GB2202232A

GB2202232A - Process for preparing metallizable monoazo dyes

Info

Publication number: GB2202232A
Application number: GB08806245A
Authority: GB
Inventors: Hans Ulrich Schutz; Gerhard Back
Original assignee: Ciba Geigy AG
Current assignee: Novartis AG
Priority date: 1987-03-19
Filing date: 1988-03-16
Publication date: 1988-09-21
Anticipated expiration: 2008-03-16
Also published as: ES2009571A6; CH677303GA3; BE1000630A5; GB8806245D0; FR2612523A1; DE3808817A1; GB2202232B; CH677303B5; FR2612523B1

Description

2r202232- 1-163821+ Process for preparing metallizable monoazo dyes The

coupling of diazotized o-hydroxyaminobenzenes or o-aminonaphthols onto some coupling components, for example naphthols, which couple in the o-position relative to the hydroxyl group, proceeds in some cases slowly and in unsatisfactory yields.

In recent years there has been an increasing trend towards automating and optimizing processes for preparing dyes and intermediates thereof, not only as regards the process of preparation but also as regards the working-up. To obtain satisfactory results here it is necessary to use processes which are distinguished by the following criteria: high quantitative yield, consistently good quality and reactions in highly concentrated solutions.

The process according to the invention for preparing azo dyes of the formula H -I, N.t4_H (1) 1 in which A is a benzene or naphthalene radical which can be substituted by nitro, halogen, Cl-C6alkyl, sulfO, C2-C6alkanoylamino, Cl- C6alkoxycarbonylamino, sulfonamido and sulfone groups, and B is a naphthalene radical which can be substituted by amino, phenylamino, c 1. cc 6 alkylamino and sulfo. these radicals being bonded to the azo group in the o-position relative to the laydroxyl groups, comprises diazotizing in aqueous solution an amine of the formula H NH2 (2) and coupling the diazotization product in the presence of pyridine or pyridine bases onto a coupling component of the formula J 11 (3) where A and B in the formulae (2) and (3) are as defined under the formula (1).

It is true that the use of pyridine or pyridine bases has previously been described for individual coupling reactions, but pyridine was predominantly used as a coupling accelerant in the preparation of polyazo compounds, i-e- in the coupling reaction of a secondary or tertiary azo dye. In the preparation of monoazo dyes which give a satisfactory yield in conventional synthesis, pyridine has only been used in a few cases as an assistant for the coupling reaction. It is surprising that the amines and coupling components used in the process according to the invention lead to a substantial increase in the yield of monoazo dyes if the coupling is carried out in the presence of pyridine or pyridine bases.

The pyridine bases used in the processes according to the invention are those pyridine bases as obtained in the production of technicalgrade pyridine, for example picolines, lutidines and the like; cf. in this context Ullmann's Encyklop9die der technischen Chemie, 3rd edition, volume 14, Urban & Schwarzenberg, Munich-Berlin (1963), pages 481 et seq.

Examples of C2-C6alkanoylamino are acetylamino, propionylamino and butyrylamino.

Suitable Cl-C6alkoxy!-arbonylamino is for example methoxycarbonylamino and ethoxycarbonylamino.

Suitable Cl-C6alkyl is for example methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, isobutyl, pentyl and hexyl.

Suitable halogen is for example fluorine, bromine and in particular chlorine.

1 4 4 Suitable sulfonamido is for example -S02NH2, -S02NHCl-6alkyl, for example -S02NHCH3 and -S02NW2H5, and -S02N(C1-6alkyl)2, for example -SO2N(CH3h and -S02N(C2H5)2, and also -SO2NH- where the phenyl radical may be substituted, for example by sulfo or carboxyl.

Suitable sulfone is for example -S02-Cl-6alkyl, such as -S02-CH3, and S02aryl, such as phenylsulfonyl.

Suitable Cl-C6alkylamino is for example methylamino and ethylamino.

According to the present invention, it is preferable to use 10 to 90 per cent by volume, based on the entire reaction volume, of pyridine or pyridine base in the coupling reaction. It is particularly preferable to use 30 to 50 per cent by volume of pyridine or pyridine base in the coupling reaction and very particularly preferable to use 30 to 40 per cent by volume of pyridine or pyridine base.

It is surprising that even with 10 to 15 per cent by volume of pyridine or pyridine base it is possible to obtain a very substantial increase in yield.

