The methanolysis kinetics and dissociation constants of 1-(subst. benzoyl)-3-phenylthioureas

A series of seven 1-(subst. benzoyl)-3-phenylthioureas have been prepared and their dissociation constants and solvolysis rate constants have been measured in methanol at 25 °C. The reaction constants found show that the solvolysis rate is limited by the attack of methoxide ion on the benzoyl carbonyl group of the non-dissociated substrate. The polar effect of substituents in benzoyl group is extensively transferred also by the intramolecular hydrogen bond.

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Hydrogen bonding, configuration and conformation of substituted α-oxo oximes and hydrazones

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19792494 ◽

1979 ◽

Vol 44 (8) ◽

pp. 2494-2506 ◽

Cited By ~ 6

Author(s):

Otto Exner ◽

Jorga Smolíková ◽

Václav Jehlička ◽

Ahmad S. Shawali

Keyword(s):

Hydrogen Bond ◽

Hydrogen Bonding ◽

Carbonyl Group ◽

Intramolecular Hydrogen Bond ◽

Benzene Solution ◽

Dipole Moments ◽

H Nmr ◽

Intramolecular Hydrogen ◽

Derivatives Of ◽

Configuration And Conformation

Substituted 2-bromo-1-phenylglyoxal 2-phenylhydrazones IIIa-f exist in tetrachloromethane or benzene solutions prevailingly in E-configuration and in conformation A with an intramolecular hydrogen bond. The latter was evidenced by the N-H valence frequency at 3 290 cm-1 and by 1H NMR shifts with reference to derivatives without a carbonyl group - α-chlorobenzaldehyde phenylhydrazones V. From dipole moments of IIIa-d, measured in benzene solution, the contribution of the hydrogen bond (μH) was evaluated to 17 . 10-30 C m. This quantity is twice larger than in any other reported compound but the direction of the vector is as usual: approximately from H to N. In structurally similar derivatives of hydroxylamine, substituted 2-phenylglyoxylhydroximoyl chlorides IVa-d, no intramolecular hydrogen bond was detected; the dipole moments found were interpreted in terms of the Z-configuration and the prevailing conformation G.

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Effect of substituents at the proton-donor nitrogen atom on an intramolecular hydrogen bond of type NH...O

Journal of Structural Chemistry ◽

10.1007/bf00747038 ◽

1974 ◽

Vol 15 (3) ◽

pp. 353-356

Author(s):

L. N. Kurkovaskaya ◽

I. L. Radushnova ◽

N. N. Shapet'ko ◽

S. M. Kvitko ◽

Yu. S. Andreichikov ◽

...

Keyword(s):

Hydrogen Bond ◽

Nitrogen Atom ◽

Intramolecular Hydrogen Bond ◽

Proton Donor ◽

Effect Of Substituents ◽

Donor Nitrogen Atom ◽

Donor Nitrogen ◽

Intramolecular Hydrogen

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Reactions of 1,3-diacylthioureas with methoxide ion and with amines

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19870120 ◽

1987 ◽

Vol 52 (1) ◽

pp. 120-131 ◽

Cited By ~ 2

Author(s):

Jaromír Kaválek ◽

Josef Jirman ◽

Vojeslav Štěrba

Keyword(s):

Carbonyl Group ◽

Rate Constants ◽

Dissociation Constants ◽

Equilibrium Constants ◽

Rate Limiting Step ◽

Limiting Step ◽

Order Of Magnitude ◽

Acetyl Group ◽

Methoxide Ion ◽

Rate Limiting

Rate constants of base-catalyzed methanolysis and dissociation constants in methanol have been determined for benzoylthiourea (II), 1,3-diacetylthiourea (III), 1,3-dibenzoylthiourea (IV), and 1-acetyl-3-benzoylthiourea (V). With the diacyl derivatives III and IV, the reaction of methoxide ion with the neutral substrate is accompanied by that of methoxide with the substrate anion (at higher alkoxide concentrations). Above 0.1 mol l-1 CH3O(-), the rate constants are also affected by medium. The rate of the reaction of neutral diacyl derivative is decreased, and that of the reaction of methoxide with the substrate anion is rapidly increased. The dissociation constant of II is higher than that of acetylthiourea (I) by about one order of magnitude, but the attack of methoxide on the carbonyl group of II is about three times slower than that in I. The benzoyl group at the N1 nitrogen exhibits a greater activating influence (in both the rate and the equilibrium constants) on the other NHCOR group than the acetyl group does. With V the ratio of methanolysis rate constants is 9 : 1 in favour of the acetyl group. The reaction of diacetyl derivative III with 1-butanamine has been followed in butanamine buffers. At the lowest butanamine concentrations, the reaction is second order in the amine, and the rate-limiting step is the proton transfer from the intermediate to the second amine molecule. At the highest butanamine concentrations the reaction becomes first order in the amine, and the rate-limiting step changes to the attack of butanamine on the carbonyl group of diacetyl derivative III.

