Abstract: 3,6-bis(3,5-dimethylpyrazol-1-yl)-1,2-dihydro-1,2,4,5-tetrazine (DHBT) serves as a precursor for the synthesis of energetic tetrazine materials. In this study, DHBT was synthesized via the cyclization of prepared triaminoguanidine hydrochloride with acetylacetone. A newly established high-performance liquid chromatography (HPLC) method was applied to quantitatively analyze the reaction kinetics, while an intermediate, 1,1'-(3,5-dimethyl-pyrazol-1-yl)-enaminohydrazine, was characterized. Based on this intermediate, the cyclization mechanism of DHBT was proposed. Subsequently, the reaction conditions for DHBT synthesis in a batch reactor were optimized, with the effects of reactor type, stirring method, reactant concentration ratio, reaction temperature, and solvents on DHBT yield investigated. The results showed that the optimal conditions were as follows: a 250 mL glass-jacketed kettle equipped with internal baffles, an inclined blade stirrer operated at 400 r/min, deionized water (5.0 times the mass of the raw material), acetylacetone (2.0 times the molar amount of the raw material), a reaction temperature of 70℃, and a reaction time of 2 h. Under these optimal conditions, the actual yield of DHBT reached 77.5% with a purity of 96.3%. A scale-up synthesis of DHBT (480 g scale) was further conducted under the optimized conditions, achieving a yield of 72.9%. Kinetic studies revealed that the rate-determining step of the reaction was the conversion of the intermediate to the final product. For the cyclization process starting from the intermediate (at 70~90℃), the reaction followed second-order kinetics, with an apparent activation energy (E?) of 112.66 kJ/mol, a pre-exponential factor (A) of 1.64×1018 mol/(L?min), and a linear correlation coefficient (R2) of 0.9967. Additionally, calorimetric tests of the reaction process were performed using a reaction calorimeter, and the enthalpy change of the chemical reaction (??H?) was determined to be 364.03 kJ/mol.

Key words: 3,6-bis(3,5-dimethylpyrazol-1-yl), -1,2-dihydro-1,2,4,5-tetrazine, triaminoguanidine hydrochloride, high-performance liquid chromatography, reaction kinetics, reaction heat

摘要： 3,6-二(3,5-二甲基吡唑-1-基)-1,2-二氢-1,2,4,5-四嗪(DHBT)是合成四嗪类含能材料的前体化合物。本研究以自制三氨基胍盐酸盐为原料，与乙酰丙酮通过成环反应制备DHBT。使用新建立的高效液相色谱方法定量分析该反应的动力学过程，表征反应过程中产生的中间体1,1'-(3,5-二甲基-吡唑-1基)-烯胺肼，并基于该中间体提出DHBT关环反应机理。随后对间歇釜式合成DHBT的反应条件进行优化，探究反应器类型、搅拌方式、反应物浓度配比、反应温度和溶剂种类对DHBT收率的影响。结果表明，在采用带内挡板的250 mL玻璃夹套釜和斜叶搅拌桨，转速400 r/min，反应体系中加入5.0倍原料质量的去离子水与2.0倍原料摩尔量的乙酰丙酮，并在70℃下反应2 h的条件下，DHBT的实际收率达77.5%，产品纯度为96.3%。在该优选条件基础上，进一步完成480 g级放大合成，收率达到72.9%。动力学研究显示，反应决速步为中间体向产品的转化过程，对70~90℃下以中间体为起点的环化过程分析表明，该反应遵循二级反应动力学，表观活化能Ea=112.66 kJ/mol，指前因子A=1.64×1018 mol/(L?min)，线性相关系数R2=0.9967。此外，结合反应量热仪对反应过程进行量热测试，测得化学反应焓变?rHm=364.03 kJ/mol。

关键词: 3,6-二(3,5-二甲基吡唑-1-基), -1,2-二氢-1,2,4,5-四嗪, 三氨基胍盐酸盐, 高效液相色谱, 反应动力学, 反应热