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Synthesis of New Substituted 4‐Amino‐3,5‐dinitropyridine Derivatives
Abstract
Facile synthetic routes for the preparation of some new 4‐amino‐3,5‐dinitropyridine derivatives have been revealed. Nitration of 2‐chloropyridin‐4‐amine (1) as a starting material, in an unexpected one‐step reaction, to give dinitrated derivatives, followed by nucleophilic substitution reactions with sodium azide, potassium fluoride, ammonia, methylamine, and 4‐nitroimidazol, respectively, gave substituted 4‐amino‐3,5‐dinitropyridine derivatives. Meanwhile, its azide derivative underwent a ring closure conversion into 7‐amino‐6‐nitro‐[1,2,5]oxadiazolo[3,4‐b]pyridine‐1‐oxide. It is of significance that all of the nucleophilic substitution reactions were carried out under mild conditions.
... By the addition of electron donating substituents, such as the amino group to the heteroaromatic ring, nitration may proceed more readily. Based on our successful synthesis of some new 4-amino-3,5-dinitropyridine derivatives under mild conditions using 4-amino-2-chloropyrine as the starting material [14], we herein would like to report the synthesis of 4-amino-2,6-dichloro-3,5-dinitropyridine (7) from readily available 2,6-dichloropyridine (1), followed by nucleophilic displacement reactions to form fully substituted energetic pyridine derivatives (Scheme 1). ...
... Polyamino-and polynitro-substituted pyridine-1-oxide with alternating amino and nitro groups are high performance explosives that are inherently stable and insensitive, with an additional energy contribution from the N-oxide functionality [15]. On the basis of the synthesis of 4-amino-2-chloro-3,5-dinitropyridine derivatives [14] and a rather lengthy and tedious synthesis of 4-amino-2,6-dichloropyridine-1-oxide [16], in the present work, 2,6-dichloropyridine (1) was used as the starting material for the synthesis of several pyridine derivatives (Scheme 1). Compound 1 was oxidized to the oxide 2 with hydrogen peroxide. ...
A facile synthetic route to an important intermediate 4-amino-2,6-dichloropyridine was developed. Oxidation of 2,6-dichloropyridine as a starting material gave pyridine
In this work, we designed and synthesized a series of novel triazolopyridine fused-ring compounds with alternating nitro and amine groups. Three compounds showed remarkable thermal stability at 256, 310, and 294 °C, respectively, and a low mechanical sensitivity [impact sensitivity (IS) = 40 J, friction sensitivity (FS) = 324 N; IS = 35 J, FS = 240 N; and IS > 40 J, FS = 324 N, respectively]. Significantly, two of these compounds exhibited a better detonation performance [detonation velocity (D) = 8200 and 8335 m s–1, Detonation pressure (P) = 25.6 and 27.2 GPa, respectively] than the widely used heat-resistant explosive hexanitrostilbene (HNS; D = 7612 m s–1, P = 24.3 GPa). Additionally, a nitramine derivative displayed a detonation performance (D = 8569 m s–1, P = 31.3 GPa) similar to that of the high-energy explosive RDX. The superior properties of the materials were further confirmed by X-ray diffraction analysis and by several theoretical calculations (ESP, LOL–π, Hirshfeld surfaces, RDG, and NCI analyses). These results indicated that the three compounds might be potential candidates for use as heat-resistant energetic materials.
The chapter intends to update the chemistry of bicyclic (5,6)heterocycles with four heteroatoms in a 3:1 orientation, since the third edition of Comprehensive Heterocyclic Chemistry. The different studies found in the literature regarding the theoretical and experimental techniques used to elucidate the structure of this type of heterocycles, the methods used to synthesize or to transform them into other compounds and their wide array of applications are herein summarized. The main types of hetereocycles covered in this chapter are triazolopyridines, triazoloquinolines, oxadiazolopyridines, thiadiazolopyridines, selenadiazolopyridines and diazaphospholopyridines.
