METHOD FOR PRODUCING 4-(OR 5)-AMINOTETRA-C-C-ALKYLRODAMINES Russian patent published in 2021 - IPC C07D311/82 C09B11/28 

FIELD: analytical chemistry.

SUBSTANCE: invention relates to a method for the production of 4-(or 5)-aminotetra-C₁-C₂-alkylrodamines, which can be used in analytical chemistry. The method consists in the reduction of the corresponding nitrotetraalkylrodamines. The initial products are a mixture of isomers of 4-(or 5)-nitrotetra-C₁-C₂-alkylrodamines obtained by nitrophthalic anhydride reacting with C₁-C₂-dialkylaminophenol. Tin chloride is used as a reducing agent. The process includes the following sequential steps: treatment of the initial mixture of isomers of 4-(or 5)-nitrotetra-C₁-C₂-tetraalkylrodamine with hydrochloric acid and heating of the reaction mass at a temperature of 50-60ºC until the initial product is completely dissolved, cooling the resulting solution to 25-30ºC and then adding to it a solution of tin chloride in an aqueous solution of hydrochloric acid in amounts taken from the calculation of 0.3-0.4 mole of tin chloride to 0.025-0.04 mole of nitrotetraalkylrodamine, and boiling the reaction mixture for 1.0-1.5 hours, the subsequent cooling of it to room temperature and pouring it into a dilute aqueous solution of caustic soda until complete precipitation, which is then filtered, extracted with acetone and the extract is evaporated until dry. After that, the obtained isomers of aminotetraalkylrodamines are separated into individual isomers by applying the resulting mixture of isomers in the form of an acetone solution to a chromatographic column filled with aluminum oxide, and washing the isomer of 5-aminotetra-C₁-C₂-alkylrodamine from the column with acetone, followed by washing the isomer of 4-aminotetra-C₁-C₂-alkylrodamine with ethyl alcohol and isolating the target products by evaporation of eluants.

EFFECT: increase in the process efficiency, low energy consumption and improved quality of the resulting amino derivative.

1 cl, 2 ex