Reducing meta content of isomeric mixtures of halo substituted alkylbenzenes

A method of reducing the content of metachloroethylbenzene in a mixture with parachloroethylbenzene comprising

• (A) adding to said mixture about 0.01 to about 1 wt % of a Friedel-Crafts catalyst;
• (B) heating said mixture to a temperature between 0° C. and reflux;
• and
• (C) adding about ¼ to about 5 equivalents of BR2 to said mixture per equivalent of said metachloroethylbenzene;
• (D) after said Br2 has reacted and formed HBr, adding Cl2 to said mixture to react with said HBr and form additional Br2;
• and
• (E) heating said mixture to a temperature above the boiling point of said parachloroethylbenzene but below the boiling point of said brominated metachloroethylbenzene.

A method of reducing the content of a metachloroalkylbenzene having the general formula

• where R is alkyl from C2 to C6 in a mixture with its parachloroalkylbenzene isomer comprising
• (A) adding to said mixture about 0.01 to about 1 wt % of a Friedel-Crafts catalyst;
• (B) heating said mixture to a temperature between 0° C. and reflux;
• (C) adding about 1 to about 2.5 equivalents of Br2 to said mixture per equivalent of said metachloroalkylbenzene;
• (D) after said bromine has reacted and formed HBr, adding chlorine to said mixture to react with said HBr and form additional bromine;
• and
• (E) heating said mixture to a temperature above the boiling point of said parachloroalkylbenzene isomer but below the boiling point of said brominated metachloroalkylbenzene.

A method of separating the meta isomer of an alkylbenzene 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, comprising
• (A) adding to said mixture about 0.0001 to about 5 wt % of a Friedel Crafts catalyst;
• (B) exposing said mixture to about ½ to about 10 equivalents of a brominating agent per equivalent of said meta isomer, whereby said meta isomer is preferentially brominated;
• and
• (C) heating said mixture to a temperature above the boiling point of said other isomers but below the boiling point of said brominated meta isomer.