1-amino-2-bromo-4-hydroxyanthracene-9,10-dione

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

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

Procedure: The progress of the bromination may be followed by thin layer chromatography or high pressure liquid chromatography so as to insure that the byproducts, 1-amino-2-bromoanthraquinone and 1-amino-4-bromoanthraquinone, represent less than 1% of the product mixture. This is essential, since hydroxylation of these two products results in 1-amino-2-hydroxyanthraquinone and 1-amino-4-hydroxyanthraquinone respectively. Both products are isolated along with the desired 1-amino-2-bromo-4-hydroxyanthraquinone and therefore give rise to a product with unsatisfactory quality.

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

Procedure: The progress of the bromination may be followed by thin layer chromatography or high pressure liquid chromatography so as to insure that the byproducts, 1-amino-2-bromoanthraquinone and 1-amino-4-bromoanthraquinone, represent less than 1% of the product mixture. This is essential, since hydroxylation of these two products results in 1-amino-2-hydroxyanthraquinone and 1-amino-4-hydroxyanthraquinone respectively. Both products are isolated along with the desired 1-amino-2-bromo-4-hydroxyanthraquinone and therefore give rise to a product with unsatisfactory quality.

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:110.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Hydrolysis is carried out by adding 195.3 parts of 66% oleum and 16 parts of paraformaldehyde to the reaction mixture and heating it to 110° C. The mixture is heated in a stream of nitrogen to 110° C. until the presence of 1-amino-2,4-dibromoanthraquinone can no longer be detected. The reaction time is from 1 to 2 hours. Upon completion of the reaction, the reaction mixture is cooled to room temperature and diluted with 523 parts of water. The precipitated crystals of 1-amino-2-bromo-4-hydroxyanthraquinone are isolated by filtration and washed with water until neutral, affording 149 parts of product, corresponding to a yield of 93.7%, based on 1-aminoanthraquinone. Melting point: 226°-228° C. (lit.: 231°-232° C.). According to elemental analysis, the bromine content is 25.0% (calculated: 25.2%). Hydrolysis Upon completion of the reaction the reaction mixture is cooled to room temperature

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

Procedure: Further, German Offenlegungsschrift No. 28 17 890 discloses a one-vessel process and starting from 1-aminoanthraquinone, which is first converted by bromination into 1-amino-2,4-dibromoanthraquinone, which is in turn, without being isolated, reacted in sulfuric acid, in the presence of boric acid, to give 1-amino-2-bromo-4-hydroxyanthraquinone. The process is simple to perform and affords the desired product in good yield. The shortcoming of this process is, however, that the mixture of dilute sulfuric acid and boric acid formed during working up cannot be easily regenerated. For example, glassy residues are obtained and it is often necessary to neutralise the waste sulfuric acid, e.g. with calcium carbonate or slaked lime. In addition, the 1-amino-2-bromo-4-hydroxyanthraquinone obtained by this process is contaminated by compounds that are brominated in the 3-position. Such impurities result in changes in shade during the dye synthesis, i.e. standard shade dyes are not obtained. without being isolated

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

Procedure: Ya. B. Shteinberg and S. S. Tkachenko, Zh. Prikl. Khim. 49 (1976) 4, 904-905, describe a process for the preparation of 1-amino-2-phenoxy-4-hydroxyanthraquinone in an aqueous medium. In this process, 1-amino-2-bromo-4-hydroxyanthraquinone is reacted with phenol in aqueous potassium hydroxide solution in the presence of dispersants at 150° C. The authors claim yields of 87-90%. On repeating this process with various dispersants, we were unable to obtain a phenoxyanthraquinone derivative which could be used as a dye. In every case, the content of 1-amino-2-phenoxy-4-hydroxyanthraquinone in the products was less than 80%. The authors claim yields of 87-90%

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

Procedure: The progress of the bromination may be followed by thin layer chromatography or high pressure liquid chromatography so as to insure that the byproducts, 1-amino-2-bromoanthraquinone and 1-amino-4-bromoanthraquinone, represent less than 1% of the product mixture. This is essential, since hydroxylation of these two products results in 1-amino-2-hydroxyanthraquinone and 1-amino-4-hydroxyanthraquinone respectively. Both products are isolated along with the desired 1-amino-2-bromo-4-hydroxyanthraquinone and therefore give rise to a product with unsatisfactory quality.