Oxidations of 3,6-diamino-1,2,4,5-tetrazine and 3,6-bis(s,s-dimethylsulfilimino)-1,2,4,5-tetrazine

Oxidation of 3,6-diamino-1,2,4,5-tetrazine ( 1 ) with most peracids gave 3,6-diamino-1,2,4,5-tetrazine 1,4-dioxide ( 3 ) as the major product; however, treatment of 1 with peroxytrifluoroacetic acid (PTFA) gave 3,6-diamino-1,2,4,5-tetrazine 1-oxide ( 4 ) as the major product along with a small amount of 3-amino-6-nitro-1,2,4,5-tetrazine 2,4-dioxide ( 5 ). Oxidation of 3,6-bis(S,S-dimethylsulfilimino)-1,2,4,5-tetrazine ( 6 ) with 3-chloroperoxybenzoic acid (MCPBA) gave 3-S,S-(dimethylsulfilimino)-6-nitroso-1,2,4,5-tetrazine ( 7 ), which was oxidized further with dimethyldioxirane to 3-(S,S-dimethylsulfoximino)-6-nitro-1,2,4,5-tetrazine ( 8 ). All attempts to obtain 3,6-dinitro-1,2,4,5-tetrazine ( 2 ) by further oxidation of 7 or 8 failed.     

Basicity of 3,6-diphenyl-1,2,4,5-tetrazine

We have determined the basicity of 3,6-diphenyl-1,2,4,5-tetrazine in aqueous solutions of sulfuric acid (pK_BH+ is –4.8). According to quantum chemical calculations done by the MNDO method and theab initio method in a 6-31G++ basis, the tetrazine ring is a nonpolar, highly aromatic system similar to benzene. The aromaticity of the tetrazine hererocycle decreases significantly upon protonation, which considerably destabilizes the protonated form.St. Petersburg State Technological Institute, St. Petersburg 198013, Russia, Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 34, No. 1, pp. 120–123, January, 1998.     

A polymeric sodium complex of 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine

The ligand 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine forms a 1:1 complex with Na[BPh4], which has been structurally characterised as a one-dimensional polymeric system with an unusual coordination geometry about the sodium.     

Theoretical Study on the Azido-cyclization of 3,6-Di(azido)-1,2,4,5-tetrazine

The reactions of azido‐cyclization in 3,6‐di(azido)‐1,2,4,5‐tetrazine were studied by B3LYP hybrid density functional method. The geometries of the reactants, transition states and products were optimized, and the conformation of the initial reactant was determined by IR spectra. In addition, the nucleus‐independent chemical shift (NICS) indices were used to discuss the aromaticity of the products. Moreover, solvent effects were investigated. Results show that the polar solvent DMSO can hardly influence the activation barriers of all the reaction paths; however, it can stabilize the products. Since the activation barriers of azido‐rotation are far less than that of the rate‐determining step (the cyclization of second azido), the products are most probably the mixtures of two isomers (DAT2c and DAT2c').     

3,6-二叠氮基-1,2,4,5-四嗪的合成及理论研究

以3,6-双(3,5-二甲基吡唑基)-1,2,4,5-四嗪为原料, 经过肼解反应和重氮化反应, 制得了3,6-二叠氮基-1,2,4,5-四嗪(DAT). 在DFT-B3LYP/6-31G*水平下求得了DAT的分子几何、IR光谱和热力学性质. 计算模拟IR光谱和实测IR光谱的对比表明DAT在固态下不发生叠氮-四唑互变异构反应. 根据IR光谱计算了DAT的热容、焓、熵等热力学参数, 也给出了这些参数和温度T之间的函数关系. 在不破坏四嗪环和叠氮基的原则下通过构建等键反应求得了DAT的精确生成热为1088 kJ•mol^—1. 爆轰性能计算表明DAT爆速D＝8.45 km•s^－1, 爆压P＝31.3 GPa, 高于TNT和HMX.     

