Preparation of azo colorants in microreactors

(54) PREPARATION OF AZO COLORANTS IN MICROREACTORS

(75) Inventors: Uwe Nickel, Bad Homburg; Riidiger Jung, Kelkheim; Klaus Saitmacher, Kriftel; Leonhard Unverdorben,

Nidderau, all of (DE)

(73) Assignee: Clariant Finance (BVI) Limited,

Tortola (VG)

( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.

(21) Appl. No.: 09/780,218

(22) Filed: Feb. 9, 2001

(65) Prior Publication Data

US 2001/0029294 Al Oct. 11, 2001

(30) Foreign Application Priority Data

Feb. 9, 2000 (DE) 100 05 550

Aug. 16, 2000 (GB) 100 40 100

(51) Int. CI.7 C09B 41/00

(52) U.S. CI 534/582; 534/565; 534/602;

534/642; 534/712; 534/724; 534/863; 534/DIG. 4

(58) Field of Search 534/582, 602,

534/642, 712, 724, 863, DIG. 4

(56) References Cited

U.S. PATENT DOCUMENTS

4,920,206 A 4/1990 Behringer et al 534/582

5,534,328 A 7/1996 Ashmead et al 428/166

5,560,760 A 10/1996 Toeppen 65/407

5,811,062 A 9/1998 Wegeng et al 422/129

FOREIGN PATENT DOCUMENTS

DE 1 544 453 4/1970

DE 246 257 6/1987

DE 39 26 466 2/1991

EP 0 006 190 1/1980

EP 0 244 686 11/1987

OTHER PUBLICATIONS

Derwent Patent Family Abstract for DE 1 544 453, Apr. 2, 1970.

Derwent Patent Family Abstract for DD 246 257, Jun. 3,1987.

Derwent Patent Family Abstract for DE 39 26 466, Feb. 14, 1991.

PCT Search Report.

U.S. patent application Ser. No. 09/972,102, filed Oct. 5, 2001, Dietz, et al.

Primary Examiner—Fiona T. Powers

(74) Attorney, Agent, or Firm—Anthony A. Bisulca

4,268,437 A

5/1981 Behringer et al.

534/565

17 Claims, 2 Drawing Sheets

1

PREPARATION OF AZO COLORANTS IN
MICROREACTORS

CROSS-REFERENCES TO RELATED 5
APPLICATIONS

The present invention is described in the German priority applications No.10005550.8, filed Feb. 9, 2000, and No. 10040100.7, filed Aug. 16, 2000, which are hereby incorporated by reference as is fully disclosed herein.

BACKGROUND OF THE INVENTION

The present invention relates to the field of azo colorants. Azo colorants are customarily produced in industry in batch 15 operations in reaction vessels by mixing the starting materials together in aqueous phase (Fisher, Organische Chemie, Verlag Chemie, Weinheim/Bergstra|3e, 1965, p. 890 ff., 1431, 1796 ff.).

Another way is the continuous mixing of equivalent 20 amounts of the starting materials in the form of aqueous acidic or aqueous alkaline solutions in, for example, mixing nozzles and continuous flow reactors with or without a postreaction phase in a reaction vessel (azo coupling: DE 1 544 453, EP 244 686; diazotization: EP-A-0 006 190). 25

The principal process operations involved are the diazotization of aromatic or hetaromatic amines and the azo coupling reaction. Certain azo pigments may subsequently require a metal exchange reaction (laking) and/or an after- ^ treatment in water/solvents to obtain the desired crystal properties. In the case of some azo dyes, a reaction is subsequently carried out to form metal complexes.

In all these processes, it is essential that the process parameters, such as temperature, time and (in the case of azo 35 pigments) also in particular the degree of mixing, be controlled, if the products are to be pure and of high and consistent quality. One problem with these processes is the scaleup of new products from the laboratory scale to the large industrial scale. 40

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a process for preparing azo colorants that provides optimal control of the process parameters, ensures improved mixing of the 45 reactants and simplifies scaleup.

DD 246 257 Al discloses the possibility of using miniaturized apparatuses for chemical reactions where the chemical entities to be treated are only available in small quantities or are very costly, so that large dead spaces in the equipment 50 become unaffordable. DE 3 926 466 C2 describes strong exothermic chemical reactions of two chemical entities in a microreactor.

