Benzenes sulphonylation

The Schotten-Baumann reaction may also be carried out, using, for example, benzene sulphonyl chloride, CeH,SO,Cl (. e., the acid chloride of benzene sulphonic acid, C H5SOjOH) in place of benzoyl chloride, and similar deri a-tives are obtained. Thus when phenol is dissolved in an excess of 10% sodium hydroxide solution, and then shaken with a small excess of benzene sulphonyl... 

Give benzoyl and toluene-/>-sulphonyl derivatives (Schotten-Baumann reaction) (p. 243) also benzene-sulphonyl derivatives. 

Benzene-sulphonylotion. Benzene-sulphonyl chloride, which can be used in place of toluene-/>-sulphonyl chloride, is liquid at room temperature and consequently reacts rapidly when the reaction mixture (as in 3(a)) is vigorously shaken. In general, however, the toluene-/>-sulphonyl derivatives crystallise even more readily than the benzene-sulphonyl analogues, and have lower solubilities and higher m.ps. 

Benzoyl and Toluene -sulphonyl derivatives. Proceed as in 3 (p 374)- benzene sulphonyl derivatives can be similarly prepared. 

Phenylurea Derizatives. These are prepared precisely as those from primary amines, except that the toluene-/)-sulphonyl and benzene sulphonyl derivatives are insoluble in aqueous sodium hydroxide and therefore separate on formation. (M.ps., p. 552.)... 

Primary and Secondary Amines. Picrates (pp. 374, 376), Acetyl derivatives (pp. 373, 376), Benzoyl derivatives (pp. 374, 376), Toluene-p-sulphonyl and benzene-sulphonyl derivatives (pp. 374, 376), Phenylurea derivatives (pp. 374, 377)-... 

Reduction of a nitro compound to a primary amine. In a 50 ml. round-bottomed or conical flask fitted with a reflux condenser, place 1 g. of the nitro compound and 2 g. of granulated tin. Measure out 10 ml. of concentrated hydrochloric acid and add it in three equal portions to the mixtiue shake thoroughly after each addition. When the vigorous reaction subsides, heat under reflux on a water bath until the nitro compound has completely reacted (20-30 minutes). Shake the reaction mixture from time to time if the nitro compound appears to be very insoluble, add 5 ml. of alcohol. Cool the reaction mixture, and add 20-40 per cent, sodium hydroxide solution imtil the precipitate of tin hydroxide dissolves. Extract the resulting amine from the cooled solution with ether, and remove the ether by distillation. Examine the residue with regard to its solubility in 5 per cent, hydrochloric acid and its reaction with acetyl chloride or benzene-sulphonyl chloride. 

Fig. 3.133. Preparation of 4-fluorosulphonylaniline and synthesis of 4-(4-diethylamino-2-methyl-phenylazo)benzene sulphonyl fluoride. Reprinted with permission from J. Koh et al. [180].

It has been reported that the reaction of 2-(2-pyridyl)indole with benzene-sulphonyl chloride, under phase-transfer catalytic conditions, yields three products, which have been recorded as being the 3-, 4- and 6-benzenesulphonylindoles [56], or 3-chloro-l-benzenesulphonyl-2-(2-pyridyl)indole, as the major product, with the 1-benezenesulphonyl- and l,3-bis(benzenesulphonyl) derivatives, as the minor products [55]. In the light of the earlier discussion, the latter structural assignments appear to be more likely to be correct. 

Method To a solution of (Et0)2P(0)TeNa (5 mmol) in EtOH (10 mL) is added a solntion of benzene sulphonyl chloride (0.88 g, 5 mmol) in THF (10 mL) under N2. An instantaneous reaction occurs and the colour of the mixture changes from colourless to deep black. After stirring for 20 min, a solution of benzyl chloride (0.64 g, 5 mmol) and catalytic amounts of BzEtjN Cr (0.01 g) in THE (10 mL) is added. The mixture is refluxed for 4 h. After evaporating the solvent nnder reduced pressure, the residue is treated with CHCI3 (50 mL). After filtration, the organic phase is evaporated to dryness. The crnde product is recrystallized from EtOH, giving the pure product (1.93 g (82.4%) m.p. 145-147°C). 

The Schotten-Baumann reaction can also be applied to primary and secondary aromatic amines (see p. 303) it is much used in the identification of compounds to which it can be applied, by the preparation of their benzoyl, phenylacetyl, or benzene sulphonyl derivatives. 

Mixtures of primary, secondary and tertiary amines can usually be separated by Hinsberg s method. This is based on the fact that reaction with benzene-sulphonyl (or toluene-p-sulphonyl) chloride converts primary amines into alkali-soluble sulphonamides, secondary amines into alkali-insoluble sulphon-amides and leaves tertiary amines unaffected. 

SYNS BENZENE SULFONCHLORIDE BENZENESULFONIC (ACID) CHLORIDE BENZENE SULPHONYL CHLORIDE (DOT) BENZENO-SULFO-CHLOREK (POLISH) BENZENOSULPHOCHLORIDE... 

Chhrosidphoitic Acid. Diphenyl chloroarsine, on treatment with chlorosulphonic acid forms, besides benzene sulphonyl chloride, a chloride of diphenyl arsenic acid having the formula (CjH5)2AsOOH.HC1, which forms prisms and melts at 130° C. 

Fluorosulphonic Acid. This converts diphenyl chloroarsine into benzene sulphonyl fluoride and the sulphate of diphenyl arsenic acid, 2(CgH5)2As00H.H3S04, melting at 117° C. 

The free and active amino fimction in sulphanilic acid is first protected by acetylation and the resulting -acetamido-benzene sulphonie acid is chlorinated with chlorosulphonic acid to obtain para-acetamido benzene sulphonyl chloride. This on amination with concentrated ammonia solution changes into its corresponding sulphonamide analog, which on hydrolysis results into the formation of sulfanilamide. 

Replacement of the ethyl chlorocarbonate in the foregoing b benzene sulphonyl chloride and carrying out the reaction at 60° C yields benzenesulphonyl-p-aminophenylstibinic acid, CgHg.SO2-XH.CgH4. SbOa-HgO. ... 

Another important aspect of Schotten-Baumann reaction is sulphonylation whereby benzene sulphonyl chloride, CgH SOgCl (i.e., the corresponding acid chloride of benzene sulphonic acid, CgH SOgOH) is employed instead of benzoyl chloride, and almost similar structural analogues may be obtained. 

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