Patented Feb. 29, 1944 2,342,662 UNITED STAT Es PATENT OFFICE 2,342,662 MERCAPTO-PHTHALOCYANINEs. Norman Hulton Haddock, Black?ey, Manchester, England, assignor to imperial Chemical Indus tries Limited, a corporation of Great Britain No Drawing. Application April 29, 1941, serial No. 390,912. In Great Britain May 13, 1940 1 Claims. (C. 8-3) This invention relates to novel textile dyes, amino compounds by converting the amino pigments and intermediates of the phthalo groups over the diazo derivatives into mercapto. cyanine Series. More particularly, this inven groups, by methods well known in the prior art. tion relates to mercapto compounds of the gen However, such known and synthetically prepared eral formula, Q- (SH), wherein a is a nu 5 aromatic mercapto compounds do not possess meral from 1 to 4, while Q stands for the radical sufficient substantivity to textiles and similarity of a phthalocyanine compound selected from the to commercial sulfur colors in dyeing properties group consisting of metal-free phthalocyanines to be useful as textile dyes. . . . . and metallic phthalocyanines of the benzene and It is known that substituents can be intro-3, naphthalene series, their homologs and substitu 0 duced into the phthalocyanine molecule, either tion derivatives, e. g., halogen, nitro, phenyl, by a direct Substitution process, such as for in phenoxy, benzoyl, etc.; and to sulfur-type dyes stance by halogenation or sulfonation, or by derivable therefrom by oxidation of the mer synthesizing phthalocyanines from substituted captO groupS. - w intermediates, such as aromatic substituted ni Compounds of the phthalocyanine series find 5 triles, ortho-dicarboxylic acids, or derivatives at present their greatest commercial use as valu thereof. However, the introduction of the mer able pigments for printing inks, paints and other capto or disulfide groups into a phthalocyanine pigmented coating compositions. It is known molecule has not heretofore been accomplished that the introduction of certain substituents, by any method described in the prior art. such as for instance sulfonic acid groups into the 20 This invention has as its object to prepare new phthalocyanine molecule, renders the products mercaptophthalocyanine derivatives which can Soluble in water and produces direct dyes which be applied to textiles in much the same way as can be used for textile and paper dyeing. How commercial sulfur colors, but which possess ever, such known water-soluble phthalocyanines much superior fastness properties and very de are deficient in exhausting properties, and the 23 sirable bright bluish-green to greenish-blue wash fastness and other fastness properties of shades, such as have not been obtained hereto the dyeings on Cotton are not entirely satisfac fore from any known commercial sulfur dye. A tory. further object of the invention is to utilize the It is known that many aromatic intermediates well known and outstanding tinctorial strength of the benzene and naphthalene series and some 30 and clarity of the pigment shade, shown by com heterocyclic compounds can be fused with sul pounds of the phthalocyanine series, for the dye fur and alkali polysulfides to give vattable dyes, ing and printing of cotton, wool and other come generally referred to as sulfur colors, which con mon fabric. A still further object is the prep tain sulfur atoms in the molecule, and which aration of intermediates of the phthalocyanine can be dissolved in diluted alkaline sodium sul 35 Series which possess one or several functional fide or hydrosulfite to give what appears to be groups not heretofore available in phthalocy a Solution of the alkali salt of a mercapto com anine compounds. These groups serve particu pound. From this solution (or vat) textiles are larly well for the introduction of very desirable dyed in various shades. When these dyeings are substituents into commercial phthalocyanines. exposed to the air or other oxidizing agents, the 40 These objects are accomplished by the follow Water-Soluble alkali salts are converted on the ing invention. It was discovered that mercapto fiberinto the original insoluble dye. While these compounds of the phthalocyanine series can be known sulfur dyes are comparatively inexpen obtained readily from the corresponding amino sive, and are therefore used to a great extent phthalocyanines by known methods, for instance for the dyeing of cotton and other fabric, they 45 by converting the amino compounds into the show, in general, quite inferior fastness proper- . diazo derivatives which in turn are converted ties and dull shades and they cannot be used to the xanthate esters, followed by hydrolysis at for commercial textile