Quality of phthalic acids improved by haloacetic acid
AssigneeThe Standard Oil Company
InventorGeorge E. Kuhlmann
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Abstract
Phthalic acids of improved quality are obtained direct from oxidation of xylenes with molecular oxygen in oxidation zone having small amounts of haloacetic acid present in liquid phase acetic acid solution of one or more heavy metal oxidation catalyst and bromide ion releasing bromine-containing compound. Particularly useful haloacetic acids are those having aqueous dissociation constant K.sub.A greater than 1.0 .times. 10.sup..sup.-3. Such quality improvement is manifested by decrease in carboxybenzaldehyde and toluic acid impurity contents and/or metal salt content.
Claims5
A method for preparing a phthalic acid of improved quality by the oxidation of a xylene hydrocarbon with molecular oxygen in an oxidation zone containing a liquid phase of acetic acid solvent having dissolved therein one or more of cobalt, manganese or cerium and bromine as catalyst components at a temperature in the range of 50.degree. to 275.degree.C., which improvement consists essentially of also having in the acetic acid solution a catalytic amount of a mono-haloacetic acid having an aqueous dissociation constant K.sub.A greater than 1.0 .times. 10.sup..sup.-3 wherein said catalytic amount is in the range of 0.1 to 12 weight percent of the xylene.
Dependencies are inferred from the claim text.