Phthalonitrile reaction scheme

Phthalic anhydride is also used to make polyester and alkyd resins. It is a precursor for phthalonitrile by an ammoxidation route used to produce phthalamide and phathilimide. The reaction scheme for producing phthalonitrile, phthalamide, and phathilimide is shown in Figure 10-17. ... 

Figure 10-17. The reaction scheme for o-xylene to phthalonitrile. " CH3 COOH...

Toledo et al. [66] described an in situ synthesis of cobalt phthalocyanine in the pores of silica gel. The synthetic route can be visualized in the reaction scheme shown in Fig. 16a. In the first step Co(II) is adsorbed on the silica surface by an ion-exchange reaction. In the second step, the adsorbed metal served as the template for the formation of the metallated macrocyclic complex by reaction with phthalonitrile. Extraction and characterization by UV-Vis spectroscopy of the... 

Hydroxyphthalazin-l(2//)-one is obtained in a smooth reaction between phthalic anhydride and hydrazine hydrate and this is again the starting compound for many 1-substituted and/or 1,4-disubstituted phthalazines. The transformations of 1,4-dichloro-phthalazine, which is prepared in the usual manner, follow a similar pattern as shown for pyridazines in Scheme 110. On the other hand, phthalonitrile is the preferential starting compound for amino- and hydrazino-phthalazines. The most satisfactory synthesis of phthalazine is the reaction between a,a,a, a -tetrachloro-o-xylene and hydrazine sulfate in sulfuric acid (67FRP1438827), alt iough catalytic dehalogenation of 1-chloro- or 1,4-dichloro-phthalazine or oxidation of 1-hydrazinophthalazine also provides the parent compound in moderate yield. 

The unsymmetrical complexes LnPcPc can also be prepared in a stepwise manner (Scheme 8.1, D, upper part) [87, 112-114]. Treatment of phthalonitrile with excess of Lu(OAc)3- H2Oand DBU gives the half-sandwich compound LuPc(0Ac)(H20)2. The latter complex reacts with Na2Nc in 1-chloronaphthalene leading to the formation of LuPcNc [87]. Similarly, the template reaction of unsubstituted and crown-substituted phthalonitriles with lutetium acetate was carried out in boding w-hexanol in the presence of DBU [115-117]. Bi- and tri-nuclear [118] lutetium complexes could also be obtained following this approach [111, 119]. 

Although direct reaction of lanthanide mono-porphyrins with free phthalo-cyanine or its lithium derivatives is generally more efficient than the template synthesis, and gives rise to mixed-ligand complexes, the template strategy can also be applied for synthesis of phthalocyanine-porphyrin complexes, as in the case of unsymmetric bisphthalocyanine complexes (Scheme 8.2, B(b)) [106, 136, 145, 146]. Thus, metallation of free porphyrins with lanthanide salts in TCB or n-octanol leads to single-decker complexes, which then react with phthalonitriles under the action of DBU in alcoholic media to give the desired compounds. 

The reaction of 77 with alkynes has further been elaborated for the synthesis of substituted phthalonitriles 81. An alternative for the synthesis of these compounds is the cycloaddition reaction of 77 with enamines followed by a retro-Diels-Alder loss of N2 and elimination of the amine (Scheme 16). Generally, more forcing reaction conditions are required and lower yields are obtained in reactions with alkynes than in reactions with enamines, for example, 4-ethyl-5-methylphthalonitrile is obtained in 51% yield from 2-pentyne (xylene, 150°C, 18 days) and in 73% yield from 4-(l-ethylprop-l-en-l-yl)morpholine (CHCI3, 70°C, 7 days) <1998T1809>. The mechanism of the reaction with enamines has been studied in detail. This revealed a [1,5] sigmatropic rearrangement in the cyclohexa-2,4-dien-1-amine intermediates formed after the loss of N2 <1998T10851>. 

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... 

Dihydro-27/-pyran 455 was found to undergo a Diels-Alder reaction with 4,5-dicyanopyridazine in refluxing toluene <2003JOC3340>. Subsequent expulsion of N2 provided phthalonitrile 528, which could be converted to 529 and 530 (Scheme 97). 

Aromatic imides are another type of product which can be synthesized by catalytic ammoxidation. o-Xylene is converted over vanadium-titanium oxide catalysts to tolunitrile and then, depending on catalyst composition and reaction conditions, phthalimide or phthalonitrile can be selectively synthesized (Scheme 20.3) [94]. 

