Steric effects on forming different by-products in the formylation reaction of 2,4-dialkylphenol (dialkyl = t-Bu/t-Bu, t-Bu/Me and Me/Me) proved by their structural and spectral characterizations

In the formylation reaction of 2,4-dialkylphenol (2,4-di-tert-butylphenol, 2-tert-butyl-4-methylphenol and 2,4-dimethylphenol) in the presence of hexamethylenetetramine, steric effects of alkyl groups play important roles in forming different types of by-products, namely 2,4-di-tert-butyl-6-[(6,8-di-tert-butyl-2H-1,3-benzoxazin-3(4H)-yl)methyl]phenol (1), 2-tert-butyl-4-methyl-6-[(6-tert-butyl-8-methyl-2H-1,3-benzoxazin-3(4H)-yl)methyl]phenol (2) and tris(2-hydroxy-3,5-dimethylbenzyl)amine hydrochlorate (3). These three compounds are fully characterized and single-crystal structures of 1 and 3 are further elucidated.