Solvent dyes .are used for a great variety of purposes although principally they are used in the mass coloration of plastics materials or in various lacquers and varnishes.

Whilst solvent dyes may, in some cases, be incorporated directly into the product to be colored, as their name suggests, they are usually applied from solutions in organic solvents or mixture of such solvents.

It has been normal practice to dissolve solvent dyestuffs in solvents such as ethers, esters, ketones, chlorinated hydrocarbons and alcoholic solvents e.g. ethanol. Of these solvents, the alcoholic solvents have become increasingly important because of environmental considerations. Unfortunately, however, dyestuffs having desirably high solubility in alcoholic solvents have not until now been available. There is a need for solvent dyestuffs which are highly soluble in alcoholic solvents, in particular ethanol.

It has now been found that certain new 1:2 iron azo-dyestuff complexes that exhibit desirably high solibilities in ethanol.

The invention provides in one of its .aspects a compound of the formula (I)

or mixtures thereof wherein

R] is hydrogen,

Alkyl

R ₂ .and R ₃ independently of each other are hydrogen, alkyl, alkoxyalkyl, cycloalkyl and aryl

R, is H or OH

R ₅ is hydrogen, alkyl, alkoxyalkyl and cycloalkyl

R, and R ₅ together with the ring to which they .are attached form a naphthyl group,

R _ό is hydrogen or a group

R ₇ ⁺ is a quaternised aliphatic or cycloaliphatic amine with the proviso that

(i) when R, and R ₅ together with the ring to which they .are attached form a naphthyl group then R ₄ is hydrogen .and R _$ is hydrogen .and

(ii) R ₄ is OH when R, is hydrogen,

Alkyl

R ₅ is hydrogen, alkyl, alkoxyalkyl and cycloalkyl.

Preferred alkyl groups are C alkyl, which may be linear or branched, e.g. methyl, ethyl or n-propyl, iso-propyl and n- and t-butyl. Preferred alkoxyalkyl groups have 1 to 8 carbon atoms and may be, for example, methoxyalkyl or ethoxyalkyl, more particularly methoxypropyl.

Preferred cycloalkyl groups are those forming a 5 or 6 membered ring.

As aryl groups one can mention the phenyl group or fused rings, for ex _* ample naphthyl groups. Aryl groups may be unsubstituted or they may be substituted with substituents selected from halogen (preferably Cl and Br), OH, C alkyl, C alkoxy, cyano, -NO ₂ , C^alkylcarbonyl, SCN, C ₁ - ₄ alkoxycarbonyl, benzoyl, phenoxycarbonyl, C^alkylcarbonyloxy, .aminocϊirbonyl, mono(C alkyl)juninocarbonyl, di(C alkyl)aminocarbonyl, mono(C alkoxy-C _2J| alkyl)- aminocarbonyl, di(C alkoxy-C ₂ - ₄ alkyl)aminocarbonyl, aminosulphonyl, monoCC _j ^alkyl)- aminosulphonyl, di(C ₁ - ₄ .alkyl).aminosulphonyl, mono(C,- ₄ alkoxy-C ₂ - ₄ alkyl)amino sulphonyl, di(C alkoxy C^alkyl) amino sulphonyl and phenylaminosulphonyl.

The group R ₇ ⁺ may be selected from ammonium, mono C ₅ - ₂₀ alkyl ammonium, di(C ₅ - ₂₀ alkyl)- ammonium, tri(C ₅ - ₂₀ alkyl)ammonium, preferably mono C ₈ - ₁₆ alkyl ammonium, di(C ₈ -ι ₆ alkyl)- ammonium, tri(C ₈ -| ₆ alkyl)ammonium and more preferably 4-amino-2,2,6,6-tetra-

alkylpiperidinium, 4-hydroxy-2,2,6,6-tetraalkylpiperidinium .and 4-keto-2,2,6,6-tetraalkyl- piperidinium. Particularly preferred groups R ₇ ⁺ are mono-octyl ammonium, 2-ethylhexyl- ammonium, 4-amino-2,2,6,6-tetr.amethyl-piperidinium, 4-hydroxy-2,2,6,6-tetramethyl- piperidinium or 4-keto-2,2,6,6-tetramethylpiperidinium.