printing by conventional elevated temperatures. These alkali-soluble vat dye methods, since the presence of free sul mercapto compounds are readily oxidized by air fur or sulfides in the printing paste renders the 50 or other oxidizing agents to form water-insolu same unsatisfactory to be printed from engraved ble disulfides. These dyes can be redissolved in copper cylinders which are stained by such sul aqueous Sodium sulfide solution, forming a vat fur compounds. . from which textiles can be dyed much in the It is known that one or several mercapto or disulfide groups can be introduced into aromatic sis finalsame bluish-greenmanner as commercial or greenish-blue sulfur colors.dyeings Theob 2 2,842,862 tained from these products on cellulosic material Berichte der deutschen Chemischen Giesellschaft, show outstanding fastness to washing and light 1890, volume 23, page 738) and alkali metal and are, in general, equal in fastness properties thiosulfates (see Die Methoden der organischen and clarity of shade to the best known anthra Chemie, Houben, 1924, volume 4, page 628). quinone vat dyes. The dyeings are discharge In its broadest aspects, this invention includes able to good whites by steaming after treatment the manufacture of sulfur-containing, dyestuffs with dimethyl (sulfobenzyl) phenyl ammonium by the oxidation of mercaptophthalocyanines, chloride, sodium hydroxide and sodium formal however obtained, and also the use of these mer dehyde sulfoxylate solutions. The new sulfur captophthalocyanines as intermediates for novel containing dyes may also be used for printing O dyes Suitable for pigmentation purposes or deco on textiles by conventional printing methods ration of textiles or the coloring of frasoline, oils, which are used for the printing of anthraquinone plastic masses and similar material. and indigoid vat dyes, preferably by the glucose I have further found that the intermediate caustic soda method. products in the manufacture of the above-men The new mercapto compounds, obtained by 5 tioned sulfur dyestuffs, namely, the phthalocya this invention, also serve as intermediates for nine xanthate esters or thiocyanophthalocya the preparation of desirable new pigments and nines, can themselves be applied to cellulosic ma colored compounds such as thioglycolic acids, terial from Sodium sulfide solution according to thioethers, thioesters, and other products which the usual practice with sulfur dyestuffs. By this can be obtained by replacement of the reactive 20 procedure the phthalocyanine Xanthate esters or hydrogen (attached to the sulfur atom) by vari thiocyanophthalocyanines become hydrolysed in ous aliphatic or aromatic radicals. the sodium Sulfide Solution to mercaptophthalo Instead of starting with the amino-phthalo cyanines. Thus by the dyeing technique usual cyanines, one or more mercapto groups can also with sulfur dyestuffs there are produced on the be introduced into the phthalocyanine molecule 25 fiber, the same sulfur dyestuffs, to the production by replacing hydrogen or halogen atoms in in substance of which the aforementioned process phthalocyanines by sulfur, whereby disulfides relates. In this way also, there are obtained dye are formed which may be treated with alkaline ings with the properties which have already been reducing agents to give the corresponding mer described. Accordingly, the present invention re capto compounds. Thus, chlorinated copper 3) lates not only to the manufacture by the afore phthalocyanine reacts under suitable conditions. said process of Sulfur dyestuffs in Substance but (for instance when treated in pyridine solution also to their production on the fiber, that is on with alkali polysulfides) to give disulfide deriva the cellulosic material, directly by application tives which are similar in dyeing properties to the thereto of the intermediate products in the man . mercapto compounds obtained from amino cop 35 ufacture process, which are phthalocyanine per phthalocyanines. Xanthate esters and thiocyanophthalocyanines. The amino-phthalocyanines, which serve as the . The above special feature of this inveption is preferred starting materials for the products of being described in further detail and claimed in a this invention, are obtainable by the methods de copending application, filed by me as a continua scribed in British Patent 529,847. They are pref O tion-in-part of the instant application, Ser. No. erably made by subjecting 4-nitro-phthalimide, 482,822, filed April 12, 1943. or mixtures of 4-nitro-phthalimide together with The invention is further illustrated, but not unsubstituted phthalimide in molecular proport intended to be limited, by the following examples, tions (in ratios of 1:3, 2:2, or 3:1), to the usual in which the parts are by weight. fusion with metal salts in the presence of urea 45 and ammonium molybdate, followed by reduc Eacample I tion of the resulting nitro compounds with sodium 20 parts of copper tetra- (4) -aminophthalocya hydrogen sulfide. They may also be obtained nine in the form of a finely-milled 5% aqueous from the corresponding nitro-phthalomitrile or 50 paste are added to 240 parts of 36% hydrochloric from mixtures of nitro-phthalonitrile with un acid with good agitation. The mixture is stirred substituted phthalonitrile, according to known at 5 C. and a Solution of 13 parts of Sodium ni methods. Among the aminophthalocyanines trite in 250 parts of Water is added quickly, the which are particularly suitable as starting ma temperature of the mixture being allowed to rise terials for the mercapto compounds covered by 55 to 10° C. The clear green solution of the tetra this invention, may be mentioned: diazo compound is added to a solution of 40 Copper-tetra- (4) -aminophthalocyanine, parts of potassium ethyl Xanthate in 200 parts of Copper-tri-(4) -aminophthalocyanine, water at 50-55. During the addition. Of the Copper-di-(4)-aminophthalocyanine, tetradiazo compound sufficient of a 20% solution Copper-mono-(4) -aminophthalocyanine, 60 of sodium carbonate is added simultaneously to Cobalt-tetra- (4) -aminophthalocyanine, keep the mixture alkaline. The green precipi Nickel-tetra-(4)-aminophthalocyanine, tated xanthate ester is filtered and washed with Metal - free - tetra-(4) -aminophthalocya Water. nine. p 10 parts of the xanthate ester are boiled with The conversion of the diazo compounds, ob 65 100 parts of.33% aqueous sodium hydroxide solu tained from the above aminophthalocyanines, to tion for one hour. The mixture is poured into the mercapto derivatives is preferably carried 300 parts of water. The resulting dark blue Solu out by the xanthate method, illustrated in the tion is made acid with acetic acid and the pre examples. However, other reagents, which are cipitate filtered off and dried. The product is a known to be suitable for the conversion of 70 green powder, insoluble in water and dilute al aromatic diazo groups into mercapto groups, may kalis but soluble in hot dilute aqueous sodium be employed, among which may be mentioned: sulfide to give a dark blue Solution. It is prob Alkali metal thiocyanates, the resulting thio ably a polydisulfide derived from copper tetra cyanate being treated with, e. g., potassium Sulf (4)-mercaptophthalocyanine. A hot solution of fydrate (see Gattermann and Hausknecht, 75 the product in dilute aqueous sodium sulfide dyes 2,842,862 3 cotton in dull blue shades which on exposure to capto derivatives of copper phthalocyanine, the the air yield bright bluish-green dyeings of outs solutions containing the sodium salts of the mer standing fastness to Washing, soap boiling, capto compounds are treated with chloroacetic chemick and light. acid in alkaline solution at temperatures between acample II 40 C. and 100 C., the corresponding thioglycolic acid derivatives of copper phthalocyanine are A mixture of 55 parts phthalinaide, 24 parts 4 formed. For example, the reaction mass obtained nitrophthalinide, 111 parts urea, 20 parts cupric by refluxing the xanthate ester from 25 parts of chloride, 2 parts boric acid and 0.5 part am tri- (4) -nitro copper phthalocyanine (which has monium molybdate in 400 parts kerosene, was O been reduced, diazotized and reacted with sodium heated at 190 to 210° C. for 4 hours while stir Xanthate) with 80 parts alcohol, 25 parts caustic ring. After cooling, the product was separated Soda for two hours, is diluted with about 80 parts from the kerosene by filtration and drying. The water and cooled to about 40° C. To this sus crude product was extracted repeatedly with pension are added 20 parts chloroacetic acid, and dilute hydrochloric acid and caustic Soda. The the resulting alkaline mixture heated to the boil dry, extracted mono nitro-copper phthalocyanine ing point and the alcohol distilled out. The sus was stirred into ten times its weight of 98% pension is then diluted and acidified by a mineral sulfuric acid at 5-7 C. and the resulting solution acid. The tri- (4)-thioglycolic acid derivative of was drowned in hot water to give a finely divided copper phthalocyanine is completely precipitated product. After filtering off and washing free of and can be filtered off, Washed and dried. The acid, the filter cake was made up to a 10% paste alkali salts of this product are slightly soluble in by stirring with water. 