Bis-isoxazole tetranitrate (BITN): a high-energy propellant plasticizer and melt-castable eutectic explosive ingredient
09994532 ยท 2018-06-12
Assignee
Inventors
- Jesse J. Sabatini (Bel Air, MD, US)
- Gregory W Drake (Madison, AL, US)
- Leah A. Wingard (Landenberg, PA, US)
Cpc classification
C06B25/00
CHEMISTRY; METALLURGY
C06B45/105
CHEMISTRY; METALLURGY
International classification
Abstract
A method and compound includes mixing a salt compound to 2-butyne-1,4-diol in an alcohol to create a mixture; adding a solution of dichloroglyoxime in an alcohol to the mixture to create 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol; and nitrating the 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol to create 3,3-bis-isoxazole-4,4,5,5-tetrylbis(methylene) tetranitrate, which has the structural formula: ##STR00001##
The alcohol may include ethanol, wherein the adding may occur at 60 C., or alternatively the adding may occur at 80 C. The alcohol may include n-butanol, wherein the adding may occur at 100 C., or alternatively the adding may occur at 120 C. The mixing may occur at 120 C. The method may further include cooling the nitrated 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol to 0 C.; stirring the cooled nitrated 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol for at least four hours creating a precipitate; warming the precipitate; pouring the precipitate onto ice while stirring creating a solid material; collecting the solid material; and drying the solid material to yield the 3,3-bis-isoxazole-4,4,5,5-tetrylbis(methylene) tetranitrate.
Claims
1. A method comprising: mixing a salt compound to 2-butyne-1,4-diol in an alcohol to create a mixture; adding a solution of dichloroglyoxime in an alcohol to said mixture to create 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol; and nitrating said 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol to create 3,3-bis-isoxazole-4,4,5,5-tetrylbis(methylene) tetranitrate.
2. The method of claim 1, wherein said alcohol comprises ethanol.
3. The method of claim 2, wherein the adding occurs at 60 C.
4. The method of claim 2, wherein the adding occurs at 80 C.
5. The method of claim 1, wherein said alcohol comprises n-butanol.
6. The method of claim 5, wherein the adding occurs at 100 C.
7. The method of claim 5, wherein the adding occurs at 120 C.
8. The method of claim 1, wherein the mixing occurs at 120 C.
9. The method of claim 1, further comprising nitrating said 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol with nitric acid.
10. The method of claim 9, wherein said nitric acid comprises at least a concentration of 90% nitric acid in water.
11. The method of claim 1, further comprising nitrating said 3,3-biisoxazole-4,4,5,5-tetryltetramethanol with 100% nitric acid and acetic anhydride.
12. The method of claim 1, wherein the adding occurs over at least a four-hour period.
13. The method of claim 1, further comprising: cooling the nitrated 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol to 0 C.; stirring the cooled nitrated 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol for at least four hours creating a precipitate; warming said precipitate; pouring said precipitate onto ice while stirring creating a solid material; collecting said solid material; and drying said solid material to yield said 3,3-bis-isoxazole-4,4,5,5-tetrylbis(methylene) tetranitrate.
14. A compound having the structural formula: ##STR00005##
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The embodiments herein will be better understood from the following detailed description with reference to the drawings, in which:
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DETAILED DESCRIPTION
(13) The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
(14) The embodiments herein provide for the synthesis, energetic properties, and analytical properties of a new energetic molecule, 3,3-bis-isoxazole-4,4,5,5-tetrylbis(methylene) tetranitrate (BITN). Referring now to the drawings, and more particularly to
(15) The embodiments herein provide for a new molecule, BITN, which can serve energetic functions as an energetic plasticizer in rocket and gun propellant formulations, as well as a melt-castable eutectic explosive ingredient. Because BITN possesses some weak Lewis basic functionality (i.e., NO isoxazole linkage), this material will favorably interact with nitrocellulose (NC) in double-base propellant formulations. Thus, BITN can provide benefits when interacting with NC in terms of being a good wetting agent and surfactant.
