Aromatic nitro substitution reaction between 4‐nitro‐N‐n‐butyl‐1,8‐naphthalimide and n‐heptanethiol in water–methanol binary mixtures |
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Authors: | Eduardo Rezende Triboni Julio Cesar Artur Pedro Berci Filho Iolanda Midea Cuccovia Mario José Politi |
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Institution: | 1. Departamento de Bioquímica, Instituto de Química da Universidade de S?o Paulo, Av. Prof. Lineu Prestes 748, CEP 05508900, S?o Paulo, SP, Brazil;2. Departamento de Físico‐Química, Instituto de Química de S?o Carlos, Universidade de S?o Paulo, Av. Trabalhador S?o Carlense 400, CEP 13566590, S?o Carlos, SP, Brazil |
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Abstract: | The second‐order rate constants of thiolysis by n‐heptanethiol on 4‐nitro‐N‐n‐butyl‐1,8‐naphthalimide (4NBN) are strongly affected by the water–methanol binary mixture composition reaching its maximum at around 50% mole fraction. In parallel solvent effects on 4NBN absorption molar extinction coefficient also shows a maximum at this composition region. From the spectroscopic study of reactant and product and the known H‐bond capacity of the mixture a rationalization that involves specific solvent H‐donor interaction with the nitro group is proposed to explain the kinetic data. Present findings also show a convenient methodology to obtain strongly fluorescent imides, valuable for peptide and analogs labeling as well as for thio‐naphthalimide derivatives preparations. Copyright © 2008 John Wiley & Sons, Ltd. |
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Keywords: | nitro‐1 8‐naphthalimide aromatic nitro substitution kinetic solvatochromism water– methanol binary mixtures |
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