The complex course of the reaction of pyrrole with formaldehyde has been completely elucidated by quantitative 13C NMR spectroscopy using the inverse-gated decoupling technique. The final product is 2,5-bis(hydroxymethyl)pyrrole (with a free 1-position), but three main intermediates containing 1-hydroxymethyl groups were identified, and the rise and subsequent fall of their populations followed. The intermediacy of additional compounds (formals) also renders the reaction more complex. The molar fractions of four hydroxy-methylpyrroles present in the reaction mixtures were calculated from the 13C NMR data and plotted against time. At 45 and 65°C pyrrole reacted completely with formaldehyde in 1 h and in less than 30 min, respectively. This work illustrates the utility of the 13C NMR investigation of an industrially important reaction.
通过采用反向门控去耦技术,利用定量13C NMR光谱法,对
吡咯与
甲醛反应的复杂过程进行了全面阐释。最终产物是2,5-双(羟甲基)
吡咯(1位为游离基),但确定了三个含有1-羟甲基基团的主要中间体,并跟踪了它们数量的上升和下降。其他化合物(
甲醛)的中间产物也使反应更加复杂。根据13C NMR数据计算了反应混合物中四种羟甲基
吡咯的摩尔分数,并绘制了随时间变化的曲线。在45和65°C下,
吡咯分别在1小时和不到30分钟内与
甲醛完全反应。这项工作说明了13C NMR对工业上重要反应的实用性。