Zur Synthese sulfonierter Derivate von 4‐Fluoranilin

Abstract

Synthesis of 2-amino-5-fluorobenzenesulfonic acid (2) was achieved by baking the hydrogen sulfate of 4-fluoroaniline (1). Sulfonation of p-fluoroacetanilide (4) with oleum followed by hydrolysis gave 5-amino-2-fluorobenzenesulfonic acid (3). The same reaction with 1 yielded 3 in an impure state. The structures of 2 and 3 were confirmed by converting the diazonium chlorides derived from 5-fluoro-2nitroaniline (5) and from 2-fluoro-5-nitroaniline (8) to 5-fluoro-2-nitrobenzenesulfonyl chloride (6) and 2-fluoro-5-nitrobenzenesulfonyl chloride (9), respectively, followed by hydrolysis of 6 to 5-fluoro-2-nitrobenzenesulfonic acid (7), and of 9 to 2-fluoro-5-nitrobenzenesulfonic acid (lo), and by final reduction. Compound 10 was also obtained by sulfonation of 1-fluoro-4-nitrobenzene (11) with oleum.

Acetamidoarenediazonium Salts: Opportunities for Multiple Arene Functionali­zation

“…The synthesis of 1e (Scheme ) started from m ‐fluoroaniline ( 4 ), which was first acetylated to produce 5 . Nitration of 5 with nitrous acid had previously been reported to afford primarily the unwanted regioisomer 6b in moderate yield,38,39 so this prompted us to test guanidinium nitrate, a reagent introduced by Ramana et al40 and subsequently used successfully by us for regioselective nitration 21. Treatment of 5 with guanidinium nitrate furnished regioisomers 6a and 6b in a 1:1 ratio; they were easily separated by column chromatography and isolated in good yield.…”

Organic Sulfinic Acids and Salts in Visible Light-Induced Reactions

“…7 8 9 There are lone pairs on the soft nucleophilic S atom and the hard nucleophilic O atom, and these lead to various synthetic transformations with organic sulfinic acids or their salts involved. Sharing of the S-lone pair with carbon electrophiles leads to sulfone products, 10 and reaction of the O-lone pair with carbon electrophiles leads to alkylsulfinates. 11] When the S-lone pair is shared with oxygen, the sulfinic acid is oxidized to sulfonic acid, 12 but when sulfinic acid reacts with oxyphilic elements, the oxygen atoms could be abstracted, generating reduction products.…”