| Abstract: | The NMR spectroscopy of cresols, benzylphenols, and di-, tri-, and tetra-nuclear phenolformaldehyde condensates using pyridine as solvent proved that their methyl or methylene groups which have ortho-phenolic hydroxyl groups show their signals at much lower τ-values as compared with those compounds having no ortho-phenolic hydroxyl groups. Thus, the signals of ortho-ortho, ortho-para, and para-para methylene types in novolak compounds could be separately observed in pyridine solution. Due to this specific properties of pyridine as NMR solvent, various phenol novolak resins could be characterized according to their modes of methylene links. |
