PROCESS FOR PREPARING STILBENE DIOLS

摘要

Described is a process for preparing dihydroxy stilbene compounds which includes the steps of: (a) combining (i) at least one coumpound containing one phenolic hydroxyl group per molecule with (ii) a Lewis acid which may be mixed with the compound at a temperature above the melting point temperatures of (i) and (ii) to form a solution of (i) in (ii), which will remain in liquid form when the temperature of the solution is brought to a temperature in the range of from -30 DEG C to 10 DEG C, wherein (i) and (ii) were combined in amounts sufficient to provide a mole ratio of (ii):(i) of at least 0.3:1.0; (b) contacting (iii) at least one alpha-haloketone compound or the corresponding ketal or hemiketal, or at least one alpha-haloaldehyde compound or the corresponding acetal or hemiacetal with the solution obtained from step (a) under reaction conditions sufficient to form the corresponding halogen-containing bisphenol compound, wherein (iii) is employed in an amount of at least 10 mole percent of the molar amount of (i) present in the solution obtained from step (a); and (c) dehydrohalogenating the halogen-containing bisphenol compound under reaction conditions sufficient to form the corresponding dihydroxy stilbene compound. It has been discovered that the Lewis acid provides an effective solvent for the reaction between (i) and (ii) in step (a), thereby reducing or eliminating the need for using inert reaction solvents. A substantial absence of inert solvents in the reaction mixture results in a process that is relatively fast and selective to the desired product.