Sulfonic acid ring substituted

A number of water-soluble polyaniline derivatives have been developed in recent years. Incorporation of sulfonate groups onto the polymer backbone imparts water solubility to the polymer. In one process, this is accomplished by treating the polymer with fuming sulfuric acid which results in a sulfonic acid ring-substituted derivative that is alkali soluble but only upon conversion to the nonconducting sulfonate salt form. 

Substitution with an electron acceptor, such as chlorine for poly(2-chloroaniline) (33a), yields polymers that switch between yellow in the neutral form to blue in the oxidized form [122]. Sulfonic acid ring-substituted polyaniline (33b) can be prepared by direct chemical reaction of polyaniline with concentrated sulfuric acid [132]. This polymer film switches from transmissive yellow to blue even in solutions of elevated pH up to 7. 

Li, C. and S. Mu. 2004. Electrochromic properties of sulfonic acid ring-substituted polyaniline in aqueous and non-aqueous media. Synth Met 144 143-149. 

J. Yue, A. J. Epstein, A. G. MacDiarmid, Sulfonic acid ring-substituted polyaniline, a self-doped conducting polymer, Molecular Crystals and Liquid Crystals 1990,189, 255. 

C. M. Li, S. L. Mu, The electrochemical activity of sulfonic acid ring-substituted polyaniline in the wide pH range, Synthetic Metals 2005, 149, 143. 

S. A. Chen, G. W. Hwang, Structure characterization of self-acid-doped sulfonic acid ring-substituted polyaniline in its aqueous solutions and as solid film, Macromolecules 1996, 29, 3950. 

Action of HSO3CI on 2-substituted thiazoles affords the 5-chlorosulfonyl derivatives (337, 338). Addition of 6-phenylthiazolo[2,3-e]tetra2ole to oleum opens the tetrazole ring to form 2-azido-4-phenyI-thiazolyl-5-sulfonic acid, isolated as its salt (339). 5-Chloro-sulphonyl derivative is obtained similarly by action of HSO,Cl. 

Ozonation of Aromatics. Aromatic ring unsaturation is attacked much slower than olefinic double bonds, but behaves as if the double bonds in the classical Kekule stmctures really do exist. Thus, benzene yields three moles of glyoxal, which can be oxidized further to glyoxyUc acid and then to oxahc acid. Substituted aromatics give mixtures of aUphatic acids. Ring substituents such as amino, nitro, and sulfonate are cleaved during ozonation. 

Sulfonation. Aniline reacts with sulfuric acid at high temperatures to form -aminoben2enesulfonic acid (sulfanilic acid [121 -57-3]). The initial product, aniline sulfate, rearranges to the ring-substituted sulfonic acid (40). If the para position is blocked, the (9-aminoben2enesulfonic acid derivative is isolated. Aminosulfonic acids of high purity have been prepared by sulfonating a mixture of the aromatic amine and sulfolane with sulfuric acid at 180-190°C (41). 

SuIfona.tlon, Sulfonation is a common reaction with dialkyl sulfates, either by slow decomposition on heating with the release of SO or by attack at the sulfur end of the O—S bond (63). Reaction products are usually the dimethyl ether, methanol, sulfonic acid, and methyl sulfonates, corresponding to both routes. Reactive aromatics are commonly those with higher reactivity to electrophilic substitution at temperatures > 100° C. Tn phenylamine, diphenylmethylamine, anisole, and diphenyl ether exhibit ring sulfonation at 150—160°C, 140°C, 155—160°C, and 180—190°C, respectively, but diphenyl ketone and benzyl methyl ether do not react up to 190°C. Diphenyl amine methylates and then sulfonates. Catalysis of sulfonation of anthraquinone by dimethyl sulfate occurs with thaHium(III) oxide or mercury(II) oxide at 170°C. Alkyl interchange also gives sulfation. 

The ring-chlorinated derivatives of toluene form a group of stable, industrially important compounds. Many chlorotoluene isomers can be prepared by direct chlorination. Other chlorotoluenes are prepared by indirect routes involving the replacement of amino, hydroxyl, chlorosulfonyl, and nitro groups by chlorine and the use of substituents, such as nitro, amino, and sulfonic acid, to orient substitution followed by their removal from the ring. 

The iso)tazole ring is rather resistant to sulfonation. However, on prolonged heating with chlorosulfonic acid, 5-methyl-, 3-methyl- and 3,5-diraethyl-isoxazoles are converted into a mixture of the sulfonic acid and the corresponding sulfonyl chloride. The sulfonic acid group enters the 4-position even when other positions are available for substitution. The sulfonation of the parent isoxazole occurs only under more drastic conditions (20% oleum) than that of alkyl isoxazoles isoxazole-4-sulfonic acid is obtained in 17% yield. In the case of 5-phenylisoxazole (64), only the phenyl nucleus is sulfonated to yield a mixture of m-and p-arenesulfonic acid chlorides (65) and (66) in a 2 1 ratio (63AHC(2)365). 

More recently, screening efforts at Novartis have identified a hydroxamic acid containing a benzothiazinone ring system (32) [108]. This inhibitor is very potent versus S. aureus Ni -PDF (<5nM) and displays good selectivity versus matrix metalloprotease-2 (MMP-2) and MMP-13. Unfortunately (32), and all other analogues prepared, such as carbon isosteres (33), sulfones (34), N-substituted analogues (35) and N-formyl-N-hydroxylamines (36), lacked appreciable antibacterial activity in spite of their potent enzyme inhibitory activity. Further studies performed by Novartis suggest that these molecules are unable to penetrate the outer cell membrane of E. coli, and may bind to the cell membrane of S. aureus [108]. 

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