Metal-free Phthalocyanine Blue

There are several pathways to metal-free Phthalocyanine Blue  

The first route to preparing metal-free Phthalocyanine Blue involves treating phthalonitrile with the sodium salt of a higher-boiling alcohol, for instance with sodium amylate. The resulting phthalocyanine disodium salt is demetallized by stirring in cold methanol  

Phthalocyanine is likewise obtained by hydrolyzing a corresponding calcium or magnesium salt in an acidic medium. 

The similarly blue and equally polymorphous metal-free phthalocyanine existing in five different crystal modifications (a, (3, y, k, t) is chemically somewhat less stable than its copper complex [26] it decomposes slowly in a sulfuric acid solution. On the other hand, it can be chlorinated to afford metal-free Phthalocyanine Green. 

Three dimensional X-ray diffraction analysis has been employed to elucidate the molecular and crystal structure of Copper Phthalocyanine Blue ((3-modifica-tion). In all modifications, the planar and almost square phthalocyanine molecules are arranged like rolls of coins, i.e., in one dimensional stacks. The modifications vary only in terms of how these stacks are arranged relative to each other. One important aspect is the angle between staple axis and molecular plane. The a-phase features an angle of 24.7°, while the stacks in the -modification deviate by as much as 45.8° [13]. 

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The e-modification has gained some interest in recent years. Commercial types of metal-free phthalocyanine blue are now also available. 

Metal-free phthalocyanine has been prepared in several forms a (tetragonal), P (monoclinic), x (hexagonal), and x. Figure 7 shows the interconversions. For example, treatment of Monolite Fast Blue GS (ICI) with hot dimethylformamide followed by ball milling in isopropyl alcohol yields the fi-form as needles, whereas acid pasting produces the a-form as needles and flakes (Loutfy, 1981). Milling under different conditions yields either the x-form as needles or flakes (Takano et al., 1984 Kakuta et al., 1985) or the x-form as needles (Sharp and Lardon, 1968 Hackett, 1971). The x-form as rods has been... 

Recently, Nemykin et al. (1998) have also prepared a series of half-sandwich complexes containing a phthalocyanine radical anion. Treatment of rare-earth -diketonates RX3 [R=Sm,Eu,Gd,Lu X = l,l,l,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,6-dionate (hfdmod), l,l,l-trifluoro-4-phenylbutane-2,4-dionate (t bd) or 3-heptafluorobutyryl-D-camphorate (hfbc)] with metal-free phthalocyanine H2(Pc) in DMSO gives the novel R(Pc )X2 as red-brown crystals in up to 6% yield. The major products (up to 86%) are the normal blue R(Pc)X which contain a dianionic Pc ring. The complexes R(Pc)X2 are highly soluble in nonpolar solvents such as benzene, CHCI3, and hexane, and the solutions remain red for a week. The complexes are even more stable in the solid state. 

Dainippon Ink and Chemicals markets its photoconductive X-form metal-free phthalocyanines as the Fastogen Blue 8120 series. Products include materials for printers and material for plate-making. X-form metal-free phthalocyanine is less... 

Dainippon Ink and Chemicals markets its photoconductive X-form metal-free phthalocyanines as the Fastogen Blue 8120 series. Products include materials for printers and material for plate making. X-form metal-free phthalocyanine is less sensitive than titanyl phthalocyanine, but is considerably lower in price. The prices are only 2000 to 5000 a kilogram. Figure 17.6 shows a comparison of the transient decay curve of surface potential of single layer photoreceptors with the X-form metal-free phthalocyanine and the Y-form titanyl phthalocyanine. The... 

Metal-free copper phthalocyanine blue, ie. Pigment Blue 16 [574-93-6] is one of the eadiest forms of phthalocyanine. Environmental concerns about copper in pigments tended to increase the use of metal-free copper phthalocyanine, but certain shortcomings (greenish hue, lack of stabiHty in aromatic solvents) allowed only specialty uses (109). The stabiH2ed a-NC-type is used in certain automotive coatings. 

Cu(OAc), H20 (0.75 g, 3.7 mmol) was added to a refluxing solution of metal-free 1,4,8,11.15,18,22,25-octa(propyloxy)phthalocyanine (0.1 g, 0.1 mmol) in BuOH (5 mL). The solution was maintained at reflux for 0.5 h, cooled, and chromatographed (silica gel, CH2C12 and Et20). The green-blue fraction eluted first was crystallized from a slowly evaporating solution in CH2Cl2/py yield 0.086 g (81 %). 

Copper Phthalocyanine Blue exhibits more than one crystal modification. This is also true for the metal-free ligand whose greenish blue crystal phase was used on a large industrial scale for a certain period of time (Sec. 3.1.2.6). Free-base Phthalocyanine Blue was largely displaced by (3-Copper Phthalocyanine Blue as it became possible to produce the latter more economically (Sec. 3.1.2.3). 

The insolubilities of phthalocyanines made their analysis difficult and it took some time before a satisfactory structure was elucidated. Initial work was undertaken by the Linstead group at Imperial College in the 1930s that culminated in a series of six back to back papers published in 1934 [14], It was also Linstead who named the compounds in recognition of their synthesis from phthalic anhydride and similarity to the blue cyanine dyes. Definitive characterization of the nickel, platinum and copper phthalocyanine complexes, together with the metal-free compound, was revealed in 1935 following the publication of their X-ray structures by Robertson [15] the copper and metal-free compounds are illustrated in Fig. 7.5. 

Phthalocyanines are widely used in blues and greens. They offer excellent fastness to heat, light, chemicals, and solvents high tinting strength and transparency low cost and intense, pure shades. Most are copper based, although metal-free variations are also commercial. This family is widely used in plastics. 

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