Synthesis of Several Substituted Pyridine-3-Sulfonyl Chlorides, -Sulfonic Acids, and -Sulfonyl Amides*

Abstract

Diazotation of substituted 3-aminopyridines with subsequent substitution of diazo groups with sulfonyl groups in the obtained diazonium chlorides was used to synthesize the corresponding pyridine-3-sulfonyl chlorides. The conditions for this synthesis were optimized by taking into account the detailed understanding of this substitution. The synthesized pyridine-3-sulfonyl chlorides were converted to pyridine-3-sulfonic acids and -sulfonyl amides.Aromatic and heteroaromatic sulfonic acids are compounds of high importance for industry and agriculture, serving as intermediates for the synthesis of many valuable technical and pharmaceutical compounds. In particular, sulfonic acid derivatives -aryl-and hetarylsulfonyl amides find use as pharmaceuticals [1,2], plant growth regulators [3], herbicides [4], etc. These acids generally are synthesized by two methods: -sulfonation of the corresponding pyridines; -diazotation of 3-aminopyridines, followed by substitution of diazo group with sulfonyl group. In that case, intermediate pyridine-3-sulfonyl chlorides are formed, which are hydrolyzed to sulfonic acids.Direct sulfonation of pyridines can be accomplished under harsh conditions: with concentrated oleum at the temperature range of 180-230°С and catalysis by mercury salts, and is applicable to the synthesis of unsubstituted [5, 6] and monosubstituted pyridine-3-sulfonic acids [6,7].Another method for the synthesis of pyridine-3-sulfonic acids uses mild conditions and has been described primarily for the preparation of monosubstituted acids [8][9][10]. At the same time, the limited number of literature references for the synthesis of polysubstituted pyridine-3-sulfonic acids and their derivatives shows that very few studies have been performed on this topic.Our goal was to search for promising biologically active compounds in this direction through synthesis of new pyridine-3-sulfonyl chlorides as synthons for the preparation of N-substituted sulfonic acids and sulfonyl amides. _______ *Dedicated to Academician of the Russian Academy of Sciences Yu. N. Bubnov on the occasion of his 80th birthday.

Kinetics and Mechanism of Sorption of Copper (Ii) Ions by Ion Exchanger

“…In addition, in the "fingerprint" region, absorption bands are found due to bending vibrations (out-of-plane vibrations) of aromatic fragments [27] with less (at 792, 686, 615 cm -1 ) and medium intensity (at 920, 539, and 472 cm -1 ). According to the literature data [28,29], the absorption band at ν max = 3406 cm-1 can be attributed to the stretching vibrations of the OH group of sulfonic acid. A relatively broad absorption band with a maximum ν max = 1599 cm -1 is due to in-plane vibrations of aromatic fragments.…”