Azine pigments, processes for their preparation, and their use

Azine pigments having the probable structure ##STR1## wherein the rings designated by T, R', X and X' can be substituted or expanded to naphthalene systems. The pigments can be prepared by reacting compounds having the probable structures ##STR2## in the presence of hydrazine. The compounds having the probable structures (IV) and (IVa) are formed by reacting isatoic anhydrides or anthranilic acid esters or anthranilic acid amides with at least one mol of an aminoiminoisoindolenine.

The invention relates to azine pigments having the probable structure 
##STR3## 
processes for their preparatin, and their use. 
In formula (I), the rings designated by X, X', T and T' can be substituted, 
for example in each case by 1, 2, 3 or 4 substituents from the series 
comprising halogen, in particular chlorine and bromine; C.sub.1 -C.sub.6 
-alkyl, in particular methyl; aryl, in particular phenyl, which in turn 
can be substituted by halogen, such as chlorine and bromine, C.sub.1 
-C.sub.6 -alkyl, such as methyl, acylamino, such as acetylamino or 
benzylamino, nitro, carboxyl or carbamoyl; C.sub.1 -C.sub.6 -alkoxy, in 
particular methoxy; acylamino, in particular acetylamino and benzoylamino; 
carboxyl; nitro or cabamoyl. The rings X, X', T and T' can furthermore be 
expanded by means of fused benzo rings, which may be substituted, to give 
naphthalene systems. Suitable substituents in the naphthalene rings are 
halogen, such as chlorine and bromine, C.sub.1 -C.sub.6 -alkyl, such as 
methyl, acylamino, such as acetylamino or benzylamino, nitro, carboxyl or 
carbamoyl. 
Symmetric azine pigments having the probable formula 
##STR4## 
in which the rings denoted by X and/or the rings denoted by T are 
substituted by 1, 2, 3 or 4 chlorine or bromine atoms, are preferred. 
Other preferred symmetric azine pigments of the probable formula (II) are 
those in which the rings denoted by X and/or the rings denoted by T carry 
a substitute from the series comprising methyl, methoxy, acetylamino, 
benzoylamino, carboxyl, carbamoyl and nitro. 
The symmetric azine pigment of the probable formula 
##STR5## 
is also preferred. 
The new azine pigments of the probable formula (I) can be obtained by a 
method in which a compound of the probable formula 
##STR6## 
is reacted with a compound of the probable formula 
##STR7## 
in the presence of hydrazine or of a hydrazine-donating compound, such as 
hydrazine hydrate or a hydrazinium salt. In the formulae (IV) and (IVa), 
T, T', X and X' have the meanings given for formula (I). 
In this procedure, the reaction is advantageously carried out in water or 
in an organic solvent under slightly acidic conditions and at elevated 
temperature, preferably at 50.degree.-180.degree. C. Suitable organic 
solvents are alcohols, such as methanol, ethanol, amyl alcohol or glycol 
monoalkyl ethers; aromatics, such as chlorobenzene, nitrobenzene or 
toluene; amide solvents, such as formamide, dimethylformamide or 
N-methylpyrrolidone; or acids, such as formic acid or acetic acid. 
Suitable acids for establishing the acid conditions are inorganic acids, 
such as hydrochloric acid, sulphuric acid or phosphoric acid, and organic 
acids, such as formic acid, acetic acid, chloroacetic acid, dichloroacetic 
acid, oxalic acid, benzenesulphonic acid or p-toluenesulphonic acid. 
Instead of the intermediate products of the formulae (IV) and (IVa), it is 
also possible to use their acylation products of the probable formulae (V) 
and (Va): 
##STR8## 
In the formulae (V) and (Va), T, T', X and X' have the meanings given for 
formula (I); R designates alkyl, preferably C.sub.1 -C.sub.6 -alkyl, in 
particular methyl, or aryl, in particular phenyl. 
The compounds of the probable formula (IV) are obtainable by reacting an 
isatoic anhydride of the formula (VI) 
##STR9## 
or an anthranilic acid ester or anthranilic acid amide of the formula 
(VII) 
##STR10## 
with at least one mol of an aminoiminoisoindolenine of the formula 
##STR11## 
in an inert organic solvent, for example ethanol, at elevated temperature, 
preferably at 50.degree.-100.degree. C. 
