SYNTHESIS AND COMPARATIVE ANALYSIS OF NITROGEN, SULFUR, CALCIUM AND COPPER-CONTAINING PHTHALOCYANE PIGMENTS

ABSTRACT

Phthalocyanine pigments are a small but very popular group of organic dyes. Their properties are not lost in various conditions and environments, so the substances are considered a model of strength. The article studies the high-temperature synthesis of a high-intensity phthalocyanine pigment with a new composition of calcium, copper, nitrogen and sulfur and the elemental analysis of the resulting high-intensity pigment, the elemental analysis of the resulting organic phthalocyanine. The pigment is shown in the form of a figure, table and comparison with imported pigment in order to add the same mass to alkyd enamel and compare them.

АННОТАЦИЯ

Пигменты фталоцианиновые – небольшая, но очень востребованная группа органических красителей. Их свойства не теряются в различных условиях и средах, поэтому вещества считаются образцом прочности. В статье исследован высокотемпературный синтез высокоинтенсивного фталоцианинового пигмента с новым составом кальция, меди, азота и серы и элементный анализ полученного высокоинтенсивного пигмента, элементный анализ полученного органического фталоцианина. Пигмент показан в виде рисунка, таблицы и сравнения с импортным пигментом, чтобы прибавить ту же массу к алкидной эмали и сравнить их.

Keywords: Phthalocyanine pigment, elemental analysis, copper salts, calcium compounds, phthalic anhydride, sulfur compounds, comparison, copper phthalocyanine pigment.

Ключевые слова: Фталоцианиновый пигмент, элементный анализ, соли меди, соединения кальция, фталевый ангидрид, соединения серы, сравнение, фталоцианиновый пигмент меди.

Introduction

The early history of the synthesis and study of the properties of phthalocyanines was fully described by Moser and Thomas in 1983 [1]. Metal-free phthalocyanine (H₂Pc) was first synthesized in 1907 by Brown and Czerniak, and copper phthalocyanine (CuPc) was prepared in 1927 by Diesbach and van der Weijd. After this, many other substituted metal phthalocyanines were synthesized, and in 1934 Linstead and his colleagues began a comprehensive study of their chemical properties [2].

The structure of the flat phthalocyanine molecule, which consists of four isoindole fragments connected to each other through a nitrogen atom into a tetrabenzotetraazaporphine (tetrabenzoporphyrazine) ring (Fig. 1), was first reported by Dent and his colleagues [3]. This aromatic cycle of the phthalocyanine molecule is an 18-electron multi-circuit conjugated system: an internal system involving pyrrole and bridging nitrogen atoms and an external conjugation system involving benzene rings.

Phthalocyanines are fine powders that are brightly colored, often in shades of blue and green due to the long conjugation chain and absorption in the visible range in the region of approximately 500 - 800 nm.

Figure 1. Metal-free phthalocyanine molecule

In metal (II) phthalocyanine (MPc), the two central hydrogen atoms are replaced by one metal atom. Phthalocyanines form complexes with almost all metals of the periodic table. In this case, the heterocycle is an equatorial ‘ligand,’ and other ligands associated with the metal atom are located perpendicular to the plane of the cycle (occupy trans-axial positions). The most important feature of the molecule is the presence of a coordination cavity, limited by four nitrogen atoms, capable of coordinating metal ions, while the metal occupies either the center of the cavity, forming a flat coordination node, or is outside the plane of the macrocycle in which the nitrogen atoms lie, and forms coordination nodes of various geometric structures. Thus, using the example of a number of phthalocyanines of divalent metals (M = Co, Fe, Cu, Ni, etc.) [4,5], it was shown that all atoms of the phthalocyanine ring lie practically in the same plane. However, in the case of heavy metal phthalocyanines such as lead and tin [5,6], due to the relatively large size of the metal atom and the presence of a lone pair of electrons, as well as in the case of the presence of a substituent in the axial position, for example, AlClPc and VOPc [7,8], the ‘flat’ structure of the molecule is distorted, and the metal atom leaves the plane of the macro-ring (Fig. 2).

