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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.

A mild and sustainable synthesis of 2, 2-disubstituted oxetanes has been achieved through the use of a flow microreactor system. By controlling the residence time a highly unstable intermediate such as 2-phenyloxetan-2-yl lithium can be generated and trapped with various electrophiles affording in moderate to good yields 2-substituted-2-phenyloxetanes at higher temperatures with respect to macrobatch-mode where –78 °C is required.

An unprecedented enantioselective oxetane opening with chloride provides access to a range of highly functionalized three-carbon building blocks. The excellent enantiocontrol is enabled not only by a new catalyst, but also by the unusual use of wet molecular sieves for the controlled release of HCl. The enantioselective ring opening of oxetanes with chloride provides access to a range of highly functionalized three-carbon building blocks. The use of a new catalyst in combination with wet molecular sieves for the controlled release of HCl leads to high enantioselectivities. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An unprecedented enantioselective oxetane opening with chloride provides access to a range of highly functionalized three-carbon building blocks. The excellent enantiocontrol is enabled not only by a new catalyst, but also by the unusual use of wet molecular sieves for the controlled release of HCl. The enantioselective ring opening of oxetanes with chloride provides access to a range of highly functionalized three-carbon building blocks. The use of a new catalyst in combination with wet molecular sieves for the controlled release of HCl leads to high enantioselectivities. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An unprecedented enantioselective oxetane opening with chloride provides access to a range of highly functionalized three-carbon building blocks. The excellent enantiocontrol is enabled not only by a new catalyst, but also by the unusual use of wet molecular sieves for the controlled release of HCl. The enantioselective ring opening of oxetanes with chloride provides access to a range of highly functionalized three-carbon building blocks. The use of a new catalyst in combination with wet molecular sieves for the controlled release of HCl leads to high enantioselectivities.

This article presents a series of ring-extended gramicidin S derivatives, 9-14, that have four ornithine residues as polar protonated side chains and one modified turn region containing a mono-functionalized cis-δ-oxetane, δ-furanoid, or δ-pyranoid sugar amino acid residue. Of the GS analogs evaluated, we identified compound 7, which contains the mono-benzyloxy cis-δ-pyranoid sugar amino acid, as having a better biological profile than the clinically applied topical antibiotic gramicidin S. Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich, Switzerland.

The search in the field of four-membered heterocycles, where a non-carbon atom is part of the ring, has been actively pursued in 2009 within Organic Chemistry, Inorganic Chemistry, Medicinal Chemistry, and Material Science. In particular, the synthesis and chemistry of oxygen- and nitrogen-containing heterocycles dominate the field in terms of the number of publications. It should be clearly stated that a comprehensive description of all the aspects of the vast research area of four-membered heterocyclic chemistry can not be fully covered in this book chapter. Instead, the present overview presents a personal selection of the topics which we believe are the more relevant.

One lot of BAMO/GAP/RDX (3,3-bisAZIDOMETHYL oxetane/glycidyl azide polymer/cyclotrimethylenetrinatramine) next-generation gun propellant was tested in uniaxial compression at strain rates of 100(exp s-1) The material was conditioned at temperatures of 21 deg, 50 deg, and -20 deg C. End strain of the tested material was ^60%. The stress at failure, strain at failure, compressive modulus, failure modulus, incremental energy density, and the fracture assessment values were recorded for each test., Original contains color plates: All DTIC reproductions will be in black and white.

The primary objective of this research was to develop thermally stable dioxetanes which could be chemically and enzymatically triggered to provide efficient chemiluminescence in aqueous solution.

Nitrato alkyl oxetanes are synthesized directly from the corresponding hydroxy alkyl oxetanes by nitrating the hydroxy alkyl oxetane under non-acidic anhydrous conditions. A hydroxy alkyl oxetane is reacted with an anhydrous nitrate ester of a carboxylic acid at temperatures below about 10 deg C. The product of the method, nitrato alkyl oxetane, is produced in relatively high yield without opening of the oxetane ring., Supersedes PAT-APPL-377 398-89.

