CH620700A5 - Process for the preparation of 2-bromo-4'-nitro-6-chloro-4-(N,N-di(beta-methoxycarbonylethyl)amino)az obenzene having a novel crystal structure - Google Patents

Description

The invention relates to a process for the preparation of a stabilized form of 2-bromo-4-nitro-6-chloro-4 '- [N, N-di- (β-methoxycarbonylethyl) amino] azobenzene with a new crystal structure .

2-bromo-4-nitro-6-chloro-4 '- [N, N-di- (ß-methoxycarbonyl-ethyl) -amino] -azobenzene is a compound known from CH-PS No. 515 976, which by Coupling of diazotized 2-bromo-4-nitro-6-chloroaniline with N, N-di- (ß-methoxycarbo-nylethyl) -aniline is obtained in an aqueous medium at temperatures below 25 ° C. This azo compound was previously only known as an intermediate for dyes. However, it has now been found that this compound is potentially suitable as a dye for dyeing or printing textiles from aromatic polyesters. For this purpose it is necessary to convert the dye into a suitable form by grinding it in the presence of dispersants. Although the dye obtained in the above process can be ground satisfactorily, when the resulting dispersion is stored in liquid form, crystal growth occurs for a long time, resulting in loss of coloring power and speckled prints when the dye is subsequently applied by a printing process becomes. X-ray studies have confirmed a change in the crystal structure of the dye during storage. The new crystal structure that is formed during storage is considerably more stable than the original shape. If the dye in its new crystal structure is brought into a suitable physical dispersed form in the conventional manner as described above, then this dispersion is equivalent in terms of the coloring and printing properties to the original form of the dye, but has the advantage that it Storage in liquid form is completely stable for a long time.

The present invention therefore relates to a process for the production of this new crystal structure of the dye, which is characterized by an X-ray diffraction diagram which has four strong lines at lattice spacings of 7.4 Â, 4.44 Â, 3.70 Â and 3, 58 Â and five lines of medium intensity with network spacing of 4.00 Â, 3.77 Ä, 3.48 Â, 3.16 Â and 3.08 Â.

The process according to the invention for the preparation of 2-bromo-4-nitro-6-chloro-4 '- [N, N-di- (ß-methoxycarbonylethyl) -

-amino] -azobenzene with the indicated X-ray diffraction pattern is characterized in that the azo compound obtained by coupling diazotized 2-bromo-4-nitro-6-chloroaniline with N, N-di (β-methoxycarbonyl-ethyl) aniline in Water or heated in an organic liquid or in a mixture of water and an organic liquid.

The process according to the invention can expediently be carried out by stirring the azo compound in water and / or an organic liquid at a temperature between 35 ° C. and the boiling point of the medium, preferably at a temperature of 60 ° to 80 ° C. The conversion of the azo compound to the form with the specified X-ray diffraction pattern usually requires heating for half an hour to three hours. The new form of azo compound can then be isolated in a conventional manner. For example, if it is insoluble in the liquid medium at the reaction temperature, it can be filtered off directly. However, if an organic liquid in which it is soluble is used, it is preferred to cool the mixture to room temperature before filtering off the solid.

If desired, the liquid medium may contain a cationic, anionic or non-ionic dispersant.

As examples of the organic liquids, lower aliphatic alcohols having 1 to 4 carbon atoms, such as methanol, ethanol, n-propanol and n-butanol; Ketones, especially di (lower alkyl) carbonyls (in which the lower alkyl group contains 1 to 4 carbon atoms), such as acetone; and hydrocarbons such as toluene.

However, it is preferred to carry out the process according to the invention immediately after the azo compound mentioned has been formed. Thus, preferably after coupling the diazotized 2-bromo-4-nitro-6-chloroaniline with N, N-di (β-methoxycarbonylethyl) aniline in an aqueous medium at a temperature below 25 ° C, the temperature to 60 to 80 ° C increased and held there for a certain time (usually 1 to 3 hours) until the entire azo compound was converted into the new form with the indicated X-ray diffraction pattern. The dye can then be filtered off.

The drawing shows a characteristic X-ray diffraction pattern of the azo compound and the new form of the dye. The abscissa of the diagram shows the lattice plane distances of the crystal, while the ordinate shows the approximate relative intensities. The new form of the dye is indicated by the dashed lines. The diagram shows that with the new dye, four strong lines at network spacings of 7.4 Â, 4.44 Â, 3.70 A and 3.58 Â and five lines of medium intensity at 4.00 A, 3.77 Â, 3.48 Â, 3.16 Â and 3.08 Â are present. The X-ray diffraction pattern for the azo compound (from which the new shape is made) is shown by the solid lines in the diagram.

The values of the X-ray diffraction diagram given here have been obtained with the conventional powder technique using Cu-K-a radiation, the diffraction intensity being recorded as a curve with a scintillation counter in which the abscissa represents the diffraction angle and the ordinate represents the diffraction intensity. For the recording, the diffraction angles were converted using standard tables into the network plane distances expressed in units of A, which are independent of instrument fluctuations. The specified values are accurate within 2%, with the deviations being less than 1% in most cases. These deviations

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After conversion into an aqueous dispersion by grinding in an aqueous medium which contains one or more dispersants, the 2-bromo-4-nitro-6-chloro-4 '- prepared according to the invention is - [N, N-di- (β-methoxycarbonylethyl ) - amino] -azobenzene with the specified X-ray diffraction pattern for dyeing aromatic polyester textile materials by dyeing, padding and printing processes. The aromatic polyester textile materials are dyed in brown shades, which have excellent fastness to light, wet treatments and the like. have dry heat treatment.

