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The objective of this work was to investigate energetic polyether glycol prepolymers for cast-cured propellants and explosives. We investigated the synthesis of several energetic cyclic ether monomers and methods for their polymerization. To optimize the physical properties of the polymers, we examined the relationship of monomer structures to polymerization ability. This information was then used to select monomer pairs that would produce random copolymers, materials that have a very low degree of crystallinity. This low crystallinity is reflected in the superior elastomeric properties and plasticizer retention of the polymers examined. Preliminary evaluation of the polyether glycols and cured gum stocks indicate that binders can be produced that will add considerable energy content to propellant formulations. Ten polymers were investigated; one of these, the BAMO/THF copolymer, has been produced in multipound quantities and actual propellant formulation and testing is being conducted in various laboratories. (Author)

Contents: Ab-initio quantum chemical investigations of the mechanism of cationic polymerization; Development of theoretical procedures for prediction of crystal structures and densities; Ab-initio quantum chemical MODPOT/VRDDO/MERGE calculations on nitro-explosives; and Decomposition pathways of energetic compounds.

Three general synthetic routes to the preparation of energetic oxetanes and tetrahydrofurans were investigated during the first year of the program. Subsequently, 3-(2-fluoro-2,2-dinitroethyl-3-methyloxetane (FOE) was prepared and polymerized to give oligomers with molecular weights ranging from 6,000 to 15,000. Efforts to develop a general synthetic route to 3-nitroalkyl substituted oxetanes starting with methylene malonate were not successful. However, work on an alternative general route to oxetanes afforded oxetane 3,3-diacetic acid in low yield. This material could be used to prepare a series of nitro esters of oxetane, but this work was terminated as our experience has shown that cationic polymerization of esters does not produce significant conversion of the monomer. Work on a general route to nitroalkyl-substituted tetrahydrofurans resulted in 3-(2,2-dinitropropyl)tetrahydrofuran (3-DNPTHF), which was prepared using a synthetic route of general applicability to other 3-substituted tetrahydrofurans. A preliminary polymerization study yielded dimer and trimer, suggesting that polymerization was possible.

The mechanism of chemiluminescence of organic peroxides is reviewed. The topics covered are: General Requirements for Chemiluminescence; Generalized Mechanisms for Chemiluminescence of Organic Compounds in Solution; Chemiluminescence of Molecular Systems; Peroxyoxalate Chemiluminescence; Dioxetane Chemiluminescence; Diphenoyl Peroxide Chemiluminescence; Acyclic Secondary Peroxyester Chemiluminescence; Luminol Chemiluminescence; Miscellaneous Chemiluminescent Systems. (Author)

Applications of chemical reactions to produce light (chemiluminescence, CL) has been used for marking and viewing, and for analytical purposes. 1,2-Dioxetanes have been one of the most important types of compounds in studies of CL processes. Research was directed to a study of the mechanism of dioxtane thermolysis. Since the Cl process will be intimately related to the mechanism of thermolysis, we have been interested to define the parameters that control the mechanism. Currently three mechanisms are considered: (1) stepwise biradical; (2) concerted; and (3) electron transfer (CIEEL). A key intermediate in the thermolysis of dioxetanes by the stepwise process is the 1,4-dioxy biradical. Attempts were made to estimate the lifetime of this biradical by competitive beta-scission and by trapping with hydrogen atom donors. The efficiency of producing an excited carbonyl product from a dioxetane varies widely. Both electronic and steric effects influence the efficiency. To study soley electronic effects, we prepared a series of para-and meta-substituted 3-aryl-3-methyl-2,2-dioxetanes, where steric effects are held constant. Both electron releasing and electron withdrawing groups decrease the triplet efficiency. We observed triplet, singlet energy transfer with (6,12-dibromotetracene) (DBT) and acetophenones, but not with DBT and alkanones.

