Far infrared spectra and barriers to internal rotation of benzaldehyde, benzoyl fluoride, benzoyl chloride and acetophenone

Durig, J. R.; Bist, H. D.; Furić, Krešimir; Qiu, J.; Little, T. S.

doi:10.1016/0022-2860(85)80191-5

Cited by 61 publications

(53 citation statements)

References 20 publications

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“…Note that in column I all the vibrational frequencies were used to calculate the covariance matrix elements according to Equation (12). In column II w n = 49.5 cm À1 corresponding the the torsion about f 1 was omitted whereas in column III both w n = 49.5 cm À1 and w n = 152.0 cm À1 (this last corresponding to the torsion about f 2 ) [1] were omitted. