A theoretical and experimental study of hydrazone protonation centers

Зверев, В. В.; Pylaeva, T. N.; Stolyarov, A. P.; Kitaev, Yu. P.

doi:10.1007/bf01143896

Cited by 4 publications

(6 citation statements)

References 5 publications

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“…the imino nitrogen atom. This conclusion is in accordance with the results of the protonation site of hydrazones known from the literature [16,29,30]. Furthermore, the hydrazones H 5 and H 3 have greater proton affinity compared to the other investigated hydrazones, which have similar values for proton affinity.…”

Section: Physicochemical Parameters and Proton Affinitiessupporting

confidence: 81%

Analysis of acid-base properties of some p-substituted aromatic hydrazones in aqueous perchloric acid by spectrophotometric and semiempirical methods

Jankulovska¹,

Spirevska²

2014

Maced. J. Chem. Chem. Eng.

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The acid-base properties of some p-substituted aromatic hydrazones were examined in aqueous perchloric acid medium by spectrophotometric methods. The changes in the UV spectra occurred due to the protonation reaction of the investigated hydrazones. The possible site where protonation may take place was discussed using the values of the total energy, binding energy, heat of formation and proton affinity, calculated according to the semiempirical methods AM1 and PM3. Furthermore, the stability of the protonated forms, as well as the stability of the isomers (E and Z) was discussed. Electronic absorption studies were utilized to determine the dissociation constants of the protonated form (pK BH + ), numerically and graphically, at different ionic strengths (0.1, 0.25 and 0.5 mol/dm 3 ), as well as the thermodynamic dissociation constants. The obtained values ranged between 3.08 and 3.47. The influence of the solvent on the appearance of the spectra was compensated by the use of the method of characteristic vector analysis (CVA).Keywords: UV spectroscopy; protonation; thermodynamic dissociation constants; p-substituted aromatic hydrazones; AM1 and PM3 semiempirical methods АНАЛИЗА НА КИСЕЛИНСКО-БАЗНИТЕ СВОЈСТВА НА НЕКОИ p-СУПСТИТУИРАНИ АРОМАТИЧНИ ХИДРАЗОНИ ВО ВОДНИ РАСТВОРИ ОД ПЕРХЛОРНА КИСЕЛИНА СО СПЕКТРОФОТОМЕТРИСКИ И СЕМИЕМПИРИСКИ МЕТОДИКиселинско-базните својства на некои p-супституирани ароматични хидразони се испитани во водни раствори од перхлорна киселина со спектрофотометриски методи. Како резултат на реакцијата на протонирање се забележани промени во UV-спектрите. Местото каде протонира-њето може да се одвива е дискутирано со користење на вредностите на вкупната енергија, сврзу-вачката енергија, топлината на формирање и протонскиот афинитет, пресметани со примена на семиемпириските методи AM1 и PM3. Исто така е дискутирана стабилноста на протонираните форми, како и стабилноста на изомерите (E и Z). Електронските апсорпциони спектри се иско-ристени за определување на константите на дисоцијација на протонираната форма (pK BH + ), нумерички и графички, при различна јонска сила (0,1, 0,25 и 0,5 mol/dm 3 ), како и термоди-намичките константи на дисоцијација.Добиените вредности се движат во границите од 3,08 до 3,47. Влијанието на растворувачот на изгледот на спектрите е компензирано со примена на методот на карактеристична векторска анализа (CVA).Клучни зборови: UV-спектроскопија; протонирање; термодинамички константи на дисоцијација; p-супституирани ароматични хидразони; семиемпириските методи AM1 и PM3

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Section: Physicochemical Parameters and Proton Affinitiessupporting

confidence: 81%

Analysis of acid-base properties of some p-substituted aromatic hydrazones in aqueous perchloric acid by spectrophotometric and semiempirical methods

Jankulovska¹,

Spirevska²

2014

Maced. J. Chem. Chem. Eng.

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“…No purification of the product was attempted. Protonation of the hydrazones at the more basic nitrogen atom gave sensitive hydrazonium ions that could be examined spectroscopically, but they hydrolyzed upon attempted purification by crystallization or chromatography.…”

Section: Resultsmentioning

confidence: 99%

“…Alkyl iminium salts are commercially available, and simple protonated imines have been isolated and are amenable to X-ray crystallographic analysis . Similar ions can be formed from hydrazones, which are typically protonated at the double-bonded nitrogen atom to form stable cations …”

Section: Introductionmentioning

confidence: 99%

Spectroscopic and X-ray Crystallographic Evidence for Electrostatic Effects in 4-Substituted Cyclohexanone-Derived Hydrazones, Imines, and Corresponding Salts

Dibble

Woerpel

2011

J. Org. Chem.

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The axial conformer of several 4-substituted cyclohexanone hydrazone salts was found to predominate in solution. Changes in the charge of the molecule and the polarity of the solvent led to changes in the conformational preference of each molecule that was consistent with electrostatic stabilization of the axial conformer. 1 H NMR spectroscopic analysis was utilized to determine the structure of cyclohexanone-derived substrates by comparison to conformationally restricted transdecalone derivatives and computational models. X-ray crystallography demonstrated that the axial configuration of a pendant benzyloxy group is the preferred conformation of an iminium ion in the solid state. The structure of a neutral hydrazone was also determined to favor the axial configuration for a pendant benzyloxy group in the solid state.

