SYNTHESIS OF POLYMETHYLENEANTHRACENESULFONIC ACID BASED ON THE SECONDARY PRODUCT

ABSTRACT

Currently, the chemical industry is carrying out processes of transition from raw materials to finished products on the basis of new production capacities through the production of semi-finished products, including organic synthesis and nanotechnology, with the effective use of domestic raw materials.

Based on the secondary product of the pyrolysis process: the physicochemical properties of the anthracene fraction separated from the tar product by vacuum fractionation were studied. By polycondensation of the obtained mono- and dianthracene sulfoacids with formalin, polymethyleneanthracene sulfoacids with a spatial structure (SOF-2) were synthesized. Process parameters were studied.

АННОТАЦИЯ

В настоящее время в химической промышленности происходит процесс перехода от сырья к готовой продукции на основе новых производственных мощностей посредством производства полуготовых продуктов, включая органический синтез и нанотехнологии, с эффективным использованием отечественного сырья.

На основе вторичного продукта процесса пиролиза изучены физико-химические свойства антраценовой фракции, выделенной из смолистого продукта методом вакуумного фракционирования. Полиметиленантраценсульфокислоты (СОФ-2) с пространственной структурой синтезированы поликонденсацией полученных моно- и диантраценсульфокислот с формалином. Были изучены параметры процесса.

Keywords: pyrolysis, secondary product, chemical composition, anthracene, sulfoacids, polymethyleneanthracene sulfoacid, chromato-mass spectrum, IR spectrum, SEM, TG and DTA analysis.

Ключевые слова: пиролиз, вторичный продукт, химический состав, антрацен, сульфокислоты, полиметиленантраценсульфокислота, хромато-масс-спектр, ИК-спектр, СЭМ, ТГ и ДТА анализ.

Introduction. As a result of the development of the oil and gas chemical industry the number of enterprises producing polymer products based on natural gas is increasing in our country. One of them is the Ustyurt gas-chemical complex belonging to "Uz-KorGas Chemical" LLC, which produces 3 mln. per year from the "Surgul" mine. m³ of natural gas and more than 115,000 tons of gas condensate are extracted. Natural gas is separated into methane, ethane and propane-butane fractions; methane as a finished product, ethane, propane-butane fractions are pyrolyzed separately; ethylene and propylene are then polymerized into granulated polyethylene and polypropylene. The annual capacity of the complex is 387,000 tons of polyethylene, 83,000 tons of polypropylene, and secondary products: 102,000 tons of pyrolysis disaryl, 8,000 tons of pyrolysis oil and 10,000 tons of tar products. These secondary products are not processed in the complex and at low prices. poor quality fuel, steam is used as boiler fuel.

Method and material. Tar-product is an odorless, black secondary product, its physico-chemical properties are listed [6,10].

The composition of the fractions was determined by chromato-mass-spectroscopy method. [6,10].

It was found that fraction with 320-360⁰C contain polycyclic aromatic hydrocarbons. In particular, it was determined that 38,64% of phenanthrene was present in the interval 15,824-15,942 minutes and 93% similarity compared to the base, and 10,55% anthracene was present in the interval 16,649-16748 minutes and 98% similarity compared to the base [9].

Anthracene sulfoacids are solid substances with a melting temperature in a certain range, they are well soluble in water, poorly soluble in organic solvents. In the process of anthracene sulfonation, unlike halogenation and nitration, α and β-anthracene sulfoacids are formed.

Compared with naphthalene, the interaction of anthracene with electrophilic reagents mainly goes to the 9th and 10th states, that is, the meso-state. Quantum-chemical calculations show that the meso-states have a high electron density and electrophilic exchange. When anthracene is treated with oleum in acetic acid solution, equal amounts of 1- and 2-sulfonic acids are formed.

As a result of sulfation with 75% H₂SO₄ at 100⁰C, the 2-sulfoacid is formed and the addition of mercury shifts the sulfo group to the 1st state.

The reaction initially produces 9-anthracenesulfoacid as a primary product and then, during of desulfation, it was formed 1- and 2-anthracenesulfoacids, which are thermodynamically stable.

Discussion of results. As the temperature and duration of the reaction have been increased, the formation of a mixture of 2-sulfoacids and disulfoacids from 1-sulfoacid also was increased.

The process reaction is as follows:

The mechanism of the reaction[8]:

Control of the sulfonation process determines the completion of the reactions, the composition of the sulfoacids formed and the concentration of sulfuric acid.

Results and discussion. The total amount of sulfoacids formed in the reaction mixture is determined according to the following scheme:

1) titration determines the total amount of acids (sulfonic and sulfuric acids);

2) the amount is determined by precipitation of sulfuric acid;

3) the amount of sulphonic acids is determined by the difference between the amount of total acid and the sulfuric acid.

Figure 1. IR-spectrum of 1-anthracene sulfonate sodium

Table 1.