Figure 2. Molecules of unsubstituted vanadyl phthalocyanine

Novelty of the work

For the first time, a phthalocyanine pigment was synthesized based on the chemical reaction of phthalic anhydride, urea, nitrogen, sulfur and metal salts. The above reagents are local raw materials and reduce the share of imports.

Materials and Methods

Copper phthalocyanine paints occupy the most important place among pigmented paints, i.e., they are distinguished from other types of paints by their very attractive blue color. Copper phthalocyanine pigment can withstand high temperatures up to 500 °C, in a vacuum up to 580 °C, rarely dissolves in water, oils, most organic solvents, and is resistant to concentrated acids. Copper phthalocyanine pigment is obtained by heating a composite mixture of phthalic anhydride, urea, CaCl₂ and CuSO₄ at a temperature from 200 °C to 350 °C and using a catalyst. In this study, we used 16 g of copper sulfate, 10 g of calcium chloride, 14 g of ammonium sulfate, 150 g of urea, 30 g of phthalimide, 25 g of NPK in the ratio 20.20.20, adding a catalyst in an amount of 1% relative to the weight of phthalimide, stirring in heating oven HP-550-C at high temperature for 20-30 minutes until homogeneity is achieved (light blue color). The homogeneous mixture is heated to 253 °C in a heating oven (SNOL) for 3 hours. The resulting powdery reaction mixture is cooled to room temperature, after adding 85% sulfuric acid, boiling water is added. Primary products and intermediate products that do not react are dissolved. The resulting copper phthalocyanine pigment precipitates. The precipitated phthalocyanine pigment is filtered on a Buchner funnel and washed with distilled water until a neutral state is achieved from an acidic medium. The washed product is dried in the ShS- 8001 ShSU oven. The yield of the resulting organic high-intensity phthalocyanine pigment is 75%.

Results and Discussion

Fig.1 Shows the elemental analysis of the obtained sample.

Figure 3. Elemental analysis of the synthesized CuCaSPc phthalocyanine pigment

Scanning electron microscope (SEM) - All microscopes of the EVO series use advanced TTL and BeamSleeve technologies in their design, which allows for quality imaging at constant pressure (VP). A large 5-axis table, low vacuum mode as standard, many additional accessories and convenient SmartSEM software make the SEM-EVO MA 10 (Carl Zeiss, Germany) an excellent solution for analysis in modern setups. This device is designed for microscopic analysis of structure and surface defects and elemental composition determination of the substance (EDS - Oxford Instrument). Scanning electron microscope experiments were performed as follows. To carry out the sample preparation process, metal alloy pieces were placed on the stage of the microscope, glued aluminum foil was placed on it, pressed in the form of a tablet to determine the pigment content, the finished samples were pasted on this foil, and then installed in the working chamber of the microscope. is carried out.

Based on the results of the analysis, the elemental analysis of the samples was presented in tabular form.

Table 1.

Water-dispersion paints made on the basis of methyl acrylate-ethyl latex emulsions with imported CuPc pigments and synthesized CuCaSPc pigments showed approximately the same results when applied to wooden surfaces (Fig. 4). However, the paint on the surface of a wooden board painted with paint based on the synthesized CuCaSPc pigment maintained its stability during the 2-month observation period, while paint based on the imported CuPc pigment lost its uniformity very quickly.

Figure 4. Image of imported CuPc and synthesized CuCaSPc pigments and latex-based water-emulsion paints applied to wood surfaces

Conclusion

Thus, by condensation of phthalic anhydride with urea, mineral salts and metal salts, a phthalocyanine pigment with high physicochemical properties was synthesized and the results obtained were studied using modern physicochemical methods. The chemical composition of the resulting high-intensity pigments is indicated above in the form of figures and tables. When using the resulting pigments in acrylic enamels up to 4%, high intensity paint can be obtained.

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