2,3-dimethyl-1,3-bis-(3-sulfo-propyl)-3H-indolium sodium salt → 3-methyl-2-((1E,3E)-4-phenylamino-buta-1,3-dienyl)-1,3-bis-(3-sulfo-propyl)-3H-indolium sodium salt

Participants

Reaction Conditions

Reaction Steps

0.822 g (2 mmol) 2,3-dimethyl-1,3-bis-(3-sulfo-propyl)-3H-indolium sodium salt 7 and 0.65 g (2.5 mmol) malonaldehyde-bisphenylimine-hydrochloride are dissolved in a mixture of 10 ml acetic acid and 20 ml acetic anhydride and stirred at 120° C. for four hours. The solvent is removed in vacuum after cooling to room temperature. The residue is washed carefully with ethyl acetate. A dark brown solid is obtained which is processed without further purification.

Provenance & Evidence