DD207920B1 - METHOD FOR THE PRODUCTION OF A MONOAZO DYE - Google Patents

Description

Field of application of the invention

The. The invention relates to a process for the preparation of the monoazo dye of the formula

This monoazo dye is used primarily as a so-called "blue component" in the Mischbobaltierung with suitable o, o-Dihydroxymonoazofarbstoffen, which ultimately dyes are obtained, the wool and polyamide from acetic acid or neutral bath dyeing with excellent fastness properties.

Characteristic of the known technical solutions

It is known to prepare the dye of formula I by coupling diazotized 5-nitro-2-aminophenol with 2-aminonaphthalene (US Patent 1394823) or diazotized S-nitro-2-aminophenol with 2-aminorraprithalin-1-sulfonic acid im acetic acid environment optionally coupled in the presence of naphthalene-1-sulfonic acid (DE-PS 928 901, US-PS 2776961).

The process described in US Pat. No. 1394823 gives good yields, but handling with 2-aminonaphthalene has often already led to serious damage to health during its preparation or use. These can be z. B. by direct contact with the 2-aminonaphthalene or by staying in rooms where the air contains dust of 2-aminonaphthalene, caused. The production of the dye of the formula I from 2-aminonaphthaene is therefore associated with considerable disadvantages, since, especially in the production, but also in the use of 2-aminonaphthalene, health damage can be avoided only with very strict precautions. In the processes described in DE-PS 928301 and US Pat. No. 2,776,961, the disadvantage of handling 2-aminonaphthalene is avoided by desulfonating coupling of diazotised 5-nitro-2-aminophenol with 2-aminonaphthalene-1-sulfonic acid.

However, the processes according to DE-PS 928901 (Example 3) and US Pat. No. 2,776,961 (Example 6) give only poor yields. In the process described in DE-PS 928901 (Example 2) or US Pat. No. 2,776,961 (Example 4), an improvement in the coupling yield compared with the methods just mentioned is achieved, but this can by no means be satisfactory. It is only 60 to 70% of theory.

The dye obtained, in the preparation according to the said process, contains a relatively high proportion of simultaneously formed decomposition products, which are a hindrance to further processing of the dye and have to be eliminated by a washing process after isolation of the dye.

The disadvantages of such a method are on the rfand: in addition to the already low coupling yield resulting from the necessary washing process an increased time and equipment costs.

Object of the invention

The object of the invention is to find a process which is free of the disadvantages of the processes described above and allows the monoazo dye of the formula I to be prepared in high yield and purity with little equipment.

-2- 207 920 Explanation of the nature of the invention

It has been found that the dyestuff of the formula I can be obtained with high purity and a coupling yield of 93 to 98% with at the same time minimal equipment expenditure if the coupling of the diazotized 5-nitro-2-aminophenol with the 2-aminonaphthalene-i-sulfonic acid in a pH range of 1 to 1.5 at temperatures between 40 to 6OX in the presence of an adjuvant combination of a naphthalene-1-sulfonic acid and the surfactant obtained according to DO-PS 150391. The S-nitro-2-aminophenol is usually denatured in aqueous-hydrochloric medium. Oie suspension of the o-quinone diazide is added to the heated to 50 ⁰ C congo acidic suspension of 2-aminonaphthalene-i-sulfonic acid. the still naphthalene-1-sulfonic acid and the surfactant obtained according to DD-PS150391 in a molar ratio of 2-aminonaphthalene-1-sulfonic acid: naphthalene-1-sulfonic acid: surfactant = 1: 0.9 to 1.1: 0.01 to 0, 1, given.

The reaction is completed at 50 ⁰ C and the dye is isolated by filtration. As a result of its high purity, the dyestuff can be subjected to mixed cobalting immediately without aftertreatment with suitable o, o'-dihydroxymonoazofartostoffen. The coupling conversions achieved via the process according to the invention, determined by titration of the unreacted 2-aminonaphthalene-1-sulfonic acid, reach almost the theoretical value and are between 94 and 98%. According to another embodiment of the method according to the invention, the above adjuvant combination is produced only when the diazotized 5-nitro-2-aminophenol is combined with 2-aminonaphthalene-1-sulfonic acid. It sets the required amount of the naphthalene-1-sulfonic acid of the aqueous slurry of the 2-Amininaphthalin-1-sulfonic acid added and heated to 50 ⁰ C. The total required amount of the surfactants is then introduced with the diazotized 5-nitro-2-aminophenol. The reaction is completed as above and the dye is isolated by filtration. The coupling yields are also in this embodiment at 94 to 98%.

