Anthraquinone compounds and process for preparing same

Abstract

The present invention relates to a new class of compounds belonging to the anthraquinone series, having the general formula: ##STR1## wherein R, R', R", R'", R' are indifferently H or Chlorine, ##STR2## Such compounds exhibit a color varying from yellow to violet depending on the nature and position of substituents R, R', R", R'", R'.sup.v and, in virtue of their excellent stability characteristics, they are particularly useful as pigments and vat dyes.This invention relates furthermore to the preparation of compounds having general formula (I) and to the utilization thereof, particularly in the following applications:Pigmentation of plastic materials, such as polyvinyl chloride, polystyrene, polyolefins, polymethylmethacrylate, polycarbonates and ABS copolymers (acrylonitrile-butadiene-styrene);Pigmentation of varnishes, stoving enamels, inks and pastes for the printing of textiles;Vat dyeing of cellulose fibres such as cotton, flax, rayon.BACKGROUND OF THE INVENTIONAs far as it is known, the anthraquinone derivatives of 1,2,5-thiadiazole-3,4-dicarboxylic acid of formula (I), which are the object of the present invention, are not described in the Art.The prior Art, however not directly pertinent, generically describes dyestuffs of the anthraquinone series deriving from dicarboxylic acids, for example benzenic, pyridinic, aliphatic acids etc.OBJECTS OF THE INVENTIONIt is an object of this invention to provide a new class of anthraquinone compounds of general formula (I), having useful applications in the field of the pigments and of the vat dyes. Another object is to provide a process for preparing same.GENERAL DESCRIPTION OF THE INVENTIONThese and still other objects, that will more clearly appear to those skilled in the Art from the following description, are achieved by compounds having general formula (I), prepared by means of a process characterized in that the dichloride of 1,2,5-thiadiazole-3,4-dicarboxylic acid (II) is reacted with 1-aminoanthraquinone or substituted derivatives (III) thereof according to a substantially stoichiometric molar ratio, in the presence of an inert solvent, at a temperature ranging from 100.degree. to about 170.degree. C.The reaction can be schematically represented by the following equation (1): ##STR3## wherein R', R", R'", R'.sup.v have the meaning already specified; HCl forms and liberates as a gas from the reacting mixture. It is not necessary, therefore, to employ basic substances to neutralize hydrochloric acid. As mentioned hereinbefore, the reaction is conducted in an inert solvent and at a temperature comprised between 100.degree. and about 170.degree. C, preferably between 120.degree. and about 150.degree. C.1-aminoanthraquinones (III) employable in the present invention are in particular:1-aminoanthraquinone, 1-amino-4-hydroxyanthraquinone, 1-amino-4-benzamidoanthraquinone, 1-amino-5-benzamidoanthraquinone, 1-amino-4-(p-acetamidoanilino)-anthraquinone, 1-amino-4-(p-toluidino)-anthraquinone, 1-amino-5-methoxyanthraquinone, 1-amino-2-phenoxy-4-hydroxyanthraquinone, 1-amino-2,4-dibromoanthraquinone, 1-amino-2-bromo-4-hydroxyanthraquinone, 1-amino-6,7-dichloroanthraquinone etc.As inert solvent it is possible to use chlorobenzene, the various dichlorobenzenes and trichlorobenzenes, and nitrobenzenes.The time required for the reaction varies from 2 to 8 hours, depending on the reaction temperature and on the type of 1-aminoanthraquinones utilized. The molar ratio is practically stoichiometric, that is: 2 moles of anthraquinone compound (III) for 1 mole of dichloride (II).The raw materials necessary for the process according to this invention are easily available, as 1-aminoanthraquinone and the substituted derivatives (III) thereof are commercial products usually employed as intermediates for dyestuffs and pigments.As to the dichloride of 1,2,5-thiadiazole-3,4-dicarboxylic acid (II), such product is known since long and is obtained, according to known techniques, by chlorination with SOCl.sub.2 of the monopotassium salt of 1,2,5-thiadiazole-3,4-dicarboxylic acid, that is, in its turn, a known compound.According to an effective embodiment, the present invention is conducted by operating in practice as follows: the dichloride of 1,2,5-thiadiazole-3,4-dicarboxylic acid (II) and the 1-aminoanthraquinone or its substituted derivatives (III) are heated, after mixing in the inert solvent, to 100.degree.-170.degree. C, preferably to 120.degree.-150.degree. C, until the anthraquinone compound (III) has thoroughly disappeared.The thin layer chromatography is useful for this check.At the end of the reaction the reaction mixture is filtered, preferably in hot conditions, and the pigment cake is then washed with the reaction solvent and successively with methanol until the washings result colourless.The pigments obtained according to this invention are substances exhibiting a colour varying from yellow to violet and characterized by a high insolubility in the common organic solvents and by a high melting point, generally higher than 300.degree. C.To impart the particular desired applicative characteristics to the products so obtained it is impossible to utilize the grinding, for example in a ball mill, or the precipitation from sulphuric acid and in general the techniques already known.Also for the dyeing of plastic materials, of varnishing products and for the vat dyeing the pigments of the present invention are consistent with the conventional techniques.Due to the simple preparation conditions and applicative characteristics of the obtained pigments, the present invention appears particularly advantageous.Preparation and application of the present invention will be now described more in detail in the following examples, which are given, however, by way of example only.

Description

Claims

1. Anthraquinone derivatives characterized by the general formula: ##STR15## where R, R' , R" , R'", R'.sup.v are indifferently ##STR16##

2. A compound having the formula: ##STR17##

3. A compound having the formula: ##STR18##

4. A compound having the formula: ##STR19##

5. A compound having the formula: ##STR20##

6. A compound having the formula: ##STR21##

7. A compound having the formula: ##STR22##

8. A compound having the formula: ##STR23##

9. A compound having the formula: ##STR24##

10. A compound having the formula: ##STR25##

11. A compound having the formula: ##STR26##

12. A compound having the formula: ##STR27##