200 parts of this paste Water with a blue coloration. The sodium salts were heated under agitation with 68 parts of a of the mono- and di-thioglycolic acid derivatives solution containing 33% of sodium sulfhydrate of Copper phthalpcyanine are less soluble than for several hours at 85-90° C. The resulting the tri-thioglycolic acid, while the salts of the mono-amino-copper phthalocyanine was filtered tetra-thioglycolic acid are more soluble. off and washed. The filter cake was dispersed with Water to give a diluted suspension and the Eacample VI product was diazotized by adding 12 parts of con One mole of chlorinated copper phthalocyanine centrated hydrochloric acid solution, cooling to (containing 14.5 atoms of chlorine per molecule) 0-5. C., and adding 12.5 parts of 20% sodium was heated with four moles of sodium disulfde in nitrite solution. The resulting diazo Suspension pyridine Solution for 24 hours at reflux tempera was added at 50-60C. to a solution containing 6.5 ture. A bright green sulfur-containing dye was parts of Sodium Xanthate and 4 parts of Soda ash. isolated from the reaction mass by filtration of After cooling to about 40 C., the resulting the diluted fusion, after acidification with hydro Xanthic ester was filtered off, Washed and the chloric acid. A somewhat bluer product was ob product refuxed with 100 parts of alcohol and 20 tained by refluxing one mole of chlorinated cop parts of caustic soda for 2 hours. The resulting per phthalocyanine (containing ten atoms of reaction mass was acidified and the product chlorine per molecule) with four moles of sodium filtered off, Washed and dried. The copper-mono 40 disulfide in pyridine solution. Both products, (4)-mercaptophthalocyanine, thus obtained, is when treated with sodium sulfide and caustic slightly soluble in sodium sulfide solution from soda give deep colored solutions from which cot which Cotton is dyed in greenish-blue tints. ton was dyed in bluish shades which, by air oxi dation, were converted to bright green to bluish Eacample III 45 green dyeings of excellent fastness properties. By proceeding as in the above Example II, ex The above-described, sulfur-containing prod cept using 36.8 parts of phthalimide and 48 parts ucts can be applied to textiles satisfactorily by of 4-nitrophthalinide instead of the amounts commercial dyeing methods, such as are used for there given, a di-nitro-copper phthalocyanine is sulfur colors. The following procedure Serves to obtained. This product was reduced to a diamino 50 illustrate a preferred dyeing method. copper phthalocyanine with sodium sulfhydrate Eacample VII and subjected to the same series of reactions, de 7 parts of the isolated dyes (from Examples I Scribed in the preceding example, to give copper to V) are dissolved in a solution of 100 parts of di- (4)-mercaptophthalocyanine. This product sodium sulfide and 50 parts of soda ash at 190 shows better solubility in sodium sulfide solution F. The cotton fiber is dyed in this solution at 180 than the product of Example II and gives strong to 190° F. for one hour, with the addition of 30% and bright bluish-green shades on Cotton when of common salt. The dyeings are then removed dyed from an alkaline sodium sulfide vat, fol from the bath and oxidized by exposure to air lowed by exposure of the dyeings to air oxida or with sodium perborate or sodium bichromate tion. 80 to develop the final shade which is soaped and Eacample IV finished in the usual manner. By substituting 18.4 parts phthalimide and 72 parts 4-nitrophthalimide in the above Example Eacample VIII II, a tri-nitro-copper phthalocyanine is obtained. 20 parts of copper tetra- (4) -aminophthalo When carried through a similar series of reduc cyanine in the form of a finely-milled 5% aque tion and other reactions as described above, ous paste are added to 240 parts of 36% hydro copper tri- (4)-mercaptophthalocyanine is ob chloric acid with good agitation. The mixture is stirred at 5° C. and a solution of 13 parts of tained, which shows better solubility than the di sodium nitrite in 250 parts of water is added mercapto derivative in alkaline sodium sulfide 70 quickly, the temperature of the mixture being solution and dyes cotton therefrom in very strong allowed to rise to 10° C. To the clear diazo solu shades, similar to those obtained from the product tion at 10° C. is added a solution of 40 parts of of Example I. sodium thiocyanate dissolved in the minimum Ezample W quantity of water. There is an immediate evo If in the bove examples for preparing mer 75 lution of nitrogen and a green precipitate is 4. 