Tautomeric, spectroscopic, DFT calculations and X-ray studies on O2N-4-C6H4–NHNC(COCH3)2

Bustos, Carlos; Sánchez, C. O.; Martínez, Rolando; Ugarte, Ricardo; Schott, Eduardo; MacLeod‐Carey, Desmond; Garland, Marı́a Teresa; Espinoza, Luis

doi:10.1016/j.dyepig.2006.04.002

Cited by 21 publications

(18 citation statements)

References 10 publications

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“…The para ‐substituted 3‐(phenylhydrazo)pentane‐2,4‐diones (HL, Scheme 1) were prepared by aqueous diazotization and azocoupling. The synthesis and some properties of HL 1,3–5 were reported before 49, 53–55. It has also been found that diazotized aromatic amines couple successfully with a range of reactive methylene coupling components in an organic solvent and in the presence of sodium acetate 1–3.…”

Section: Resultsmentioning

confidence: 78%

“…The ADB prepared in this study potentially can exist in the enol‐azo, keto‐azo and hydrazo tautomeric forms (Scheme 1), but earlier it was shown experimentally that hydrazones formed from pentane‐2,4‐dione exist in the hydrazo form both in solution and in the solid state 49, 53–55. An intramolecular hydrogen bridge linking one of the carbonyl groups to the NH‐moiety of the hydrazone unit and forming the six‐membered hydrogen bonding ring was found to be a characteristic feature of the hydrazo form (Scheme 1) thus stabilizing this particular tautomer.…”

Section: Resultsmentioning

confidence: 78%

“…It has also been found that diazotized aromatic amines couple successfully with a range of reactive methylene coupling components in an organic solvent and in the presence of sodium acetate 1–3. However, attempts to prepare our para ‐substituted HL 1,3–5 compounds using this base either failed completely or gave a low yield of a highly impure product 49, 53–55. Thus, we modified the reported procedure and found that good yields of HL could be obtained when the coupling was undertaken in a sodium hydroxide solution (described in Experimental section).…”

Section: Resultsmentioning

confidence: 99%

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Trends in properties of para‐substituted 3‐(phenylhydrazo)pentane‐2,4‐diones

Kopylovich¹,

Mahmudov²,

Silva

et al. 2010

J of Physical Organic Chem

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Abstract:Trends between the Hammett's sigma(p) and related normal sigma(n)(p), inductive sigma(I), resonance sigma(R), negative sigma(-)(p) and positive sigma(+)(p) polar conjugation and Taft's sigma(o)(p) substituent constants and the N-H center dot center dot center dot O distance, delta(N-H) NMR chemical shift, oxidation potential (E-p/2(ox), measured in this study by cyclic voltammetry (CV)) and thermodynamic parameters (pK, Delta G(0), Delta H-0 and Delta S-0) of the dissociation process of unsubstituted 3-(phenylhydrazo)pentane-2,4-dione (HL1) and its para-substituted chloro (HL2), carboxy (HL3), fluoro (HL4) and nitro (HL5) derivatives were recognized. The best fits were found for sigma(p) and/or sigma(-)(p) in the cases of d(N center dot center dot center dot O), delta(N-H) and E-p/2(ox), showing the importance of resonance and conjugation effects in such properties, whereas for the above thermodynamic properties the inductive effects (sigma(I)) are dominant. HL2 exists in the hydrazo form in DMSO solution and in the solid state and contains an intramolecular H-bond with the N center dot center dot center dot O distance of 2.588(3)angstrom. It was also established that the dissociation process of HL1-5 is non-spontaneous, endothermic and entropically unfavourable, and that the increase in the inductive effect (sigma(I)) of para-substitutents (-H < -Cl < -COOH < -F < -NO2) leads to the corresponding growth of the N center dot center dot center dot O distance and decrease of the pK and of the changes of Gibbs free energy, of enthalpy and of entropy for the HL1-5 acid dissociation process. The electrochemical behaviour of HL1-5 was interpreted using theoretical calculations at the DFT/HF hybrid level, namely in terms of HOMO and LUMO compositions, and of reactivities induced by anodic and cathodic electron-transfers.

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Section: Resultsmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 99%

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Trends in properties of para‐substituted 3‐(phenylhydrazo)pentane‐2,4‐diones

Kopylovich¹,

Mahmudov²,

Silva

et al. 2010

J of Physical Organic Chem

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“…13.2-14.1 can be assigned to N-NH adjacent to the aryl unit similarly to the reported analogs [8][9][10][11][12][13][37][38][39][40][41][42]. Moreover, the presence of two C O resonances in 13 C{ 1 H} NMR spectra in the range of 185.…”

Section: Synthesis Of 1-6 and Spectroscopic Studymentioning

confidence: 89%

Quantum chemical simulations of solvent influence on UV–vis spectra and orbital shapes of azoderivatives of diphenylpropane-1,3-dione

Kuźnik

Kityk

Kopylovich³

et al. 2011

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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“…In fact, several isoxazoles [1][2][3][4][5][6][7] and pyrazoles [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] have a remarkable importance in medicine and particularly pyrazole's chemistry has been extended toward the catalysis 23 and coordination chemistry [24][25] . On the other hand, it is well known that β-diketones as pentane-2,4-dione, CH 2 (COCH 3 ) 2 , in basic medium, may couple with substituted diazonium salts [26][27] yielding series of compounds that belong to the β-diketohydrazones family, namely 3-[2-(R 1 -phenyl)hydrazono)]pentane-2,4-dione, see Schemes. In this work, we show that these compounds may be used as precursors for obtaining easily heterocycles series, namely isoxazole and pyrazole derivatives.…”

mentioning

confidence: 99%