Chlorosulfonic acid, reaction with benzene

Aromatic sulfonyl chlorides (51) are conveniently prepared by treatment of the aromatic compound with an excess of chlorosulfonic acid (Scheme 29). The reaction occurs via the sulfonic acid (step 1) which is then chlorinated by the excess reagent (step 2) (Scheme 29). The mechanism probably involves the chlorosulfonic acid acting as the electrophile, as shown for the reaction with benzene (23) in Scheme 30.5... 

Studies of the reaction of benzene with chlorosulfonic acid (one molar equivalent) showed that the major product was benzenesulfonic acid (Equation 21) with a little diphenyl sulfone. When an excess of chlorosulfonic acid was used benzenesulfonyl chloride was obtained (Equation 22). Spryskov and Kuz mina demonstrated the reversibility of Equation 22 and measured the equilibrium constants for several different aromatic substrates. In the benzene-chlorosulfonic acid reaction, the quantity of diphenyl sulfone produced was increased by addition of anhydrous benzenesulfonic acid, but not by benzenesulfonyl chloride. The sulfone therefore apparently derived from reaction of benzenesulfonic acid and benzene under the influence of chlorosulfonic acid. Sulfone formation appeared to be relatively favoured at low temperatures and this may be due to the formation of an intermediate pyrosulfuric acid (Equations 23,24). 

Kinetic and product studies were carried out on the reactions in dichloromethane for the reaction of chlorobenzene with chlorosulfonic acid, the electrophilic species was probably CIS2O6H. In the analogous reaction with benzene, unlike chlorobenzene, there was an induction period in the sulfonation. The sulfonating entity for the main reaction was concluded to be PhS206H.ClS03H, whereas for the initial reaction the electrophile was the same as for chlorobenzene, namely CIS2O6H. The sulfonation therefore may proceed as shown in Equations 35 and 36, in which the formation of the a-complex is the rate-decisive step. 

A polymer matrix of 75% polyethylene and 25% styrene divinyl benzene copolymer was chlorosulfonated by reaction with chlorosulfonic acid in dichloro-methane-dioxan-ethyl acetate mixture and subsequently treated with amines, e.g. aniline, butylamine, etc. The resultant sulfonamidopolymer membranes were useful cation-exchange materials having modified properties. ... 

Sulfonation. Benzene is converted iato benzenesulfonic acid [98-11-3] C H SO, upon reaction with fuming sulfuric acid (oleum) or chlorosulfonic acid. y -Benzenedisulfonic acid [98-48-6] CgHgS20, is prepared by reaction of benzene-sulfonic acid with oleum for 8 h at 85°C. Often under these conditions, appreciable quantities ofT -benzenedisulfonic acid [31375-02-7] are produced. 1,3,5-Benzenetrisulfonic acid [617-99-2] C H S Og, is produced by heating the disulfonic acid with oleum at 230°C (21). 

The second route utilizes the introduction of the chlorosulfonyl substituent directly onto the aromatic nucleus. The reaction of substituted benzenes with chlorosulfonic acid gives good yields of arylsulfonyl chlorides however, the aryl substituent dictates the position of attachment of the chlorosulfonyl function in this electrophilic aromatic substitution.7 The method described herein allows replacement of a diazotized amine function by the chlorosulfonyl group. The ready availability of substituted anilines makes this the method of choice for the preparation of arylsulfonyl chlorides. 

ANILINE (62-53-3) Combustible liquid (flash point 158°F/70°C). Unless inhibited (usually by methanol), readily able to polymerize. Violent reaction, including the possibility of fire, explosion, and the formation of heat- or shock-sensitive compounds may result from contact with acetic anhydride, benzene diazonium-2-carboxylate, aldehydes, alkalis, benzenamine hydrochloride, boron trichloride, l-bromo-2,5-pyrrolidinedione, chlorosulfonic acid, dibenzoyl peroxide, fluorine nitrate, halogens, hydrogen peroxide, isocyanates, oleum, oxidizers, organic anhydrides, ozone, perchloryl fluoride, perchromates, potassium peroxide, P-propiolactone, sodium peroxide, strong acids, trichloromelamine. Strong reaction with toluene diisocyanate. Reacts with alkaline earth and alkali metals. Attacks some plastics, rubber, and coatings. Incompatible with copper and copper alloys. 

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