In the research on part I of this project we are carrying out ab-initio quantum chemical calculations and generating electrostatic molecular potential maps for cationic polymerization: on energetic monomers, on their interaction with catalysts and on the attack of the monomer-catalyst complexes on the substrates. This research is in support of an ongoing overall project of the Power Program Branch of ONR designed to develop energetic binders for use with energetic propellants. We are pursuing several approaches to the predictions of crystal structures and densities. The first is to calculate (from calculations on the super-molecules) the SCF intermolecular interaction, separate it into its various components and use these to construct the crystal structure. The second approach is to carry over the concept recently used successfully in calculations for biological systems where the same ab-initio calculations between two or several of such molecules for a large variety of inter-molecular configurations is used to derive atom class-atom pair-pair and three-body potentials which are then used to calculate the intermolecular structure of an arrangement of molecules.

During this first year of the program, three general synthetic routes to the preparation of energetic oxetanes and tetrahydrofurans were investigated. Efforts to develop a general synthetic route to 3-nitroalkly-substituted oxetanes starting with methylene malonate were not successful. However, one specific oxetane monomer was prepared to provide an immediate subject for polymerization studies. (Author)

The objective of this program is to develop new synthetic methods for classes of compounds with potential utility in high energy propellant and explosives. Emphasis was continued on studies of the chemistry of 2-fluoro-2-nitro-1, 3-propanediol and related compounds, and on polymerization studies of nitrooxetanes and epoxides. A manuscript on Michael reactions of nitro compounds with methylenemalonates comprises Appendix A of this report. The products are potentially useful nitrooxetane intermediates.

This report is divided into two parts. The first part describes an attempt to extend earlier work on step-growth photopolymerization leading to polyoxetanes to the synthesis of fluorinated polyoxetanes. This work, which was the primary objective of the research, was unfruitful. A variety of olefin and carbonyl containing monomers were prepared but all polymerization attempts failed. The second part of the report describes work undertaken in response to the difficulties encountered with the initial project, several topics involving the use of aromatic carbonyl compounds as components of potential step-growth photoreductive photopolymerizations were investigated. Some work was carried out on photoreductive polymerization leading to polypinacols, and the possibility of extending this approach to the synthesis of polymers with pentaphenylglycerol or tetraphenylethanol repeat units was also examined. This work led to the synthesis of some novel polymers and provided information on the limitations of some photochemical reactions.

Contents: Nitrosilicone Chemistry; Chemistry of 2-Fluoro-2-nitropropanediol; Experimental -- Bis(2-fluoro-2,2-dinitropropyl)silanediols; Reaction of bis(2-fluoro-2, 2-dinitropropyl) silanediol with chlorotrimethylsilane, Bis(3-3-fluoro-3,3-dinitropropyl)polysiloxane, Reaction of Bis(N-pyrrolidino-N'-Phenylureido)dimethylsilane with Bis-2-fluoro-2,2-dinitropropyl)silanediol, 2-Fluoro-2-nitro-1,3-propanediol, 2-Fluoro-3-hydroxy-2-nitro-1-propyl p-Toluenesulfonate, 2-Fluoro-2-nitro-1,3-propylene Di-p-toluenesulfonate, 2,6-Difluoro-7-hydroxy-2,6-dinitro-4-oxa-1-heptyl p-Toluenesulfonate, 3-Azide-2-fluoro-2-nitro-1-propanol, 3-Bromo-2-fluoro-2-nitro-1-propanol, 1,3-Diazido-2-fluoro-2-nitropropane, 2-Fluoro-3-hydroxy-2-nitro-1-propyl Triflate, 2-Fluoro-2-nitro-1,3-propylene Ditriflate, 3-Fluoro-3-nitrooxetane, Reaction of 2-Fluoro-3-hydroxy-2-nitro-1-propyl Triflate with Pyridine, 3-Chloro-2-fluoro-2-nitro-1-propanol, Reaction of 2,2-Dinitro-1,3-propanediol with Triflic Anhydride; References; Appendices -- Synthesis of Organosilanes and Polysiloxanes with Nitro and Fluoro Substituents, Synthesis of Bis(3,3-dinitrobutyl)cyclopolysiloxanes; and Distribution List.

