Benzoxanthene and Benzothioxanthene Dicarboxylic Acid Imide Dyestuffs and Process for Their Manufacture

The present invention relates to valuable novel benzoxanthene and benzothioxanthene dicarboxylic acid imide dyestuffs of the general formula ##SPC2##

Wherein X is O or S, R.sub.1 and R.sub.2 each is hydrogen, chlorine, bromine, cyano, lower alkyl, lower alkoxy, lower carbalkoxy or phenyl, R.sub.3 and R.sub.4 each is hydrogen, lower alkoxy or hydroxy lower alkoxy, and R.sub.5 and R.sub.6 each is hydrogen, alkyl, cyclohexyl, benzyl, alkanoyl, phenyl lower alkanoyl, phenoxy lower alkanoyl, cyano lower alkyl, hydroxy lower alkyl, phenyl sulfonyl, benzoyl, dichlorobenzoyl, sulfamido-benzoyl, carbonamido-benzoyl, sulfamido-dichlorobenzoyl, lower alkyl-sulfamido-benzoyl or benzimidazolyl.

The novel dyestuffs of the above formula (1) are obtained by condensing benzoxanthene or benzothioxanthene-3,4-dicarboxylic acid anhydrides of the general formula ##SPC3##

With a compound of the general formula

in which formulae (2) and (3) X, R, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are defined as above, at a temperature within the range of from 100.degree. to 280.degree.C. The dyestuffs, in which R of the general formula (1) stands for an optionally substituted acylamino group, may also be obtained by reacting benzoxanthene or benzothiexanthene-3,4-dicarboxylic acid hydrazides of the general formula ##SPC4##

At a temperature within the range of from about 50.degree. to about 200.degree.C with carboxylic acid halides or anhydrides of the general formula

or

or sulfonic acid halides of the general formula

x, r.sub.1, r.sub.2, r.sub.3 and R.sub.4 of the cited formula (4) being as defined above, R' of the cited formulae (5), (6) and (7) representing an optionally substituted alkyl, cycloalkyl, aralkyl or aryl group and Y of the cited formulae (5) and (7), representing a halogen atom, for example a chlorine or bromine atom.

In the case where R of the cited formula (3) stands for a substituted amino group, the benzoxanthene or benzothioxanthene-3,4-dicarboxylic acid anhydrides of the formula (2) are advantageously heated, optionally under pressure, preferably at 120.degree.- 220.degree.C, with at least equimolar, preferably excess, amounts of the corresponding compound of the formula (3), optionally in an inert solvent and/or diluent, for example water, ethanol, ethylene-glycol monoalkyl ethers or dimethylformamide, furthermore in higher-boiling aromatic hydrocarbons, for example chloro-, dichloro- or trichlorobenzene, .alpha.-chloronaphthalene, or in quinoline or pyridine, for a prolonged period.

Advantageously, acid condensation agents, for example, zinc chloride, zinc acetate or the corresponding cadmium salts, as well as acetic acid, toluene-sulfonic acid, hydrochloric acid, sulfuric acid or phosphoric acid, are added, the condensation agent chosen depends on the solvent or diluent used.

The dyestuffs formed precipitate from the reaction mixture and may be isolated in known manner.

In the case where R of the cited formula (3) stands for a substituted 1,3,5-triazinyl radical, condensation with the anhydride of formula (2) is advantageously carried out, preferably at a temperature within the range of from 180.degree. to 240.degree.C, in a high-boiling solvent, such as quinoline or nitrobenzene in the presence of acid condensation agents, for example, zinc chloride, zinc acetate or zinc tosylate or the corresponding cadmium salts.

The dyestuffs isolated in known manner may optionally be freed from unreacted amino triazine or anhydride by treating them with dilute acid or dilute alkaline solution.

Acylation of the benzoxanthene or benzothioxanthene-3,4-dicarboxylic acid hydrazides of the formula (4) may be carried out with equimolar or excess amounts of the acid halides or anhydrides of formulae (5) - (7), whereupon mono- or diacyl hydrazides or mixtures thereof are obtained.

The hydrazides (4) are advantageously heated, optionally under pressure, preferably at 70.degree. to 150.degree.C, with the acylation agents of formulae (5) to (7) optionally in an inert solvent and/or diluent, for example dimethyl-formamide, N-methyl-pyrrolidone, chloro- or dichlorobenzene, pyridine or quinoline.