The amine of the formula (2) is diazotized in a manner known per se, for example by the action of nitrous acid In aqueous mineral acid solution at low temperature.

The coupling in the presence of pyridine or pyridine bases is carried out in aqueous solution containing about 90 to 10 per cent by volume of water at a pH of about 7.5 to 8.5.

In a particularly preferred embodiment of the prucess according to the invention, coupling is carried out at a temperature of 0 to 300C. In particular, coupling is performed adiabatically.

The use of pyridine or pyridine bases in the preparation of the azo dyes according to the invention,produces the following benefits:

The yields are substantially increased. The reaction product is of better quality; that is, the number and the quantity of by-products is low. Couplings in the presence of pyridine can be carried out at higher concentrations; that is, it is possible to produce more product per unit time per reaction vessel, so that for example coupling effected at a concentration of 0.3 to 1.2 moles of amine or coupling component per litre of coupling reaction mixture. Pyridine or pyridine bases can be recovered almost quantitatively after the coupling.reaction..

In a particularly preferred embodiment of the process according to the invention, coupling is carried out in the presence of pyridine bases.

The diazo and coupling components which are preferably reacted by the process according to the invention are o-aminophenols, which may be substituted by nitro, halogen, such as fluorine, chlorine or bromine, sullo and Cl-C6alkyl, such as methyl, or o-aminonaphthols, which may be substituted by sulfo and nitro, naphthols, which may be sUbstituted by amino, acetylaminc, phenylamino and suifo. In the COUDling components, the coupling-position is the position adjacent to the hydroxyl group.

Very particular preference is given to using in the process according to the invention as amines of the formula (2) 2-amino-S-nitrophenol, 2-amino4-nitrophenol, 2-amino-4-chloro-S-nitrophenol, 2-amino-4chloro-6nitrophenol, 2-amino-4-sulfo-6-nitrophenol, 2amino-4,6-dichlorophenol, 2amino-4-ni:ro-6-sulfophenol', 2amino-4methyl-6-nitrophenol, 1- amino-2hydroxy-4-sulfonaphthalene or 1-amino-2-hydroxy-6nitro-4-sulfonaphthalene and as coupling component of the formula (3) 1-hydroxynaphthalene-4s'ulfonic acid, 1-hydroxy-naphthalene-5-sulfonic atid,-2-hydrox,,naphthalene, I-Imdroxy-6- or 11 -7-aminonaphthalene-3-sulfonic acid, 1-hydroxy-8-aminonaphthalene-3, 6disulfonic acid or 2-hydroxy--6-acetylaminonaphthalene-4-sulfonic acid.

As important amines of the formula (2), 2-amino-S-nitrophenol, 2amino-4chloro-S-nitrophenol, 2-amino-4,6-dichlorophenol, 2-amino-4nitro-6sulfophenol and 2-amino-4-methyl-6-nitrophenol are used in the process according to the invention together with the very particularly preferred coupling components of the formula (3).

In a very particularly important embodiment of the process according to the invention, after the coupling has ended the monoazo dye formed Is separated from the pyridine or the pyridine bases - by steam distillation, or - by precipitation in the presence of acids, filtering off the monoazo dye, and purifying the pyridine or the pyridine bases after the pH has been set to 7 to 10, for example by addition of a base, for example sodium hydroxide solution, by subsequent steam distillation.

The steam distillation is preferably carried out at a pH of 7 to 10.

Using the above-specified procedure of the process according to the invention, comprising coupling in the presence of pyridine or pyridine bases and subsequent steam distillation or prior precipitation and filtration and subsequent steam distillation, it is possible to separate the pyridine or the pyridine bases almost quantitatively from the monoazo dye formed; in general, 99 per cent by weight of the starting pyridine or pyridine bases used are thus recoverable and therefore available for a further reaction. The pyridine is separated from the water by known methods, for example salting out with subsequent separation of the organic phase, which contains the pyridine, from the aqueous phase.

An advantage of this procedure is that, following complete ezupling of the components under mild reaction conditions, an almost quantitative separation from the monoazo dye formed and the solvent is possible in an extremely mild manner.

Coupling reactions which give azo dyes only in an unsatisfactory manner generally lead to pollution of the waste water, since unconverted components are frequently impossible to separate quantitatively from the solvent used, which in general is water.

