. J. Mehta. "Ether-Free Organometallic Amide Compositions," U. S. Patent 4,944,894, 1990.
[4]R. Sanchez and W. Scott. "Unsolvated Magnesium Diisopropylamide (MDA) in Organic Synthesis. The Reduction of Aldehydes and Ketones to Alcohols," Tetrahedron Letters 29 (1988): 139; R. Sanchez, G. Vest, W. Scott, and P. S. Engel. "The Reduction of Nitro, Nitroso, and Azoxy Compounds with Unsolvated MDA," J. Org. Chem. 54 (1989): 4026; R. Sanchez, G. Vest, and L. Despres. "The Direct Conversion of Carboxylic Acids To Carboxamides via Unsolvated Magnesium Amides," Synth. Comm. 19 (1989): 2909; R. Sanchez, C. Arrington, and C. A. Arrington. "Reaction of Trimethylaluminum with Carbon Monoxide in Low Temperature Matrices," J. Am. Chem. Soc. 111 (1989): 9110.
[5]R. Sanchez and O. Felan. "Unsolvated Bis(N,N'-Diorganocarbamoxy)Magnesium Compounds: A Novel Family of Reagents For The Storage and Transfer of Carbon Dioxide and the Facile Preparation and Transfer of The N,N'-Substituted Carbamoxy Structural Unit," Main Group Metal Chemistry 18.4 (1995): 225.
[6]R. Sanchez and M. Anderson. "The Use of A New Family of Reagents, Unsolvated Bis(N,N'-diorganocarbamoxy)magnesium Compounds, To Effect The Uncatalyzed Conjugate Addition of Organoaluminum Compounds," Synthetic Letters (1997). (Submitted for publication.)
[7]R. Sanchez, G. Lubertino, and D. Henninger. "A Novel Reaction For The Direct Fixation and Conversion of Nitrogen Dioxide to N-Nitrosoamines, Alcohols and Ketones," Invention Disclosure formally to be presented to The University of Houston System and NASA-JSC, 1997.
[8]A. L. Fridman, F. M. Mukhametshin, and S. S. Novikov. Russian Chemical Reviews 40.1 (1971): 34; P. Beak and W. Zajdel. Chem. Rev. 84 (1984): 471, and references therein.

Invention Disclosure
R. Sanchez and G. Lubertino. "A Novel Chemical Process For The Benign Direct Fixation And Conversion Of Nitrogen Oxides (NOx) At Atmospheric Pressure And Room Temperature." University of Houston Clear Lake, July 22, 1997.

Contents
ISSO -- Institute for Space Systems Operations
1996-1997 Annual Report