Crystal structure and hydrogen-bonding characteristics of N,N-bis(3,5-dimethyl-2-hydroxybenzyl)methylamine, a benzoxazine dimer

The X-ray crystal structure of N,N-bis(3,5-dimethyl-2-hydroxybenzyl) methylamine as a model dimer for benzoxazine-based phenolic resins is presented, and a hydrogen-bonding scheme involving both inter- and intramolecular hydrogen bonding is proposed. Hydrogen bonding of this model dimer is further studied with Fourier transform infrared (FT-IR) spectroscopy in crystalline, quenched, and molten phases as well as in solution, Additional hydrogen-bonding schemes are proposed. These results are compared to results obtained from molecular modeling using a model dimer with a tert-butyl functionality. The preferred conformations of methyl functional trimers are modeled based on preferred dimer conformations.