(16) As shown in
(17) In a second embodiment, to a mixture of DCG and 2-butyne-1,4-diol in n-butanol is added an aqueous solution of sodium bicarbonate over approximately four hours. When the reaction is performed at 100 C., a 34% yield of tetrol is obtained. When the reaction is performed at 120 C., 68% of tetrol is obtained.
(18) According to the embodiments herein, creating 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol involves several steps and may be formulated according to the following exemplary procedure: 2-Butyne-1,4-diol (13.72 g, 0.159 mol, 5.0 eq), sodium bicarbonate (6.7 g, 0.080 mol, 2.50 eq), and 200 mL.sup.nBuOH are combined in a 1 L round bottom-3-neck-flask equipped with a stirbar and a reflux condenser. The mixture is heated to 120 C. DCG (5 g, 0.032 mol, 1.0 eq) is dissolved in 400 mL.sup.nBuOH, and added dropwise via an addition funnel over 4-6 hours. Once the addition is complete, the reaction mixture cools to room temperature, and then is concentrated in vacuo on a rotary evaporator to dryness. Ice cold water (400 mL) is added to the resulting solid material and stirred for 5 minutes. The solid is collected by Bchner filtration, washed with an additional 400 mL of cold water, and is left under suction for 3 hours. The solid is then left to dry overnight in a fume hood yielding 5.56 g (68.1%) of tetrol as a pale tan-colored powder: T.sub.melt=183.0 C. (onset), 184.4 C. (peak) (shown in
(19) According to the embodiments herein, creating 3,3-bis-isoxazole-4,4,5,5-tetrylbis(methylene) tetranitrate involves several steps and may be prepared according to the following exemplary procedure: To a 100 mL round-bottom flask equipped with a stirbar a 50 mL of 90% HNO.sub.3 is added. The flask is cooled to 0 C. in an ice-water bath, and the bis-isoxazole tetrol (5.00 g, 19.5 mmol, 1.00 eq) is added portion wise over a 10 minute period. The ice-water bath is removed, and the reaction mixture is stirred for 4 hours at room temperature. The reaction mixture is then poured onto crushed ice with stirring for 15 minutes, and the solid precipitate is collected by Buchner filtration. The solid precipitate is left to dry on the Bchner funnel under suction for 3 hours, and is dried overnight in a fume hood to afford 7.24 g (85%) of 3,3-bis-isoxazole-4,4,5,5-tetrylbis(methylene) tetranitrate (BITN) as a white powder: T.sub.melt=121.9 C. (onset), 125.0 C. (peak); T.sub.dec=193.7 C. (onset), 219.1 C. (peak) (shown in
(20) Nitration of the tetrol with 90% HNO.sub.3 furnishes BITN in the optimal spherical morphology in high yield. Nitration of tetrol with 100% HNO.sub.3/acetic anhydride furnishes BITN in the needle-like morphology. These processes provided by the embodiments herein do not require flash chromatography on silica gel purification throughout the synthesis of BITN. Rather, all pure products are isolated by filtration in accordance with the embodiments herein. BITN can be synthesized reproducibly at the 5 g scale. The embodiments herein provide a process of getting internal alkynes to react with hydroximoyl chlorides in the absence of a ruthenium catalyst, and instead use heating, which offers a cost-effective process. Accordingly, in addition to the BITN molecule itself, the reaction of the internal alkyne 2-butyne-1,4-diol to DCG in the presence of heat is unique in accordance with the embodiments herein.
(21) Differential scanning calorimetry (DSC) analysis, on BITN shows that the molecule has an onset melting temperature of 121.9 C. and exothermic onset decomposition temperature of 193.7 C. The melting point of BITN is ideal to form eutectics with other energetic materials for the purposes of serving in melt-castable applications.
(22) The sensitivity of BITN is given in Table 1. BITN has an impact, friction, and ESD sensitivity on par with PETN, and accordingly BITN is of potential use as a pyrotechnic primer ingredient.
