| abstract |
PURPOSE: To inexpensively obtain a corresponding ortho-methylated deriv. having relatively high purity under mild reaction conditions by cleaving an ortho- hydroxylated aromatic Mannich bases by a novel catalytic hydrogenation. n CONSTITUTION: An ortho-hydroxylated aromatic Mannich base, for example, 5-acetamide-2[(N,N-dimethylamino)methyl]phenol is catalytically hydrogenated in a neutral or alkaline aq. solvent in the presence of a metal catalyst (palladium/carbon is pref.) on a proper support under a hydrogen pressure of 30-75 psi, pref., 50-60 psi to obtain an ortho-methylated hydroxy aromatic compd. (e.g.; 5-amino-0-cresol). As the Mannich base, either one of compds. represented by formulae I-V (wherein X, Y, Z, R 1 and R 2 are each H, an alkyl, NO 2 , NH 2 , alkoxy, halogen, aryl or acetamide) are pref. n COPYRIGHT: (C)1990,JPO |