基于3,6-二肼基-1,2,4,5-四嗪的两种高氮含能离子盐

本文通过3,6-二肼基-1,2,4,5-四嗪(DHT)分别与高氯酸和硝酸反应得到2种高氮含能离子盐,并通过X-射线单晶衍射技术对它们的结构进行了表征。(DHT)(NO₃)₂(1)属于单斜晶系,C2/c空间群,晶胞参数:a=1.3000(6)nm,b=0.8349(3)nm,c=1.0187(5)nm,β=118.89(5)°,Z=4;(DHT)(ClO₄)₂(2)属于正交晶系,P2₁2₁2空间群,晶胞参数:a=0.9804(4)nm,b=1.0747(4)nm,c=0.5325(2)nm,Z=2。采用DSC和TG-DTG技术研究了这两种含能离子盐的热分解机理,并对这两种含能离子盐的非等温动力学、爆热及感度进行了测试分析。研究表明这两种含能离子盐在敏感型含能材料领域具有潜在的应用前景。     

基于3,6-二肼基-1,2,4,5-四嗪的两种高氮含能离子盐

本文通过3,6-二肼基-1,2,4,5-四嗪(DHT)分别与高氯酸和硝酸反应得到2种高氮含能离子盐,并通过X-射线单晶衍射技术对它们的结构进行了表征。(DHT)(NO₃)₂(1)属于单斜晶系,C2/c空间群,晶胞参数：a=1.300 0(6) nm,b=0.834 9(3) nm,c=1.018 7(5) nm,β=118.89(5)°,Z=4;(DHT)(ClO₄)₂(2)属于正交晶系,P2₁2₁2空间群,晶胞参数：a=0.980 4(4) nm,b=1.074 7(4) nm,c=0.532 5(2) nm,Z=2。采用DSC和TG-DTG技术研究了这两种含能离子盐的热分解机理,并对这两种含能离子盐的非等温动力学、爆热及感度进行了测试分析。研究表明这两种含能离子盐在敏感型含能材料领域具有潜在的应用前景。     

3,6-二肼基-1,2,4,5-四嗪的晶体结构及理论研究

通过缓慢蒸发溶剂法培养得到3, 6-二肼基-1, 2, 4, 5-四嗪(DHT)的单晶, 用X-射线单晶衍射仪进行了结构测定. 该晶体属于单斜晶系, P2(1)/c空间群, a=4.032 (4) ?, b=5.649 (6) ?, c=12.074 (14) ?. β=99.32°, Z=2, V=271.4(5) ?3. DHT分子中肼基N原子与四嗪环基本位于同一平面呈现轴对称结构, 分子中的大量氢键使之形成箭尾形排列的三维网络结构. 通过实验测得DHT的燃烧热为1787kJ?mol-1, 5s爆发点为454 K. 在DFT-B3LYP/6-311G*水平下对DHT的电子结构和自然键轨道进行了分析. 通过原子化能的方法计算得到DHT的标准生成热为1075 kJ?mol-1, 与实验值接近. 爆轰性能计算表明, DHT在密度为1.64 g?cm-3时, 爆速和爆压分别为9.27 km?s-1和36.02 GPa, 高于TNT和HMX.     

Conformation and bonding in unsymmetrically 3,6-disubstituted dihydro-1,2,4,5-tetrazine

The molecular structure of the title compound, I, has been determined by single-crystal X-ray diffraction. The crystals are triclinic, space group PI. The analysis revealed that the dihydro-s-tetrazine molecule is in a slightly twisted boat conformation with the nitrogen atoms carrying the two hydrogens, N(2) and N(4), pointing upward. All substituents on the dihydro-s-tetrazine ring exist in pseudo-equatorial configurations. Adjacent hydrogen and bulky groups (CF₃ and p-Cl-C₆H₄) have cis-relationships. The p-chlorophenyl group is twisted with respect to the dihydro-s-tetrazine ring. The unit cell for I contains six molecules. Each dihydro-s-tetrazine ring participates in four intermolecular hydrogen bonds (N···H bond distance 2.23 to 2.41 A), two hydrogen bonds to each adjacent tetrazine ring in the same unit cell.     

An improved synthesis of 3,6-diamino-1,2,4,5-tetrazine. I

Treatment of 1,3-diaminoguanidine monohydrochloride ( 1 ) with 2,4-pentanedione ( 2 ) in alcohols under carefully controlled conditions gave 3,6-diamino-1,2-dihydro-1,2,4,5-tetrazine monohydrochloride ( 3 ) in 45-50% yields along with 3,5-dimethyl-1H-pyrazole ( 4 ) and its hydrochloride 5 . Oxidation of 3 with sodium perborate produced 3,6-diamino-1,2,4,5-tetrazine ( 6 ) in quantitative yield.     

