Production of dibenzopyrans, their isomeric fluorenols and dibenzothiopyrans

摘要

Phenols and thiophenols having an ortho-phenyl substituent react with most aldehydes and ketones in very strongly acidic liquid media to form a dibenzopyran or dibenzothiopyran. The dibenzopyrans, but not the dibenzothiopyrans, can be isomerized to their corresponding fluorenols. The pyran or thiopyran ring can be cleaved chemically or electrochemically to produce phenols and thiophenols which have an ortho substituent in the ortho position of the phenyl substituent of the starting phenol or thiophenol which is characteristic of the aldehyde or ketone reactant. These products as well as the fluorenols, being phenolic bodies, are useful as stabilizers and antioxidants.