Sulfonyl halides hydrolysis

Azoles containing a free NH group react comparatively readily with acyl halides. N-Acyl-pyrazoles, -imidazoles, etc. can be prepared by reaction sequences of either type (66) -> (67) or type (70)->(71) or (72). Such reactions have been carried out with benzoyl halides, sulfonyl halides, isocyanates, isothiocyanates and chloroformates. Reactions occur under Schotten-Baumann conditions or in inert solvents. When two isomeric products could result, only the thermodynamically stable one is usually obtained because the acylation reactions are reversible and the products interconvert readily. Thus benzotriazole forms 1-acyl derivatives (99) which preserve the Kekule resonance of the benzene ring and are therefore more stable than the isomeric 2-acyl derivatives. Acylation of pyrazoles also usually gives the more stable isomer as the sole product (66AHCi6)347). The imidazole-catalyzed hydrolysis of esters can be classified as an electrophilic attack on the multiply bonded imidazole nitrogen. 

Substitution of fluorine for halogen in aromatic and alkyl sulfonyl halides can be carried out with or without using a solvent. An aqueous system such as 70 % aqueous potassium fluoride is also used because the rate of hydrolysis is much slower than the rate of fluorination as reported for the conversion of methanesulfonyl chloride (1) to methanesulfonyl fluoride (2).23... 

Methanesulfonyl chloride is the largest-volume alkanesulfonyl chloride. Benzenesulfonyl chloride is the only aromatic sulfonyl halide with significant commercial production, primarily as a feedstock for the manufacture of A-butyl benzenesulfonamide. All sulfonyl chlorides are poorly water soluble, which limits their hydrolysis except at elevated temperatures or in the presence of a homogenizing agent such as a cosolvent, surfactant or phase-transfer agent. 

Aliphatic and aromatic sulfonamides are prepared from the corresponding sulfonyl halide (RSO2X) and ammonia, 1°- or 2°-amines.The reaction requires alkaline conditions and thus a stoichiometric amount of additional base to neutralize the by-product hydrohalide (see below Eq. (27)). This base may be a second molecule of the reactive amine, a 3°-amine, or an inorganic base. The reaction can be performed in organic or aqueous solvents, although excessive temperatures must be avoided in water to prevent hydrolysis of the... 

Simple sulfonyl carbanions which do not contain additional carbanion-stabilising groups, e.g. carbonyl groups or heteroatoms, can be readily alkylated in high yield by modern techniques with the use of alkyllithiums and lithium amide bases. A number of allylic halides have been successfully used. In allylic halides, the halogen directly attached to the double-bonded carbon is relatively inert towards nucleophilic attack (Scheme 41). In this way, sulfones (96) can be transformed via desulfonation into vinyl halides (97) or into ketones (98) by hydrolysis (Scheme 41). In contrast to ordinary alkyl sulfones, triflones (99) can be alkylated under mildly basic conditions (potassium carbonate in boiling acetonitrile) (Scheme 42). The ease of carbanion formation from triflones (99) arises from the additional electron-withdrawing (-1) effect of the trifluoromethyl moiety. 

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