天然橡胶小分子模型物的溴化反应机理研究

Study on Brominated Mechanism of Small Molecular Model for Natural Rubber

选择与天然橡胶(NR)分子链节具有相似结构的小分子2-甲基-2-丁烯作为天然橡胶溴化反应的参照模型,通过溶液法使小分子发生溴化反应,应用傅立叶红外光谱、核磁共振、气相色谱-质谱联用等手段对小分子溴化反应产物的结构进行表征,并探讨小分子溴化反应的机理。结果表明:小分子2-甲基-2-丁烯的C=C双键在溴化过程中被氧化为C-C单键,同时发生甲基氢原子的溴化取代,反应产物主要是二溴和三溴取代C5烷烃。2-甲基-2-丁烯的溴化可能按自由基历程进行反应,反应速度很快。

The small molecule 2-methyl-2-butene, with similar structure to the molecular chain of natural rubber （NR） , was chosen as the reference model for natural rubber bromination. The small molecule was brominated in solution phase. The product structure for small molecule bromination was characterized using fourier transform infrared spectroscopy, nuclear magnetic resonance and GC-MS, and the bromination mechanism of small molecule was investigated. The results showed that in the process of bromination, the C=C double bond on the molecule of 2-methyl-2-butene was reduced to the C-C single bond and the hydrogen atoms of methyl were substituted by bromine. The bromination products were mainly dibromo and tribromo substituted C5 alkanes. The bromination of 2-methyl-2-butene was regarded as a kind of free radical reaction, and the reaction speed was very fast.