Characterization studies of 1-(4-cyano-2-oxo-1,2-dihydro-1-pyridyl)-3-(4-cyano-1,2-dihydro-1-pyridyl)propane formed from the reaction of hydroxide Ion with 1,3-Bis-(4-cyano pyridinium)propane

Fiori, Simone; Schuquel, T. A.; Silva, Idelcio N. da; Politi, Mário José; Catalani, Luiz Henrique; Chaimovich, Hernán; Meyer, Edenilson; Hioka, Noboru

doi:10.1590/s0103-50532011000900004

Cited by 3 publications

(11 citation statements)

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“…All reactions of C n bis(CP) 2+ and RCP + derivatives with OH − ‐generated products constituted of pyridone and carbamidopyridinium rings (absorption band at 262 nm). However, an unexpected result was found involving only C 3 bis(CP) 2+ ; at pH higher than 11.5, that is, a new product was formed, which we had previously identified as 1,3‐(4‐cyano‐2‐pyridone)‐(4‐cyano‐1,2‐dihydropyridine)propane . The profile of the P o /A + ratio (calculated using Eq.…”

Section: Resultsmentioning

confidence: 92%

“…N ‐Methyl‐4‐cyanopyridinium bromide (MCP + ) and 1,1′(1,3‐propanediyl)bis[4‐cyanopyridinium] bromide (C 3 bis(CP) 2+ ) were synthesized as described below.…”

Section: Methodsmentioning

confidence: 99%

“…Following the same strategy used for the previous bis‐positive reactants , compounds constituted by two 4‐cyanopyridinium rings were synthesized (C n bis(CP) 2+ ) and their reactivity with the hydroxide ion was studied. In the present work, the allied effects of charge and conformation on kinetics are investigated, including the existence of the complex between C n bis(CP) 2+ and the nucleophile, as we previously suggested (Scheme ) .…”

Section: Introductionmentioning

confidence: 98%

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Kinetic Study of the Alkaline Hydrolysis of 1,n‐Bis(4‐cyanopyridinium)alkanes: Charge Density and New Conformational Effects on the Reactivity of 1,3‐Bis(4‐cyanopyridinium)propane

Fiori

Carvalho

Tessaro

et al. 2013

Int J of Chemical Kinetics

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The alkaline hydrolysis reaction rates of 1,n-bis(4-cyanopyridinium)alkane derivatives C n bis(CP) 2+ with n = 3, 6, and 8 were studied and compared to the reaction rate of the N-methyl-4-cyanopyridinium (MCP + ). C 6 bis(CP) 2+ and C 8 bis(CP) 2+ obeyed the first-order kinetic law. However for C 3 bis(CP) 2+ data fitted to a consecutive two-step model reaction, the observed rate constants (k obs ) of C 8 bis(CP) 2+ and C 6 bis(CP) 2+ are approximately 50% and 100%, respectively, higher than those for MCP + , an effect mainly assigned to the higher charge density of these two derivatives. For C 3 bis(CP) 2+ , the k obs of the second (slow) step is almost twofold the value observed for C 6 bis(CP) 2+ , whereas the first (fast) step is approximately six times higher. As for MCP, the hydrolysis of C n bis(CP) 2+ generates pyridone (P o ) and carbamidopyridinium (A + ) units. For C 3 bis(CP) 2+ , however at pHs above 11.5, one additional product is formed. From the existence of the new product and the kinetic evidence, a "sandwichedtype" complex with the OH − inserted between the rings is proposed. This structural effect in the C 3 bis(CP) 2+ due to the conformational effect justifies the (i) two kinetic steps, (ii) high rate constants, (iii) high P o /A + ratios, (iv) observed temperature and salt effects, and (v) the formation of the new product. C 2013 Wiley Periodicals, Inc. Int J Chem Kinet 45: 478-486, 2013

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Section: Resultsmentioning

confidence: 92%

“…N ‐Methyl‐4‐cyanopyridinium bromide (MCP + ) and 1,1′(1,3‐propanediyl)bis[4‐cyanopyridinium] bromide (C 3 bis(CP) 2+ ) were synthesized as described below.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

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Kinetic Study of the Alkaline Hydrolysis of 1,n‐Bis(4‐cyanopyridinium)alkanes: Charge Density and New Conformational Effects on the Reactivity of 1,3‐Bis(4‐cyanopyridinium)propane

Fiori

Carvalho

Tessaro

et al. 2013

Int J of Chemical Kinetics

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“…O C 4 (4CP ) + (Figura 1.1a)é formado por apenas um anel piridínio e experimentalmente tem sido amplamente estudado desde a década de 1950 [21]. Já o C 3 bis(4CP ) 2+ (Figura 1.1b)é formado por dois anéis conectados por uma cadeia carbônica (derivado bispiridínico), tendo sido estudado recentemente por Hioka e colaboradores [34,35,[55][56][57][58].…”

