Sulfonation of aromatic compounds

Nitration and sulfonation of aromatic compounds probably occur via the formation of the nitryl and sulfonyl cations ... 

Earle and Katdare reported a process for the sulfonation of an aromatic compound in the presence of an IL. The method for the sulfonation of aromatic compounds in water-stable ILs offered advantages over conventional sulfonation reactions (1) no by-products were formed (2) the IL was not consumed, and (3) the sulfonating agent (e.g., SO3) was relatively inexpensive. 

Sulfonation of aromatic compounds is generally carried out with sulfuric acid, halosulfuric acids, or sulfur trioxide as reagent with or without solvent.458,459 Friedel-Crafts catalysts such as aluminum chloride and boron trifluoride are effective catalysts in certain sulfonations with sulfuric acid and chlorosulfuric acid. 

Fig. 5.17. Effective electrophiles in sulfonations of aromatic compounds with sulfuric acids of different concentrations.

Sulfonation of aromatic compounds is very important in the manufacture of dyes. As sulfonic acids are generally water-soluble, the sulfonation of aromatic compounds provides a means to make aromatic compounds water-soluble. Also, the sulfonic acid group is easily displaced by a variety of other groups. Therefore, aryl-sulfonic acids are useful synthetic intermediates. 

Concentrated or fuming sulfuric acid (oleum) is widely used for the direct sulfonation of aromatic compounds (see Chapter 7, p. 97).5,6 The active sulfonating agent in sulfuric acid is the electrophile sulfur trioxide, and the sulfonating power of sulfuric acid is proportional to the concentration of S03. Consequently, fuming sulfuric acid, which contains excess sulfur trioxide, is a more powerful sulfonating agent than concentrated sulfuric acid. The sulfonation of an aromatic hydrocarbon is depicted in Scheme 26. 

Absorphon of CO2 in aqueous solutions of MEA absorption of H2S and mercaptans in aqueous soluhons of alkanolatnines and caushc soda absorption of carbon monoxide in aqueous cuprous ammonium chloride solutions absorphon of lower olefins in aqueous soluhons of cuprous ammonium compounds absorption of pure chlorine in aqueous solutions of sodium carbonate or sodium hydroxide conversion of dithiocarbamates to thiuram disulfides sulfonation of aromatic compounds with lean SO3 recovery of bromine from lean aqueous solutions of bromides reactions of importance in pyrometallurgy absorphon of CO2 in aqueous solutions of caustic alkahes and amine absorption of O2 in aqueous solutions of sodium dithionite absorphon of O2 in aqueous sodium sulfite soluhons absorption of O2 in alkaline solutions containing the sodium salt of 1,4-napthaquinone- 2-sulfonic acid (NQSA) special case role of diffusion in the absorption of gases in blood in the human body. 

Knowing that sulfonation of aromatic compounds is a reversible process, can you think of a way to remove the sulfonate groups from Kraft lignin The product would be an analogue of organosolv lignin. 

The sulfonates of aromatic compounds, especially hydrocarbons, are of prime importance respecting both the volume and variety of products and uses. 

The sulfonation of aromatic compounds occurs readily in ionic liquids, with the simplest case being the direct sulfonation of aromatic compounds with sulfur trioxide to give the aryl sulfonic acid [113]. Ionic liquids such as triflate or triflimide ionic liquids were found to enhance the reaction rate. In the reaction of chloro-sulfuric acid with aromatic compounds, the reaction in the ionic liquid gave a... 

The very mechanisms of sulfonation of high polymers have been reviewed by Kucera and Janc. The sulfonation reaction proceeds easily in the presence of groups, such as —Cl, —NH2, —OH, —SH, etc. In fact, the active agent in the sulfonation reaction is the SO3 cation. The sulfonation of aromatic compounds is a reversible reaction. Sulfonating agents can be classified into three groups, namely... 

The scarcity of quantitative results available on the relative rates of sulfonation of aromatic compounds is due to the uncertainty about the exact nature of the electrophile, the reversibility of the process and the isomerizations occurring during the reaction. In addition to these factors, the sulphonated products are, as a rule, difficult to isolate, thus impeding an adequate analysis of isomer proportions and partial rate factors. A good review of the subject appeared recently... 

Step 1 The active electrophile in the sulfonation of aromatic compounds is sulfur trioxide and reacts with benzene in the rate-determining step. 

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