The chemical mechanism for formation of electronically excited state molecules from the thermal reaction of dimethyldioxetanone was probed. Light production in the presence of certain easily oxidized aromatic hydrocarbons was found not to conform to the classical mechanistic schemes for chemiexcitation. Detailed investigation of the dioxetanone system revealed light formation by the recently discovered chemically initiated electron exchange process. This result is extrapolated to bioluminescent systems. In particular, the key high energy molecule involved in firefly luminescence, which has been identified as a dioxetanone, is postulated to form excited states as a result of intramolecular electron transfer from the phenoxythiazole moiety to the dioxetanone. Subsequent rapid decarboxylation results in direct formation of an excited singlet state of the emitting amide. (Author)

Contents: Kinetics of Dioxetane Thermolysis; Efficiency of Excited State Carbonyl Production; Energy Distribution Between Dissimilar Carbonyls Produced from Dioxetanes; Kinetics of Thermolysis of 1,2-Dioxolanes; Photolysis of alpha-Hydroperoxy Ketones; Peroxide Fragmentation Reactions.

Tetramethyldioxetane was excited with a single 10 psec pulse at 264 nm. The resulting acetone fluorescence was observed and the rise time was found to be less than 10 psec. A mechanism accounting for this and previous experimental evidence is proposed. (Author)

The goal of this research is to provide a theoretical and experimental basis for the understanding of the properties of excited molecules and their emission characteristics. A particular emphasis has been directed toward the identification of chemiluminescent systems which might have the highest likelihood of providing a framework for the development of operating chemical lasers which emit in the visible spectral range. The thermal chemistry and photochemistry of dioxetanes and of valence isomers of benzene have been investigated. The chemistry of singlet oxygen is being explored to develop simple and convenient means of producing this species. An important development has been the discovery that the catalytic thermal generation of singlet oxygen from ground state (triplet) oxygen may be feasible. The possibility of using singlet oxygen in developing chemical lasers is also being explored. Finally, the mechanisms of electronic energy transfer and oxidation in polymers is being investigated with the goal of providing a fundamental understanding of these processes that will allow the systematic and rational development of strategies for stabilization of polymer systems.

Prerequisite to the logical design of efficient chemiluminescent systems is the detailed knowledge of the fundamental excitation steps in known chemiluminescent processes. The study of the unimolecular thermal decomposition of 1,2-dioxetanes, subsequent to the isolation and characterization of the first dioxetane in 1969, has provided considerable insight into the chemistry of this ring system. Primary emphasis in the study of the excitation process in 1,2-dioxetanes has been given to the determination of those factors (energetic, geometric, Franck-Condon) which control the total excited state yield and the ratio of triplet to singlet excited state products. Any postulated excitation mechanism must account for the relatively high activation energies, the efficient production of eta pi excited state carbonyl containing products, and the high triplet to singlet excited state ratios observed for nearly all alkyl or phenyl substituted 1,2-dioxetane thermal decompositions.

The thermal unimolecular reaction of the 1-2-dioxetane ring system to generate electronically excited state carbonyl containing compounds is by far the most carefully and extensively studied of all chemiluminescent reactions. The mechanism for this intriguing transformation has been hotly debated by proponents of stepwise and concerted decomposition paths. The ammunition in this controversy ranges from purely theoretical calculations to experimental substituent, solvent, and isotope effects. Of pivotal importance to the dissection of the reaction path have been studies of kinetics and of excited state yields for variously substituted dioxetanes.