3,6-二氨基-1,2,4,5-四嗪二聚体分子间相互作用的理论研究

在DFT-B3LYP/6-31G(d)水平下,求得3,6-二氨基-1,2,4,5-四嗪二聚体势能面上3种优化几何构型和电子结构。经基组叠加误差(BSSE)和零点能(ZPE)校正,求得分子间最大相互作用能为-38.88kJ/mol。电荷分布与转移分析表明,二子体系间的电荷转移很少,但接触点上氮原子和氢原子电荷变化比较大。由自然键轨道(NBO)分析揭示了分子间相互作用的本质。对优化构型进行振动分析,并基于统计热力学求得200.0~800.0 K温度范围从单体形成二聚体的热力学性质变化,发现二聚主要由强氢键所贡献,二聚过程在较低温度或常温下能自发进行。     

Synthesis and inverse electron demand Diels-Alder reactions of 3,6-bis(3,4-dimethoxybenzoyl)-1,2,4,5-tetrazine

The synthesis of 3,6-bis(3,4-dimethoxybenzoyl)-1,2,4,5-tetrazine (2) and the scope of its reactivity in inverse electron demand Diels-Alder reactions are disclosed representing the first systematic study of the [4 + 2] cycloaddition reactions of 3,6-diacyl-1,2,4,5-tetrazines.     

3,6-双(1氢-1,2,3,4-四唑-5-氨基)-1,2,4,5-四嗪的合成与表征

研究了低感度高氮化合物3,6-双(1氢-1,2,3,4-四唑-5-氨基)-1,2,4,5-四嗪的合成,其结构经元素分析,IR,^1H NMR和^13C NMR表征。     

3,6-二肼基-1,2,4,5-四嗪的热行为、比热容及绝热至爆时间

利用差示扫描量热法(DSC)、热重-微商热重法(TG-DTG)研究了3,6-二肼基-1,2,4,5-四嗪(DHT)的热行为, 其分解过程可分为两个放热的分解过程, 且热分解反应的表观活化能分别为154.8和123.4 kJ·mol-1, 指前因子分别为1016.63和109.48 s-1. DHT热爆炸的临近温度为426.10 K. 同时, 利用微量热法和理论计算方法研究了DHT的比热容, 298.15 K时的标准摩尔比热容为183.61 J·mol-1·K-1. 计算获得了DHT的绝热至爆时间为263.84-297.58 s之间的某一值.     

Crystal and electronic structure of heteromolecular complexes of 3,6-bis(3,5-dymethylpyrazole-1-yl)-1,2,4,5-tetrazine with azoles

X-ray crystallography is used to investigate heteromolecular crystals of 3,6-bis(3,5-dimethylpyrazole-1-yl)-1,2,4,5-tetrazine with NH-donating azole derivatives. The effect is studied of the structure of azole on molecular packing in the crystal and the characteristics of covalent bonds in the molecule of 3,6-disubstituted tetrazine. The distribution of electron density critical points inside crystal cells is analyzed to identify and quantitatively describe the intermolecular interactions underlying the formation of lateral and stacking motifs.     

Synthesis, characterization and quantum chemistry study of 3,6-bis(1H-1,2,3,4-tetrazol-5-yl-amino)-1,2,4,5-tetrazine

3,6-bis(1H-1,2,3,4-tetrazol-5-yl-amino)- 1,2,4,5-tetrazine (BTATz) was synthesized by the condensation of triaminoguanidinium nitrate with 2,4-pentanedione, followed by oxidation and substitution reaction. The product was characterized by elemental analysis, IR, NMR spectrometry and DSC analysis. Instead of nitrogen dioxide/N-methylpyrrolidone, acetic acid/sodium nitrite was used as the oxidizer during the oxidation. Thus, the cost was reduced and the process was simplified. The theoretical properties of BTATz were estimated by a B3LYP method based on a 6-31G(d,p) basis set, and the stable geometric configuration and bond order were obtained. The vibrational frequencies, IR spectrum and thermodynamic properties under different temperatures were obtained from vibrational analysis and the relationship between temperature and thermodynamics properties was deduced. Pyrolysis mechanism of BTATz was discussedand the transition state and activation energy of ring opening reaction of the tetrazole were deduced. __________ Translated from Chinese Journal of Organic Chemistry, 2008, 28(3) (in Chinese)