6,7-dichloro-2,3-dihydrochromen-4-one

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 500 mg of 3-(3,4-dichlorophenoxy)propionic acid, is stirred in 50 ml. of liquid hydrogen fluoride surrounded by a solid carbon dioxide/acetone bath. This slurry is allowed to stir overnight without replenishing the cooling bath. The hydrogen fluoride is removed by a stream of air. The residual solid was then dissolved in ether and washed with 10% aqueous sodium carbonate solution. The organic layer is dried over anhydrous magnesium sulphate and the solvent is evaporated to give the required chromanone with sufficient purity. The hydrogen fluoride is removed by a stream of air The residual solid was then dissolved in ether washed with 10% aqueous sodium carbonate solution The organic layer is dried over anhydrous magnesium sulphate the solvent is evaporated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 500 mg of 3-(3,4-dichlorophenoxy)propionic acid, is stirred in 50 ml. of liquid hydrogen fluoride surrounded by a solid carbon dioxide/acetone bath. This slurry is allowed to stir overnight without replenishing the cooling bath. The hydrogen fluoride is removed by a stream of air. The residual solid was then dissolved in ether and washed with 10% aqueous sodium carbonate solution. The organic layer is dried over anhydrous magnesium sulphate and the solvent is evaporated to give the required chromanone with sufficient purity. The hydrogen fluoride is removed by a stream of air The residual solid was then dissolved in ether washed with 10% aqueous sodium carbonate solution The organic layer is dried over anhydrous magnesium sulphate the solvent is evaporated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 6,7-dichloro-2,3-dihydro-4H-1-benzopyran-4-one (59.7 g), methanol (750 ml), water (75 ml), potassium carbonate (76 g), hydroxylamine HCl (76.4 g) was heated at reflux for 4 hours, then poured into ice-water: the oxime of 6,7-dichloro-2,3-dihydro-4H-1-benzopyran-4-one was filtered off, washed with water, with a small volume of ether, then dried in air. Yield: 62.7 g; m.p. 192°-193°. was heated at reflux for 4 hours the oxime of 6,7-dichloro-2,3-dihydro-4H-1-benzopyran-4-one was filtered off washed with water, with a small volume of ether dried in air

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 500 mg of 3-(3,4-dichlorophenoxy)propionic acid, is stirred in 50 ml. of liquid hydrogen fluoride surrounded by a solid carbon dioxide/acetone bath. This slurry is allowed to stir overnight without replenishing the cooling bath. The hydrogen fluoride is removed by a stream of air. The residual solid was then dissolved in ether and washed with 10% aqueous sodium carbonate solution. The organic layer is dried over anhydrous magnesium sulphate and the solvent is evaporated to give the required chromanone with sufficient purity. The hydrogen fluoride is removed by a stream of air The residual solid was then dissolved in ether washed with 10% aqueous sodium carbonate solution The organic layer is dried over anhydrous magnesium sulphate the solvent is evaporated