Polycyclic dyes

Abstract: Polycyclic dyes of Formula A: wherein: X is -C₂₋₄-alkyl; and Y is C₁₋₄-alkyl. X is preferably ethyl and Y is preferably C₁₋₃-alkyl, more preferably C₁₋₂-alkyl. It is further preferred that when X is ethyl, Y is ethyl or methyl and especially the latter.

Description: This specification describes an invention which relates to certain novel polycyclic dyes which have improved dyeing properties. Example 27 of EP-A-33583 has the structure: According to the present invention there are provided polycyclic dyes of Formula A: wherein: X is -C₂₋₄-alkyl; and Y is C₁₋₄-alkyl. X is preferably ethyl and Y is preferably C₁₋₃-alkyl, more preferably C₁₋₂-alkyl. It is further preferred that when X is ethyl, Y is ethyl or methyl and especially the latter. The dyes of the present invention are conveniently prepared by reacting a phenyltartronic acid of Formula B: wherein X and Y are as defined above with a compound of Formula C: and oxidation of the intermediate compound to dehydrogenate the peripheral heterocyclic rings. The present process may be performed by heating the reactants in a melt but preferably in an acidic medium, preferably an organic acid, and especially an alkanecarboxylic acid such as acetic acid, propionic acid or butyric acid. The process is preferably performed at a temperature from 50°C to 100°C, especially 70°C to 100°C, where a solvent is present, conveniently under reflux. Reaction is preferably continued until all the starting materials are consumed which can take up to 25 hours. The final oxidation step may be effected by any convenient oxidising agent for dehydrogenating a carbon-carbon single bond, such as a persulphate or hydrogen peroxide. A compound of Formula C may prepared by reacting mandelic acid with 1,4-dihydroxybenzene. This reaction is conveniently performed in an acidic medium as described above for the preparation of the compound of Formula A but at a lower temperature in the range 40°C to 80°C especially from 49°C to 75°C. It is preferred to perform the process in the presence of a strong acid catalyst. It is especially preferred that the catalyst is sulphuric acid. The compounds of Formula A described above give blue shades when applied to synthetic fibres, especially polyesters, by disperse dyeing processes, and build up exceptionally well to give strong navy shades for example the dye of Formula A where X is ethyl and Y is methyl has superior build up on polyester to the closest dye disclosed previously in European Patent Application No. 0363034. Specific examples of preferred dyes of Formula A are shown in Table 1: The invention is further illustrated by the following example in which all parts and percentages are by weight unless otherwise indicated. Example 1 A mixture of 2.26 parts of 5-hydroxy-2-oxo-3-phenyl-2,3-dihydrobenzofuran, 4.9 parts of 4-amino-3-ethyl-5-methylphenyl tartronic acid (dipotassium salt) and 50 parts glacial acetic acid was stirred under reflux for 12 hours before adding 2.5 parts of ammonium persulphate and continuing heating for a further 1 hour. After cooling to ambient temperature the precipitated solid was filtered, washed acid-free with water, washed with methanol and further purified by column chromatography to give 3-phenyl-7-(4-amino-3-ethyl-5-methylphenyl)-2,6-dioxo-2,6-dihydrobenzo[1:2-b, 4'5-b']difuran. The product dissolved in dichloromethane to give a blue solution with an absorption maximum at 580nm. When applied to polyester material from an aqueous dispersion it built up well to give navy blue shades with excellent fastness to heat and wash treatments. Example 2 The procedure of Example 1 was repeated except that the 4.9 parts of 4-amino-3-ethyl-5-methylphenyl tartronic acid (dipotassium salt) was replaced by 4.9 parts of 4-amino-3,5-diethylphenyltartronic acid (dipotassium salt), to give 3-phenyl-7-(4-amino-3,5-diethylphenyl)-2,6-dioxo-2,6-dihydrobenzo[1:2-b, 4:5-b']difuran. This dissolved in dichloromethane to give a blue solution with an absorption maximum at 584nm. When applied to polyester material from an aqueous dispersion it built up well to give navy blue shades with excellent fastness to heat and wash treatments.

Claims: A polycyclic dye of the formula: wherein: X is -C₂₋₄-alkyl and Y is C₁₋₄-alkyl. The polycyclic dye according to claim 1 wherein X is ethyl and Y is methyl. The polycyclic dye according to claim 1 wherein X is ethyl and Y is ethyl.

Inventors: HALL NIGEL, ROBINSON FRANK, HALL, NIGEL, ROBINSON, FRANK
Applicants: ZENECA LTD, ZENECA LIMITED
Application year: 1991
Main classification: C09B57
IPC codes: C07D493, C09B57