Vibrational assignments of 3-alkyl-3,4-dihydro-6-methyl-2H-1,3-benzoxazines in the fingerprint region

Fundamental vibrational assignments of a series of 3-alkyl-3,4-dihydro-6-methyl-2H-1,3-benzoxazines are made by analysis of the fingerprint region (2000-500 cm−1) of their infrared and Raman spectra. The linear amine group is varied from methyl to amyl which alters the position of the peaks resulting from the oxazine ring but has little influence on the benzene ring vibrations. To aid in the peak assignments, 3,4-dideutero-3,6-dimethyl-2D-1,3-benzoxazine has also been synthesized. The structures of the compounds are verified by 1H and 13C NMR.