IR-spectral analysis of sodium 1-anthracenesulfonate 

Research on the synthesis of anthracene disulfoacids

Anthracene is formed in the presence of concentrated sulfuric acid at a high temperature above 160⁰C at the synthesis of disulfoacids. When the duration of the process is 4-8 hours a mixture of 1,5- and 1,8-anthracenesulfoacids is formed. The reaction equation is as follows:

Anthracenesulfoacids contained in sulfomasa were isolated according to the following sequence:

1) calcium hydroxide is added to sulfomasa. The reason for this is the loss of excess sulfuric acid in the form of calcium sulfate. Excess sulfuric acid is neutralized with calcium hydroxide, precipitates and the precipitate is filtered;

2) at adding sodium carbonate to the filtrate the calcium salt of anthracene disulfonic acid is converted to the sodium salt, and the excess calcium hydroxide is precipitated as calcium carbonate. The resulting mixture is filtered again;

3) the aqueous solution of sodium 1,5-anthracene disulfonate and sodium 1,8-anthracene disulfonate, synthesized and purified from by-products of the reaction, is purified from water using a vacuum evaporator.

The following reactions occur in the above processes:

C₁₄H₁₀ + 2H₂SO₄(kons) → C₁₄H₈(SO₃H)₂ + 2H₂O

C₁₄H₈(SO₃H)₂ +2Са(OH)₂ + H₂SO₄ → Са(C₁₄H₈(SO₃)₂)+ СаSO₄↓ + 4H₂O

Са(C₁₄H₈(SO₃)₂) +Са(OH)₂ + 2Na₂CO₃ → C₁₄H₈(SO₃)Na₂ + 2NaOH + 2СаСO₃↓

Synthesized sodium 1,5-and 1,8-sodium disulfonated were separated from each other by adsorption chromatography. For this purpose a small amount of cotton was placed at the bottom of the chromatographic column (length 2 m, diameter 4 cm) and it was placed on a tripod in a vertical position. Then 3/4 of the chromatographic column is filled with silica gel adsorbent of the same size. For this, put silica gel and solvent (water) in the flask were shaked well. Then the resulting suspension is poured into the column little by little, and the column is periodically hit with a thick piece of vacuum rubber to ensure good placement of the adsorbent. The adsorbent stuck to the column wall is washed off with solvent (water). The sulfonate solution is gradually added to the column filled with adsorbent, the column is washed with solvent (water). The flow rate of the solvent from the column is controlled using a tap, in which the speed of the solvent flowing from the column should not exceed 30-40 drops/min. In the result of washing, the formed products as a result of the reaction begin to separate from each other and form rings. In this, the sulfonates began to separate from each other. First, each washed part was divided into fractions, dried and weighed. As a result, 1,5-anthracenesulfonate sodium (µ=25%), 1,8-anthracenesulfonate sodium (µ¹=49%) were obtained. The IR spectrum of the synthesized 1,8-anthracenesulfonic acid was obtained and analyzed. [9,11]

Figure 2. Infrared spectrum of the sodium salt of 1,8-anthracene disulfoic acid

Table 2.

Analysis of the infrared spectrum of the sodium salt of 1,8-anthracene disulfoic acid

Synthesized anthracenesulfoacids were used for synthesize of polymethyleneanthracenesulfoacid with spatial structure.

Technological parameters of the process of synthesis of polymethyleneanthracenesulfoacid based on anthracene isolated from the secondary "tar product" of Uz-KorGas Chemical LLC were studied. Polymethyleneanthracenesulfoacid (SOF-2) was synthesized as a result of polycondensation of anthracenesulfoacids with formalin.

The following processes were performed to synthesize SOF-2:

1. the secondary product of the pyrolysis process anthracene was extracted and purified by fractional extraction under vacuum and then under normal pressure;

2. the obtained anthracene was sulfonated using concentrated sulfuric acid (mol ratio 1:2) at 160-165⁰C for 8 hours, as a result, a dark black sulfomasse was obtained;

3. the resulting sulfoma mass was placed in a pressure vessel and polycondensed with 35% formalin (initially, the mole ratio of anthracene and formaldehyde was 1:2) at 110-120⁰C and a pressure of 30 atm;

4. the synthesized, water-insoluble solid polycondensate was washed by mechanical grinding and heated at 90-95⁰C for 12 hours to complete the polycondensation.

Reaction 1:

Reaction 2:

Reaction 3:

The reaction mechanism is as follows:

1. H⁺ is formed as a result of dissociation of sulfuric acid.

2. The resulting H⁺ cation combines with formaldehyde to form +CH₂OH hydroxymethylene carbocation.

3. The hydroxymethylene carbocation interacts with the 5th carbon atom in the 1-anthracene sulfonic acid with formation first a p-complex and then a s-complex. In the Gaussian program, it was determined that the 5th carbon atom of the 1st anthracene sulfoacid has a strong negative charge of -0,229, the 6th carbon atom -0,144, the 9th carbon atom -0,146, and the 10th carbon atom – 0,194. Therefore, electrophilic reactions were carried out with respect to carbon atoms 5, 6, 9 and 10.

