Phthalocyanine phthalonitrile process

The phthalonitrile process has the particular advantage over the phthalic anhydride process of forming ring-substituted chloro-copper phthalocyanines. Using copper(I)chloride produces so-called semi-chloro Copper Phalocyanine Blue, a pigment which possesses a statistical average of 0.5 chlorine atoms per copper phthalocyanine molecule. Copper(II)chloride, on the other hand, affords a product which comprises an average of one chlorine atom per copper phthalocyanine molecule. A prerequisite for the formation of the chloro substituted compound, however, is the absence of ammonia or urea in the reaction mixture. 

Moreover, the phthalonitrile process has the added advantage of being the more elegant of the two syntheses. This technique makes it possible to produce comparatively pure copper phthalocyanine without obtaining substantial amounts of side products, a phenomenon which is understandable in view of the fact that the phthalonitrile molecule provides the parent structure of the phthalocyanine ring. Formally, rearrangement of the bonds necessitates donation of two electrons to the system ... 

Phthalic anhydride initially reacts with ammonia, which in turn is liberated, for instance, by decomposition of urea. Diiminophthalimide is then produced via phthalimide and monoiminophthalimide. Subsequent self-condensation (as in the phthalonitrile process) under cleavage of ammonia affords polyisoindolenines, which form complexes with copper ions. Ring closure is achieved through further release of ammonia, and copper phthalocyanine is finally obtained by reduction. 

Only a minor amount of chlorinated copper phthalocyanine, for instance, especially in the 4-position of the copper phthalocyanine molecule, prevents a change of modification from a to (3. Approximately 3 to 4% chlorine is commonly used, which corresponds to the formula CuPc-Cl0.5, also referred to as semi-chloro-CuPc . The phthalic anhydride/urea synthesis, for instance, affords a partially chlorinated product if 4-chlorophthalic anhydride is added to the reaction mixture. Copper chlorides in the phthalonitrile process have the same effect. 

In the second manufacturing process for copper phthalocyanine, phthalonitrile, copper(II) acetate and ammonium acetate are heated in the presence of a base, with or without a solvent such as pyridine. The mechanism of this has been less studied than that of the phthalic anhydride/urea reaction. It is, however, significant that metal-free phthalocyanine is manufactured by heating phthalonitrile with the sodium derivative of a high-boiling alcohol in an excess of the alcohol. This reaction is believed148 to occur by the route outlined in Scheme 7, which is supported by the isolation of compounds of types (223) and (224). If this or a related mechanism operates in the... 

The template methods have also been used for the synthesis of a number of substituted Ln di(naphthalocyanine) complexes, LnNc2 [82-88]. Apart from thermal fusion by conventional heating processes, complexation has been initiated by microwave radiation, although only a few publications are devoted to the template synthesis of lanthanide bis(phthalocyanine) complexes by this method [89, 90]. The use of microwave radiation (MW) reduces the reaction time from several hours to several minutes. Unsubstituted complexes LnPc2 (Ln = Tb, Dy, Lu) were prepared [90] by irradiation (650-700 W) of a mixture of phthalonitrile with an appropriate lanthanide salt for 6-10 min (yields >70%). 

Crude Copper Phthalocyanine Blue which is prepared by the phthalonitrile or urea process typically evolves as the -modification with a coarse particle size. 

Phthalocyanines or tetrabenzoporphyrazines are prepared by the Wyler-Riley process (37BRP464126, 37BRP476243) via condensation of phthalic anhydride and urea in the presence of copper(I) chloride or by reaction of phthalonitrile with copper salts. Metal-free phthalocyanine, no longer of commercial importance, is prepared by reaction of phthalonitrile with sodium amylate, followed by demetallization in methanol. 

The second approach stemmed from the observation that a 1-substituted 3-iminoisoindolenine (223) was a probable intermediate in the synthesis of copper phthalocyanine from phthalonitrile. This led to the development of processes for the manufacture of 1,3-diiminoisoindolenine and its... 

Macrocycle 9.105, in the form of its pentaligated uranyl complex, was first characterized by Marks and Day. While earlier reports had claimed the successful preparation of normal U02-phthalocyanine from the reaction of U02 and phthalonitrile, the results of Marks and Day revealed that it is the pentameric uranyl superphthalocyanine, contaminated with only small quantities of metal-free phthalocyanine, that is the dominant product obtained as the result of such a process. The findings of Marks and Day were thus consistent with one other earlier report (see reference 57 and references therein) wherein mass spectrometric evidence... 

Mg, Be, Ag, Fe(II), Sb(III), Mn(II), Sn(II), alkali metals, alkaline earth metals, rare earths, Cd, Hg, and Pb 19, 21, 54, 119, 226). The rate of demetallation varies considerably 19) (see Section VI,B). The phthalo-cyanines of Cu, Zn, Co(II), Ni, Pt, Pd, VO, Al, Ga, and In resist demetallation in concentrated sulfuric acid at room temperature 10, 21, 56, 57). Phthalocyanine may also be prepared by the condensation of phthalonitrile or 1,3-diiminoisoindoline in hydrogen-donor solvents 10, 81, 86, 346), and by the catalytic condensation of phthalonitrile in the dry with platinum metal 10). Processes involving intermediates such as phthalic acid and urea have also been developed 380). 

Phthalonitrile was reduced at controlled potential in alcoholic solution at a C cathode in a two-compartment cell in which cathode and anode were separated by a Nafion cation-exchange membrane. The anolyte contained metallic salts such as CUSO4, NiS04, etc. The products formed in the cathode compartment were metal phthalocyanine complexes. Low yields were obtained when the metal ions were placed into the cathode compartment. The phthalonitrile radical anion formed by a 1-electron transfer was invoked as being important in the cyclization process leading to the metal complexes. Several intermediates... 

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