A new compound N-(6-azido-3, 5-dinitropyridin-2-yl)-2, 6-diamine-3, 5-dinitropyridine(3) was designed and synthesized via C-N cross-coupling reaction and azide substitution reaction, using 2-amine-6-chloro-3, 5-dinitropyridine as a primary material with a total yield of 69%.Its structure was confirmed by 1H NMR, 13C NMR, MS and elemental analysis. Theoretical calculations at DFT-B3LYP/6-31G** level were performed. Results show that the detonation performance of compound 3 are detonation velocity D=7.89 km·s-1 and detonation pressure p=28.37 GPa, revealing that its detonation performance is better than that of 2, 4, 6-trinitrotoluene (TNT). ©, 2015, Institute of Chemical Materials, China Academy of Engineering Physics. All right reserved.
A novel preparation method for 2-amino-3, 5-dinitro-6-chloropyridine (4) and its derivatives was described starting from cheap and easily available 2, 6-dichloropyridine (1). Compound 4 was obtained by nitration, amination and again nitration reaction, followed by reacting with several nucleophilic reagents, such as ammonia, sodium azide to form 2-amino-3, 5-dinitropyridine-6-substituted derivatives 5~7, respectively. The results showed that this synthetic route had the advantages of easy-obtained raw materials, simple work-up and high purity product.
Pyridines are widely used in energetic materials. Based on molecular structure, and classified themselves by nitropyridines, pyridine-based energetic salts, pyridine-based energetic complexes, a large number of energetic pyridines are summarized. The characteristics and main applications of some important energetic pyridines are also introduced briefly.
Substrate (I), prepared by nitration of 2-chloropyridine-4-amine, is treated with various reagents to give the corresponding 2-substituted products.
Research and development efforts for realizing higher performance levels of high energy materials (HEMs) are continued unabated all over the globe. Of late, it is becoming increasingly necessary to ensure that such materials are also eco-friendly. This has provided thrust to research in the area of force multiplying HEMs and compounds free from pollution causing components. Enhancement of the performance necessitates introduction of strained structure or increase in oxygen balance to achieve near stoichiometry. The search for environment friendly molecules is focused on chlorine free propellant compositions and lead free primary explosives. Energetic polymers offer added advantage of partitioning of energy and thus not necessitating the concentration of only solid components (HEMs and metal fuels) in the formulations, to achieve higher performance, thereby leading to improvement in energetics without adversely affecting the processability and mechanical properties. During recent times, research in the area of insensitive explosives has received impetus particularly with the signature of STANAG. This paper gives a review of the all-round advances in the areas of HEMs encompassing oxidizers, high-energy dense materials, insensitive high-energy materials, polymers and plasticizers. Selected formulations based on these materials are also included.Defence Science Journal, 2010, 60(2), pp.137-151, DOI:http://dx.doi.org/10.14429/dsj.60.327
Monoperoxosulphuric acid oxidized 4-nitro-benzofuroxan into 1,2,3-trinitrobenzene (80%) and 4, 6-dinitrobenzofuroxan into 1,2,3,5-tetranitrobenzene (100%).
Energetic materials (explosives, propellants and pyrotechnics) are used extensively for both civilian and military applications. There are ongoing research programs worldwide to develop pyrotechnics with reduced smoke and new explosives and propellants with higher performance or enhanced insensitivity to thermal or shock insults. In recent years, the synthesis of energetic, heterocyclic compounds have received a great amount of interest. Heterocycles generally have a higher heat of formation, density, and oxygen balance than their carbocyclic analogues. This review will concentrate on recent advances in the synthesis of heterocycles as energetic materials and will complement the excellent review of recent advances in energetic materials published in 1998 by Agrawal [Prog. Energy Combust. Sci. 24 (1998) 1].
Nucleophilic substitution reactions on 1-methyl-2,4,5-trinitroimidazole (MTNI) are described.
Synthesis of a new nitro-substituted 1-amino and 1-nitraminoimidazoles is described. A novel solid state nitration has been developed.
The preparation and properties of high-melting aromatic nitrate esters are described. An objective of the study is to provide nitrate esters that exhibit good short-term stability at temperatures of 150°C and above.
A number of substituted imidazo[b]pyridines, imidazo[c]pyridines, pyrido[2,3-d]-v-triazoles and pyrido[3,4-d]-v-triazoles have been synthesized. These compounds are being screened for antimetabolite activity.