4. Carbocation and alcohol are formed as a result of release of water or H⁺ from the obtained s-complex.

5. Reaction of carbocation and alcohol with 1-anthracene sulfonic acid forms dimer and H⁺ and H₂O.

6. Oligomers are formed by reaction of dimer with carbocations or alcohols.

7. As a result of heating the obtained oligomers at 90-95⁰C for 12 hours polymethyleneanthracene-sulfonic acid with spatial structure was formed as a result of their mutual polycondensation:

The properties of spatially salt polymethyleneanthracene sulfonic acid obtained as a result of the reaction depend on the duration of the polycondensation process.

Table 3.

SOF-2 synthesis parameters (t=100-110⁰C, P=const)

In the process of polycondensation, the increase in pressure serves to increase the molecular mass of the obtained spatial polymer.

IR-spectrums of  SOF-2 polymethyleneanthracenesulfoacids synthesized on the basis of anthracene obtained from the secondary product of the pyrolysis process “Tar product” were obtained and analyzed.

Figure 3. IR-spectrum of SOF-2 polymethylenenaphthalene sulfonic acid

Table 4.

Analysis of the IR spectrum of SOF-2 polymethylenenaphthalene sulfonic acid

SEM (scanning electron microscope) was used to determine the surface morphology and element composition of the synthesized polymethyleneanthracene sulfoacid with spatial structure   SOF-2.

The results of SEM analysis of SOF-2 polymethyleneanthracene sulfoacid are presented in Figures. According to the analysis, it contains macropores from 120 to 650 µm. The elemental composition of SOF-2 consists of 68,3% C, 18,8% O and 12,9% S.

Figure 4. Surface structure and element composition of SOF-2

Thermal stability of SOF-2 was studied by thermogravimetric analysis (TGA) method. Thermogravimetric analysis with mass loss in two stages, the first is 20,009% in the range of 23,58-205,00⁰C, and the second stage is 20,495% in the range of 205,00-543,72⁰C, 543,72-801,7 and up to 15,259% mass of matter decreased. It was determined that the sample loses 55,763% of its total mass when heated to 800⁰C. The differential thermal curve of the studied substance is represented by one endothermic peak and one exothermic peak. The first endothermic reaction occurs at 36,72-115,76⁰C, which is explained by the loss of hygroscopic and crystallization water from the substance. Exothermic peaks are observed at 392,71-504,57⁰C, and in these intervals, it is due to the release of water as a result of mutual polycondensation of active groups in the substance -OH, -SO₂OH. We can observe that the destruction of the substance occurs at a temperature above 600⁰C. For cationite KU-2-8, an endothermic peak with energy absorption is observed at 353-413 K, and its destruction is observed at 423 K. Thus, it was found that the thermal stability of the obtained polymethyleneanthracene sulfoacid based on anthracene is higher than the imported KU-2-8 cationite [2,8,11-13].

Figure 5. TG of SOF-2 - thermogravimetric curve; DSC is a differential scanning calorimetry curve

Conclusion. In order to study the composition of the secondary product of pyrolysis of hydrocarbons, the liquid part was first separated by vacuum extraction. The composition of the fractions at 200-220⁰C and 320-360⁰C was analyzed by chromato-mass spectrum. The physical properties of co-products and residues that were not plowed were studied.

Anthracene sulfoacids were synthesized by sulfonation of anthracene isolated from tar-product. The influence of temperature, duration of reaction, molar ratio of reagents and concentration of acid on the course of the process was studied, and optimal conditions for the synthesis of 1-anthracene sulfoacid were following: molar ratio of anthracene and concentrated sulfuric acid (93%) 1:1.2, temperature 160⁰C and duration of reaction 6 hours. The product yield is 82%.

Based on the synthesized anthracene sulfoacids, the optimal conditions for the synthesis of spatially structured polymethyleneanthracene sulfoacid were determined. The structure, composition and properties of the synthesized substances were determined using IR-spectroscopy, chromo-mass spectrometry, SEM and thermogravimetric methods.

COE = 0,80 g/cm³, Vs = 5 cm³/g of spatially structured polymethyleneanthracene sulfoacid (SOF-1) obtained by polycondensation of 1-anthracene sulfoacid with formaldehyde in a 1:1.6 mol ratio at 100-110⁰C temperature and pressure for 5 hours was determined .

COE = 1,044 g/cm³, Vs = 4,6 cm³/g of spatially structured polymethyleneanthracene sulfoacid (SOF-2) obtained as a result of polycondensation at 100-110⁰C temperature and pressure for 4 hours in a 1:2 mole ratio of anthracene sulfoacids and formaldehyde was determined.

Conclusion. Based on the secondary product of the pyrolysis process, the anthracene fraction was separated from the tar product. Synthesis of mono- and disulfoanthracene was carried out as a result of sulfonation of the obtained anthracene. Polymethyleneanthracenesulfoacid was synthesized by polycondensation of anthracenesulfoacid with formalin under high pressure.

Due to the presence of an active sulfo group in this spatial polymer, its properties as a cationite were studied by chromato-mass-spectrum, IR-spectrum, SEM analysis, TG and DTA analysis.

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