The chemistry of the 1.2-dioxetane ring system that has been reported during the past three years is reviewed. Special emphasis is placed on those aspects that deal with the thermal generation of electronically excited states and chemiluminescence. (Author)

The photolysis of tetramethyldioxetane at 264 nm was probed using picosecond spectroscopic techniques. Singlet exited acetone was one of the observed products. The rise time for acetone fluorescence was determined to be less than 10 psec. A mechanism consistent with these results is proposed. (Author)

Trans-Diphenyl-1,2-dioxetane was prepared by cyclization of the corresponding beta-bromohydroperoxide. Thermal decomposition of this compound proceeds with an activation energy of 23 + or - 1.6 kcal/mol to yield benzaldehyde 10 + or - 2% of which was in an excited triplet state. The effects of replacement of a dioxetane ring proton with a deuterium were investigated. No detectable partitioning between electronically excited protio and deutero benzaldehyde was detected. The secondary deuterium isotope effect on the rate of thermal decomposition of this dioxetane was found to be 1.01 + or - .02. That the absence of an isotope effect is consistent only with a stepwise decomposition for 1,2-dioxetanes is suggested. (Author)

In search for molecular structures that contain higher energies than normal jet fuel liquids, nine compounds were measured by combustion calorimetry to obtain their enthalpies of combustion in the liquid state at 25C. These results show 6.0 to 24.4 percent higher heats per unit volume than a better-than-average hydrocarbon jet fuel. New measurements on the vapor heat capacity, enthalpy of vaporization, and vapor pressure of 1,3-epoxypropane (trimethylene oxide) complete a comprehensive experimental thermodynamic investigation of a small ring molecule that has high ring strain energy.

A process for preparing 3-hydroxyoxetane comprising the following steps is disclosed: (1) reacting a carboxylic acid of the formula CH3(CH2)nCOOH with epichlorohydrin in the presence of anhydrous ferric chloride to produce an ester; (2) protecting the secondary hydroxy group of the ester with a blocking group, z, that is stable oto bases; thus forming a blocked ester; (3) hydrolyzing the blocked ester formed in step (2) with an aqueous base to remove the carboxylic acid and form a 3-hydroxyoxetane derivative; (4) removing the blocking group from the 3-hydroxyoxetane derivative by heating it with an alcohol and an acid to form the product 3-hydroxyoxetane., Supersedes PAT-APPL-378 167-82, AD-D009 716.

Azidooxetane is prepared by reacting 3-oxetyl p-toluenesulfonate with an alkali metal azide in a polar solvent. In the presence of a Lewis acid catalyst, 3-azidooxetane polymerizes to form a poly(3-azidotrimethylene ether) which can be cured with diisocyanates to form energetic, rubbery polyurethanes., Supersedes PAT-APPL-388 049-82, AD-D009 718.

The present invention provides a method for synthesizing a novel oxether-1 monomer by a two step reaction scheme which involves effecting a reaction between 3-methyl-3-hydroxymethyl oxetane and 1,1,1-trinitroethane to form an intermediate reaction product which in turn is reacted with methyl iodide to produce the oxether-1 monomer. The monomer is easily polymerized using conventional polymerization techniques to produce a poly(oxether-1) polyol useful as a binder component in smokeless propellants and explosives., Supersedes PAT-APPL-400 179-82, AD-D009 771.

The object of this invention is to provide an improved method of producing 3,3-bis (azidomethyl) oxetane. Another object of this invention is to provide a safer method of producing 3,3-bis (azidomethyl) oxetane. A further object of this invention is to provide a more economical method of producing 3,3-bis (azidomethyl) oxetane.

This invention relates to the preparation of 3-fluoro-3-nitrooxetane and the use of this compound as a precursor for nitro containing polyethers. Nitro containing polyethers have a potential utility as explosives and propellant binders and a potential route to such materials is polymerization of oxetanes. The present invention comprises reacting 2-fluoro-2-nitropropanediol with trifluoromethane sulfonic (triflic) anhydride to give the monotriflate. The latter reacts with a base to give the desired oxetane.

A novel process is described for preparing 2-fluoro-2-nitro-3-propanediol by reacting diethyl fluronitromalonate with formaldhyde in the presence of an alkali metal hydroxide.