In a preferred compound according to the invention the sulphamoyl group on a phenyl ring is in the 4- or 5 -position whereas the sulfamoyl group on a naphthyl ring is in the 4- or 6-ρosition.

More preferred compounds .according to the invention have the following formulae

or mixtures thereof wherein R ₂ , R ₃ and R _$ are as hereinabove defined and the group -SO ₂ NR ₂ R ₃ is in the 4- or 5-position when the ring is a phenyl ring and in the 4- or 6-position when the ring is a naphthyl ring.

wherein R ₃ is methoxypropyl and the group -SO ₂ NR ₂ R ₃ is in the 4- or 5-position, more preferably the 5 -position.

Compounds according to the formula (I) are obtained as mixtures of symmetric .and asymmetric compounds. By "symmetric" is meant compounds wherein both of the groups Rg are hydrogen or both are azo-sulphamoyl phenyl whereas by "asymmetric" is meant those compounds wherein the significances of Rg are at the same time different.

It follows from the preceding paragraph that those compounds wherein R, and R ₅ together with the ring to which they are attached form a naphthyl group are formed not as a mixture of symmetric .and asymmetric compounds but as the symmetric compound only.

The skilled person will understand that the relative amount of symmetric and asymmetric compound formed in a mixture will depend upon a number of factors, for example the proportion in which the reactants, that is the diazotised amine of formula (II) and compound of formula III, are employed; and the reaction conditions, e.g. the rate and sequence of addition of the reactants and temperature.

A compound of formula (I) can be prepared by known method for producing 1 :2 metal dyestuff complexes, for example by coupling a diazotised amine of formula (II)

with a compound of formula (III),

with subsequent or contemporaneous metallisation with an iron donating compound, and introduction of the cation.

Coupling reactions are known in the art and may be carried out under basic conditions, suitably in an aqueous medium at pH values of at least 7.5, principally in the range of 8 to 14, and under mild temperatures, preferably in the range of -5°C to +25°C, more preferably 0 to 20°C. The pH conditions may be adjusted using alkali metal hydroxides, carbonates, ammonia or amines.

Metallisation of monoazo or disazo compounds may be carried out by employing convention,al iron compounds, for example ferrous sulphate, ferric sulphate, ferrous nitrate, ferric nitrate or iron trichloride, suitably in an aqueous medium advantageously at a pH of from 3.5 to 6.5, preferably 4 to 6, with heating.

Metallisation is preferably carried out at temperatures in the range of 40°C up to reflux temperature, more preferably 60°C to 100°C.

The dyestuff so formed can be isolated from the reaction mixture in a conventional manner i.e., by salting out and filtration.

The compounds of formula I are usefully employed as dyes (especially for dyeing in the mass) for plastics material including solvent-free and solvent containing plastics masses and solvent- free or solvent containing plastics resins. They .are used in finishes based on oil or water based paints, in various lacquers, in wood stains, in spin dyeing of viscose or cellulose acetate, for dyeing of natural or synthetic polyamides, polyester, polyethylene, polystyrene, polyvinylchloride, rubber and synthetic leather. The compounds can be used for printing of graphic material, for dyeing of paper masses, for coating of textile and leather or for printing uses.

The compounds of formula I have exceptionally high solubility in ecologically acceptable solvents, e.g. ethwol in which solvent solubility may be as high as 400 to 500 g/1. This has the benefit that for a given quantity of dyestuff, less solvent needs to be employed in a given dyeing operation. Furthermore, the use of iron .as the metal instead of heavy metals such as copper, cobalt or chromium means that the new compounds can be used in .an ecologically beneficial way to dye or print substrates for example aluminium foils used for packaging. This enables the aluminium to be recycled easily. Therefore the compounds are useful in reducing waste that results from recycling and for reducing the amount of h.armful products.

Dyeings with the new compounds have good properties generally, for example good heat stability properties, good light and weathering properties, good chemical resistance, good migration properties, low blooming, good overcoating properties, good fastness in solvent properties, good dyeing strength .and good application properties (e.g. flocculation fastness).

