Anisole-4-sulphonic acid

Bourns (1963) investigated the bromination of anisole-4-sulphonic-2,6- 2 acid. In the presence of 0 0 to 2-Om bromide ions the ratio kgjkjy increases from 1-00 to 1-31. As a competitive reaction bromode-sulphonation takes place, bromine substituting the sulphonic group in the 4-position. Using anisole-4-sulphonic acid containing the natural abundance of the sulphur isotopes. Bourns measured sulphur isotope effects k jk is 1-003, 1-013 and 1-017 for initial bromide ion concentrations of 0-0, 0-05 and 0-50m respectively. This confirms, that bromodesulphonation also follows mechanism (6-2). 

The work on isotope eifects in the iodination of p-nitrophenol, and on the bromination and bromodesulphonation of anisole-4-sulphonic acid not only excludes mechanisms (10-11), (12-13) and (14-15), but also shows that the mechanism (6-2) does not involve a rapid and reversible first step and a slow proton transfer, but a typical steady-state intermediate ( iPa]... 

These compounds are suggested if sulphur is present. If nitrogen is also present the compound may be an aminosulphonic acid. The infrared spectrum will show absorption at 3400-3200 cm -1 (OH str.) and 1150 and 1050 cm-1 (S=0 str. in a sulphonic add) or at 1090cm-1 (S=0 str. in a sulphinic acid). For derivative preparations for sulphonic acids see Section 9.6.26, p. 1284. The presence of an aromatic sulphinic add may be further confirmed by dissolving in cold concentrated sulphuric add and adding one drop of phenetole or anisole when a blue colour is produced (Smiles s test), due to formation of a para-substituted aromatic sulphoxide. The reaction is ... 

Positive bromination was first observed by Shilov and Kaniaev189 who found that the bromination of sodium anisole-m-sulphonate by bromine-free hypo-bromous acid was accelerated by the addition of nitric or sulphuric acids, and was governed by the kinetic equation... 

Derbyshire and Waters202 carried out the first kinetic study, and showed that the chlorination of sodium toluene-m-sulphonate by hypochlorous acid at 21.5 °C was catalysed more strongly by sulphuric acid than by perchloric acid and that the rate was increased by addition of chloride ion. A more extensive examination by de la Mare et al.203 of the rate of chlorination of the more reactive compounds, anisole, phenol, and />-dimethoxybenzene by hypochlorous acid catalysed by perchloric acid, and with added silver perchlorate to suppress the formation of Cl2 and C120 (which would occur in the presence of Cl" and CIO-, respectively),... 

Compound [54] was reported to be formed on reaction of benzoic anhydride and sulphuric acid and its structure was assigned on the basis of its ir spectrum and its ability to sulphonate anisole (Collet et al., 1974). It would... 

A similar conclusion was drawn from the C- and O-protonation of anisole and phenol in sulphuric acid of various concentration by UV spectroscopy In 30-90% HjSO at 0 °C anisole and phenol are only protonated at oxygen In 100% HjSO at about 25 °C anisole, according to yields a methoxybenzenium ion. It was shown later that in 92—98 % H2SO4 and in HSO3F at room temperature anisole is sulphonated so rapidly that it is impossible to observe its protonation 147,148) hoYvever, So the above conclusion should be considered to be wrong. However, for phenol in H2SO4 at —64 °C only C was protonated... 

Poly(ethylene terephthalate) is most usually encountered in the crystalline form and, as such, it is soluble at normal temperatures only in proton donors which are capable of interaction with the ester group. Effective solvents of this kind are chlorinated and fluorinated acetic acids, phenols and anhydrous hydrofluoric acid. The polymer is soluble at elevated temperatures in various organic liquids, which include anisole, aromatic ketones, dibutyl phthalate and dimethyl sulphone. Chloroform has the peculiar property of dissolving amorphous poly(ethylene terephthalate) at temperatures below 0°C,but on warming such solutions the polymer separates in crystalline form. Chloroform is without effect on polymer which has already been crystallized. 

---