(23) TABLE-US-00001 TABLE 1 Sensitivities of 3,3-bis-isoxazole-4,4,5,5- tetrylbis(methylene) tetranitrate Compound IS.sup.[a] [J] FS.sup.[b] [N] ESD.sup.[c] [J] RDX 6.2 141 0.0625 PETN 3.0 60 0.0625 BITN 3.0 60 0.0625 .sup.[a]IS = impact sensitivity, h.sub.50 value .sup.[b]FS = friction sensitivity .sup.[c]ESD = electrostatic discharge
(24) The theoretical energetic properties of BITN are summarized in Table 2, which shows that BITN has power that is roughly equivalent to nitroglycerin (NG). Its high degree of power, coupled with its melting and decomposition temperatures make BITN a candidate as an ingredient for melt-castable eutectic explosives. BITN's potential as an energetic plasticizer stems from the solubility of BITN in organic solvents such as acetone, its possession of alkyl pendant primary nitrate ester chains, and its Lewis basic character owing to the NO linkage in the isoxazoles.
(25) TABLE-US-00002 TABLE 2 Properties of 3,3-bis-isoxazole-4,4,5,5- tetrylbis(methylene) tetranitrate Data category BITN NG PETN T.sub.m [ C.].sup.[a] 121.9 14.0 141.3 T.sub.dec [ C.].sup.[b] 193.7 50.0 210.0 .sub.CO2 [%].sup.[c] 36.7 3.50 10.1 .sub.CO [%].sup.[d] 0 +24.7 +15.2 [gcm.sup.3].sup.[e] 1.76 1.60 1.76 P.sub.cj [GPa].sup.[f] 25.6 25.3 31.5 V.sub.det [ms.sup.1].sup.[g] 7656 7700 8274 .sub.fH.sup.o [kJmol.sup.1].sup.[i] 393.5 370.0 538.6 .sup.[a]T.sub.m = onset temperature of melting .sup.[b]T.sub.dec = onset temperature of decomposition .sup.[c].sub.CO2 = CO.sub.2 oxygen balance .sup.[d].sub.CO = CO oxygen balance .sup.[e] = experimental density .sup.[f]P.sub.cj = detonation pressure .sup.[g]V.sub.det = detonation velocity .sup.[h].sub.fH.sup.o = molar enthalpy of formation
(26) The synthesized molecule, BITN is not known in the literature and industry, and hence both the molecule itself, and its synthesis, are new in accordance with the embodiments herein. Moreover, its energetic properties, impact, friction, and ESD sensitivities, and its analytical and physical properties are not known in the industry either.
(27) The major hindrances to modern formulation, processing, and production of high-energy plasticizers are three-fold. First, many of these solvents have a preponderance to be water soluble, making them intractable for field use. Second, most hydrophobic plasticizers are so fuel-rich (triacetin and phthalates, for example) they erode performance and burn rate horribly, making them useless in large amounts. Third, molecules with strong Lewis base character chemically react with the electrophilic nitrocellulose backbone, destroying molecular weight and generating NO.sub.x.
(28) However, BITN contains a CO oxygen balance of 0%, a reasonable density, and possesses the proper characteristics to make it an excellent candidate as a neutral, energetic plasticizer and wetting agent/energetic surfactant. BITN is soluble in organic solvents such as acetone, but is insoluble in water. BITN still possesses some weak Lewis base activity (i.e., NO isoxazole linkage) to interact with electrophilic binders and solid fillers. BITN possesses energetic, electrophilic properties to solubilize in the lacquer in typical double-base lacquers. BITN only contains primary nitrate functionalities which are known to possess good stability as compared to those with secondary nitrates. Also, the nitrates coupled with the polarized ring structure enhances the solubility in commonly used nitrate-based lacquers. Furthermore, BITN has a very high thermal stability by DSC analyses.