This paper discusses: Program Enhancements and New Program Developments on the CRAY Supercomputer; MRD-CI Calculations for Cationic Polymerization of Energetic Oxetanes; Ab-Initio MRD-CI Calculations for Breaking a Chemical Bond in a Molecule in a Crystal; or Other Solid Environment POLY-CRYST; This past year we have made a significant breakthrough. We developed and implemented and used successfully the strategy for ab-initio MRD-CI(multireference double excitation - configuration interaction) calculations for breaking a chemical bond in a molecule in a crystal or other solid environment. Keywords: Cationic polymerization; Energetic polymers; Oxetanes; Quantum chemical calculations; Configuration interaction (CI); Multi-Reference double excitation - Configuration interaction.

The thermal decomposition of tetramethyl-1,2-dioxetane (TMD) sorbed into zeolite Y containing Europium ions and bipyridine (samples abbreviated as ZYEBT) has been investigated. Decomposition of TMD yields, by energy transfer processes, chemiluminescence (CL) characteristic of the Eu3+ ion. At loading levels corresponding to an upper limit average of 0.5, 1.0, and 2.0 TMD molecules per unit cell, the CL decay curves are nonexponential at short times; at longer times, roughly exponential curves are characterized by a unimolecular rate constant k. Analyses of the long-time decays based on an Arrhenius expression for the rate constant provide evidence for a kinetic compensation effect: pilots of log k vs. the activation energy as a function of TMD loading level are linear. Solution data (benzene, benzonitrile) fall on the same line, suggesting that TMD decomposes by a common rate-limiting mechanism in these various environments. The Arrhenius parameters (Ea and the pre-exponential factor A) are smaller than that solution values and increase with TMD loading. When TMD is sorbed to the extent of an upper-limit average of approximately 7 molecules per unit cell, CL decay curves are initially nearly flat and then show an increase in decomposition rate with time. Mechanistic implications of these results are discussed.

Accurate and absolute molecular weights for new propellant binders are determined with difficulty by conventional gel permeation chromatography (GPC) which relies upon known calibration standards.

The present study involves crystalline block copolymers based on poly(3,3-bis(ethoxymethyl)oxetane, polyBEMO, and random copolymers based on other either forming monomers. The objective of the work is to generate a block copolymer consisting of crystallizable polyether end blocks based on poly(BEMO) and an amorphous rubbery center block based on the polyether random copolymers. This paper will examine the interrelationships among glass and melting transition behavior, viscoelastic characteristics, tensile properties, and morphological features of these new block copolymers. The properties of the block copolymers will be compared with those of the homopolymer poly(BEMO)., Prepared in cooperation with East Stroudsburg Univ., PA and Thiokol Chemical Corp., Brigham City, UT. Wasatch Div.

A new route to the synthesis of nitrooxetanes was explored. The final ring-closure step to yield 3-methyl-3-nitrooxetane has not yet been carried out successfully. Precursors to the synthesis of 3,3-dinitro-oxetane have been prepared. 3-Azidomethyl-3-methyloxetane has been prepared by a new synthetic route that should be useful in the event of a scale-up. Polymers derived from 3-(2,3-diazidopropoxymethyl)-3-methyl oxetane and 2-azidomethyl-3-(2,3-diazidopropoxy-methyl)-3-methyl oxetane and 3-azidomethyl-3-(2,3-diazidopropoxymethyl)oxetane have been prepared and appear to have good low temperature and stability properties. (Author)

This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and electrostatic molecular potential contour maps for cationic polymerization; Prediction of crystal density; Ab-initio calculations on polynitropolyhedranes and polynitropolyazapolyhedranes; Ab-initio configuration interaction calculations on the CH3-N02 decomposition pathway of nitromethane; Ab-initio configuration interaction calculations on RDX; and Conversion of our programs to vector supercomputers, CYBER 205 and CRAY.