Scheme 20.3 Reaction network in o-xylene conversion to phthalimide and phthalonitrile. Adapted from [84].

The phthalocyanines (e.g., 2.277) are well known for their ready availability and their tendency to form stable complexes with a wide variety of metals. They are typically prepared via the metal-templated macrocyclization of a phthalonitrile derivative (e.g., 2.276) as shown in Scheme 2.3.1. The ease of preparation as well as the remarkable coordinative ability of the phthalocyanines led Meller and Ossko in 1972 to attempt to prepare boron-containing phthalocyanine derivatives. This they tried via the reaction of phthalonitrile with haloboranes. What they in fact obtained, however, was not the desired tetrameric phthalocyanine derivative, but rather a contracted trimeric phthalocyanine 2.284, a species that has since come to be known as subphthalocyanine (Scheme 2.3.2). A similar fluorine-containing subphthalocyanine 2.285 was also prepared using this procedure. 

In an attempt to preclude the formation of the various side-products observed in the above reactions, Wohrle and coworkers developed a modified means of effecting this type of ring expansion.They found that reacting the subphthalocyanine 2.284 with a phthalonitrile derivative such as 2.328 or 2.329 in the presence of zinc(II) acetate led to reasonable yields of the zinc(II) mono-substituted phthalocyanine 2.308 or 2.330 (Scheme 2.1l3). Importantly, they also found that the amount of... 

One final example of a cryptand-like expanded porphyrin is the niobium(IV) bicyclophthalocyaninato system 9.132 reported by Gingl and Strahle in 1990. Interestingly, 9.132 was isolated as a by-product of a standard phthalocyanine-form-ing reaction (i.e., metal-templated cyclocondensation of phthalonitrile 9.102) in which NbOCls was used as the catalyst (Scheme 9.2.10). As such, it represents the fourth type of system to be prepared using this type of procedure (the other three being the parent phthalocyanines, the subphthalocyanines discussed in Chapter 2, and the superphthaolcyanines discussed in Section 9.2.1 of this chapter). 

Scheme 12 sets out a number of the transformations observed of the furoxandicarboxylic esters, dicarboxamide (224), and dicarbonitrile (226). Some of the products were found during studies of the chemistry of the cyanilic acids (see Section V,C,2 and Scheme 7). The chemistry of dicyano-furoxan (226) has recently been reinvestigated372 in its reactions it shows some similarities to phthalonitrile.

Low molecular-weight phthalocyanines are synthesized from 1 2-disubstituted benzene derivatives such as phthalonitriles and phthalic anhydrides. The cyclote-tramerization reaction taking place with urea, metal salts and catalysts is shown in Scheme 17.1 [3,49-52]. 

Scheme 17.3 (a) Preparation of heteroatom bridged phthalonitriles by nitrodisplacement reaction, (b) and (c) Preparation of... 

Reaction of 4-fluorophthalodinitrile 15 with perfluoroisobutylene in sulfolane in the presence of CsF affords 4-perfluoro-ferf-butyl substituted phthalonitrile 108 which upon heating with CuCl gives the phthalocyanine complex 109 [12] (Scheme 28). The cyclotetramerization of 3-substituted dinitrile produced similarly failed, evidently due to steric hindrances of bulky perfluoro-fert-butyl groups. 

Another approach to perfluoroaUcyl substituted phthalonitrile includes reaction of 4-iodophthalonitrile 73 with perfluoroalkyliodides in the presence of activated Cu in DMSO [73]. In such way 4-perfluoroheptylphthalodinitrile 110 was obtained (115-120 °C, 2 h) (Scheme 29). Some amount of the Cu" complex 111 is formed in a side reaction of cyclotetramerization. Melting of the dinitrile with SnCl2 at 170-200 °C leads to the formation of the Sn complex 112. 

Phthalocyanines containing (per)fluorinated aUcoxygroups are usually obtained by cyclotetramerization of corresponding (per)fluoroalkoxy substituted phthalonitriles. The latter can be easily prepared by nucleophilic substitution reaction of halo or nitrosubstituted phthalonitriles in the presence of the corresponding fluorinated alcohol (Scheme 30). 

The synthesis of peripherally substituted octa-alkoxyphthalocyanines is straightforward (Scheme 49) [186]. Catechol is alkylated then brominated to give a dialkoxydi-bromobenzene. Reaction with copper cyanide in DMF affords the phthalonitrile, which can be converted to a phthalocyanine under standard cyclization conditions. The lithium alkoxide/alcohol method is usually avoided to prevent any possibility of transetherification. 

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