Copper phthalocyanine synthesis

The first commercial copper phthalocyanine synthesis, a baking process, involved melting phthalic anhydride with urea at 150°C in the presence of boric acid. Cop-per(II)chloride was then added and the temperature increased to approximately 200°C until the copper phthalocyanine production was completed. The reaction mixture was cooled and the crude product milled. After being washed, first with dilute sodium hydroxide solution and then with dilute sulfuric acid, the material was filtered off and dried. The crude copper phthalocyanine obtained was then... 

A second reaction which is very often used for the preparation of phthalonitriles, although the yields are usually not reproducible, is the Rosenmund-von Braun reaction (see Houben-Weyl, Vol. E5, p 1460).106 107 Herein, a benzene derivative with a 1,2-dibromidc or 1,2-dich-loride unit is treated with copper(I) cyanide in dimethylformamidc or pyridine. During this reaction the formation of the respective copper phthalocyanine often occurs. This can be used as an easy procedure for the exclusive synthesis of copper phthalocyanines (see Section 2.1.1.7.),1 os-109 but can also lead to problems if the phthalonitrile is required as the product. For example, if l,2-dibromo-4-trifluoromethyl-benzene is subjected to a Rosenmund-von Braun reaction no 4-trifluoromethylphthalonitrile but only copper tetra(tri-fluoromethyljphthalocyanine is isolated.110... 

Due to its commercial importance, the synthesis of copper phthalocyanine (PcCu) is the best investigated of all the phthalocyanines. Copper phthalocyanine is prepared from phthalonitrile and copper(I) chloride without solvent137 and also in a melt of urea.229,277 Additionally, the insertion of copper into metal-free phthalocyanine in butan-l-ol and pentan-l-ol is possible. The copper salts used in this case are copper(I) chloride112 and copper(II) acetate.290 Starting from copper(II) acetate, copper phthalocyanine can also be prepared in ethylene glycol.127 As mentioned above, copper phthalocyanine often occurs as a byproduct of the Rosenmund-von Braun reaction. To increase the yield of the phthalocyanine the solvent dimethylformamide can be substituted by quinoline. Due to the higher boiling point of quinoline, the copper phthalocyanine is the main product of the reaction of copper(I) cyanide and 1,2-dibromoben-zene.130... 

The synthesis of the crystal modification is controlled primarily by the finishing technique of the crude pigment. There are basically two different methods to produce a finely dispersed pigment treatment with acid to form copper phthalocyanine salts, followed by precipitation in water on the one hand, and mechanical treatment (milling, kneading) on the other hand. The following methods are used ... 

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. 

The early days of Copper Phthalocyanine Green synthesis were dominated by two competitive routes. One method was the synthesis of tetraphenyl copper phthalocyanine (Bayer), while the second method involved chlorination of copper phthalocyanine in carbon tetrachloride to form copper tetradeca to hexadeca-chloro phthalocyanine (BASF). It was on the grounds of economical considerations that manufacturers began to prefer the chlorination technique in industrial scale production. 

The fully chlorinated copper phthalocyanine is used as precursor for the synthesis of IR-absorbers, applied in optical recording layers for data storage [27],... 

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... 

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... 

Two processes are commonly used for the production of copper phthalocyanine the phthalic anhydride-urea process patented by ICI [33,34] and the I.G. Farben dinitrile process [48], Both can be carried out continuously or batchwise in a solvent or by melting the starting materials together (bake process). The type and amount of catalyst used are crucial for the yield. Especially effective as catalysts are molybdenum(iv) oxide and ammonium molybdate. Copper salts or copper powder is used as the copper source [35-37] use of copper(i) chloride results in a very smooth synthesis. Use of copper(i) chloride as starting material leads to the formation of small amounts of chloro CuPc. In the absence of base, especially in the bake process, up to 0.5 mol of chlorine can be introduced per mole of CuPc with CuCl, and up to 1 mol with CuCl2. 

As apparatus for the batch process, an enamel or steel reactor with an agitator and pressure steam or oil heating suffices. Apparatuses used in the continuous synthesis in the presence of solvents and in the bake process are described in [50] and [51,52], respectively. The choice of process depends on the availability and cost of the starting materials phthalodinitrile or phthalic anhydride. Although the phthalodinitrile process has certain advantages over the phthalic anhydride process, the latter is preferred worldwide because of the ready accessibility of phthalic anhydride. In this process the molar ratio of phthalic anhydride, urea, and cop-per(i) chloride is 4 16 1, with ammonium molybdate as catalyst. The mixture is heated in a high-boiling solvent such as trichlorobenzene, nitrobenzene, or kerosene. The solvent is removed after the formation of copper phthalocyanine. Fre-... 

Substitution. Copper phthalocyanine is preferred as starting material. Very little is known about the position of substitution. With the exception of hexadeca-chloro CuPc, all commercial Pc substitution products, as well as the tetrasubsti-tuted derivatives synthesized from monosubstituted phthalic acids, are mixtures of isomers. Despite the 16 hydrogen atoms that can be substituted, only two different monosubstituted Pc s are possible. The number of disubstituted isomers is higher. Mono- to heptasubstituted Pc derivatives have not yet been isolated in isomerically pure form. In addition, only a limited number of isomers are accessible in pure form by synthesis. Only symmetrically substituted phthalic acids, phthalimides, or phthalodinitriles (3,6-di-, 4,5-di-, or 3,4,5,6-tetrasubstituted derivatives) yield pure isomers of octa- or hexadecasubstituted phthalocyanine derivatives. All other substituted phthalic acids give mixtures of isomers. 

First synthesis of copper phthalocyanine (H. de Diesbach and E. von der Weid)... 

In the case of the dye from copper phthalocyanine (C.I. Sulphur Green 25), the synthesis can follow one of two paths ... 

Synthesis of Copper Phthalocyanine from Metallic Copper and Phthalonitrile (Classic Experiments of Linstead [3])... 

Synthesis of Copper Phthalocyanine Starting from Metallic Copper (Without Electrolysis) [41] (This Method is Widely Used in the Pigment Industry)... 

Synthesis of Copper Phthalocyanine in the Presence of Tetramethylurea as a Promoter [41]... 

Synthesis of Copper Phthalocyanine from Urea and Phthalic Anhydride in Various Solvents... 

Most reported phthalocyanine derivatives (sulfo-, nitro-, amino-, triphenylmethyl-, polymeric, etc.) are copper complexes, although at present the synthetic chemistry of other d- and /-metal Pc derivatives is being rapidly developed (Examples 30-36) [5,6,116-118]. Some of them (in particular, copper phthalocyanine sulfonic acids) are of industrial interest because of their usefulness as dyes. Phthalocyanine sulfonic acids themselves are prepared both by urea synthesis from sulfonated phthalic anhydride and by the sulfonation of the phthalocyanine [6], Some substituted metal phthalocyanines can be obtained by chemical or electrochemical reduction [118e]. Among a number of reported peculiarities of substituted phthalocyanines, the existence of three electronic isomers for magnesium derivative PcMn was recently confirmed [118f]. 

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. 

The synthesis of the copper phthalocyanine (CuPc) system is achieved as shown in Fig. 13.136. Here it can be seen that any of... 

The example given here is copper phthalocyanine (13) its synthesis is illustrated in Figure 2.3, and is one of the easiest to prepare. Many metal complexes are known but the copper complex, shown in Figure 2.4, is perhaps the most representative. The initial reaction often generates the /3-form of the material which can be transformed to the more stable a-form by grinding and precipitation... 

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