One step diazotization coupling process
AssigneeCiba-Geigy Corporation
InventorEmil Stocker
Life of this patent
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Abstract
A process for producing metal-free azo pigments in purely organic liquid or aqueous/organic liquid containing at most 10% of water calculated on the total weight of the suspension is described. In this one-step process, a suitable aromatic amine is diazotized without isolation of the obtained diazo compound and coupled with a coupling component. Both reactions are carried out in purely or essentially organic medium. The latter consists essentially of such amount of an organic liquid that a substantial portion either of the diazo component or of the coupling component or of both these reactants remain undissolved. Both reactants must be free from sulphonic acid groups. If the resulting azo pigment contains carboxylic acid groups, these can be subsequently converted to the corresponding amido or ester groups.
Claims10
In a process for the preparation of a metal free azo pigment having at least two -CONH- groups per molecule and a molecular weight of at least 500, by diazotization of a diazotizable amino benzene with a diazotizing agent to form a diazo compound and coupling said diazo compound with a coupling compound, the improvement wherein the diazotization and coupling are performed in a simple operation without separation of the diazo compound, said process comprising admixing:
- a. a diazotizable amino benzene having no sulphonic acid groups
- b. a coupling component which is a 2-hydroxy-naphthalene-3-carboxylic acid phenyl or naphthyl amide, said component having no sulphonic acid groups, active methylene or tertiary nitrogen groups, and
- c. a diazotizing agent selected from the group consisting of alkyl nitrite, dinitrogen tetroxide, dinitrogen trioxide, nitrosyl chloride, nitrosyl bromide and sodium nitrite
- in an organic liquid selected from the group consisting of liquid aromatic hydrocarbons or liquid aromatic hydrocarbons which are substituted by halo, nitro or lower alkyl, said solvent containing at most 10% water,
- the amount of said organic liquid being such that a substantial portion either of the diazo component or of the said coupling component, or of both these reactants remains undissolved therein.
A process for manufacturing an azo pigment wherein 31.6g. 4-chloro-3-amino-benzoic acid-2'4'-dichloranilide and 29.5g. 2-hydroxy-naphthalene-3-carboxylic acid-2'4'-dimethylanilide are added to 71.0g. o-dichlorobenzene to form a mixture and then 60.0 g. of glacial acetic acid is added to the mixture;
- the mixture is cooled to 15.degree.C and gaseous ethyl nitrite is added;
- the resultant pigment is heated and recovered by filtration.
Dependencies are inferred from the claim text.