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New insights in the discovery of novelh-MAO-B inhibitors: structural characterization of a series ofN-phenyl-4-oxo-4H-chromene-3-carboxamide derivatives

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989015007859 ◽

2015 ◽

Vol 71 (5) ◽

pp. 547-554 ◽

Cited By ~ 3

Author(s):

Ligia R. Gomes ◽

John Nicolson Low ◽

Fernando Cagide ◽

Daniel Chavarria ◽

Fernanda Borges

Keyword(s):

Hydrogen Bond ◽

Carbonyl Group ◽

Intramolecular Hydrogen Bond ◽

Structural Characterization ◽

Phenyl Ring ◽

Carbonyl Groups ◽

Pyrone Ring ◽

Mao B ◽

Intramolecular Hydrogen

SixN-substituted-phenyl 4-oxo-4H-chromene-3-carboxamides, namelyN-(2-nitrophenyl)-4-oxo-4H-chromene-3-carboxamide, C16H10N2O5(2b),N-(3-methoxyphenyl)-4-oxo-4H-chromene-3-carboxamide, C17H13NO4, (3a),N-(3-bromophenyl)-4-oxo-4H-chromene-3-carboxamide, C16H10BrNO3, (3b),N-(4-methoxyphenyl)-4-oxo-4H-chromene-3-carboxamide, C17H13NO4, (4a),N-(4-methylphenyl)-4-oxo-4H-chromene-3-carboxamide, C17H13NO3, (4d), andN-(4-hydroxyphenyl)-4-oxo-4H-chromene-3-carboxamide, C16H11NO4, (4e), have been structurally characterized. All compounds exhibit ananticonformation with respect to the C—N rotamer of the amide and atrans-related conformation with the carbonyl groups of the chromone ring of the amide. These structures present an intramolecular hydrogen-bonded network comprising an N—H...O hydrogen bond between the amide N atom and the O atom of the carbonyl group of the pyrone ring, forming anS(6) ring, and a weak Car—H...O hydrogen bond in which the carbonyl group of the amide acts as acceptor for the H atom of anortho-C atom of the exocyclic phenyl ring, which results in anotherS(6) ring. The N—H...O intramolecular hydrogen bond constrains the carboxamide moiety such that it is virtually coplanar with the chromone ring.

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Competition between the intramolecular hydrogen bond and the π-electron delocalization in some RAHB systems: A theoretical study

Журнал структурной химии ◽

10.26902/jsc_id40420 ◽

2019 ◽

Vol 60 (5) ◽

Keyword(s):

Hydrogen Bond ◽

Intramolecular Hydrogen Bond ◽

Theoretical Study ◽

Electron Delocalization ◽

Intramolecular Hydrogen

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Effect of the intramolecular hydrogen bond in the active metabolite analogs of leflunomide for blocking the Plasmodium falciparum dihydroorotate dehydrogenase enzyme: QTAIM, NBO, and docking study

Current Computer - Aided Drug Design ◽

10.2174/1573409916666200527133126 ◽

2020 ◽

Vol 16 ◽

Author(s):

Reihaneh Heidarian ◽

Mansoureh Zahedi-Tabrizi

Keyword(s):

Hydrogen Bond ◽

Plasmodium Falciparum ◽

Molecular Orbital ◽

Intramolecular Hydrogen Bond ◽

Active Metabolite ◽

Chemical Hardness ◽

Dihydroorotate Dehydrogenase ◽

Molecular Orbital Analysis ◽

Intramolecular Hydrogen ◽

Orbital Analysis

: Leflunomide (LFM) and its active metabolite, teriflunomide (TFM), have drawn a lot of attention for their anticancer activities, treatment of rheumatoid arthritis and malaria due to their capability to inhibit dihydroorotate dehydrogenase (DHODH) and Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) enzyme. In this investigation, the strength of intramolecular hydrogen bond (IHB) in five analogs of TFM (ATFM) has been analyzed employing density functional theory (DFT) using B3LYP/6-311++G (d, p) level and molecular orbital analysis in the gas phase and water solution. A detailed electronic structure study has been performed using the quantum theory of atoms in molecules (QTAIM) and the hydrogen bond energies (EHB) of stable conformer obtained in the range of 76-97 kJ/mol, as a medium hydrogen bond. The effect of substitution on the IHB nature has been studied by natural bond orbital analysis (NBO). 1H NMR calculations show an upward trend in the proton chemical shift of the enolic proton in the chelated ring (14.5 to 15.7ppm) by increasing the IHB strength. All the calculations confirmed the strongest IHB in 5-F-ATFM and the weakest IHB in 2-F-ATFM. Molecular orbital analysis, including the HOMO-LUMO gap and chemical hardness, was performed to compare the reactivity of inhibitors. Finally, molecular docking analysis was carried out to identify the potency of inhibition of these compounds against PfDHODH enzyme.

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