Abstract

An online Raman analysis technique was used for the first time to study the mechanism underlying the synthesis of 5-bromomethylpyridine-2,3-dicarboxylic acid methyl ester (CMPE) via a bromination reaction with 5-methylpyridine-2,3-dicarboxylic acid dimethyl ester (MPE) as the raw material, N-bromosuccinimide (NBS) as the brominating reagent, and azobisisobutyronitrile (AIBN) as an initiator. The apparent thermodynamics and the reaction kinetics of bromination reaction of MPE were explored, a reaction kinetics model was established, and the bromination reaction of MPE was a typical reaction initiated by free radicals. The activation energy of bromination of MPE was 37.02 kJ mol^–1, and the apparent reaction heat was 2.23 kJ mol^–1 (calculated in the moles of NBS). The adiabatic temperature rise was 6.30°C under thermal runaway. The kinetic equation of the synthesis reaction: r = 3.26 × 10⁶exp(–37.02/RT)\(C_{{{\text{NBS}}}}^{{1.52}}\).

中文翻译：

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5-甲基吡啶-2,3-二甲酸二甲酯的溴化机理和动力学

摘要

首次使用在线拉曼分析技术研究了通过与 5-甲基吡啶-2,3-二羧酸二甲酯的溴化反应合成 5-溴甲基吡啶-2,3-二羧酸甲酯 (CMPE) 的机理以酯（MPE）为原料，N-溴代丁二酰亚胺（NBS）为溴化试剂，偶氮二异丁腈（AIBN）为引发剂。探讨了MPE溴化反应的表观热力学和反应动力学，建立了反应动力学模型，认为MPE的溴化反应是典型的自由基引发反应。MPE的溴化活化能为37.02 kJ mol ^–1，表观反应热为2.23 kJ mol ^–1（以 NBS 的摩尔数计算）。热失控时绝热温升为6.30℃。合成反应的动力学方程：r = 3.26 × 10 ⁶ exp(–37.02/ RT ) \(C_{{{\text{NBS}}}}^{{1.52}}\)。