Novel block polymers which are thermoplastic elastomers are provided for use as binders in high-energy compositions such as propellants, explosives, gasifiers or the like. The block polymers have an ABA structure wherein the A blocks are crystalline at temperatures below 60 deg C. and the B blocks are amorphous at temperatures above -20 deg C. Both the A and B blocks are polyethers formed from monomers of oxetanes and/or tetrahydrofuran. The block polymers melt in the range of 60' C. to 120' C. and have low viscosities above their melting points due to mutual miscibility of the A and B blocks., Supersedes PAT-APPL-815 878-92.

New generations of super-energetic materials are required for the SDI mission. Cubane is a very dense, exceptionally energetic hydrocarbon; its heat of formation, density, and strain energy are all extraordinarily high -- in combination unexceeded by any other stable hydrocarbon. This dense, energetic system has 8 identical methine C-H groups at which hydrogen may be replaced by energy-rich substituents. Such substitution can provide smoke-free propellant components of enormous power, far superior to present-day metalized propellants. For example, tetrakis(dinitramino)cubane admixed with 15% BAMO/NMMO should have an I sub sp (into vacuum) 24 seconds greater than HAP with 15% HTPPB. Realizing even a fraction of this would lead to enormous payload enhancements.

Information on the structure and functionality of poly(3- nitratomethyl-3-methyloxetane), polyNIMMO, is presented and the properties of binders cured with the isocyanate Desmodur N-100 are considered. Results from the ageing of crosslinked polyNIMMO are presented and the effects of adding the stabiliser 2-nitrodiphenylamine, (2NDPA), are demonstrated. It is shown that decomposition of the nitrate ester groups of unstabilised polyNIMMO is a major process but the rate of this process is much lower than that observed for nitroglycerin. Decomposition of the nitrate ester groups in polyNIMMO is accompanied by chain scission of the polyether backbone. Two effects were observed as a result of adding 1% of 2NDPA, - the rate of nitrate ester breakdown was significantly reduced and the rate of polymer chain scission was greatly retarded. Results indicate that chain scission only becomes significant when the stabiliser has been consumed. Current results show that the stabilised binder still retains its network structure after one year at 60 C.

Partial contents: Combustion of solid fuels under crossflow conditions; Carbon dioxide laser pyrolysis and ignition; Nonintrusive FT-IR diagnostics for species and temperature measurements of products from solid propellants; and Steady-state combustion behavior of MG/PTFE/VITON and boron- based solid fuels; Appendices include papers on: Ignition and combustion of solid fuels under high-velocity crossflows; Combustion characteristics and CO2 laser ignition behavior of boron/magnesium/PTFE pyrotechnics; Analysis of plumes of solid propellant combustion using an FT-IR spectrometer; and Combustion behavior of boron-based BAMO/NMMO fuel rich solid propellants., Pages missing from original document.

The objectives of this program were to: 1) investigate the synthesis of compounds with furazan, furoxan, and tetrazole rings fused to saturated heterocyclic rings such as piperazine, hexahydropyrimidine, hexahydrotriazine, tetrazocine and the nitramine derivatives of these compounds, and 2) conduct basic research on internal plasticizers (IP) and energetic internal plasticizer (EIPs) so as to develop design criteria for IPs and EIPs for various polymer systems. This should allow combining the advantages of EIP and energetic polymers so as to optimize the energy and mechanical properties of propellant binder systems.

Thermally stable 1,2-dioxetanes bearing tert-butyldimethylsilyloxyaryl groups have been prepared. Reaction of these dioxetanes with fluoride ion at ambient temperature in Methyl cyanate and DMSO generates chemiluminescence with efficiencies up to 25%. Keywords: Chemiluminescence; Oxetanes; High Efficiency; 1,2-Dioxetanes, Fluoride triggering; Photooxygenation.