Effusion mass spectrometeric investigation of BAMO, AMMO, AZOX and GAP yielded primary decomposition of N2 release at approximately 120 C and Ea values of 170 - 180 kJ (mol-1) (43-43 kcal (mol-1)). The 50-50% copolymer of BAMO-BNMO decomposes initially through the nitrato constituent at approximately 100 C followed by the azide decomposition. The thermal degradation mechanism for BEMO appears to be a stepwise breaking of the ethoxy-methyl bonds followed by the stripping of the methylene groups. BFMO is stable to temperatures greater than 200 C with initial decomposition products of HF, with considerable depolymerization occurring. The major decomposition product of the NSWC novel nitramine, C6H8N8012, is the eight-membered nitramine ring less two N02 molecules, molecular weight 292. The decomposition product is stable in the gas phase at 300 C.

Strained small ring systems were investigated as possible group constituents in synthetic high energy fuels. Determination of the thermodynamic properties of trimethylene oxide (oxetane) in the ideal gas state from 0 to 1000 K by statistical mechanical methods is a continuation of comprehensive experimental calorimetric investigations reported previously. Thermodynamic properties of methylenecyclobutane including experimental measurements of its low-temperature thermal properties, enthalpies of combustion and formation, and vapor pressures were determined for solid, liquid, and gaseous states. (Author)

The ring puckering vibration has been observed in the Raman spectrum of the vapour phase of trimethylene oxide. The pure ring puckering transitions, combination band progressions with a C--H stretching vibration and hot band structre of a Raman active C--H fundamental are reported. (Author)

Strained small ring systems were investigated as possible group constituents in synthetic high energy fuels. Thermodynamic properties of cyclopropylamine and oxetane were determined from a comprehensive investigation of the heat capacities and heats of transition in condensed phases, the enthalpies of formation, and vapor pressure relations. Gibbs energies and equilibrium constant of formation were calculated for the gas phase at 298.15K. A comparison of the effects on enthalpy of formation of alkyl-substituted, aliphatic ring systems was made for cyclopropanes, cyclopentanes, and cyclohexanes. The enthalpy of combustion and formation was reported for six alkyl-substituted cyclopropanes. Vapor pressures and the enthalpy of vaporization were determined for 1,2-diaminoethane. (Author)

A NiCl2(PEt3)2-catalyzed regioselective C−H coupling of 8-aminoquinoline-derived benzamides with oxetanes has been developed. The reaction proceeds with concomitant removal of the 8-aminoquinoline auxiliary to directly form the corresponding seven-membered benzolactones, which frequently occur in natural products and bioactive molecules. Additionally, no stereochemical erosion is observed during the course of the reaction, and the use of enantioenriched and substituted oxetane thus provides a new avenue to the optically active benzolactone., This is the accepted version of the following article: Xu S., Takamatsu K., Hirano K., et al. Synthesis of Seven-Membered Benzolactones by Nickel-Catalyzed C−H Coupling of Benzamides with Oxetanes. Chemistry - A European Journal 25, 9400 (2019), which has been published in final form at https://doi.org/10.1002/chem.201900543. This article may be used for non-commercialpurposes in accordance with the Wiley Self-ArchivingPolicy [https://authorservices.wiley.com/author-resources/Journal-Authors/licensing/self-archiving.html]

This is the accepted version of the following article: Xu S., Takamatsu K., Hirano K., et al. Synthesis of Seven-Membered Benzolactones by Nickel-Catalyzed C−H Coupling of Benzamides with Oxetanes. Chemistry - A European Journal 25, 9400 (2019), which has been published in final form at https://doi.org/10.1002/chem.201900543. This article may be used for non-commercialpurposes in accordance with the Wiley Self-ArchivingPolicy [https://authorservices.wiley.com/author-resources/Journal-Authors/licensing/self-archiving.html], A NiCl2(PEt3)2-catalyzed regioselective C−H coupling of 8-aminoquinoline-derived benzamides with oxetanes has been developed. The reaction proceeds with concomitant removal of the 8-aminoquinoline auxiliary to directly form the corresponding seven-membered benzolactones, which frequently occur in natural products and bioactive molecules. Additionally, no stereochemical erosion is observed during the course of the reaction, and the use of enantioenriched and substituted oxetane thus provides a new avenue to the optically active benzolactone.