The X-ray crystal structure 6-K is quite interesting.
Mekhman karimov full#
1H and 13C NMR spectra of these crystals were in full agreement with the NMR spectra of IBS provided in the Supporting Information of Ishihara's paper and, in particular, displayed the characteristic signals of the ortho-protons (relative to iodine(V)) at 8.28 ppm. The needle-shaped organic crystals were manually separated from the inorganic salts and analysed by NMR spectroscopy and X-ray crystallography. After cooling the aqueous solution to room temperature, the formation of a precipitate consisting of needle-shaped organic crystals and microcrystalline powder of inorganic salts was observed. NMR monitoring indicated 95% conversion of the starting sodium salt 5 to the iodine(V) product 6 after about 3 h stirring at 70 ☌ (Figure S1 in Supporting Information File 1). The oxidation of sodium 2-iodobenzenesulfonate ( 5) by Oxone was performed under Ishihara's conditions in water at 70 ☌ ( Scheme 2).
Mekhman karimov free#
We have investigated the oxidation of 2-iodobenzenesulfonic acid as sodium salt and as a free acid using Oxone, sodium periodate or periodic acid. Furthermore, we have developed a new method for the preparation of the IBS reduced form, 2-iodosylbenzenesulfonic acid ( 4), with the use of periodic acid as an oxidant. In the present work, we report the preparation and isolation of IBS (as potassium or sodium salts) and its structural study by X-ray analysis. However, all previously reported attempts to grow single crystals of IBS from methanol or acetonitrile resulted in reduction with the formation of 2-iodosylbenzenesulfonic acid as confirmed by X-ray diffraction analysis. Despite these problems, IBS was previously characterized by 1H and 13C NMR, IR spectroscopy, high-resolution mass spectrometry, and elemental analysis. Moreover, IBS has high reactivity towards polar organic solvents (acetonitrile, DMSO, methanol) being readily reduced to 2-iodosylbenzenesulfonic acid upon contact with these solvents. The resulting IBS is insoluble in nonpolar solvents (dichloromethane, chloroform, etc.). Because of the high solubility of IBS in water, this mixture is difficult to separate. The direct oxidation of 2-iodobenzenesulfonic acid ( 2) with Oxone leads to the formation of the desired IBS ( 1, Scheme 1), however, contaminated with inorganic impurities. The hydrolysis of sulfonic ester 3 forms IBS as a mixture with methanol which is quickly oxidized by IBS in situ producing the corresponding iodine(III) heterocycle, 2-iodosylbenzenesulfonic acid ( 4) as main product. The first preparation and isolation of IBS ( 1) was attempted in 2006 using two different approaches: direct oxidation of 2-iodobenzenesulfonic acid ( 2) by Oxone or hydrolysis of methyl 2-iodoxybenzenesulfate ( 3, Scheme 1). Recent research has revealed the extreme activity of IBS as a catalyst in numerous other oxidations, such as: the oxidation of benzylic and alkane C–H bonds, the oxidation of phenols to 1,2-quinones, the cyclization and cross-coupling reactions, and the site-selective hydroxylative dearomatization of 2-substituted phenols to either 1,2-benzoquinols or their cyclodimers. K 2SO 4) in nitromethane, acetonitrile, or ethyl acetate.In particular, it can be used as a highly efficient and selective catalyst (0.05–5 mol %) for the oxidation of primary and secondary alcohols to the respective carbonyl compounds with Oxone ® (2KHSO 5 IBS (or its sodium salt) is much more active as catalyst than IBX derivatives. In 2009, Ishihara and co-workers have reported an extremely active catalytic system for oxidation of alcohols based on 2-iodoxybenzenesulfonic acid (IBS) as the active species. Moreover, these reagents are generally not suitable as active species in catalytic reactions due to the low reactivity and harsh conditions required for their in situ generation.
IBX and DMP are mild oxidants with a relatively low reactivity towards some substrates. 2-Iodoxybenzoic acid (IBX) and the product of its acetylation Dess–Martin periodinane (DMP) are the most common oxidants used for selective oxidation of alcohols to carbonyl compounds as well as for a variety of other synthetically useful oxidative transformations. Hypervalent iodine(V) compounds represent an important class of oxidative reagents extensively employed in organic synthesis. Recently, the interest in synthetic applications of hypervalent iodine compounds as stoichiometric reagents or catalysts has experienced an explosive growth.
0 kommentar(er)