Suitable hydrazines of formula (3) for the condensation with benzoxanthene or benzothioxanthene-3,4-dicarboxylic acid anhydrides are, for example, .beta.-cyano-ethyl hydrazine, .beta.-hydroxy-ethyl hydrazine, phenyl hydrazine, 4-chloro-phenyl hydrazine, 2,4-dichloro-phenyl hydrazine, p-tolyl hydrazine, 3-methoxy-phenyl hydrazine, 4-hydrazino-benzamide, 3- and 4-hydrazinobenzene-sulfonamide, 2-hydrazino-5-sulfonamidobenzimidazole, 2-hydrazino-benzothiazole, 2-hydrazino-pyridine; furthermore the hydrazides of stearic acid, phenylacetic acid, phenoxy-acetic acid, benzoic acid, 2,4-dichlorobenzoic acid, 3-sulfonamido-benzoic acid, 2-hydroxy-5-sulfonamido-benzoic acid, 2,4-dichloro-5-sulfonamido-benzoic acid, 3-methylsulfonyl-benzoic acid, 2-hydroxy-4- methyl-benzoic acid, 3-hydroxy-diphenylene-oxide-2-carboxylic acid, benzenesulfonic acid, 2,5-dichlorobenzene-sulfonic acid, p-toluenesulfonic acid.

For the acylation of the hydrazides of formula (4) there may also be used, in addition to the acid chlorides or acid bromides (formula (5) or the carboxylic acid anhydrides (formula 6) already mentioned with the acyl hydrazides, for example, also those of acetic acid or lauric acid, 4-sulfonamido-benzoic acid and the acid chlorides or bromides (formula 7) of ethanesulfonic acid, benzene-sulfonic acid, 2,5-dichlorobenzene-sulfonic acid, p-toluene-sulfonic acid, 2-bromobenzene-sulfonic acid, 2,4,5-trimethyl-benzene-sulfonic acid and 4-hydroxybenzene-sulfonic acid.

The benzoxanthene-3,4-dicarboxylic acid anhydrides or hydrazides of the formulae (2) or (4) used as starting compounds may be obtained by heating the diazonium salts of the correspondingly substituted 4-(2'-aminophenoxy)-naphthalic acid ornaphthalic acid anhydrides in the presence of metallic copper powder or copper salts. Consequently the compounds having the benzothioxanthene ring are prepared in the same way by cyclisizing the corresponding 4-(2'-aminophenylmercapto)-naphthalic acids or -naphthalic acid anhydrides. Preparation of these compounds is described in Italien Patent 863.081, German Patent 1.297.259 and British Patent 1.112.726.

The term "lower" whenever used in this specification means those groups which have 1 to 4 carbon atoms.

The novel compounds according to the invention are valuable, greenish yellow to orange fluorescent dyestuffs which are particularly suitable for the dyeing of condensate resins and synthetic polymers, such as polyvinyl chloride, polystyrene and polymethacrylate. They are also excellently suitable for dyeing synthetic materials, eg., polyethyleneglycol-terephthalate, polyamides or cellulose acetate. They yield brilliant shades showing very good fastness properties, especially very good fastnesses to light, to wetting and to thermofixation.

The most important dyestuffs according to the present invention are those of formula (1) in which X stands for an oxygen atom. On the materials mentioned above they produce greenish yellow to orange dyeings of intensely blue-green to yellow fluorescence, which are distinguished by a very good fastness to light and some of them, by high reflectance values.

The following Examples serve to illustrate the invention:

31.8 g of 10-methoxy-benzoxanthene-3,4-dicarboxylic acid anhydride, 24.2 g of phenyl hydrazine and 5.0 g of glacial acetic acid were refluxed for 7 hours. The dyestuff of the formula ##SPC5##

which precipitated in brilliant yellow crystals, was suction-filtered, washed with methanol and dried. It dyes polystyrene and polymethacrylate materials yellow with shades of intense green fluorescence and a good fastness to light. If, instead of phenyl hydrazine, equivalent amounts of 2,4-di-chloro-, p-tolyl-, 3-methoxyphenyl hydrazine or 2-hydrazinopyridine were used, dyestuffs of similar properties were obtained.

