Sulfonic acids aryl, from aromatic compounds

Diaryl sulfones can be formed by treatment of aromatic compounds with aryl sulfonyl chlorides and a Friedel-Crafts catalyst. This reaction is analogous to Friedel-Crafts acylation with carboxylic acid halides (11-14). In a better procedure, the aromatic compound is treated with an aryl sulfonic acid and P2O5 in polypho-sphoric acid. Still another method uses an arylsulfonic trifluoromethanesulfonic anhydride (ArS020S02CF3) (generated in situ from ArS02Br and CF3S03Ag) without a catalyst. ... 

Aromatic derivatives are known, including benzene sulfonic acid (81 see Chapter 21). Sulfonic acid 82 is a generic sulfonic acid derived from an aromatic compound (Ar = aryl), where an aryl group is any benzene derivative. The aryl group may also be a polynuclear aromatic compound (see Chapter 21, Section 21.8). The nomenclature for 78 and aryl derivatives is presented in Chapter 21. 

Sulfonation with Sulfuric Acid and Sulfur Triozide. Various mechanisms for the reaction of aromatic hydrocarbons or aryl halides with sulfuric acid or with sulfur trioxide have been proposed. Since.the reaction is heterogeneous, it is not favorable for experimental study. Solvents that dissolve sulfuric acid or sulfur trioxide form addition compounds with the reagent hence any conclusion drawn from a homogene ous sulfonation might not be applicable to the ordinary sulfonation. One possibility is that an electrophilic reagent such as sulfur trioxide with its relatively positive sulfur atom or an ion such as HOaS" " in the case of sulfuric acid attacks the negative center of the polarized form of the hydrocarbon, as illustrated for benzene. 

Practically any aromatic hydrocarbon or aryl halide can be sulfonated if the proper conditions are chosen. As the compound becomes more complex, however, the tendency toward the production of by-products and mixtures of isomers is increased. It is usually difficult to prevent polysubstitution of a reactive hydrocarbon. For example, even when phenanthrene is sulfonated incompletely at room temperature, some disulfonic acids are formed. The sulfonation of anthracene follows such a complex course that the 1- and 2-sulfonic acid derivatives are made from the readily available derivatives of anthraquinone. The foUowii sections include comments.on the accessibility of the reaction products of the commonly available hydrocarbons and aryl halides. The examples cited and still others are listed in Tables I-XIII. 

Shingare and co-workers have presented for the first time a successful implementation of ultrasound irradiation for the rapid synthesis of a-hydroxy phosphonates (521) and a-amino phosphonates (525) under solvent-free conditions from triethyl phosphite (524), aromatic aldehydes (523) and amines (522) using camphor sulfonic acid (CSA) (Scheme 130). One-pot, three-component Kabachnik-Fields synthesis of a-aminophos-phonates (529) from carbonyl compounds (526), primary amines (527), and dibenzyl/dimethyl/diethyl substituted phosphites (528) has been carried out in high yields, using H-beta zeolite as a reusable catalyst (Scheme 131). Zhang and co-workers have developed the nickel-catalysed Arbuzov type phosphonylation to afford phenyl substituted phosphonates (532) in the reaction of aryl triflates (530) with triethyl phosphite (531), in which KBr, as an additive, promoted the Sn2 catalytic step (Scheme 132). ... 

---