Hexamethylenetetramine → Benzo(b)thiophene-6-carboxaldehyde

Participants

Reaction Conditions

Reaction Steps

In 350 mL of benzene is dissolved 23.53 g of a mixture of 4-methylbenzo[b]thiophene and 6-methylbenzo[b]thiophene, to which are added 0.77 g of benzoyl peroxide and 39.56 g of N-bromosuccinimide. The mixture thus formed is heated under reflux for 2 hours. After cooling the mixture to 50° C., 70 mL of acetic acid, 70 mL of water and 44.51 g of hexamethylenetetramine are added, and the mixture thus formed is heated under reflux for 2 hours. The solvent is distilled off under reduced pressure, the residue is mixed with water and ethyl acetate, and pH is adjusted to 7.5 with potassium carbonate. The organic layer is separated, washed with water and saturated aqueous solution of sodium chloride successively, and dried over anhydrous magnesium sulfate. The solvent is distilled off under reduced pressure, and the residue is purified by column chromatography (eluent: hexane:ethyl acetate=19:1 to 15:1). Thus, 5.24 g of benzo[b]thiophene-4-carboaldehyde, 5.09 g of benzo[b]thiophene-6-carboaldehyde and 6.71 g of mixture thereof are obtained as oily products.

Provenance & Evidence