Quest for green energetic materials, green rocket fuels and polyiodo biocides Thesis uri icon



  • Thesis (Ph.D., Chemistry) -- University of Idaho, 2016 | The design of more powerful and greener explosives is an ongoing major concern in the energetic materials community. After examining azoles from pyrazole to pentazole as a basis for new energetic materials, the tetrazole ring seems to be a good compromise between high performance and low sensitivity. Keeping this in mind, we synthesized a family of new nitrogen-rich energetic tetrazoles, di(1H-tetrazol-5-yl)methanoneoxime and 5,5’-(hydrazonomethylene)bis(1H-tetrazole), in very good yields from inexpensive starting materials. By taking advantage of the acidity of these compounds, syntheses of nitrogen-rich energetic salts was possible. Hypergolic ionic liquids tend to have low volatilities and high thermal and chemical stabilities, and often exhibit wide liquid ranges which could allow the use of these substances as bipropellant fuels under a variety of conditions. Borohydride ionic liquids are known for their short ignition delay times and wide liquid ranges; however, previously they were often synthesized by using toxic and expensive liquid ammonia and additionally, they are also sensitive to moisture. Now, we synthesized eight tetrahydroborate compounds using an efficient synthetic method which does not require liquid ammonia and which leads to improved hydrolytic stability of the borohydride compounds by an imaginative construction of the imidazolium cation. Current methods for the iodination of pyrazoles suffer from a variety of difficulties such as requiring use of large quantities of reactants yielding mixtures of compounds in low yields. Because of the lack of good synthetic routes, the chemistry and properties of polyiodopyrazoles have not been studied widely. Now we report an efficient synthetic route to polyiodopyrazoles employing trifluoroperacetic acid. A variety of polyiodo compounds including 3,4,5-triiodopyrazole was synthesized in good yields. The decomposition products of these materials were determined by employing Cheetah 6 calculations. Trifluoroperacetic acid-mediated electrophillic iodination was also utilized with benzimidazoles. The new polyiodo benzimidazoles proved to be very good starting materials in the preparation of novel energetic materials. Among the two triazole isomers, i.e., 1,2,3-triazole and 1,2,4-triazole, the former has favorable energy content for construction of energetic molecules. Therefore, we explored mono and diiodo 1,2,3-triazoles for their biocidal promise.

publication date

  • June 1, 2016