2,342,862 formed. The mixture is stirred at room tem dark green solution from which cotton is dyed . . perature for A hour and finally heated to 90' in green shades of excellent fastness to Washi for a further a hour. The green precipitate of ing, soap boiling and light. The shades are copper tetra- (4)-thiocyanophthalocyanine is fill yellower than those obtained from the corre tered off, washed with Water and finally with sponding copper derivative of Example VII. alcohol. Eacample X The filter-cake is now suspended in a mixture of 500 parts of alcohol and 170 parts of 20% aque 300 parts of a 5% aqueous paste of copper tri ous sodium Sulphide solution. The mixture is (4) -aminophthalocyanine are added with wig boiled and stirred until all the suspended matter 10 orous stirring to 300 parts of 36% hydrochloric has dissolved and a grey-blue solution of the so ... acid. The bright blue suspension of the hydro dium mercaptide has been obtained. A stream of chloride thus obtained is cooled to 0-5 C, and air is now passed through to oxidise the sodium 75 parts of 10% aqueous sodium nitrite solution mercaptide. The product, probably a polydisul are added rapidly. A clear, bright green solu fide, forms a green suspension. It is filtered off, s tion of the tridiazo compound is immediately washed with water and dried. formed. After stirring for one minute, a solu The product is a green powder which is insolu tion of 25 parts of sodium thiocyanate in 100 ble in dilute alkalis. It is also insoluble in wa parts of water is added quickly. The resulting ter but is soluble in hot dilute aqueous sodium green suspension is warmed to 90° C. during sulphide to give a dark blue Solution. It is probe about one hour, and maintained at 90-95 C. for ably a polydisulphide derived from copper tetra 20 A hour. The product is filtered off and washed (4)-mercaptophthalocyanine. A hot solution of with water until acid-free, and then with alco the product in dilute aqueous sodium sulphide hol. The copper tri-(4) -thiocyanophthalocy dyes cotton in dull blue shades which on exposure anine, so-obtained, is hydrolysed and oxidised in to the air yield bright green dyeings of outstand the manner described in the first part of Ex ing fastness to Washing, soap boiling, chemick 25 ample VIII. and light. A. is The resulting product is a sulfur-containing The above sulphur dyestuffs can also be pro dyestuff which dyes cotton in bright green shades duced directly on the cellulosic fibre in the foll of excellent fastness to washing, chemick, soap lowing manner. In this way a similar shade is 30 boiling and light. ... obtained to that got by applying to the cellulosic Eacample XI material the sulphur dyestuff first made in sub stance. 300 parts of a 5% aqueous paste of copper di 1 part of copper tetra- (4)-thiocyanophthalo (4) -aminophthalocyanine (obtained as described cyanine (obtained as described above), 1.5 parts below) are diazotised as in Example X but using of sodium sulphide crystals, 1 part of anhydrous 50 parts of 10% sodium nitrite solution instead sodium carbonate and 20 parts of water are boiled of 75 parts. The diazo solution is added to a together until a clear solution is obtained. The solution of 20 parts of potassium ethyl Xanthate Copper tetra- (4)-thiocyanophthalocyanine in 100 parts of water at 50-60° C. At the same thereby becomes hydrolysed to copper tetra- (4)- 40 time sufficient sodium carbonate is added to keep mercaptophthalocyanine. The solution is diluted the solution alkaline. The Suspension of Xanth with 3000 parts of warm water, and 100 ate ester so-obtained is cooled to 40° C. and fl parts of bleached cotton yarn, previously well tered. The xanthate ester is washed with water, wetted-out by soaking in cold water, are im hydrolysed to copper di- (4)-mercaptophthalocy mersed therein. The solution is aeated to 85° C. 45 anine and oxidised, as described in Example I. 15 parts of sodium chloride are added. The tem The resulting sulphur-containing dyestuff perature is maintained at 85°C. and at the end of (probably a polydisulfide) dyes Cotton from So A hour a further addition of 15 parts of sodium dium sulfide solution, in green shades of excel chloride made, the cotton being occasionally lent fastness to washing, soap-boiling, chemick turned. After a further 4 hour the cotton yarn 50 and light. The shades are bluer than those is removed, Squeezed, rinsed in cold water and obtained from the dyestuff of Example X, allowed to hang in the air. The copper tetra Copper di- (4) -aminophthalocyanine is made (4)-mercaptophthalocyanine cn the yarn be by heating 38.4 parts of 4-nitrophthalimide, 29.4 comes oxidised (probably forming a polydisul parts of phthalimide, 120 parts of urea, 20 parts phide) and the cotton yarn acquires a bright 55 of anhydrous cupric chloride, 1 part of am green shade. monium molybdate, 2 parts of boric acid and Eacample IX 300 parts of commercial ot-chloronaphthalene at 20 parts of nickel tetra- (4) -aminophthalo 140-145° C. for 3 hours, and reducing the so cyanine in the form of a finely-milled 2.2% aque obtained copper di- (4) -nitrophthalocyanine with out paste are added to 300 cc. of 36% hydro 60 sodium hydrogen sulphide. chloric acid with good stirring. 