A. Chemical and Enzymatic Triggering of 1,2-Dioxetanes A series of dioxetanes which are thermally stable at ambient temperature but which can be triggered for efficient chemiluminescence on demand by the addition of the appropriate chemical catalyst or enzyme have been discovered the process involves the removal of a protecting group from a stable form of the dioxetane to generate an unstable aryloxide intermediate which decomposes spontaneously to yield the luminescence. B. Chemiluminescence from Micellar System cationic surfactants such as cetytrimethylammonium bromide (CATB) can be used to significantly enhance rates of chemically triggered luminescence from appropriately substituteddioxetanes in aqueous solution. For example, CATB catalyzes the base-induced cleavage of an acetate-substituted dioxetane. Fluoride-triggering of silyloxy dioxetanes is also accelerated in the micelle. The electrostatic attraction of the cationic head group and the anionic reagent provides the observed micellar catalysis. C. Effects of Heteroatom substitutents on the properties of dioxetanes resulted in the first report of activation parameters and rates of decomposition for unstable nitrogen-and sulfur-substituted dioxetanes. The results provide support for a mechanism for decomposition involving intramolecular electron transfer. D. Hematoporophyrin-Chemiluminescence Cancer Therapy-Photoradiation therapy using a hematoporphyrin derivative (HPD) and visible light has shown considerable promise as an effective treatment for a wide variety of cancers. This procedure is being used clinically in many hospitals on an experimental basis.

The research projects during this period were focused on the oxidation chemistry of singlet molecular oxygen and on the development of efficient chemiluminescent systems. Major accomplishments of our investigations include the following: 1) The first heterogeneous photosensitizer for the photochemical production of singlet oxygen in organic solvents was prepared. This material has since been produced commercially and sold under the tradename SENSITOX. Additional sensitizers have been synthesized for use in aqueous systems. 2) 1-Phospha-2,8,9-trioxaadamantane ozonide was found to decompose at ambient temperature to provide a convenient chemical source of singlet oxygen. 3) A new method for generation of chemiluminescence by the silica-catalyzed rearrangement of thermally stable endoperoxides to 1,2-dioxetanes was discovered in the laboratory. 4) A procedure for obtaining dramatic increases in the chemiluminescence efficiency of dioxetanes by employing silica catalysis was developed. 5) A study of substituent effects on the decomposition of 1,2-dioxetanes provided new insight into the mechanisms of light production by these peroxides. 6) A new technique for triggering the chemiluminescent decomposition of a stable 1,2-dioxetane was investigated., Sponsored in part by Grants DAHC04-75-G-0005 and DAAG29-76-G-0013.

Conversion of Additional Programs to CRAY Vector Supercomputers and Program Enhancements, MRD-CI Calculations for the Propagation Step in Cationic Polymerization of Energetic Oxetanes, NMR Spectra of Oxetanes, Ab-Initio Atom-Class - Class Potential Functions and Independent Confirmations of the Validity of Our Ab-Initio MODPOT/VRDDO Energy Partitioned Method For Intermolecular Interactions, Geometry Optimization at the MC-SCF/CI Level, POLY-CRYST. We developed and implemented a new approach based on localized occupied and virtual orbitals in the interaction region with the remainder of the localized molecular orbitals being folded into an effective CI. Hamiltonian. This method is completely general and applicable to reactions and molecular decompositions of energetic compounds for ground and electronically excited states. We initiated a major research effort on ab-initio MRD-CI calculations on opening the ring of oxetane or protonated oxetane and on the opening of the protonated oxetane ring in the course of interaction with oxetane. We have carried out MRD-CI calculations for a great many geometries for various paths of attack for the system oxetane plus protonated oxetane ring (ring 'A') varied the internuclear distance between the rings and the angle between the plane of the oxetane (ring 'B') and the plane of the protonated oxetane ring. Keywords: Cationic polymerization, Energetic polymers, Oxetanes, Quantum Chemical calculations, Configuration Interaction (CI), Multireference Double Excitation - Configuration Interaction (MRD/CI), Energetic compounds, Ab-initio potential functions, Crystal and polymer orbitals.

