An examination of some effects of OH rotation in phenol and p-nitrophenol
TL;DR: In this paper, a computational analysis of phenol and p -nitrophenol was carried out with the objective of determining the extent to which the conjugation between the -OH group and the aromatic ring is affected by a 90° rotation of the former.
Abstract: A computational analysis of phenol and p -nitrophenol has been carried out with the objective of determining the extent to which the conjugation between the -OH group and the aromatic ring is affected by a 90° rotation of the former. The ab initio SCF-MO GAUSSIAN 82 procedure was used to compute optimized geometries, electronic densities and electrostatic potentials. The effect of rotation upon the structures and distributions of π electronic charge are rather small. However, the electrostatic potential reveals that as a consequence of rotation around the COH bond, there should be an overall preference for the ortho positions as the initial sites for electrophilic attack. The -NO 2 group deactivates the aromatic ring toward electrophiles and increases the positive character of the hydroxyl hydrogen.
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TL;DR: In this paper, it was shown that C-NO2 dissociation energies are related to the computed electrostatic potential maxima on the molecular surfaces above these bond regions, which presumably explains the well-established involvement of the electric potential in impact sensitivity correlations; a second factor in the latter is the internal charge separation in the molecule.
Abstract: : New data for nitroalkanes support earlier results lor nitroheterocycles indicating that C-NO2 dissociation energies are related to the computed electrostatic potential maxima on the molecular surfaces above these bond regions. This presumably explains the well-established involvement of the electrostatic potential in impact sensitivity correlations; a second factor in the latter, for unsaturated systems, is the internal charge separation in the molecule. jg p1
173 citations
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TL;DR: In this article, the harmonic vibrational frequencies and infrared intensities of p-nitrophenol as well as geometries of ortho-and para-nipponol, were calculated with density functional theory (DFT), using BLYP functional and 6-31G(d,p) basis set.
Abstract: The harmonic vibrational frequencies and infrared intensities of p-nitrophenol as well as geometries of ortho- and para-nitrophenol, are calculated with density functional theory (DFT), using BLYP functional and 6-31G(d,p) basis set. The calculated (unscaled) spectra are in very good agreement with the gas phase and solid IR spectra of p-nitrophenol. A detailed interpretation of the infrared spectra of p-nitrophenol is reported on the basis of the calculated potential energy distribution (PED). Several reassignments have been made.
94 citations
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TL;DR: In this article, the most negative-valued molecular electrostatic potential (MESP) minimum (Vmin) observed over the benzene ring is proposed as a sensitive quantity for the analysis of the electronic perturbations.
Abstract: The most negative-valued molecular electrostatic potential (MESP) minimum (Vmin) observed over the benzene ring is proposed as a sensitive quantity for the analysis of the electronic perturbations ...
83 citations
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TL;DR: In this paper, a nonlocal density functional procedure (GAUSSIAN 92/DFT, BLYP, 6-31G) was used to compute the dissociation energies of the C-NO2 bonds in five unsaturated nitroheterocyclic molecules.
Abstract: : A nonlocal density functional procedure (GAUSSIAN 92/DFT, BLYP, 6-31G) has been used to compute the dissociation energies of the C-NO2 bonds in five unsaturated nitroheterocyclic molecules. These show a definite correlation with the maxima of the surface electrostatic potentials above these bonds, which may explaln why these potential maxima are one of the properties that appear in an earlier analytical representation of the measured impact sensitivities of nitroheterocyclic compounds. jg
69 citations
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TL;DR: In this article, the Hartree-Fock 4-31G and 6-31g ∗∗ levels were used to perform electronic structure calculations for phenol and the hydrogen-bonded complexes phenol · H 2 O and d-phenol · D 2 O.