In particular, the aqueous dispersions are stable over long periods of time. In this regard, they are markedly superior to the aqueous dispersions of the azo compound, which have not been subjected to the heat treatment according to the invention.

The examples illustrate the invention. Parts and percentages are based on weight.

example 1

19.3 parts of sodium nitrite are gradually added to 260 parts of sulfuric acid (concentration 94.4%), and the temperature is allowed to rise to 70 to 75 ° C and then kept at this value by adjusting the rate of addition of the sodium nitrite. The mixture is then stirred for 30 minutes and then cooled to 30 ° C. 63.5 parts of 2-bromo-4-nitro-6-chloroaniline are then added over a period of 30 minutes at a temperature of 30 to 35 ° C and the mixture is stirred for 3 hours as it gradually cools to room temperature. The resulting solution of the diazo compound is then added to a solution of 66.3 parts of N, N-di (β-methoxycarbonylethyl) aniline and 13.2 parts of polyglyceryl ricinoleate in a mixture of 1000 parts of water, 1000 parts of ice and 25 parts of sulfuric acid . The mixture is stirred at 0 to 10 ° C for 3 h and then at 20 ° C for 3 h. The temperature of the mixture is then raised to 65 ° C and held there for 1 hour. The precipitated dye is then filtered off, washed with water and dried.

X-ray examination of the dye with a Philips diffractometer equipped with a copper target and a nickel filter shows that the dye has an X-ray diffraction pattern that has four strong lines at lattice spacing of 7.4 Â, 4.44 Â, 3, Has 70 Ä and 3.58 Â and five lines of medium intensity at 4.00 Â, 3.77 Â, 3.48 Â, 3.16 Â and 3.08 Â. In contrast, a dye that, as described above,

620700

with the exception that it was isolated without heating to 65 ° C, an X-ray diffraction pattern showing six strong lines at 19 Â, 9.5 Â, 4.55 Â, 4.12 Â, 3.82 Â and 3.48 Â and four lines of medium intensity at 6.9 Â, 5.1 Â, 4.76 A and 3.41 A.

A mixture of 50 parts of the dye of Example 1, 25 parts of disodium salt of di (2-sulfonaphth-l-yl) methane and 300 parts of water is mechanically milled until the particle size of the dye has been reduced to less than 3 µm . Half of the resulting liquid dispersion is worked into a printing paste which contains sodium alginate as a thickener. This is applied in a conventional manner to a textile material made from an aromatic polyester. A strong brown print is obtained which is not speckled. The other half of the liquid dispersion is stored at room temperature for 3 months and then similarly applied to an aromatic polyester fabric. The resulting print has the same depth of color and is also not speckled.

The dye prepared according to Example 1, but which has been isolated without heating to 65 ° C., is converted into a liquid dispersion in the same way. The print made directly with the liquid dispersion has a strong hue and is not speckled, but the print made from the liquid dispersion after 3 months storage at room temperature is weak and speckled.

Example 2

A mixture of 52.7 parts of 2-bromo-4-nitro-6-chloro-4 '- !. N, N-di- (ß-methoxycarbonylethyl) -amino] -azobenzoI, which was prepared according to Example 1, but has been isolated without heating to 65 ° C., 3 parts of a condensate of 1 mol of nonylphenol and 8 mol of ethylene oxide and 500 parts of water are stirred at 80 ° C. for 3 h. The precipitated dye is then filtered off, washed with water and dried.

X-ray diffraction shows that the dye has the same strong lines and the same medium intensity lines as the dye of Example 1.

Example 3

52.7 parts of the azo compound used as the starting compound in Example 2 are stirred for 30 minutes in 150 parts of boiling methanol. The mixture is cooled, and the precipitated dye is filtered off and dried.

The dye has the same X-ray diffraction pattern as that of Example 1.

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1 sheet of drawings

Claims (3)

620700 1. Process for the preparation of 2-bromo-4-nitro-6-chloro-4 '- [N, N-di- (ß-methoxycarbonylethyl) -amino] -azobenzene with a new crystal structure by an X-ray diffraction diagram is characterized by the fact that four strong lines at network plane spacings of 7.4 Â, 4.44 Â, 3.70 Â and 3.58 Â and five lines of medium intensity at network plane distances of 4.00 Â, 3.77 Â, 3.48 Â, 3.16 Â and 3.08 Â, characterized in that the by coupling of diazotized-2-bromo-4-nitro-6-chloroaniline with N, N-di- (ß-methoxy -carbonylethyl) -aniline obtained azo compound in water or in an organic liquid or in a mixture of water and an organic liquid. 2. The method according to claim 1, characterized in that one carries out the heating at a temperature between 60 and 80 ° C. 2nd PATENT CLAIMS 3. The method according to claim 2, characterized in that diazotized 2-bromo-4-nitro-6-chloraniIin with N, N - di- (ß-methoxycarbonylethyl) -aniline in an aqueous medium at a temperature below 25 ° C. couples and that the reaction mixture is then heated to a temperature between 60 and 80 ° C for a period of 1 to 3 hours.