Abstract: Disclosed is a method of separating the meta isomer of a haloalkylbenzene having the general formula from a mixture with at least one other isomer, where X is Cl or Br and R is alkyl from C2 to C12 or cycloalkyl from C3 to C8. About 0.0001 to about 5 wt % of a Friedel-Crafts catalyst is added to the mixture and the mixture is exposed to a brominating agent which preferentially brominates the meta isomer. The mixture is then heated at a temperature above the boiling point of the other isomers but below the boiling point of the brominated meta isomer.

Abstract: Disclosed is a method of making high purity 2,4- and 3,4-dichlorotoluene from parachlorotoluene that contains some metachlorotoluene. About 0.0001 to about 5 wt % of a Friedel-Crafts catalyst and about 0.5 to about 10 equivalents of a brominating agent are added to the parachlorotoluene. The metachlorotoluene is brominated, but most of the parachlorotoluene is not brominated. Without separating the brominated products from the unbrominated products, about 0.5 to about 1.5 equivalents of a chlorinating agent are added, whereby only the unbrominated products (i.e., the parachlorotoluene) are chlorinated. The resulting 2,4-dichlorotoluene and 3,4-dichlorotoluene can be separated by distillation.

Abstract: Disclosed is a method of separating the meta isomer of a halotoluene having the general formula ##STR1## from a mixture with at least one other isomer, where X is Cl or Br. About 0.0001 to about 5 wt % of a Friedel-Crafts catalyst is added to the mixture and the mixture is exposed to a brominating agent which preferentially brominates the meta isomer. The mixture is then heated at a temperature above the boiling point of the other isomers but below the boiling point of the brominated meta isomer.

Abstract: Disclosed is method of sulfodechlorinating an aromatic compound. A composition is prepared of (1) an aromatic compound having the general formula ##STR1## Where R is CHO or COOH and n is 1 to 3, (2) an alkali metal or alkaline earth metal sulfite or bisulfite in an amount stoichiometric to about 20 mole % in excess of stoichiometric, (3) water in an amount sufficient to form a solution of the sulfite or bisulfite, and (4) sufficient base to raise the pH of the composition to about 10 to about 14. The composition is heated at about 150 to about 200.degree. C. No catalyst is present in the composition.

Abstract: Disclosed is a method of making oxydiphthalic anhydride from oxydiphthalic acid. The oxydiphthalic acid is mixed with an organic liquid that codistills with water and the resulting slurry is heated to the boiling point of the slurry to remove any water. About 1 to about 4 moles of acetic anhydride per mole of oxydiphthalic acid are added to the slurry and the slurry is heated to a temperature between 50.degree. and 160.degree. C. until the oxydiphthalic acid content thereof is less than 0.1 weight percent. The slurry is filtered and the filter cake is heated to a temperature between about 180.degree. C. and below its melting point for about 12 to about 24 hours.

Abstract: A process for the preparation of purified oxydiphthalic acid from impure oxydiphthalic anhydride, by treating with a mixture of water and propionic acid or butyric acid to produce oxydiphthalic acid. The acid may be treated to reform oxydiphthalic anhydride. The most effective composition range for the acid-water mixture is from about 25% acid to 75% acid.