with another portion of meoh 50 ml then p950 ligroin to yield 90 44 8 g of a bright orange product more of the product 4 can be recovered if the mother liquor is concentrated chilled and the process above repeated note alternatively the oxidation can be carried out in methylene chloride however the conversion does not take place as cleanly as in toluene furthermore methylene chloride use in a production setting is not desirable for safety and disposal reasons a 40 g 97 mmol 1 eq sample of 1 4 benzenedicarboxylic acid 2 5 bis phenylamino dimethyl ester 4 65 ml large excess necessary for ease of stirring of iodobenzene 5 27 g 194 mmol 2 eq of potassium carbonate 12 3 g 197 mmol 2 eq of copper and 3 g of copper i iodide were combined in a 250 ml round bottom flask the resulting mixture was too thick to stir efficiently so about 10 ml of toluene were also added for ease of stirring the toluene gradually evaporated off the mixture was refluxed overnight around 150 160 u00b0 c the originally red mixture turned greenish brown tlc indicated one spot with very little baseline impurities the thick mixture was cooled to room temperature slurried in methylene chloride or thf and the inorganic solids were removed by filtration the solid residue which still contained product 6 was repeatedly washed with methylene chloride or thf and the washes were concentrated to a syrup the concentrate was chilled in ice the resulting solid was isolated by filtration.