Sulphonic acids, reactions aromatic, derivatives

Aromatic sulphonic acids, 554 compounds derived from, 820 reactions and characterisation of, 552, 1077 ... 

Triarylphosphines with formyl or acetyl groups substituted into the aromatic rings can be prepared by a Grignard reaction using ethylene keta derivatives. The resulting phosphines (1) are treated with toluene-p-sulphonic acid. The acetyl derivatives may also be prepared by oxidation of the ethyl derivatives (2) followed by reduction with trichlorosilane. ... 

Conant and Peterson123 made the first kinetic study of the coupling of diazonium ions with aromatics, and measured the rates of reaction of diazotised aniline and its 2-MeO, 4-Me, 4-Br and 4-S03H derivatives with the sodium salts of 4-hydroxybenzenesulphonic acid, 2-naphthol-3,6-disulphonic acid, 1-naphthol-3,8-disulphonic acid, and l-naphthol-4-sulphonic acid. The reaction was second-order, viz. 

A somewhat similar method of cyanide preparation is applicable in the aromatic series aromatic sulphonic acid potassium salts, on fusion with potassium cyanide or potassium ferrocyanide, yield aromatic nitriles. The reaction can be extended to derivatives of pyridine. 

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 ... 

Diazotization.—Like aniline and other aromatic primary amines they undergo diazotization. The resulting diazo compounds undergo the various diazo reactions (p. 601) by means of which the naphthalene group becomes coupled as an azo compound with other naphthalene or benzene rings. These azo compounds are dyes. The most important dyes of this group are derived from mixed amino and sulphonic acid or mixed amino and hydroxyl derivatives of naphthalene and will be considered a little later. Not only, however, may the naphthylamines >deld diazo compounds and through them azo compounds but they may be coupled as azo compounds with a diazotized benzene compound. 

In contrast to the usual reaction of aromatic aldehydes with cyclic ketones o-nitrobenzaldehyde condenses with 17-ketones to produce good yields of seco-acids, a reaction which has been applied to the preparation of 16-oxa-steroids. Thus, 3 -hydroxy-5a-androstan-17-one or its acetate affords the seco-steroid (153), which can be oxidised either as the free acid by ozone and alkaline hydrogen peroxide to the diacid (155) or, as its methyl ester (154), with chromium trioxide to the monomethyl ester (156). Diborane reduction of the diacid (155) or lithium aluminium hydride reduction of the dimethyl ester (157) gave the trans-diol (158), cyclised with toluene-p-sulphonic acid to 16-oxa-androstan-3)5-ol (159) or, by oxidation with Jones reagent to the lactone (152) (as 3-ketone) in quantitative yield. This lactone could also be obtained by lithium borohydride reduction of the monomethyl ester (156), whilst diborane reduction of (156) and cyclisation of the resulting (151) afforded the isomeric lactone (150). The diacid (155) reacted with acetic anhydride to afford exclusively the cis-anhydride (161) which was reduced directly with lithium aluminium hydride to the cis-lactone (160) or, as its derived dimethyl ester (162) to the cis-diol (163) which cyclised to 16-oxa-14)5-androstan-3) -ol (164). 

Chlorosulphonic acid, and other derivatives of sulphuric acid, may also be used for the formation of sulphonic acids by sulphonation of aromatic compounds. These sulphonating reagents are more reactive than sulphuric acid itself78,84 and so milder conditions (temperatures of 0-25 °C are typical) may be used with them. In addition, water is not normally involved in the reaction and the separation problems, caused by the use of excess reagents, as is the case with sulphuric acid, are significantly reduced. 

Thus, aromatic sulphonic acids are readily produced. For example, benzenesulphonic acid is formed by reaction of sulphur trioxide in chloroform with benzene (equation 15) in higher yield and at a lower temperature (0-10 °C) compared with sulphonation with concentrated sulphuric acid105. The sulphonation of a wide structural variety of aromatic compounds with concentrated sulphur trioxide and its derivatives has been extensively studied by Cerfontain and coworkers21,23,45,47,52,55,56,58,59,62,64,66,80,81,106"130 and by others5,105,131"137. In two rather interesting reports, mono-, di- and trisulphonation of perfluorobenzene was performed by reaction with liquid sulphur dioxide138,139. 

The sulphonic acids derived from the aromatic hydrocarbons are decomposed when heated with water under pressure. Hydrochloric acid facilitates the reaction. Toluene-sulphonic acid yields toluene —... 

