- Nano-CuFe2O4-supported sulfonic acid as a novel and recyclable nanomagnetic acid for diazotization of aromatic amines: efficient synthesis of various azo dyes
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Abstract: A novel heterogeneous sulfonic acid functionalized nanomagnetic CuFe2O4 was successfully prepared and characterized by analyzing different obtained data including Fourier transform infrared spectroscopy, X-ray powder diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, dynamic light scattering and vibrating sample magnetometer. Then the novel acidic reagent was examined in synthesis of various azo-containing compounds from coupling of aryl diazonium ferrite sulfate salts with aromatic and non-aromatic compounds. The procedure starts by diazotization of aromatic amines with NaNO2 and wet CuFe2O4–SO3H and then coupling reaction of aryl diazonium ferrite sulfate salts with appropriate reagent. The prepared nano-solid acid showed high activity in synthesis of variety of aryl diazonium salts. In addition the as-prepared aryl diazonium ferrite sulfate salts are stable at room temperature for many hours and reacted efficiently in coupling reactions of aryl diazonium salts. All the azo dyes are synthesized in high yields and simple reaction conditions at room temperature. Moreover, the nanomagnetic solid acid was easily recovered from the reaction mixture and reused five runs without significant loss of activity. Graphical Abstract: [Figure not available: see fulltext.]
- Nemati, Firouzeh,Elhampour, Ali,Natanzi, Mahshid B.,Sabaqian, Samaneh
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p. 1045 - 1054
(2016/05/02)
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- "Apparent" Deviations from the Beer-Lambert Law in Systems with a Prototropic Tautomeric Equilibrium
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The molar absorption coefficients have been measured in acid aqueous-salt solutions of Methyl Orange (p-N,N-dimethylaminoazobenzene-p-sulphonic acid) in the visible and the u.v. region of the spectrum for ionic strengths up to i = 5.In solutions of alkali metal chlorides we used the dependence of the prototropic tautomeric equilibrium of the indicator acids on the ionic strength of the solution to calculate the molar absorption coefficients of the separate tautomeric forms of the indicator and the tautomerisation constants.If sodium or lithium perchlorate is used to generate the ionic strength of the solution, spectral changes are caused by both the shift in the tautomeric equilibrium and the changes in molar absorption coefficients of the individual tautomers.
- Khnykin, G. D.,Bil'chenko, M. N.
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p. 961 - 964
(2007/10/02)
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