For this reason, it has been customary for some time to add to those coupling reactions which give azo dyes only in an unsatisfactory manner coupling additives to complete and, ideally, to accelerate conversion; for example, napthalenesulfonic acids are used as coupling accelerants. It is true that the coupling yield can be improved with this procedure, but these assistants, in particular naphthalenesulfonic acids, are difficult and expensive to separate quantitatively from the coupling reaction mixture.

The use of pyridine or pyridine bases thus has the advantage not only that the coupling yield is substantially increased but also that removal of this assistant from the monoazo dye formed, and also the removal from the solvent, water, is almost quantitative, in general 99 per cent by weight.

The monoazo dyes obtained by the process according to the invention are suitable for preparing metal complex azo dyes, for example chromium or cobalt complex azo dyes, the metallization being carried out in a manner known per se. They are also suitable as chroming dye for dyeing wool.

In the Examples which follow, parts are by weight. The temperatures are degrees Celsius. Parts by weight relate to parts by volume as the gramme relates to the cubic centimetre.

Example 1: 30.8 parts of 2-amino-S-nilrophenol are suspended in 120 parts of water and dissolved with 20 parts of 30% sodium hydroxide solution. The solution is then treated with 42 parts of concentrated hydrochloric acid (33%), cooled to 50 with ice, diazotized at 5 to 240 with 50 parts. of 4 N sodium nitrite solution and brought to pE 4 to 4.5 with 10% sodium carbonate solution. To the diazo compound obtained is added a solution of 45 parts of l-naphthol-4-sulfonic acid in 120 parts of pyridine and 80 parts of water, a pH of 7.8 to 8 becoming established. The coupling mixture is subsequentlystirred at room temperature for some hours until a diazo compound is no longer detectable.

To remove and recover the pyridine, the dye suspension is brought to about pR 9.5 with about 35 parts of concentrated sodium hydroxide solution and subjected to a steam distillation until pyridine is no longer detectable in the distillate. The dye suspension is then brought to pH 4 to 4.5 with concentrated hydrochloric acid, and the monoazo dye is quantitatively precipitated by addition of sodium chloride and then filtered off.

The result obtained is a reddish brown dye paste which contains dye which conformQ in the form of the free acid to the formula ?H ?H 03H (101) 0:! 141 N"..1 in a coupling yield of 95 to 97% of theory.

The coupling Is repeated as described above, except that no pyridine is added, affording the dye of the formula (101) in a coupling yield of about 55% of theory.

Example 2: Example 1 is repeated, except that the 30.8 parts of 2amino-5nitrophenol are replaced by 37.7 parts of 2-amino-4-chloro-Snitrophenol and the 45 parts of l-naphthol-4-sulfonic acid by 44.8 parts of lnaphthol-S-sulfonic acid, affording the'dye which in the form of the free acid conforms to the formula ?H H \ 02 10,H (102) and has very similar properties in an equally good coupling yield.

(I- Example 3: 47.8 parts of 2-amino-5-naphthol-7-sulfonic acid are introduced into 200 parts,of a pyridine base mixture and dissolved with 40 parts of concentrated sodium hydroxide solution. After cooling down to 0 to 50, 59 parts of 1-diazo-6-nitro-2-naphthol-4-sulfonic acid are added in the course of about 30 minutes. After the coupling has ended, the pyridine base mixture is distilled off with steam. The dye solution is neutralized with hydrochloric acid, and the monoazo dye is precipitated by addition of sodium chloride and then filtered off. Drying leaves 132 parts of a reddish brown azo dye which in the form of the free acid conforms to the formula OH YH H03S- H03s N/02 The yield is about 85% of theory.

(103) The coupling is repeated as described above, except that no pyridine is added, affording the dye of the formula (103) in an approximately 40% lower coupling yield.

Example 4: Example 1 is repeated, except that the diazo component and the coupling component are replaced by an equimolar amount of 4,6-dichloro-2aminophenol and 1-amino-8-naphthol-3,6-disulfonic acid, affording a dye which in the form of the free acid conforms to the formula ?H ?H VH2 cl \ 0.

-N=NTif The yield is about 88% of theory.

H03S S03H (104) The procedure of Examples 1 to 4 is repeated, except that the diazo component is replaced by an equimolar amount of the amine specified in column 2 of the table below and the coupling component by an equimolar amount of the coupling component specified in column 3 of the table C 111 below, affording a monoazo dye in the yield specified in column 4.