(29) BITN may be utilized as an ingredient in melt-castable eutectic explosive formulations. This includes a replacement for TNT-based, RDX-based, and DNAN-based formulations. BITN may be used as an energetic plasticizer to replace diethylene glycol dinitrate (DEGDN), triethylene glycol dinitrate (TEGDN) in double-base propellant formulations. BITN may be used as an energetic plasticizer to replace the non-energetic phthalate-based, adipate-based, and triacetin-based propellant plasticizer ingredients in rocket and gun propellant applications. BITN may be used as a plasticizing ingredient that assists in making up the general formulation of double-based propellants. BITN may be used as a RDX replacement in propellant formulations to improve wetting, plasticization with NC, and to improve rho I.sub.sp. Moreover, BITN may be used as a pyrotechnic ingredient in primer formulations.
(30) Based on the molecular structure of BITN, its sensitivity profile to impact, friction and ESD, its energetic properties, and its analytical and physical properties, BITN may be used as a potential energetic plasticizer for use in rocket and gun propellant formulations. It is also a potential ingredient in developing high-performing melt-castable eutectic explosive formulations, and may also find use in pyrotechnic primer formulations, due to its PETN-like sensitivity.
(31) BITN can be manipulated, depending on the nitration conditions, to exist in either the needle-like or spherical morphology. While the spherical morphology carries lower sensitivity, BITN in the needle-like morphology is potentially useful as an ingredient in pyrotechnic primer formulations. The high decomposition temperature of BITN (onset temperature of decomposition=193.7 C.) is unique, as most nitrates have decomposition temperatures around 150 C.
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(34) The alcohol may comprise ethanol, wherein the adding (103) may occur at 60 C., or alternatively the adding (103) may occur at 80 C. The alcohol may comprise n-butanol, wherein the adding (103) may occur at 100 C., or alternatively the adding (103) may occur at 120 C. The mixing (101) may occur at 120 C. The method may further comprise nitrating the 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol with nitric acid. The nitric acid may comprise at least a concentration of 90% nitric acid in water. The method may further comprise nitrating the 3,3-biisoxazole-4,4,5,5-tetryltetramethanol with 100% nitric acid and acetic anhydride. The adding (103) may occur over at least a four-hour period. The method may further comprise cooling the nitrated 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol to 0 C.; stirring the cooled nitrated 3,3-bis-isoxazole-4,4,5,5-tetryltetramethanol for at least four hours creating a precipitate; warming the precipitate; pouring the precipitate onto ice while stirring creating a solid material; collecting the solid material; and drying the solid material to yield the 3,3-bis-isoxazole-4,4,5,5-tetrylbis(methylene) tetranitrate.
(35) As it pertains to its potential use as a melt-castable eutectic ingredient in explosives, which is a rarity for nitrate-based materials, there is a drive to replace TNT (the standard melt-castable explosive) due to environmental concerns. DNAN-based melt-castable explosives exist as an alternative to TNT. However, DNAN has lower performance than TNT, and is lower in performance than BITN. Because of the high performance of BITN, it is believed that a eutectic material could be developed that significantly exceeds DNAN. Accordingly, BITN, with its high detonation pressure and detonation velocity, could be used as an ingredient in pyrotechnic primer formulations.
(36) As it pertains to its potential use as a propellant plasticizing ingredient, this shock sensitivity of a propellant may be reduced significantly when volatile diethyleneglycol dinitrate (DEGDN), for example, is replaced by BITN. BITN is less volatile and more thermally robust than DEGDN. The Lewis basic nature of BITN may serve as a better wetting ingredient, which may plasticize NC more effectively. The lowered vapor pressure and favorable interactions of BITN with an extensive amount of NC may improve slow cook-off and bullet/fragment impact, both of which are driven by gas phase reactions.
(37) Replacing DEGDN with other known, less sensitive plasticizers rapidly diminishes rocket performance, as oxygen balance is pushed to fuel richer formulations. Coupled with this effect is typical loss of burning rate in operational regimes. Moreover, plasticizers such as TMETN do not plasticize/solvate nitrocellulose as well as NG at a molecular level, thus hurting mechanical and shock sensitivity properties.