Cosensitized electron-transfer photooxygenation has been developed as a new method for the photochemical oxidation of various organic substrates. Compounds which are relatively resistant to standard photooxygenation procedures can be oxidized by a process that utilizes a non-light-absorbing aromatic hydrocarbon (biphenyl, BP) as a catalyst or cosensitizer in conjunction with the cyano-substituted sensitizer, 9.,10-dicyanoanthracene (DCA). Irradiation with visible light (400-500 nm) in the presence of oxygen promotes electron transfer from the cosensitizer to singlet excited DCA with subsequent generation of superoxide ion. Attack by this highly reactive species on the organic substrate or its radical cation effects the oxidation of the material. The photochemical conversion of epoxides, aziridines, and cyclopropanes to 1,2,4-trioxolanes (ozonides), 1,2,4-dioxazolidines, and 1,3-dioxolanes, respectively have been investigated. Insight into the mechanisms of the DCA-sensitized photooxygenation of epoxides and aziridines was obtained through a study of the stereochemistry of the reactions. The exclusive formation of the cios ozonide and cis 1,2,4-dioxazolidine from 2,3-diphenyloxirane and 2,3-diphenylaziridine has suggested a mechanism involving the addition of singlet oxygen as a dipolarophile to intermediate carbonyl and azomethine slides. DCA-BP cosensitized photooxygenation has also been utilized to provide a new approach to the synthesis of chemiluminescent 1,2-dioxetanes.

Contents of this report include: Conversion of Our Programs to CRAY Vector Supercomputers; Calculations for Cationic Polymerization of Energetic Monomers; MRD-CI Calculations on Decomposition Pathways of Energetic Nitrocompounds; POLY-CRYST; Ab-Initio Atom Class - Atom Class Potential Functions and Prediction of Crystal Densities. In anticipation of significant access to the NRL CRAY XMP-12 supercomputer we devoted major attention this past year to converting our programs to that computer, which runs under a COS operating systems. As a preliminary to carrying out MRD-CI calculations on the attack of oxetane on protonated oxetane in the propagation step of cationic polymerization, we initiated MRD-CI calculations on opening the oxetane ring and the protonated oxetane ring. We carried out MRD-CI calculations for the dissociation of the C-NO2 bond in nitrobenzene. We continued testing of our POLY-CRYST program for ab-initio calculations in crystals and polymers. We also implemented further additions to the INTER-MOLASYS program including the capability of calculating the dispersion energy contributions by a variation-perturbation procedure. We have also calculated further ab-initio atom class-atom class potential functions. Keywords: Quantum chemical electrostatic molecular potential maps; Nitroexplosives; Configuration interaction; Oxetanes; Localized orbitals; Multiconfiguration SCF; Crystal and polymer orbitals; Cyclic ethers.

Chemistry of compounds containing silicon-silicon double bonds was investigate. Two new disilenes were synthesized and rotational barriers to cis-trans interconversion were determined to be 25-31 Kcal/mol. Oxidation of disilenes led to the 1,3-cyclodisiloxanes, as well as to disilene epoxide and 1,2-dioxetanes, all novel structures. Many new polysilane high polymers were synthesized, and their photoactivity was investigated. Several new methods for crosslinking of polysilanes were developed, and the first polysilanes containing functional side groups were prepared. Several cyclosilane families of compounds were also investigated.

Modern rocket propellants, gun propellants, and explosives are an adaptation of the basic concept of a formulation consisting of a solid oxidizer and fuel held in a polymeric matrix. In 1978, we embarked on a research effort to synthesize energetic polymeric binders specifically designed for propellant applications. A modified cationic polymerization technique was developed, which allowed the synthesis of polymers to predetermined molecular weight and functionality, and the concept of energetic polyoxetanes was presented. Further work has now resulted in nitrate ester, nitramine polymers, copolymers, and recently nitro, cubane and carborane polymers. The latter is the subject of this paper. Boron or boron compounds have been used as a burning rate modifier and as a metal fuel source in solid propellant motors. Migration of these chemicals in the propellant grain is a continuous and serious problem. We proposed that a urethane curable polyether glycol with a carboranyl functionality would solve migration problems. Oxetane-carboranes would be good candidates as monomers for these carboranyl pendant polymers. These monomers could be homopolymerized or co-polymerized with other oxetanes for specific properties. This paper describes the synthesis, characterization, and polymerization of oxetane-carborane monomers.

The major thrust of this program was to make and characterize hydrophilic hydroxy polyethers which are interesting analogues of the important naturally occurring polysaccharides. The work, as described below, centered largely around the synthesis, properties and mechanism aspects of poly(3,3-bis(hydroxymethyl)oxetane), (PBHMO) and poly(3-hydroxyoxetane) (PHO). Two U.S. patents were filed and two publications were prepared. Keywords: Chemical analogs, Bicycle orthoesters, Tetrahydrofuran, Hydroxypolyethers, Polyoxetanes, Cellulose analogs.