Table

Example Amine Coupling component Yield ?H -NHz 98 % 02N ?H ?H 6 H03s /. \ /. \ 90 % / \ rNHz i if i -NH2 \M. /. - /..

k02 S 03H ?H NH, i if 90 % 7 if NH, 0/2 / 1 S 03H OH ?H 8 H03S -,.-NH2 80 % a \M M/---NHI, / S 03H ?H 0 N\ OH 80 % /NH;! H3 O-CH3 103H t -

Claims

What is claimed is:

1. A process for preparing an azo dye of the formula H N=N- H (1) in which A Is a benzene or naphthalene radical which can be substituted by nitro, halogen, Cl-C6alkyl, sulfO, C2-C6alkanoylamino, Cl- C6alkoxycarbonylamino, sulfonamido and sulfone groups, and B is, a naphthalene radical which can be substituted by amino, phenylamino, c 1-C 6 alkylamino and sulfol_these radicals being'bonded to the azo group in the o-position relative to the hydroxyl groups, comprises diazotizing in aqueous-solution an amine of the formula NHP (2) and coupling the diazotization product in the presence of pyridine or pyridine bases onto a coupling component of the formula H-T' (3) where A and B in the formulae (2) and (3) are as defined under the formula (1).

2. A process according to claim 1, wherein coupling is carried out in the presence of 10 to 90 per cent by volume of pyridine or pyridine bases.

3. A process according to either of claims 1 and 2, wherein coupling is carried out in the presence of 30 to 50 per cent by volume of pyridine or pyridine bases.

4. A process according to any one of claims 1 to 3, wherein coupling is carried ont at a temperature of 0 to 300C.

5. A process according to any one of claims 1 to 4, wherein coupling is performed adiabatically.

6. A process according to any one of claims 1 to 5, wherein coupling Q 11 1 h 1 is carried out in the presence of pyridine bases.

7. A process according to any one of claims 1 to 6, wherein the amine of the formula (2) is 2-amino-S-nitrophenol, 2-amino-4-nitrophenol, 2amino-4chloro-S-nitrophenol, 2-amino-4-chloro-6-nitrophenol, 2-amino4-sulfo-6nitrophenol, 2-amino-4,6-dichlorophenol, 2-amino-4-nitro-6sulfophenol, 2amino-4-methyl-6-nitrophenol, 1-amino-2-hydroxy-4sulfonaphthalene or 1amino-2-hydroxy-6-nitro-4-sulfonaphthalene and the coupling component of the formula (3) is 1-hydroxynaphthalene-4sulfonic acid, 1hvdroxynaphthalene-5-sulfonic acid, 2-hydroxynaphthalene -1-hydroxy-6- or -7-aminonaphthalene-3-sulfonic acid, 1-hydroxy-8-aminonaphthalene-3,6disulfonic acid or 2-hydroxy-6acetylaminonaphthalene-4-sulfonic acid.

8. A process according to claim 7, wherein the amine of the formula (2) is 2-amino-S-nitrophenol, 2-amino-4-chloro-S-nitrophenol, 2t--amino4,6dichlorophenol, 2-amino-4-nitro-6-sulfophenol or 2-amino-4methyl6nitrophenol and the coupling component of the formula (3) comprises those specified in claim 7.

9. A process according to any one of claims 1 to 8, wherein, after the coupling has ended, the azo dye formed is separated from the pyridine or the pyridine bases by steam distillation.

10. A process according to 'Claim 9, wherein the steam distillation Is carried out at a pH of 7 to 10.

11. A process according to any one of claims 1 to 8, wherein, after the coupling has ended, the azo dye formed is precipitated in the presence of acids from the pyridine or the pyridine bases and filtered off and the pyridine or pyridine bases, after the pH has been set to 7 to 10, are purified by steam distillation.

12. A process according to any one of claims 1 to 11, wherein the coupling is carried out at a concentration of 0.3 to 1.2 moles of amine or coupling component per litre of coupling reaction mixture.

13. A process for dyeing wool using a chroming dye prepared as speci-fied in claim 1.

14. Use of an azo dye obtained by the process according to claims 1 to 12 for preparing metal complex azo dyes.

1 C Published 1988 at The Patent Office, State House, 66171 High Holborn, London WC1R 4TP. R copies may be obtained from The Patent Office. Wee Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent. Con. 1187.