TECHNOLOGICAL FEATURES OF THE SULFATION PROCESS OF ALKYLBENZOLS WITH SULFATE ANGIDRIDE

Аннотация

During the research, sulfonation process forms sulfons. Their content in sulfonic acid is very little dependent on the technological regime parameters and constitutes about 1% of the total mass, but at a CO3/AB molar ratio greater than 1.08, their formation rate increases sharply. Keywords: sulfonation process, sulfons, hydrocarbons, alkylbenzenes, side chain, electrophilic substitution mechanism The production of sulfonic acids, which are currently used in various fields of science, in the processes of sulfonation of hydrocarbons is discussed in various sources. [1] The research results examine methods for sulfonating toluene and ethylbenzene with sulfuric anhydride, sulfuric acid, and sulfuric anhydride in the presence of methanesulfonic acid. [2] describe methods for sulfonating olefins, including using photocatalysts, as well as methods for obtaining sulfonic acids, which are essential amino acids, using a stable SO ·DMF complex as a sulfonating 3 agent. [3] The works present the results of studies on the processes of sulfonation of alcohols, amines, and phenols with sulfonyl chloride to obtain sulfo compounds used in pharmacology. [4] The literature is devoted to the optimization of the sulfonation process of alkylbenzenes with a side chain length of C -C carbon 9 13 atoms (molecular mass 230-245 g/mol), including using mathematical methods Organic raw materials - alkylbenzenes with the formula R-C H , where R is 6 5 the radical of the n-paraffin molecule with a carbon atom number from 10 to 13, react with sulfur anhydride in the reactor, resulting in the formation of sulfonic acid according to the following reaction: R-С Н + SO → R – С Н - SO H 6 5 3 6 4 3 In addition to the above, side reactions can also occur, in which other types of sulfonic acids, such as sulfonic anhydride or PSA, are formed. 2R–С Н -SO Н + 3SO → R-С Н -SO -О-SO –С Н -R + H SO 6 4 3 3 6 4 2 2 6 4 2 4 S-С Н + 2SO → R-C H -SO -O-SO H 6 5 3 6 4 2 3 Additionally, sulfonation process produces sulfons. Their quantity in sulfuric acid depends very little on the parameters of the technological regime and is about 1% of the total mass, however, their formation rate increases sharply when the molar ratio of SO /AB exceeds 1.08. Sulfones have the following 3 structural formula: 107 MODELS AND METHODS IN MODERN SCIENCE International scientific-online conference R - C H - SO - C H - R' 6 4 2 6 4 When forming sulfonic acid, the indicated compounds, except for sulfons, decompose or react directly with the AB residue or, upon mixing, are hydrolyzed with water according to the following reactions: R-C H -SO -O-SO H+ R-С Н → 2R - С Н – SO H 6 4 2 3 6 5 6 4 3 R - С Н - SO - О - SO – С Н - R + Н О → 2R - С Н - SO Н 6 4 2 2 6 4 2 6 4 3 High concentrations of SO and high molar ratios of SO :AB also lead to the 3 3 dealkylation of alkylbenzene with the formation of unsaturated hydrocarbons (olefins), which polymerize to form resinous compounds, thereby deteriorating the color of sulfonic acid. Regarding the mechanism of sulfonation reactions, there are currently several hypotheses: 1. Electrophilic substitution mechanism. This assumption is based on the fact that at the first stage of the aromatic compound sulfonation mechanism, intermediate p- and s-complexes are formed due to the electrophilic attack of the carbon atom by the sulfuric anhydride molecule. This reaction proceeds very quickly and is a first-order reaction, the rate of which depends on the diffusion factors, as well as the intensity of mixing and the removal of the released heat. 2. Another assumption is that the sulfonation reaction of aromatic compounds begins with the interaction of a mixture of sulfur trioxide and alkylbenzenes, leading to the formation of intermediate compounds ABSA and PSA. . 108 MODELS AND METHODS IN MODERN SCIENCE International scientific-online conference The mechanism of the primary reaction of a mixture of linear alkylbenzenes with SO is presented below. 3 Further, the alkylbenzene mixture reacts with PSC to form two moles of ABSC. In this case, one mole-equivalent is considered as a product of the first stage, and the second as a contribution to increasing conversion. . In this basic reaction, pyrosulfonic acid acts as a sulfonating agent. The intermediate product - sulfonic acid anhydride and PSA - are then reacted with a mixture of alkylbenzenes or water to obtain the target product - sulfonic acid. The technological scheme of the plant for sulfonation of alkylbenzenes with sulfur anhydride is presented in Figure 1. ABSA production is carried out on two parallel technological lines, each of which consists of three main technological units. In the gas mixture preparation section, liquid sulfur is burned in a furnace with excess dried air, resulting in sulfur dioxide (SO ). Further, SO is converted 2 2 into SO in a special apparatus - a converter, in the flow of dried air above the 3 catalyst layer (V O ). Dried air participates in the process, as humid air f