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Utility of 13 C NMR spectroscopy in monitoring the course of a complex reaction sequence: Reaction of pyrrole with formaldehyde
Author(s) -
Katritzky Alan R.,
Law Kam Wah
Publication year - 1988
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260260208
Subject(s) - chemistry , formaldehyde , hydroxymethyl , pyrrole , nuclear magnetic resonance spectroscopy , proton nmr , dimer , reaction mechanism , photochemistry , organic chemistry , catalysis
The complex course of the reaction of pyrrole with formaldehyde has been completely elucidated by quantitative 13 C 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 13 C 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 13 C NMR investigation of an industrially important reaction.