Two crystalline melting peaks have been observed by differential scanning calorimetry for low molecular weight poly(3,3-bis- (ethoxymethyl) oxetane), polyBEMO, whereas only one melting peak has been observed for samples of higher molecular weight. Crystallization of low mol. wt. samples at large supercoolings produces the lower melting form, while low supercooling or annealing favors the higher melting species. Enthalpy of fusion values obtained by DSC for a multiple melting endotherm sample range from 28 to 39 j/g for crystallization temperatures from 58 to 35 C, respectively. Optical microscopy studies indicate that the lower melting peak corresponds to a spherulitic type of morphology and the higher melting peak correlates to a fine grained crystal structure. Wide angle x-ray powder diffraction studies do not detect differences in the crystal structures.

Large scale synthesis of the cubane oxetane monomer, CUBOX, was developed during the last reporting period. The key intermediate from commercially available cubane dicarboxylic acid is cubane monocarboxylic acid. Several routes to its synthesis were outlined in the Fifth Quarterly Summary. The original method supplied by Dr. Eaton was abandoned when scale-up gave poor yields. In this method, the n-hydroxypyridine-2-thion ester undergoes free radical decarboxylation in ter-butylmercaptan. Also the odor (natural gas) of ter-butylmercaptan could not be contained and this was a concern in our laboratory. Energetic binders.

This report pertains to: 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, AB-Initio Multireference Coupled Cluster and Multireference CI Calculations for Protonation NH3 / Deprotonation NH4(+); MR-CC (Multireference-Coupled Cluster) - A state-of-the- theoretical-art multireference coupled cluster (for both closed and opened shell systems) was rewritten, vectorized and adapted for the CRAY XMP supercomputer. Our major emphasis this past year has been to carry out in-depth detailed ab- initio MRD-CI (multireference double excitation - configuration interaction) calculations on the propagation step of cationic polymerization of oxetane (or an energetic substituted oxetane) reacting with protonated oxetane (or a protonated energetic substituted oxetane). A. Nitromethane H3C - NO2 - We have carried out extensive further MRD-CI calculations on breaking the H3C - NO2 bond in nitromethane in a nitromethane crystal in the presence of voids.

This report summarizes our work at the Naval Weapons Center developing improved polymeric binders for energetic materials during Fiscal Year 1987., Prepared in cooperation with Aerojet Solid Propulsion Co., Sacramento, CA. Sponsored in part by the Strategic Defense Initiative Office/IST.

A program on the synthesis and characterization of energetic azido prepolymers, based on BAMO, for potential use in advanced solid propellants, gun propellants, and explosives was successfully carried out. Homopolymerization of BAMO gave polymers with molecular weights ranging from 1800 to 3000 and functionalities of two or greater. However, all of the polymers were solids, with a melting point of 75 to 78 C; the melting points were not affected by changing the molecular weight. A melting point, however, as low as -5 C was achieved for a 50/50 mol % BAMO/THF copolymer. Emphasis on the program was therefore concentrated on optimizing the preparation of this copolymer so that it would be suitable for scaleup.

Thermal decomposition kinetics, including an elucidation of the mechanisms, were determined for several energetic polymeric materials. These materials included poly(3-nitratomethyl-3-methyl) oxetane (p-NMMO), the copolymer, methyl nitramino methyl methy oxetane/azido methyl methyl oxetane (50/50 MNAMMO/AMMO), and the monomer 3,3 bis(methyl nitramino methyl) oxetane (BMNAMO). Experiments were performed on both stabilized and unstabilized dehydrofefo (DHF) to determine its decomposition and evaporation at 132 F. Keywords: Activation energies.

Structural characterization of 16 energetic materials and precursors was performed by x-ray diffraction. The trinitro and tetranitro tetraazabicyclo (3.3.0) octanes examined, compounds D and E, are significantly more dense than had been predicted. The crystal structure analysis showed that the increase in density is due to intramolecular crowding rather than extraordinary packing efficiencies which were at normal values of 0.73 and 0.75 respectively. Keywords: Tetraazabicyclooctanes, Oxetane, Nitramines, Nitro-adamantane, Nitro radicals, Benzyl radicals, Tetrazoles, Cyclic compounds.