(38) BITN may be used as a plasticizing ingredient in rocket and gun propellant formulations, as a melt-castable eutectic explosive ingredient, and as a pyrotechnic primer ingredient. Since this molecule is energetic, it is possible that BITN could be used in any application where there is a need for a high-energy fuel that possesses nitroglycerin-like power. BITN may also be used in other applications including, but not limited to: (1) An ingredient in high-energy melt-castable eutectic explosive formulations. This includes a replacement for TNT-based, RDX-based, furazan-based, and DNAN-based melt-castable formulations. (2) An energetic plasticizer to replace DEGDN and TEGDN in double-base propellant formulations. (3) An energetic plasticizer to replace the non-energetic phthalate-based, adipate-based, and triacetin-based propellant plasticizer ingredients in rocket and gun propellant applications. (4) A plasticizing ingredient that assists in making up the general formulation of double-based propellants. (5) A pyrotechnic ingredient in primer formulations. (6) As a pyrotechnic primer ingredient for the manufacturing of civilian firearms. (7) As a melt-castable eutectic explosive ingredient for the replacement of DNAN-based, TNT-based, and RDX-based formulations. (8) Enhanced handling, processing and de-tooling during the use of BITN as an energetic ingredient in typical mixing, casting and curing of modern, castable minimum signature rocket propellants. (9) Pressed and/or extruded dynamite formulations where heat of explosion is often controlled only by alteration of nitroglycerin content. The use of an insensitive, yet energetic plasticizer with reduced volatility would enhance the manufacture, transportation, and storage of new types of dynamites. Likewise, higher thermal stability with lower vapor pressure and slower aging may offer advantages in high thermal performance areas such as those in underground mining and deep petroleum fracking.
(39) While it is known that the use of non-energetic plasticizers of nitrocellulose such as triacetin, do decrease sensitivity and enhance processing and safety. However, this comes at the cost of performance, both in specific impulse and typically with a reduction of the heat of explosion. Thus, a lowering of burning rate in typical motor operational pressure regimes is typically achieved. BITN provides enhanced energy and enhanced processing safety and handling to the overall propellant making for a more competitive, less sensitive version of said propellant since it may plasticize nitrocellulose more effectively. Similarly, BITN may not take large mass quantities with specific formulations to make major improvements to processing safety, handling, tooling and machining of such propellants. BITN may provide plasticization of higher nitrogen nitrocellulose stocks (typically >12.6% N content), allowing for the use of higher nitrogen content nitrocellulose with higher resultant mechanical properties. Typical energetic plasticizers used in minimum signature propellants either as extruded or castable, notably nitroglycerin (NG) and 1, 2, 4-butane-triol-trinitrate (BTTN) suffer from high mechanically sensitivity (impact, friction) and/or thermal stability issues since they contain secondary nitrate ester functionalities. Since BITN contains only primary nitrate functionalities, it may offer reduced cost in aging, surveillance, and demilitarization costs with longer propellant shelf lives with reduced aging issues often typical of double base propellant based on energetic nitrate ester plasticizers which contain secondary nitrate ester functionalities. Finally, higher thermally stable propellants using BITN as an energetic plasticizer can exhibit lower vapor pressure and slower aging. This may offer opportunities during typical tactical platforms exposed to large thermal extremes or extended periods of thermal stress with lowered migration rates within and out/into propellants to the external environment and/or liner.
(40) Another element that hinders most commonly fielded double-base minimum signature castable propellants is poor responses to bullet/fragment insults, slow cook off scenarios, and shape charge jet threats. Much of this is due to the high volatility and reactivity of the entrained nitrate ester plasticizer notably nitroglycerine when subjected to such scenarios. Accordingly, BITN offers significant improvements in this regard, with its higher molecular interactions within the plasticizer matrix of the formulations, resulting in more homogenous, less sensitive propellants.
(41) The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.