Dyeing, printing .and padding can be carried out with the compounds on substrates by known methods.

There now follows a series of examples which illustrate the invention.

EXAMPLE 1 a) 26.0 parts of 2-amino-4-(3'-methoxypropylamino-sulphonyl) phenol are stirred into a mixture of 200 parts of water and 70 parts of 30% HC1. After the addition of 50 parts of ice, the amine is diazotized by the addition of 26.2 parts by volume of 4N NaNO ₂ solution. The resulting suspension is stirred for 3 hours at 0°C and then slowly poured

into a solution of 13.7 parts of β-naphthol in 190 parts of water and 9.5 parts of 30% NaOH. By the simultaneous addition of a further 70 parts of 30% NaOH, the pH is brought to 9.5-10. The resulting mixture is then stirred at room temperature for 8 hours and brought to pH 1.5 by the addition of 30% HCl. The resulting precipitate is filtered, washed with 4000 parts of water and dried.

500 parts of the monoazo dyestuff of part a) above are suspended in a mixture of 500 parts of water, 30 parts of dipropylene glycol monomethyl ether and 15.5 parts of sodium carbonate. After warming at 96°C for over 1 hour, a solution of 16.4 parts of iron chloride hexanhydrate in 50 parts of water is slowly added, whereupon a voluminous suspension of the iron complex results. The temperature is allowed to fall to 45°C over 2 hours (while stirring well) and the suspension is slowly reacted with a solution of 7.8 parts of 2-ethyl-hexylamine in 100 parts of water and 10 parts of 30% HCl. The resulting precipitate is adjusted to pH 6.5 by the addition of about 2 parts of HCl. The mixture is stirred a further hour at room temperature, filtered and the residue is washed salt-free and then dried. A compound of formula

in which R ₃ is methoxypropyl .and the sulph.amoyl groups are both in the 5-position is obtained.

The resulting dye dyes nitro cellulose lacquers a reddish brown shade and has a solubility in ethanol of about 100 g/1.

EXAMPLE 2 a) 40.4 parts of 2-amino-5-(4-methyliunino-sulphonyl) phenol are stirred into a mixture of 200 parts of water and 70 parts of 30% HCl. After the .addition of 50 parts of ice, the amine is diazotized by the addition of 53 parts by volume of 4N NaNO ₂ solution. The resulting suspension is stirred for 3 hours at 0°C. A solution of 22.5 parts of resorcinol in 40 parts of water and 10.6 parts of sodium carbonate is then slowly added. The resulting mixture is then stirred at room temperature for 8 hours and brought to pH 1.5 by the addition of 30% HCl. The resulting precipitate is filtered, washed with 4000 parts of water and dried.

Finally the resulting dyestuff, analogously to the process of Eχ.ample 1 is reacted with sodium carbonate iron chloride and 2-ethyl-hexylamine to a 1 :2 iron-dyestuff complex of formula as a mixture of symmetrical and unsymmetrical isomers

The sulphamoyl groups are in the 4-position.

The dyestuff colors nitrocellulose lacquers a dark brown color and yields high solubilities in ethanol (up to 400 g 1).

APPLICATION EXAMPLE

5 parts of the dyestuff of Example 1 in a Dissolver apparatus are stirred into 95 parts of a nitrocellulose lacquer prepared from:

18.8% of Nitrocellulose A15 (in the form of white floes wetted with 35% isopropanol) 6.3% of an acrylic acid butyl ester polymer, a softener resin (Acronal 4F from

BASF) 3.3% of diphenyloctylphoφhate, a softener (Santiciser 141 from Monsanto) 10.0% of methoxy propanol (Dowanol PM from Dow Chemical) 10.0% ethoxyprop.anol 41.6% ethanol, and 10.0% ethyl acetate.

This is dissolved overnight in a rolling block. The solubility is very good.

With a 25 mm blade, a wet film of this lacquer composition is placed on aluminium foil and the lacquer is dried for 5 hours at 130°C. A brownish red lacquer coating results with good light and migration fastness properties.

The Application Example is repeated with the mixture obtained in Example 2. A brownish-red lacquer is obtained exhibiting good light and migration fastness properties.