UNUSUAL SYNTHESIS, STRUCTURE, AND THERMOCHROMIC PROPERTIES OF NOVEL STERICALLY HINDERED CYCLOHEXADIENES

Article abstract of DOI:10.1007/BF00961363

Oxidation of 4-<α-morpholino-α-(2-hydroxyphenyl)>methyl-2,6-di-(tert-butyl)phenol (I) follows an unusual course, with formal loss of the benzyl carbon atom, to give 2,6-di(tert-butyl)-4-morpholino-4-(2-hydroxyphenyl)cyclohexa-2,5-dienone (II), which is thermochromic in solution.This property is due to the dissociation of (II) into morpholine and 3',5'-di(tert-butyl)-2,4'-diphenoxyquinone.The structure of (II) was established directly by x-ray diffraction, which enabled its conformational features to be related to its thermochromic properties.An x-ray examination of 3,3',5,5'-tetra(tert-butyl)-2,4'-diphenoquinone (X), together with the direct synthesis of the thermochromic analog of (II) (2,6-di(tert-butyl)-4-morpholino-4-<2-hydroxy-3,5-di(tert-butyl)phenyl>cyclohexa-2,5-dienone) (XI) from (X) and morpholine, confirmed the proposed mechanism of thermochromic dissociation.