Abstract: Ab initio electronic structure calculations for phenol and the hydrogen-bonded complexes phenol · H 2 O and d-phenol · D 2 O were performed at the Hartree-Fock 4-31G and 6-31G ∗∗ levels. Both phenol and phenol · H 2 O were fully structure optimized. Based on the minimumenergy structures so obtained, full normal coordinate analyses were carried out. The resulting harmonic frequencies were scaled and compared to available experimental data. The agreement is satisfactory and allows for an assignment of a majority of the bands observed in the experimental spectra. Comparison with previous calculations on (H 2 O) 2 reveals a considerable increase in the strength of the hydrogen bond on going from (H 2 O) 2 to phenol · H 2 O.
63 citations
References
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TL;DR: In this article, a survey of the literature related to the structures of polyatomic molecules in the gas phase has been presented, and the reported bond distances and angles have been classified as equilibrium (re), average (rz), substitution (rs), or effective (ro) parameters.
Abstract: Spectroscopic data related to the structures of polyatomic molecules in the gas phase have been reviewed, critically evaluated, and compiled. All reported bond distances and angles have been classified as equilibrium (re), average (rz), substitution (rs), or effective (ro) parameters, and have been given a quality rating which is a measure of the parameter uncertainty. The surveyed literature includes work from all of the areas of gas‐phase spectroscopy from which precise quantitative structural information can be derived. Introductory material includes definitions of the various types of parameters and a description of the evaluation procedure.
806 citations
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TL;DR: The compound 1,3, 5triamino2, 4, 6trinitrobenzene (TATB) is unusual in its thermal and solubility properties as mentioned in this paper.
Abstract: The compound 1,3, 5triamino2, 4, 6trinitrobenzene (TATB) is unusual in its thermal and solubility properties. The compound sublimes and decomposes above 300 °C. Concentrated sulfuric acid is the best of the few known solvents for TATB. These facts indicated tha t the compound would be of interest because of its hydrogen bonding system in which both interand intra-molecular hydrogen bonds are likely between amine groups and adjacent nitro groups. Another compound, 1,3-diamino-2,4,6-trinitrobenzene, form I (Holden, 1962), tha t has a similar hydrogen bond system has been reported.
367 citations
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TL;DR: In this paper, the torsional spectra of gaseous C2H6, CH3CD-3CD3, and C2D6 have been observed directly in the infrared under high pressurepath length conditions (30 −70 atm·m).
Abstract: The torsional spectra of gaseous C2H6, CH3CD3CD3, and C2D6 have been observed directly in the infrared under high‐pressure‐path‐length conditions (30‐70 atm·m). The fundamental was observed for all three species, at 289, 253, and 208 cm−1, respectively. Hot bands were observed for C2H6 (255 cm−1 [A], 258 cm−1[E]) and CH3CD3 (228 cm−1) as was the first overtone for CH3CD3 (482 cm−1). All the experimental frequencies can be very well accounted for by use of a single internal rotation potential function with a barrier height V3 = 2928 cal / mole. This implies that V6 (and higher terms) are negligibly small. Two alternative explanations for the occurrence of these spectra in the infrared, one in terms of Coriolis interaction with an infrared‐active vibration and one in terms of a ν4 + νx − νx vibration, are discussed. A more reliable determination of ν12, the “uncertain frequency” of C2H6, has been obtained from the ν12 − ν9 difference band, giving ν12 = 1206 cm−1.
251 citations
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TL;DR: In this article, the potentiels electrostatiques de benzene, aniline, nitrobenzene and 3 nitroanilines isomeres are computed for etudier l'effet des substituants NH 2 et NO 2 sur l'attaque electrophile du cycle benzenique a l'aide de fonctions d'onde SCF(STO-SG) apres optimisation des geometries au niveau STO-3G.
Abstract: Calcul des potentiels electrostatiques de benzene, aniline, nitrobenzene et de 3 nitroanilines isomeres pour etudier l'effet des substituants NH 2 et NO 2 sur l'attaque electrophile du cycle benzenique a l'aide de fonctions d'onde SCF(STO-SG) apres optimisation des geometries au niveau STO-3G
171 citations
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