反应详情

300 mg (0.55 mmol) of 2,3-dimethyl-5-sulfo-1,3-di(4-sulfobutyl)-3H-indolium and 190 mg (0.66 mmol) of N-[5-(phenylamino)-2,4-pentadienylidene]aniline monohydrochloride were heated in 6 mL acetic anhydride-acetic acid (1:1, v/v) mixture for 30 min at 110° C. After cooling the product was precipitated with ethyl acetate, filtered off and washed with ether to give 240 mg (56%) of 4-[2-[6-anilino-1,3,5-hexatrienyl]-3-methyl-5-sulfo-3-(4-sulfobutyl)-3H-1-indoliumyl]-1-butanesulfonate. λmax (abs) 505 nm (methanol). This product was used for following step without additional purification.

1. temperatureAfter cooling the product
2. customwas precipitated with ethyl acetate
3. filtrationfiltered off
4. washwashed with ether