Microreactors for chemical reactions are constructed from 5J stacks of grooved plates and are described in DE 39 26 466 C2 and U.S. Pat. No. 5,534,328. It is pointed out in U.S. Pat. No. 5,811,062 that microchannel reactors are preferably used for reactions that do not require or produce materials or solids that would clog the microchannels. gQ

It has now been found that, surprisingly, microreactors are useful for carrying out diazotization and azo coupling and also metal exchange reactions or metal complexing reactions to prepare azo colorants, such as azo pigments and azo dyes.

As used herein, microreactor comprehends micro- and 65 minireactors, which differ only by reason of the dimensions and construction of the reaction channel structures.

2

It is possible to use, for example, microreactors as known from the cited references or from publications of the Institut fiir Mikrotechnik Mainz GmbH, Germany, or else commercially available microreactors, for example SelectoTM (based on CytosTM) from Cellular Process Chemistry GmbH, Frankfurt/Main.

DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood by reference to the following detailed description of the invention and the appended drawings in which:

FIG. 1 is a perspective view of the compact parts that form the microreactor.

FIG. 2 is a schematic of the apparatus used in the process.

DESCRIPTION OF THE PREFERRED
EMBODIMENTS

The invention accordingly provides a process for preparing azo colorants by conducting the diazotization of aromatic or hetaromatic amines or the azo coupling reaction or the metal exchange reactions or the metal complexing reactions or the diazotization and the azo coupling reaction and the metal exchange or metal complexing reactions in a microreactor.

Advantageously, the preferably aqueous solutions or suspensions of the starting materials are fed to the microreactor continuously and preferably in equivalent amounts. The classic process assistants such as resins, surfactants and other additives may likewise be used in the process of the invention.

The starting materials for the diazotization reaction are aromatic or hetaromatic amines or their ammonium salts, for example aniline, 2-nitroaniline, methyl anthranilate, 2,5dichloroaniline, 2-methyl4-chloroaniline, 2-chloroaniline,

2- trifluoromethyl-4-chloroaniline, 2,4,5-trichloroaniline;

3- amino-4-methylbenzamide, 2-methyl-5-chloroaniline,

4- amino-3-chloro-N'-methylbenzamide, o-toluidine, o-dianisidine, 2,2',5,5'-tetrachlorobenzidine, 2-amino-5methylbenzenesulfonic acid, 2-amino-4-chloro-5methylbenzenesulfonic acid.

Of particular interest for azo pigments are the following amine components:

4-methyl-2-nitrophenylamine, 4-chloro-2nitrophenylamine, 3,3'-dichlorobiphenyl-4,4'-diamine, 3,3'-dimethylbiphenyl-4,4'-diamine, 4-methoxy-2nitrophenylamine, 2-methoxy-4-nitrophenylamine, 4-amino-2,5-dimethoxy-N-phenylbenzenesulfonamide, dimethyl 5-aminoisophthalate, anthranilic acid, 2-trifiuoromethylphenylamine, dimethyl

2- aminoterephthalate, l,2-bis(2-aminophenoxy)ethane, diisopropyl 2-aminoterephthalate, 2-amino-4-chloro-5methylbenzenesulfonic acid, 2-methoxyphenylamine, 4-(4-aminobenzoylamino)benzamide, 2,4dinitrophenylamine, 3-amino-4-methylbenzamide,

3- amino-4-chlorobenzamide, 3-amino-4-chlorobenzoic acid, 4-nitrophenylamine, 2,5-dichlorophenylamine,

4- methyl-2-nitrophenylamine, 2-chloro-4nitrophenylamine, 2-methyl-5-nitrophenylamine, 2-methyl-4-nitrophenylamine, 2-methyl-5nitrophenylamine, 2-amino-4-chloro-5methylbenzenesulfonic acid, 2-aminonaphthalene-lsulfonic acid, 2 - amino-5 - chlo r o - 4 methylbenzenesulfonic acid, 2-amino-5-chloro4methylbenzenesulfonic acid, 2-amino-5methylbenzenesulfonic acid, 2,4,5