One-step dehydrohalogenation-rearrangement-hydrogenation of 1,1-bis(4-hydroxyaryl)-2-haloethanes

DETAILED DESCRIPTION OF THE INVENTION Dehydrohalogenation-rearrangement-hydrogenation of 1,1-bis(4-hydroxyaryl)-2-haloethanes can be accomplished in one step under suitable acidic reaction conditions to yield 1,2-bis(4-hydroxyaryl)ethanes.
In accordance with the present process, the 1,1-bis(4-hydroxyaryl)-2-haloethane is contacted in an aliphatic carboxylic acid solvent containing carboxylic acid salt at dehydrohalogenation-rearrangement-hydrogenation conditions with gaseous hydrogen and a hydrogenation catalyst for a time sufficient to cause dehydrohalogenation-rearrangement-hydrogenation of the 1,1-bis(4-hydroxyaryl)-2-haloethane.
Suitable 1,1-bis(4-hydroxyaryl)-2-haloethanes which can be used to effect the one-step dehydrohalogenation-rearrangement-hydrogenation according to the present process are in general represented by the formula: ##STR1## in which X independently represents a halogen selected from the group consisting of chlorine, bromine, and iodine; Y independently represents a non-interfering hydrocarbyl group, including, for example, lower alkyl of 1 to 6 carbon atoms and phenyl; and a and b each independently represent an integer from zero(0) to 4, inclusive, with the proviso that the sum of a and b, with respect to each aryl ring, does not exceed 4.
The term "non-interfering hydrocarbyl group" is employed herein to mean a hydrocarbon group which can be present in the 1,1-bis(4-hydroxyaryl)-2-haloethane without rendering the dehydrohalogenation-rearrangement-hydrogenation reaction substantially inoperative under process conditions.
Such groups, as noted hereinabove, include alkyl of 1 to 6 carbon atoms and phenyl.
Of the halogens present in the 1,1-bis(4-hydroxyaryl)-2-haloethanes, chlorine is generally preferred in that the compounds, when employed as the organo-chlorides, as well as the chloride ion released during the course of the one-step dehydrohalogenation-rearrangement-hydrogenation exhibit less tendency to deactivate or poison the hydrogenation catalyst.
This problem, however, is substantially reduced or even eliminated altogether when, as noted hereinbelow, palladium on charcoal is employed as the hydrogenation catalyst