Thermal and Sensitiveness Determination of Cubanes: Towards Cubane‐Based Fuels for Infrared Countermeasures

Abstract

As infrared seeking technology evolves, threats are better able to distinguish defensive infrared (IR) flares from true targets. Spectrally matched flares, which generally employc arbon-based fuels, are bettera ble to decoy some advanced missiles by more closely mimickingt he IR emission of the target. Cubanei sahigh-energyc arbon-based scaffold whichm ay be suitablef or use as af uel in spectrally matched flares.T he enthalpy of formation and strain energy of as eries of cubanes was predicted in silico, and their ther-mal and impact stability examined. All weref ound to undergo highly exothermicd ecomposition in sealed cell differential scanning calorimetry,a nd two cubanes subsequently underwentq uantitative sensitiveness testing. Despite their F of I values beingi nt he secondarye xplosive range, cubane-1,4dicarboxylic acid (F of I = 70) and 4-carbamoylcubane-1-carboxylic acid (F of I = 90) werei dentifieda sp otentially useful fuels for pyrotechnic infrared countermeasure flare formulations.Supporting information containing full synthetic, computational, and sensitivenesst esting detailsa swell as the ORCID identification number(s)for the author(s) of this articlecan be found under: https://doi.

2-Oxabicyclo[2.2.2]octane as a new bioisostere of the phenyl ring

“…In 2012, however, Stepan and colleagues showed that a replacement of the central phenyl ring in a γ-secretase inhibitor with the bicyclo[1.1.1]pentane improved its physicochemical properties and retained bioactivity 8 – 11 . Later, analogous replacements were undertaken with cubane 12 – 19 , and bicyclo[2.2.2]octane (Fig. 1a, b ) 20 – 22 .…”

ortho-C–H Acetoxylation of Cubane Enabling Access to Cubane Analogues of Pharmaceutically Relevant Scaffolds

“…2 Recently, a kilogram-scale preparation of a derivative of cubane 3 was developed, and many chemists are attempting to utilize cubane as a functional motif for applications in various scientific fields. 4,5 Recently, the application of cubane in the field of medicinal chemistry was investigated. 6 Cubane is known as a bioisostere of the benzene ring as its body diagonal length is similar to that of benzene (Scheme 1b).…”

Cubane, Bicyclo[1.1.1]pentane and Bicyclo[2.2.2]octane: Impact and Thermal Sensitiveness of Carboxyl‐, Hydroxymethyl‐ and Iodo‐substituents

“…Certain functional groups are well known to substantially activate cubane derivatives. For example, 1,4-cubane-dicarboxylic acid (1 c, Figure 2) and 4-carbamoylcubane-1-carboxylic acid (4), [13] were recently disclosed by the authors to be thermally and impact sensitive. 1,4-Diisocyanocubane (5) [14] and azidocubanes (e.g., 6) [15] are observed to be highly thermally unstable and exceedingly shock sensitive.…”

“…Certain functional groups are well known to substantially activate cubane derivatives. For example, 1,4-cubane-dicarboxylic acid (1c,F igure 2) and 4-carbamoylcubane-1-carboxylic acid (4), [13] were recently disclosedb yt he authors to be thermally and impact sensitive.1 ,4-Diisocyanocubane (5) [14] and azidocubanes( e.g., 6) [15] are observedt ob ehighly thermally unstable and exceedingly shock sensitive. 4-[(Nitrooxy)methyl]cubane-1carboxylic acid (7), dimethyl cubane-1,4-dicarboxylate (1a), and cubane-1,4-dicarboxylic acid (1c)h ave also been reported to exhibit sensitiveness to impact, [16] whereas octanitro-(8)a nd heptanitrocubane (9)a re described as insensitive to hammer taps.…”

“…It should be noted, however,t hat many factorsa ffect impact sensitivity (e.g.,p articles ize), and that resultsc an vary from batch to batch. Diacid 1c,f or example, was quantitatively determined to have an impact sensitiveness similar to as econdary explosive, [13] but did not alwaysdisplay ag oe vent in our hands, that is, dependingo nt he batch, impurities, and the experimenter.…”