In the formulae (VI), (VII) and (VIII), T and X have the meanings given for 
formula (I). 
In formula (VII), Y designates --NH.sub.2 or --OR', wherein R' represents 
the hydrocarbon radical of an ester, preferably C.sub.1 -C.sub.6 -alkyl. 
The intermediate products of the probable formula (IVa) are obtained by a 
very similar method. 
Compounds which can be employed according to the invention and which have 
been assigned the formulae (IV) and (IVa) are known from the literature 
(Angew. Chem. 68, 135 (1956)). 
Another method of preparation for the pigments of the probable formula (I) 
comprises the condensation of a hydrazone of the probable formula 
##STR12## 
with a hydrazone of the probable formula 
##STR13## 
in an acidic medium, the pigments of the probable formula (I) being formed 
with elimination of one mol of hydrazine. This reaction is advantageously 
carried out in organic solvents at elevated temperature, preferably at 
50.degree.-180.degree. C. The solvents which are preferably used and the 
acids preferably employed to obtain the acidic medium correspond to those 
stated for the reaction of the compounds of the probable formulae (IV) and 
(IVa). 
In the formulae (IX) and (IXa), T, T', X and X' having the meanings given 
for formula (I). 
The compounds of the probable formulae (IV) and (IVa) or (V) and (Va) or 
(IX) and (IXa) can be reacted in any desired ratio. Preferably, they are 
identical compounds which react to give the symmetric azine pigments of 
the probable formula (II). 
The compounds of the probable formula (I) are obtained in the form suitable 
for use as pigments, or can be converted to the suitable form by 
after-treatment methods which are known per se, for example by dissolution 
or swelling in strong inorganic acids, such as sulphuric acid, and pouring 
onto ice. A finely divided material can also be obtained by milling with 
or without milling auxiliaries, such as inorganic salts or sand, if 
appropriate in the presence of solvents, such as toluene, xylene, 
dichlorobenzene or N-methylpyrrolidone. The tinctorial strength and the 
transparency of the pigment can be influenced by varying the 
after-treatment. 
Because of their fastness to light and to migration, the colorants of the 
probable formula (I) are suitable for a large variety of pigment 
applications. They can be used for the preparation of very fast pigmented 
systems, such as mixtures with other substances, formulations, paints, 
printing inks, coloured paper and coloured macromolecular substances. 
Mixtures with other substances can be understood as meaning, for example, 
those with inorganic white pigments, such as titanium dioxide (rutile) or 
with cement. Examples of formulations are flushed colours containing 
organic liquids or pastes and fine pastes containing water, dispersants 
and, if appropriate, preservatives. The term paint represents, for 
example, physically or oxidatively drying lacquers, stoving enamels, 
reaction lacquers, two-component lacquers, dispersion paints for 
weather-resistant coatings and distempers. Printing inks are understood as 
meaning those which are used for paper printing, textile printing and tin 
printing. 
The macromolecular substances can be of natural origin, such as rubber, can 
be obtained by chemical modification, such as acetyl cellulose, cellulose 
butyrate or viscose, or can be produced synthetically, such as polymers, 
polyadducts and polycondensates. Plastic materials, such as polyvinyl 
chloride, polyvinyl acetate, polyvinyl propionate, polyolefins, for 
example polyethylene or polyamides, superpolyamides, polymers and 
copolymers of acrylates, methacrylates, acrylonitrile, acrylamide, 
butadiene and styrene, and polyurethanes and polycarbonates, may be 
mentioned. The substances pigmented with the claimed products can be in 
any desired form. 
The pigments of the probable formula (I) also possess excellent 
water-fastness, oil-fastness, acid-fastness, lime-fastness, 
alkali-fastness, fastness to solvents, fastness to overcoating, fastness 
to overspraying, fastness to sublimation, heat-resistance and resistance 
to vulcanisation, have a very high colour yield and can readily be 
distributed in plastic materials. 
It should be pointed out that the structural formulae given in the examples 
below are probable structural formulae.