Chemistry of novolac resins. x. polymerization studies of hmta and strategically synthesized model compounds

Abstract

The reactions between hexamethylenetetramine (HMTA) and compounds which model novolac resins have been studied by 13C- and 15N-NMR techniques. The dimer and tetramer compounds vary in molecular size and structure and react with HMTA to yield benzylamines and benzoxazine as the major initial-formed intermediates and convert to methylene linked compounds at increased temperatures. The reaction of the compounds with only ortho reactive sites paralleled the 2,4-xylenolHMTA case reported by us previously; however, increasing molecular weight favored the formation of benzylamines and not benzoxazines. Those compounds with only para reactive sites paralleled the 2,6-xylenol-HMTA case. The reactivit..