A PROCESS FOR THE PREPARATION OF A WATER SOLUBLE DIRECT GREEN POLYAZO DYESTUFFS MIXTURE IN SITU AND WATER SOLUBLE DIRECT GREEN POLYAZO DYESTUFFS MIXTURE OBTAINED THEREBY

Abstract: A process for the preparation of a mixture of water soluble direct green polyazo dyestuffs comprising phosgenation or condensation of a mordant yellow dye and an acid green dye using phosgene gas in an aqueous alkaline medium at a temperature between 50°C to 80°C and isolating or recovering the dyestuffs mixture from the phosgenation or condensation reaction mass.

Description: This invention is concerned with a process for the preparation of a water soluble direct green polyazo dyestuffs mixture in situ and water soluble direct green polyazo dyestuffs mixture obtained thereby. Water soluble direct green dyestuffs commonly used for directly dyeing cellulose materials such as cotton or jute fibres or paper are benzidine based. Water soluble direct green benzidine dyestuffs are prepared by tetra-azotising benzidine followed by coupling first with 1-amino-8-hydroxy-naphthalene-3,6-disulfonic acid (H-acid), secondly with aniline diazo or substituted aniline diazo, in which the substituents are chloro, nitro, carboxy or a sulphonic acid group and finally with phenol, resorcinol or salicylic acid. Benzidine is reported to be carcinogenic and has already been banned in some countries and is being banned in several other countries. Strenuous efforts are, therefore, in progress to find water soluble direct green dyestuffs which are not benzidine based. As a result of extensive research and experiments, we have been able to obtain a mixture of water soluble direct green polyazo dyestuffs which has been found to be excellent for directly dyeing cellulose materials such as cotton or jute fibres or paper or leather. Accordingly, an object of the present invention is to provide a process for the preparation of a mixture of water soluble direct green polyazo dyestuffs in situ . According to the present invention there is thus provided a process for the preparation of a mixture of water soluble direct green polyazo dyestuffs having formulae IA, IIA and IIIA wherein R is hydrogen, sodium or potassium and X is a lower alkyl group such as a methyl or ethyl group, a lower alkoxy group such as a methoxy or ethoxy group, a chloro or nitro group, a carboxy or sulfonic acid group or hydrogen at the 2, 3 or 4 position, said process comprising phosgenation or condensation of 1 part by weight of a mordant yellow dye of formula IV wherein R is as defined above, and 3 to 12 parts by weight of acid green dye of formula V wherein R and X are as defined above using phosgene gas of the formula COCl₂ in an aqueous alkaline medium at a temperature of from 50°C to 80°C to form a mixture of dyestuffs of the said formulae IA, IIA and IIIA in situ , and isolating or recovering the said mixture from the phosgenation or condensation reaction mass. Preferably, the phosgenation or condensation reaction is carried out at a temperature of from 65°C to 75°C. Preferably, the alkali used in the aqueous alkaline medium is sodium or potassium hydroxide, carbonate or bicarbonate. Preferably, 1 part by weight of the mordant yellow dye of the said formula IV and 6 parts by weight of the acid green dye of the said formula V are phosgenated or condensed. Isolation or recovery of the mixture of dyestuffs of the formulae IA, IIA and IIIA from the phosgenation or condensation reaction mass is preferably carried out by precipitating the said mixture by treating the said reaction mass with an alkali salt such as sodium or potassium chloride or sulphate or an aqueous alkali salt solution such as that of sodium or potassium chloride or sulphate or with a mineral acid such as hydrochloric acid or sulphuric acid at a temperature from 30°C to 90°C and drying the precipitate at a temperature from 85° to 95°C. The present invention will now be illustrated by the following Examples, in which all the parts are by weight. In the Examples, the abbreviation C.I. means Colour Index. EXAMPLE 1 10.0 parts of the mordant yellow dye of the formula [Mordant Yellow 12 (C.I. No. 14045). Ref. Colour Index published by The Society of Dyers and Colourists, the United Kingdom and American Association of Textile Chemists and Colourists, The United States of America] and 61.4 parts of the acid green dye of the formula [Acid Green 20, (C.I. No. 20495). Ref. Colour Index] were stirred with 480 parts of water. The resulting reaction mass was heated to 65-70°C and 15 parts of phosgene gas was passed therethrough over a period of 6 to 8 hours maintaining alkaline test by the addition of 15 to 20 parts of sodium carbonate. At 70-75°C, the reaction mass was then treated with sodium chloride and filtered. The precipitate was dried at 85-90°C in an electric oven to obtain a dyestuffs mixture of the formulae 3A, 4A and 5A. On chemical analysis, the percentages of the dyestuffs of the formulae 3A, 4A and 5A in the mixture was found to be Formula 3A: 60 to 65% Formula 4A: 20 to 25% Formula 5A: 5 to 10% Using the dyestuff mixture of Example 1, cotton fibres, jute fibres, paper and leather were dyed in known manner to obtain a brilliant green shade. The tone and fastness properties of the cotton and jute fibres and paper dyed with the dyestuff mixture of Example 1 were found to be as good as those obtained with water soluble direct green benzidine dyestuffs namely Direct Green 6 (C.I. No. 30295 in the Colour Index) and Direct Green 8 (C.I. no. 30315 in the Colour Index) under identical dyeing conditions. The dyestuffs mixture of the present invention is thus an ideal substitute for benzidine based water soluble direct green dyestuffs.

Claims: 1. A process for the preparation of a mixture of water soluble direct green polyazo dyestuffs having formulae IA, IIA and IIIA wherein R is hydrogen, sodium or potassium and X is a lower alkyl group such as a methyl or ethyl group, a lower alkoxy group such as a methoxy or ethoxy group, a chloro or nitro group, a carboxy or sulfonic acid group or hydrogen at the 2, 3 or 4 position, said process comprising phosgenation or condensation of 1 part by weight of a mordant yellow dye of formula IV wherein R is as defined above, and 3 to 12 parts by weight of acid green dye of formula V wherein R and X are as defined above using phosgene gas of the formula COCl₂ in an aqueous alkaline medium at a temperature of from 50°C to 80°C to form a mixture of dyestuffs of the said formulae IA, IIA and IIIA insitu, and isolating or recovering the said mixture from the phosgenation or condensation reaction mass. 2. A process as claimed in Claim 1, wherein the phosgenation or condensation reaction is carried out at a temperature of from 65° to 70°C. 3. A process as claimed in Claim 1 or 2, wherein the alkali used in the aqueous alkaline medium is sodium or potassium hydroxide, carbonate or bicarbonate. 4. A process as claimed in any one of Claims 1 to 3, wherein 1 part by weight of the mordant yellow dye of the said formula IV and 6 parts by weight of the acid green dye of the said formula V are phosgenated or condensed.

Inventors: BHATT, GIRISH ISHWARLAL R & D LAB., KULKARNI, SUBRAO SHRINIVAS R & D LAB., PATEL, NAGAJIBHAI TALJABHAI R & D LAB., Bhatt, Girish Ishwarlal R &amp; D Lab., Kulkarni, Subrao Shrinivas R &amp; D Lab., Patel, Nagajibhai Taljabhai R &amp; D Lab.
Applicants: ATUL PRODUCTS LIMITED
Application year: 1986
Main classification: C09B43
IPC codes: C09B43, C09B67