NMR Study on the Reaction of Xylenol with Formaldehyde Catalyzed by Ammonia

Abstract

The reactionsof 2, 4-xylenol and 2, 6-xylenol with formaldehyde catalyzed by ammonia were studied by means of NMR spectroscopy and the chemical structure of the ammonia-resol formed was elucidated. Eight model compounds(see Fig.1)were synthesized and the chemical shiftsof their prgton signals in NMR spectra were iexamined(Table 1). It was found that the position of the 2, 6-xylenol was fairly more reactive than the 1position of the 2, 4-xyleno1. At the initial step of the reaction with 2, 4-xylenol, the tribenzylamino type compound(5 in Fig.1) was formed and it gradually changed into benzylamino-oxazine(3), while, with 2, 6-xylenol the tribenzy1-amine type compound was mainly formed together with a small amount of dibenzylamine(Fig.6). Further, methylol and dibenzyl-ether linkages were found in the product from 2, 4-xylenol, but methylol and methylene linkages were found in that from 2, 6-xyleno1(Fig.10). ApParent activiation energies of the reaction of 2, 4-and 2, 6-xylenol with formaldehyde were found tobe 17.9 and 18.2kca11mol, respectively(Flg.9).