Sulphonyl halides hydrolysis

An important feature of reactions in solvent mixtures is the effect of substituents in the reactant on the kinetic parameters. As Foon and Hambly (1962) note with reference to the hydrolysis of a series of sulphonyl halides, it is possible to obtain almost any order for the rate constants by selection of the appropriate solvent mixture. The substituent effects also depend on the temperature and, in the case of bimolecular reactions, on the nature of the attacking group, e.g. OH- instead of H20 (Tommila, 1967). 

The products of hydrolysis of sulphonyl halides, i.e. sulphonic and hydrohalic acids, can be easily titrated with bases, which accelerate the hydrolysis as well. Thus Cundiff and Markunas titrated potentiometrically benzenesulphonyl chloride (and sulphuric acid) in pyridine with tetrabutylammonium hydroxide in benzene/methanol251. Jansseune and Janssen252 titrated sulphonyl fluorides in butylamine with potassium methoxide. Krivoruchko253 estimated 2-chloroethanesulphonyl chloride in air by hydrolysing it with alcoholic potassium hydroxide and determining the chloride ion colorimetrically or nephelometrically. Jansseune and Janssen252 also hydrolysed sulphonyl fluorides with alkali, acidified the mixture, distilled the HF and titrated it with alkali. 

Amides are the least reactive of the carboxylic acid derivatives, and undergo acid or base hydrolysis to produce the parent carboxylic acids, and reduction to appropriate amines (see Section 4.3.10). They can also be dehydrated to nitriles, most commonly with boiling acetic anhydride, (AcO)20, sulphonyl chloride (SOCI2) or phosphoms oxychloride (POCI3) (see Section 4.3.18). Amines (with one less carbon) are prepared from amides by the treatment of halides (Br2 or CI2) in aqueous NaOH or KOH. This reaction is known as Hofmann rearrangement (see Section 4.3.10). 

Aminobenzenesulphonic acid (orthanilic acid, Expt 6.64) is readily prepared by the reduction of 2-nitrobenzenesulphonic acid. The latter may be prepared by the hydrolysis of the corresponding sulphonyl chloride which is obtained from di-o-nitrophenyl disulphide. The preparation of this disulphide involves the use of the reactive aryl halide, 2-chloronitrobenzene (cf. Expts 6.93... 

Further kinetic information on hydrolysis of sulphonyl chlorides (R SOgCl) is contained in a paper which correlates kinetic data for hydrolysis of these and other halides, for example of phosphonic and phosphinic acids, with i.r. and n.q.r, spectroscopic data. Hydrolysis of the adduct McaEtN.SOa has been studied over a wide pH range. The rate-law determined in basic solution indicates 5 n2 attack by hydroxide at the sulphur atom, as earlier proposed for the parent adduct EtaN.SOg,... 

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