A rapid method for resolving ( + )-carvone through the derivative (151) has been described. Reaction of carvone with allyl Grignard reagents leads to the expected products (152), and these can be aromatized with toluene-p-sulphonic acid to (153) and (154). An improved method for the preparation of carvone 1,3,8-tribromide [(155) see Vol. 1, p. 31] consists in treating the dibromide (156), obtained by Wallach from dihydrocarvone (148), with phenyltrimethylammonium tribromide in tetrahydrofuran. ... 

Nitro-toluic acid—Nitro-terephthalic acid — Nitro-iso-phthalic acjd—aiai-Nitro-naphthalene>sulphonic acid...63-65 Reaction of Gattermann — Nitro-toluenes—Nitro-p-xylene— Ldb s experiments — Aromatic nitramines — Nitro-car-boxylic acids—Nitro-sulphonic acids—Nitro-derivatives... 

Studies in aromatic sulphonation include full details of the rearrangement of sodium 1-naphthylsulphamate into the 4-sulphonate in dioxan-sulphuric acid, where S-studies show that the reaction is partly intramolecular. There are few syntheses of natural products offering an opportunity for employing aromatic sulphonation as an essential step, though a recent synthesis of the demethyl derivative establishes the structure of aeruginosin B as 2-amino-6-carboxy-10-methylphenazinium-8-sul-phonate. Ionization of aromatic sulphonic acids in aqueous sulphuric acid has been studied by u.v. spectroscopy, showing that the benzo-phenone H% and the acidity functions are followed substituent effects are small (Hammett p-value 0.7 0.2). 

The carbonyl group of aromatic aldehydes with electron-withdrawing substituents on the aromatic ring may, contrary to previous reports, act as a dienophile in a Diels-Alder reaction, giving dihydropyran derivatives, e.g. (128). Toluene-4-sulphonic acid catalyses several of these reactions and it is clear that two mechanisms must operate for this type of cycloaddition (thermal [4 +2], and acid-catalysed). 

The imides, primaiy and secondary nitro compounds, oximes and sulphon amides of Solubility Group III are weakly acidic nitrogen compounds they cannot be titrated satisfactorily with a standard alkaU nor do they exhibit the reactions characteristic of phenols. The neutral nitrogen compounds of Solubility Group VII include tertiary nitro compounds amides (simple and substituted) derivatives of aldehydes and ketones (hydrazones, semlcarb-azones, ete.) nitriles nitroso, azo, hydrazo and other Intermediate reduction products of aromatic nitro compounds. All the above nitrogen compounds, and also the sulphonamides of Solubility Group VII, respond, with few exceptions, to the same classification reactions (reduction and hydrolysis) and hence will be considered together. 

Various dehydrating agents—concentrated sulphuric acid, zinc chloride, phosphorus pentoxide—can be used. Sulphuric acid, although perhaps the most convenient, has the disadvantage that it tends to sulphonate the aromatic substances employed. At a low temperature, however, diphenylmethane can be obtained from benzyl alcohol and benzene. At 140° phosphorus pentoxide condenses benzene and diphenylcarbinol to triphenylmethane (see B., 7,1204). Not only substituted benzyl alcohols, but even mandelic acid can be brought within the scope of the reaction, while in place of benzefte its nitro, amino or phenolic derivatives may be used. 

A mechanism of action for the r-deficient 2-heteroaryl derivatives was postulated based upon the reaction of 6-(2-pyridyl)methylene penicillanic acid sulphone (28) with sodium methoxide (Scheme 6.14) [46]. Chen and co-workers proposed that after bimolecular interaction between the enzyme and (28), an aromatic acyl-enzyme ester (76) is obtained. This conjugated... 

Metal oxides have been employed to catalyse the acylation of aromatics, leading to dimethylbenzophenones and 4-substituted benzophenones. The reaction of t-butylbenzene with benzoyl chloride in the presence of small amounts of ferric oxide leads to 4-t-butylbenzophenone. Substituted benzophenones have also been obtained by hydrolysis of the dilithium salts (68) formed by the reaction of lithium carboxylates with organolithium derivatives, and benzo-phenone-2 -methoxy-2-sulphinic acids (69) have been successfully prepared by displacement of the sulphone linkage in thioxanthen-9-one 10,10-dioxides (70)... 

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