60 parts of 10% It will be understood by those skilled in the art aqueous sodium nitrite solution are added at be that many variations and equivalents may be low 10 C. As soon as a clear solution of the used in the above-illustrated processes, without tetradiazo compound has been obtained, 20 parts departing from the spirit of this invention. of ammonium thiocyanate dissolved in a little 85 Thus, the diazotization of the amino derivatives water are quickly added. The mixture is stirred may be accomplished by using sulfuric acid in for 4 hour at 15° C. and then warmed to 90° C. place of hydrochloric acid. The acid concen for a further 42 hour at complete the reaction. tration used for the diazotization may be varied The green suspension of nickel tetra- (4)-thio within wide limits, but best results are obtained cyanophthalocyanine is filtered and converted to 70 with comparatively strong acid (10%) concen nickel tetra- (4)-mercaptophthalocyanine and tration. then to a polydisulphide in the manner described Hydrolysis of the xanthate ester may be ac for the copper derivative in Example VIII. complished equally well by the use of less con The product is a green powder soluble in warm centrated (aqueous or alcoholic) caustic soda dilute aqueous sodium Sulphide solution to give a 75 Solutions, or by replacing the sodium hydroxide, 8,842,862 S. used in the above Examples I to W, by an equivae 8. In the process of producing a dyestuff of the . lent amount of potassium hydroxide. phthalocyanine series, the step which comprises In the claims below the expression "disulfide' subjecting a polymercaptophthalocyanine to or "disulfide group' when used in conjunction Oxidation whereby to produce a polydisulfide with a phthalo-cyanine compound, is to be un phthalocyanine compound. derstood as referring to the group -S-S- the 9. A process of producing a dyestuff of the free linkages of which are attached to carbon phthalocyanine series, which comprises treating atoms of the same phthalocyanine molecule or a poly-diazophthalocyanine compound with an two different phthalocyanine molecules. alkali-metal. Xanthate, followed by hydrolysis to I clain: O produce a corresponding poly-mercaptophthalo 1. Polydisulfide dyes of the phthalocyanine cyanine compound, and then oxidizing the poly Series. mercapto compound thus obtained to a poly 2. A sulfur dyestuff derived by oxidation of a disulfide compound. phthalocyanine mercaptan, said dyestuff being 10. Polymercaptophthalocyanines. characterized by solubility in aqueous sodium s 11. A compound of the phthalocyanine series, Sulfide and by dyeing cotton from said solution, characterized by possessing SH groups in its which dyeings after oxidation on the fiber are arylene nuclei, and by its capacity for yielding a fast to Washing, chemick and light. sulfur dye upon selective oxidation of the SH 3. A dyestuff compound characterized by pos grOS. sessing in its structure at least one phthalocy 12. Tetra-mercapto - metal - free - phthalocy anine radical and at least one disulfide group, anine. said compound being further characterized by 13. Tetra-mercapto-metal-phthalocyanines. solubility in aqueous sodium sulfide from which 14. Tetra-miercapto-copper phthalocyanine. solution cotton may be dyed by the usual process 15. Tri-mercapto-copper phthalocyanine, applicable to sulfur dyestuffs in general. 16. The process of dyeing textile fiber which 4. A dyestuff exhibiting the normal solubilities comprises applying thereto from an alkaline and dyeing properties of a sulfur dye but being bath containing an alkali-metal sulfide, a polya further characterized by containing in its struc disulfide dyestuff of the phthalocyanine series, ture the typical carbon-nitrogen complex of a and then oxidizing the color on the fiber. phthalocyanine compound, said dyestuff being SO 17. A compound of the general formula obtained by subjecting a polymercapto-phthalo Q-(SH), wherein at is a numeral not greater cyanine compound to oxidation. than 4, while Q is the radical of a phthalocyanine 5. Polydisulfde derivatives of metal-phthalo compound selected from the group consisting of cyanines. the metal-free and metallic phthalocyanines of 6. A polydisulfide derivative of copper phthalo- is the benzene series. cyanine, 7. A polydisulfde derivative of metal-free NORMAN EUON HADOOCEK. phthalocyanine.