A mixture of 14.4 g of benzoxanthene-3,4-dicarboxylic acid anhydride, 5.0 g of .beta.-cyanoethyl hydrazine and 180 ml of methyl-glycol were kept boiling for 6 hours. After the reaction had been terminated the reaction mixture was cooled and the yellow dyestuff of the formula ##SPC6##

was isolated as indicated in Example 1. The compound produces brilliant greenish-yellow shades having a very good fastness to light on unplasticized polyvinyl chloride.

16.9 g of 6-methoxybenzoxanthene-3,4-dicarboxylic acid anhydride were reacted at 135.degree. to 140.degree.C for 6 hours in the autoclave in 380 ml of ethanol with 4.5 g of .beta.-hydroxyethyl hydrazine. The reaction product of the formula ##SPC7##

isolated in usual manner dyes polystyrene and polymethacrylate materials with yellow shades of yellow green fluorescence and a good fastness to light.

A mixture of 15.1 g of 9-methylbenzoxanthene-3,4-dicarboxylic acid anhydride and 12.8 g of 3-hydrazinobenzenesulfonamido hydrochloride was stirred at 190.degree. to 200.degree.C for 4 hours in 85 g of quinoline while a slight nitrogen current was passed through. After cooling, the reaction mixture was diluted with 250 ml of methanol, stirring was continued for several hours, and the precipitated dyestuff of formula ##SPC8##

was suction-filtered. It was washed with methanol and then with a large amount of boiling water and dried. This dyestuff can be used for dyeing condensate resins, for example on the basis of melamine formaldehyde, yellowshades of an intense green fluorescence and a good fastness to light, and a very good fastness to bleeding.

8.4 g of 9-chloro-10-methylbenzoxanthene-3,4-dicarboxylic acid anhydride were refluxed for 6 hours with 4.0 g of benzoic acid hydrazide in 80 g of o-dichlorobenzene and 8.0 g of quinoline in the presence of 0.5 g of zinc chloride. After cooling, the reaction mixture was diluted with 100 g of ethanol and the dyestuff of formula ##SPC9##

was isolated in known manner. It dyes condensate resins, for example alcohol- modified melamine-formaldehyde resin materials in yellow shades of a green fluorescence and a good fastness to light.

36.0 g of benzoxanthene-3,4-dicarboxylic acid anhydride, 31.5 g of 2,4,6-triaminotriazine and 12.5 g of zinc acetate were introduced into 400 g of quinoline. Then the mixture was heated at 220.degree. to 235.degree.C, while a slight nitrogen current was passed through, and it was maintained at this temperature for 3 hours. The yellow condensation product was subsequently suction-filtered at room temperature, washed with a small amount of quinoline, then with ethanol and water. The moist filter cake was subsequently treated for 30 minutes each with 300 ml of boiling 5% hydrochloric acid and then with 300 ml of boiling 2% potassium carbonate solution and worked up as usual. The dyestuff of formula ##SPC10##

was obtained in the form of a yellow powder. On commercial condensate resins, for example urea-formaldehyde resins this dyestuff produces yellow shades of an intense green fluorescence and a good fastness to bleeding.

15.9 g of 9-methoxybenzoxanthene-3,4-dicarboxylic acid anhydride were kept boiling for 5 hours with 18.7 g of 2,4-diamino-6-phenyltriazine in 160 g of nitrobenzene while adding 5.0 g of zinc acetate. The reaction mixture was diluted with 150 ml of ethanol after cooling and the dyestuff of formula ##SPC11##

was worked up as described in Example6.

On condensate resins which are suitable for moulding compositions, for example urea-formaldehyde resins in powder form, shades of a green fluorescence and good fastness properties are obtained.

5 g of 9,10-dimethyl-benzothioxanthene-3,4-dicarboxylic acid hydrazide were refluxed for 3 hours in 250 ml of acetic acid anhydride. The orange-colored diacetyl compound of formula ##SPC12##

which crystallized while cooling dyes polymethacrylate materials in golden yellow shades of a green-yellow fluorescence and a very good fastness to light.

4.3 g of 2,4-dichlorobenzoic acid chloride were introduced into a suspension of 7.2 g of 6,10-dimethoxybenzoxanthene-3,4-dicarboxylic acid hydrazide in 60 g of quinoline and the mixture was stirred at 180.degree. to 190.degree. C for 3 hours. The yellow reaction product of formula ##SPC13##

isolated in known manner is very suitable for dyeing polyvinyl chloride brilliant yellow shades.

The following Table shows further fluorescent greenish yellow to orange dyestuffs which are obtained according to the methods described in the above Examples.