The combination of laser excitation of overtone vibrations with time resolved spectroscopic detection of reaction products provides uniquely detailed data on the rates and disposal of energy into products in unimolecular decompositions. The decomposition of a cyclic peroxide, tetramethyldioxetane, is the first example of a vibrational overtone initiated reaction studied in a free jet expansion, where the thermal energy content of the reacting molecules is small. Low pressure gas phase data on hydrogen peroxide reveal the partitioning of the excess energy of the reaction in the OH products and provide new data on the vibrational overtone spectroscopy of this molecule. A new molecular beam apparatus has been constructed for extending these studies to a wider range of molecules using additional detection techniques.

Most of the research deals with the effect of electronic structural variation upon the efficiency of triplet state carbonyl production from dioxetanes. Other studies involving dioxethanes include the question of preferential n, pi* state (vs pi, pi*) carbonyl formation and attempts to trap the proposed 1,4-dioxybiradical intermediate form thermolysis of dioxetanes. Some amino peroxides were also studied as potential sources of chemilumuniscence (CL). Finally, a detailed kinetic study was made on the thermolysis of a five-membered ring peroxide in order to distinguish between concerted vs stepwise decomposition routes. This study was pertinent to the mechanism of dioxetane (a four-ring peroxide) thermolysis.

Two crystal modifications have been found for poly (3,3-bis(ethoxymethyl) oxetane), poly(BEMO), by wide-angle x-ray powder diffraction and differential scanning calorimetry while only one modification has been found for poly(3,3-bis(azido methyl) oxetane), poly(BAMO). Melting temperatures for the two polymers were nearly the same, varying from about 70 deg C to about 90 deg C depending on the thermal treatment; higher crystallization temperatures resulted in higher melting temperatures. The equilibrium melting temperature, T sub m, was found to be 125 deg C and 128 deg C for poly(BEMO) and poly(BAMO), respectively, using the Hoffman-Weeks extrapolation procedure. Measurement of the melting point depression of poly(BEMO) and poly(BAMO) in di-butyl phthalate yielded enthalpy of fusion values of 2.25 kcal/mole and 12.8 kcal/mole, respectively. The percent crystallinity for poly(BEMO) and poly(BAMO), respectively was calculated to be 55-60% and 13-30% based on DSC and x-ray analysis.

Nitrogen and sulfur-substituted dioxetanes exhibit dramatically lower activation energies for decomposition compared to the corresponding oxygen-bearing dioxetane. A mechanism involving intramolecular electron-transfer processes is proposed for the cleavage of these unstable dioxetanes. (Author)

Studies of the synthesis and polymerization of energetic oxetanes were continued. The polymerization of 3-azidooxetane, catalyzed by boron trifluoride etherate gave diols with molecular weights of 3,000 to 3,600. A gumstock was prepared with TDI. An efficient reagent for reducing 3-azidooxetane was found to be triphenylphosphine, providing a high yield of 3-aminooxetane. The reaction of 3-nitrooxetane with tetranitromethane provided an improved yield of 3,3-dinitrooxetane. The polymerization of 3,3-dinitrooxetane with phosphorus pentafluoride gave a polymer with a melting point of 200 deg C. Copolymers of 3,3-dinitrooxetane with 3-fluoro-3-nitrooxetane were obtained with melting points as low as 137 deg C. Process development studies of 30-azidooxetane were carried out. The addition of acetic acid to epichlorohydrin was simplified by minimizing the amounts of acetic acid and ferric chloride catalyst and eliminating the use of solvent. The adduct, without work-up was treated with ethyl vinyl ether. Treatment of the product with aqueous base, followed by removal of the acetal protecting group with methanol gave 3-hydroxyoxetane. P-Toluenesulfonyl chloride and aqueous base gave oxetyl tosylate in 23% overall yield from epichlorohydrin. A safe procedure for reacting the tosylate with sodium azide was developed using polyethylene glycol as the reaction solvent and methylene chloride as the trapping solvent.

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)