Section: Complexos Formados Por Iodeto E Derivados Piridínicosunclassified

“…Vale ressaltar que uma conformação semelhante a essa já havia sido proposta experimentalmente para explicar a reação do C 3 bis(4CP ) 2+ com osânions hidróxido (OH − ) em meio alcalino [34,57], onde se observa a formação de um produto de reação adicional em relação ao caso da reação C 4 (4CP ) + + OH − . A formação de um com-plexo sanduíche entre o C 3 bis(4CP ) 2+ foi usada para explicar a formação do composto adicional [34].…”

Section: Complexos Formados Por Iodeto E Derivados Piridínicosunclassified

Estudo teórico de complexos de transferência de carga em solução

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In this work, we have studied theoretically charge-transfer complexes (CTC) formed by pyridinium derivatives with iodide. The formation of a CTC is characterized by the appearance of a new absorption band on the electronic spectra, in organic polar solvents like acetonitrile. These type of systems have recently received much interest in a broad variety of fields, for example, organic electronics, nonlinear spectroscopy, medical biochemistry, pharmaceutical industry, etc. The C 4 (4CP) + I − complex is characterized by the charge-transfer band with a maximum at 421 nm in acetonitrile. We have used density functional theory (DFT) and time dependent density functional theory (TDDFT) to calculate electronic properties and the excitation energies of the complex. Functionals with long-range corrections were essential in describing the charge-transfer excitations. CAM-B3LYP and ωB97X-D associated with the polarizable continuum model predicts CT excitations in good agreement with experiment. Our results also indicates the existence of different conformations for the complex formed by the C 3 bis(4CP) 2+ with iodide. Complexes were formed by the association of one or two I − to C 3 bis(4CP) 2+ , but the charge transfer excitations were calculated from only one iodide to the aromatic ring, what explain why the stoichiometry 1:1 was observed. A better description of the complex in solution was obtained using classical molecular dynamics. The OPLS-AA force field was fine-tuned to reproduce the results of a first principle molecular dynamics for the complex. No dissociation were observed. The calculated charge-transfer band using configurations sampled from molecular dynamics is in excellent agreement with experiment.

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Microenvironment Effects on the Kinetics of the Alkaline Hydrolysis of Bispyridinium Conformers

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Fiori

Biondo

et al. 2013

Int J of Chemical Kinetics

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The alkaline hydrolysis of a series of homologous reactants constituted by two reactive centers bridged by a methylene spacers chain, the 1,n-bis(2-azidepyridinium)alkanes (n = 3, 4, 5, 6, and 8), is investigated. The reaction under pseudo-first-order condition was followed by ultraviolet-visible spectrophotometry. The presence of clear isosbestic point suggests the absence of stable intermediates. However, the intermediates 1-(2-azidepyridinium), n-(2-pyridone)alkanes (monocationic compounds), were isolated and characterized as well the reaction end products 1,n-(2-pyridone)alkanes (noncharged compounds). The kinetic analysis fitted to a two-step consecutive reaction, where the k 1 /k 2 values demonstrate the larger reactivity of the first step over the second one, especially for shorter bridged reactants. The OH − reaction order is one for each step. Although Debye-Hückel law was obeyed, the experimental point at ionic strength zero is much higher than the extrapolated one. In addition, the k 1 values substantially decrease as KCl is added especially for shorter homologous whereas the effect on k 2 is almost negligible. Simple charge density effects as a function of the spacer's length do not explain the observations. On the other hand, from the pronounced anion selectivity inhibition effects on k 1 for the shorter derivatives, the existence of an equilibrium involving a conformer, a "sandwich-type" complex with the OH − between the two pyridinium rings, with an "open-stretched" conformer is proposed. For short-bridged reactants, the complex conformer

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Characterization studies of 1-(4-cyano-2-oxo-1,2-dihydro-1-pyridyl)-3-(4-cyano-1,2-dihydro-1-pyridyl)propane formed from the reaction of hydroxide Ion with 1,3-Bis-(4-cyano pyridinium)propane

Cited by 3 publications

References 14 publications

Kinetic Study of the Alkaline Hydrolysis of 1,n‐Bis(4‐cyanopyridinium)alkanes: Charge Density and New Conformational Effects on the Reactivity of 1,3‐Bis(4‐cyanopyridinium)propane

Kinetic Study of the Alkaline Hydrolysis of 1,n‐Bis(4‐cyanopyridinium)alkanes: Charge Density and New Conformational Effects on the Reactivity of 1,3‐Bis(4‐cyanopyridinium)propane

Estudo teórico de complexos de transferência de carga em solução

Microenvironment Effects on the Kinetics of the Alkaline Hydrolysis of Bispyridinium Conformers

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