We have reinvestigated the synthesis of 1-methyl-2,4,5-trinitroimidazole (MTNI; 1), and further characterized its physical properties. It is a promising candidate as an insensitive high explosive. Compound 1 was synthesized from the imidazole (2), via a 5-step sequence of reactions, and subjected to various sensitivity tests for explosives. The structure of 1 was characterized by X-ray diffraction. The crystal is orthorhombic; C4H3N5O6, M = 217.11, Z = 8, Pca21, a = 8.6183(6) Å, b = 17.7119(12) Å, c = 10.6873(7) Å, V = 1631.38(19) Å3, Dc = 1.768 g/cm3. The structure was refined to R = 0.0284 for 3201 independent reflections with I > 2σ(I). The molecular structures calculated by high levels of ab initio and density functional theories were in good agreement with those observed by X-ray experiment. According to our preliminary sensitivity tests, 1 was characterized to be intermediate in sensitivity between RDX and TNT. The explosive performances were evaluated theoretically, and were found to be comparable to those of RDX. In addition, owing to its low melting point (82 °C), 1 is believed to be an excellent candidate for inclusion in melt-castable explosives, and may lead to increased explosive power.
2,6-Diamino-3,5-dinitropyridine 1-oxide has been prepared by mixed acid nitration of 2,6-diaminopyridine, followed by oxidation using hydrogen peroxide in acetic acid. 3,5-Dinitro-2,4,6-triaminopyridine has been prepared by oxidative amination of 2-chloro-3,5-dinitropyridine or 2,6-diamino-3,5-dinitropyridine using potassium permanganate in liquid ammonia, or by “vicarious nucleophilic amination” of 2,6-diarnino-3,5-dinitropyridine using hydroxylamine in aqueous potassium hydroxide. 3,5-Dinitro-2,4,6-triaminopyridine 1-oxide has been prepared by oxidation of 3,5-dinitro-2,4,6-triaminopyridine using hydrogen peroxide in acetic acid, and by “vicarious nucleophilic amination” of 2,6-diamino-3,5-dinitropyridine 1-oxide. Nmr spectroscopy and single crystal X-ray diffraction studies have shown that these compounds have the planar structures and intra- and inter-molecular hydrogen bonding necessary to confer on the materials the high density, the thermal and chemical stability, and the explosive insensitivity required for new insensitive energetic materials.
A simple, empirical linear relationship between detonation velocity at theoretical maximum density and a factor, F, that is dependent solely upon chemical composition and structure is postulated for a gamut of ideal explosives. The explosives ranged from nitroaromatics, cyclic and linear nitramines, nitrate esters and nitro-nitrato aliphatics to zero hydrogen explosives, carbonless explosives and hydrogen rich explosives. Of the 64 explosives evaluated, 95% had calculated detonation velocity values within 5% of experimental and 98% within 7%. Only nitromethan varied grossly (−; 13%) from calculated velocity and the absolute error for all explosives is ±2.3%.
In this third part of our research on the 5,5′-azobis[1H-tetrazol-1-ides] (ZT) of the lanthanoids, we present two compounds with La2(ZT)3 moieties with very different coordination modes between the cations and the anions. One La2(ZT)3-containing compound is interesting, because it contains trimeric La3(ZT)3III cations, which are arranged in a windmill-like structure. Moreover, the first double salt of a ZT compound, namely the carbonate compound La2(ZT)2(CO3)⋅12 H2O, is presented and discussed. Another highlight of nitrogen chemistry is the first molecular structure of a 5-azido-2H-tetrazole (CHN7) molecule, in the form of the spectacular compound Dy2(ZT)3⋅4 CHN7⋅24 H2O. This is the first known complete molecular structure of an azidotetrazole molecule (the organic molecule with the highest nitrogen-content: 88.3% N). All compounds have been characterized completely including elemental analyses, vibrational (IR and Raman) spectroscopy, and X-ray crystal-structure determination. We summarize our ‘nitrogen-rich compounds of the lanthanoids’ project and extensively discuss selected literature on this topic and compare previously published results with ours.
During the last two decades, or, more precisely, ever since the introduction of metronidazole into therapy, nitroimidazoles as a class of compounds have attracted much attention. Nevertheless, no adequate review of this chemical class has appeared in literature, even though a large number of reviews on the chemotherapy of protozoal diseases refer to the various nitroimidazoles in clinical use.