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“…Available quantum computations have been limited to semi‐empirical studies and have been mainly focused on determination of protonation sites (Zverev et al, ; Jankulovska & Spirevska, ). In these studies, phenylhydrazones were found to be preferentially protonated at the imino‐nitrogen atom, but for alkylhydrazones, Zverev and coworkers () predicted protonation of the amino nitrogen atom to be more favorable. In view of the low level of theory used earlier, we recalculated the PAs of various possible protonation sites on several representative hydrazones using the G4MP2 method (Scheme ).…”

Section: Iminesmentioning

confidence: 99%

“…Experimental gas-phase proton affinities of hydrazones have not been reported. Available quantum computations have been limited to semi-empirical studies and have been mainly focused on determination of protonation sites (Zverev et al, 1977;Jankulovska & Spirevska, 2014). In these studies, phenylhydrazones were found to be preferentially protonated at the imino-nitrogen atom, but for alkylhydrazones, Zverev and coworkers (1977) predicted protonation of the amino nitrogen atom to be more favorable.…”

Section: E Heterosubstituted Imines: Hydrazones Oximes and Relatedmentioning

confidence: 99%

Gas phase basicities of polyfunctional molecules. Part 5: Non‐aromatic sp² nitrogen containing compounds

Bouchoux

Eckert‐Maksić

2016

Mass Spectrometry Reviews

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This paper constitutes the fifth part of a general review of the gas-phase protonation thermochemistry of polyfunctional molecules (Part 1: Theory and methods, Mass Spectrom Rev 2007, 26:775-835, Part 2: Saturated basic sites, Mass Spectrom Rev 2012, 31:353-390, Part 3: Amino acids, Mass Spectrom Rev 2012, 31:391-435, Part 4: Carbonyl as basic site, Mass Spectrom Rev 2015, 34:493-534). This part is devoted to non-aromatic molecules characterized by a lone pair located on a sp nitrogen atom, it embraces functional groups such as imines, amidines, guanidines, diazenes, hydrazines, oximes, and phosphazenes. Specific examples are examined under five major chapters. In the first one, aliphatic and unsaturated (conjugated and cyclic) imines, hydrazones, and oximes are considered. A second chapter describes the protonation energetic of aliphatic, conjugated, or cyclic amidines. Guanidines, polyguanides, and biomolecules containing guanidine were examined in the third chapter. A fourth chapter describes the particular case of the phosphazene molecules. Finally, diazenes and azides were considered in the last chapter. Experimental data were re-evaluated according to the presently adopted basicity scale, i.e., PA(NH ) = 853.6 kJ/mol, GB (NH ) = 819 kJ/mol. Structural and energetic information given by G4MP2 quantum chemistry computations on typical systems are presented. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 37:139-170, 2018.

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A theoretical and experimental study of hydrazone protonation centers

Cited by 4 publications

References 5 publications

Analysis of acid-base properties of some p-substituted aromatic hydrazones in aqueous perchloric acid by spectrophotometric and semiempirical methods

Analysis of acid-base properties of some p-substituted aromatic hydrazones in aqueous perchloric acid by spectrophotometric and semiempirical methods

Spectroscopic and X-ray Crystallographic Evidence for Electrostatic Effects in 4-Substituted Cyclohexanone-Derived Hydrazones, Imines, and Corresponding Salts

Gas phase basicities of polyfunctional molecules. Part 5: Non‐aromatic sp² nitrogen containing compounds

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A theoretical and experimental study of hydrazone protonation centers

Cited by 4 publications

References 5 publications

Analysis of acid-base properties of some p-substituted aromatic hydrazones in aqueous perchloric acid by spectrophotometric and semiempirical methods

Analysis of acid-base properties of some p-substituted aromatic hydrazones in aqueous perchloric acid by spectrophotometric and semiempirical methods

Spectroscopic and X-ray Crystallographic Evidence for Electrostatic Effects in 4-Substituted Cyclohexanone-Derived Hydrazones, Imines, and Corresponding Salts

Gas phase basicities of polyfunctional molecules. Part 5: Non‐aromatic sp2 nitrogen containing compounds

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Gas phase basicities of polyfunctional molecules. Part 5: Non‐aromatic sp² nitrogen containing compounds