Example 1 '

200 parts of 5-nitro-2-aminophenol are slurried in 800 parts of water, 200 parts of hydrochloric acid 20 ° 8e and 5 parts Wotamol DP (Wotamol DF s according to DD-PS150391 surfactant of VEB Chemiekombinat Bitterfeld) and heated to 80 ° C. By adding ice is cooled to 10X and within 20 min. With 90 parts of NaNO ₂ , dissolved in 300 parts of water, diazotized. It is stirred for 2 hours and destroyed residues of nitrous acid with sulfamic acid.

The suspension of o-quinone diazide flows rapidly to a suspension of 296 parts of naphthalene-1-sulfonic acid and 306 parts of 2-aminonaphthalene-1-sulfonic acid, warmed to 5 OX, in 4000 parts of water. Stir at 5 ° C until the coupling is complete, which is usually the case after 12 to 16 hours.

The coupling suspension is squeezed without further salt addition. By titration of an aliquot of the waste liquor to unreacted 2-aminonaphthalene-1-sulfonic acid, the degree of conversion is determined. He is 94.2%.

The resulting monoazo dye is added to a calculated amount of coupling suspension of diaz. 4-nitro-2-aminophenoi and Sulfamidophenylmethylpyrazolon registered and reacted at elevated temperature with a soluble cobalt salt After isolation and drying, a green dye powder is obtained, are dyed with the wool and polyamide of acetic or neutral bathing in olive shades with excellent fastness properties.

Example 2:

200 parts of 5-nitro-2-aminophenol are suspended in 800 parts of water and 200 parts of hydrochloric acid -20 ° C and heated to 8OX. By adding ice is cooled to 10X and diazotized within 20 min. With 90 parts of NaNOj dissolved in 300 parts of water. It is stirred for 2 hours and destroyed residues of nitrous acid with sulfamic acid. The diazo suspension flows rapidly to a suspension of 296 parts of naphthalene-1-sulfonic acid, 10 parts of Wotamol DF (Wotamol DF = the surfactant of the VEB Chemiekombinat ßitterfeld obtained according to DD-PS150391) and 306 parts of 2-aminonaphthalene-1-sulfonic acid in 4000 parts of water. The mixture is allowed to stir at 50X until the coupling is complete, which is usually the case after 12 to 16 hours.

The coupling suspension is squeezed without further salt addition. The coupling yield, determined analogously to above, is 95.3%. The resulting monoazo dye is diazotized in a calculated amount of the coupling suspension! 4-chloro-2-aminophenol and 2-naphthol-S-sulfonic acid registered and reacted at a higher temperature with a soluble cobalt salt. After isolation and drying, a dark dye powder is obtained, are dyed with the wool and polyamide of acetic or neutral bathing in navy blue shades with excellent fastness properties.

Claims (1)

Invention claim: Process for the preparation of monoazo dyes of the formula O ₂ N- -N "N CD by coupling stoichiometric amounts of diazotized! 5-nitro-2-aminophenol with 2-aminonaphthalene-1-sulfonic acid in an aqueous medium at a pH of between 1 and 1.5 and at temperatures of 40 to 60 ^° C., characterized in that the reaction mixture is auxiliaries naphthalene-1 - sulfonic acid and an anionic surfactant based on a condensation product of a sulfomethylated phenol and 2-naphthol, by reaction of phenol, sodium sulfite, 2-naphthol and formaldehyde in aqueous solution in a ratio of about 3 moles of formaldehyde per mole of phenol, about 1.2 mol Sodium sulfite per mole of phenol, about 120 parts by weight of 2-naphthol per 100 parts by weight of phenol and 400 to 600 parts by weight of water per 100 parts by weight of phenol in a sealed reactor with stirring at temperatures between 110 and 130 ° C and thereby adjusting Intrinsic pressure, in molar ratio coupling component: naphthalene-1-sulfonic acid: surfactant = 1: 0.9 to 1.1: 0.01 to 0.1.