Chromium phthalocyanine

Chromium phthalocyanines were mentioned several times in the early literature before they were adequately characterized (5, 10, 61, 106, 110, 226, 296, 297). The formation of mixtures when phthalonitrile is heated with chromic salts held up the early investigation of these compounds. The chemistry of the chromium phthalocyanines, as elucidated by Elvidge and Lever (87, 90), is illustrated in Fig. 9. 

Fig. 9. The chemistry of chromium phthalocyanines. Reaction pathway (1) sublime (2) CH3COOH (3) H20 (4) O2/H2O (5) alcohol (6) HCl/MeOH (7) H20/EtOH/ CH3COOH (8) alkali (9) acid (10) acid anhydride (11) KCN/EtOH (12) reflux acetic anhydride.

The data are taken from references (31, 196, 823), the numbering system from (323). Data for the first three complexes are taken from sublimed films, and for the last two from Nujol mulls. The references cited also include data for PcSnClj, PcSnBr2, PcSnL, PcSn(OH)2, PcsSn, PcSn, PcPb (196), PcZn, PcCu, PcCo, PcNi (31, 323). The infrared spectra of chromium phthalocyanines are considered in (90). 

Chromium(II) phthalocyanine (PcCr) is prepared from phthalonitrile and hexacarbonylchro-mium(O) in 1-chlornaphthalene.234 PcCr(OAc) is prepared from phthalonitrile and chro-mium(III) acetate without solvent235 or in nitrobenzene starting from chromium(II) acetate236 under reflux. Chromium(lll) phthalocyanine also forms /t-oxo dimeric complexes,237 which are more common with iron phthalocyanines. 

In an interesting study, phthalocyanine complexes containing four anthraquinone nuclei (5.34) were synthesised and evaluated as potential vat dyes and pigments [18]. Anthraquinone-1,2-dicarbonitrile or the corresponding dicarboxylic anhydride was reacted with a transition-metal salt, namely vanadium, chromium, iron, cobalt, nickel, copper, tin, platinum or lead (Scheme 5.6). Substituted analogues were also prepared from amino, chloro or nitro derivatives of anthraquinone-l,2-dicarboxylic anhydride. 

Since complexes of 2,2 -bipyridyl and 1,10-phenanthroline with chromium in oxidation states I and 0 can be obtained by reduction (Scheme 64) of the chromium(n) complexes, these oxidation states will be considered together. Oxidation, as shown in Schemes 65 and 68 of Section 35.4.2.5, gives chromium(III) complexes, which are often best prepared in this way. Earlier work has been extensively reviewed, and few complexes of 2,2 6, 2"-terpyridyl are known.32 A chromium(I) phthalocyanine derivative is mentioned in Section 35.4.9.3. 

Chromium(II) porphyrins and phthalocyanines are dealt with in Sections 35.4.9.1 and 35.4.9.3 respectively. 

Relatively few chromium complexes with phthalocyanine ligands have been reported and, ir view of the chemical relationship between the few known compounds, all of them, irrespectivt of the metal oxidation state, are dealt with in this section. In the following discussion Pi represents the dianionic phthalocyanine ligand. 

Continuous steam distillation, 147, 148 Cooling baths, 61 Cooling curve method, 26 Copper bronze, activated, 193 Copper - chromium oxide catalyst, for aldehyde synthesis, 318, 321 for hydrogenation, 872, 873 hydrogenolysis with, 872J Copper phthalocyanine, 983 Copper powder, 192 Copper sulphate, as desiccant, 40, 41 Cork stoppers, 55 boring of, 56... 

Examples of dye developers derived from heterocycles are the pyrazole (73), the chromium complex (74) and the phthalocyanine (75) (74MI11401). The pyrazole (76) is a... 

Convenient synthesis of chromium and iron phthalocyanines can be achieved by reaction of 1,2-dicyanobenzene with chromium hexacarbonyl or iron pentacarbonyl respectively in refluxing chloronaphthalene (equation 42).232... 

Direct Dyes. These water-soluble anionic dyes, when dyed from aqueous solution in the presence of electrolytes, are substantive to, i.e., have high affinity for, cellu-losic fibers. Their principal use is the dyeing of cotton and regenerated cellulose, paper, leather, and, to a lesser extent, nylon. Most of the dyes in this class are polyazo compounds, along with some stilbenes, phthalocyanines, and oxazines. Aftertreatments, frequently applied to the dyed material to improve washfastness properties, include chelation with salts of metals (usually copper or chromium), and treatment with formaldehyde or a cationic dye-complexing resin. 

Solvent dyes for solvent based ink-jet inks and hot melt ink-jet systems are selected 1 2 chromium or cobalt complex azo (C.I. Solvent Yellow 83 1 [61116-27-6], C.I. Solvent Red 91 [61901-92-6]), anthraquinone (C.I. Solvent Blue 45 [37229-23-5]), or phthalocyanine (C.I. Solvent Blue 44 [61725-69-7]) dyes. 

The tetrasulfo-Pc complexes of a number of metals are made by the urea melt process by heating the powdered metal, or its acetate, with triammonium-4-sulfophthalate, urea, boric acid, and ammonium molybdate. The metals or metal compounds used are those of chromium (III), manganese(II), iron(II), iron(III), cobalt(II), and zinc(II). Selected synthetic examples of sulfo- and other derivatives of metal phthalocyanines are presented below. 

Metals (Pt, Ag, Ni) - Metal Phthalocyanines -Removal of toxics Copper/Chromium oxides -Change of reactivity of the carbon support Catalytic gasification Inhibition of oxidation... 

Pigment green 50 is a niche player as well. Its relationship to phthalocyanine green parallels that of cobalt blue to phthalocyanine blue. Its opportunities are further constrained by chromium oxide green, which offers similar but not quite comparable performance properties and a similar but less chromatic and dirtier hue at about one-seventh the price. 

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