Furan derivatives—LXXVII : Synthesis and study of sulphides and sulphones of 5-nitrofuran series

Two series of 5-nitro-2-furfurylarylsulphides 4a–4f and 5-nitro-2-furfurylarylsulphones 5a–5g were prepared by the reaction of 5-nitrofurfurylbromide¹ with 4-substituted thiophenols 2a–2f and with 4-substituted benzenesulphinic acids 3a–3g, respectively. In these compounds the transmission of polar effects of the substituents by the -S- and SO₂ groups, respectively, was found to take place. pK Values of compounds studied has been determined spectroscopically.