1-(2-Nitroxyethylnitramino)-2,4,6-trinitrobenzene (I-A), 1, 3-bis(2-nitroxyethylnitramino)-2,4,6-trinitrobenzene (II-A) and 1,3, 5-tris(2-nitroxyethylnitramino)-2,4,6-trinitrobenzene (III-A) have been prepared by condensing picryl chloride, styphnyl chloride and 1, 3,5-trichloro-2,4,6-trinitrobenzene with ethanol amine, respectively, followed by nitration. These compounds have been characterized by infrared spectrum (IR), the elemental analysis and 1H NMR. Further, these compounds have been studied for their thermal and explosive properties. The activation energy of thermal decomposition of these compounds has also been determined using the Ozawa and the Kissinger methods. The data on explosive properties indicate that the impact, friction and velocity of detonation (VOD) increase with an increase in the number of nitrate ester groups.
Twelve N-aryl derivatives of 4-nitroimidazole, 2-methyl-4-nitroimidazole, 4-nitropyrazole or 3-nitro-1,2,4-triazole have been synthesized either by a degenerated ring transformation reaction of 1,4-dinitroimidazoles with 4-substituted anilines or by a condensation of fluoronitrobenzenes with salts prepared from C-nitro-1H-azoles and 1,8-diazabicyclo[5.4.0]-7-undecene. The Tuberculosis Antimicrobial Acquisition and Coordinating Facility has provided anti-mycobacterial data concerning inhibition activity of 12 compounds.
This paper reports the synthesis of three new derivatives of 2,4,5-trinitroimidazole namely, 1-methyl-2,4,5-trinitroimidazole (III), 1-carboethoxy-2,4,5-trinitroimidazole (V) and 1-picryl-2,4,5-trinitroimidazole (VII). The title compounds (III) and (V) were synthesized by the nitration of 1-methyl-/1-carboethoxy-(2,4,5-triiodoimidazole) (II and IV) with fuming nitric acid at 0 degrees C and (VII) was synthesized by condensation of 2,4,5-triiodoimidazole (I) with picryl chloride to obtain 1-picryl-2,4,5-triiodoimidazole (VI) followed by its nitration with fuming nitric acid at 0 degrees C. The synthesized compounds have been characterized by elemental analysis, spectral and thermal techniques. The thermolysis studies using TG-DTA revealed exothermic decomposition of the nitroimidazoles (III, V and VII) with T(max) in the temperature range of 196-225 degrees C. The energy of activation obtained for these compounds was in the range 150-170 kJ/mol. The sensitivity data obtained for the newly synthesized compounds (III, V and VII) indicated their safe nature towards external stimuli (h(50%)>100 cm; friction>36 kg) and could be potential candidates for low vulnerable applications in the futuristic systems. The theoretically predicted performance parameters suggest that 1-methyl-2,4,5-trinitroimidazole (III), exhibits higher velocity of detonation (VOD: 8.8 km/s) compared to compounds V and VII (VOD: 7.6 and 8.41 km/s, respectively).
Energetic materials such as explosives, propellants and pyrotechnics are widely used for both civilian and military explosives applications. The present review focuses briefly on the synthesis aspects and some of the physico-chemical properties of energetic materials of the class: (a) aminopyridine-N-oxides, (b) energetic azides, (c) high nitrogen content energetic materials, (d) imidazoles, (e) insensitive energetic materials, (f) oxidizers, (g) nitramines, (h) nitrate esters and (i) thermally stable explosives. A brief comment is also made on the emerging nitration concepts. This paper also reviews work done on primary explosives of current and futuristic interest based on energetic co-ordination compounds. Lead-free co-ordination compounds are the candidates of tomorrow's choice in view of their additional advantage of being eco-friendly. Another desirable attribute of lead free class of energetic compounds is the presence of almost equivalent quantity of fuel and oxidizer moieties. These compounds may find wide spectrum of futuristic applications in the area of energetic materials. The over all aim of the high energy materials research community is to develop the more powerful energetic materials/explosive formulations/propellant formulations in comparison to currently known benchmark materials/compositions. Therefore, an attempt is also made to highlight the important contributions made by the various researchers in the frontier areas energetic ballistic modifiers, energetic binders and energetic plasticizers.
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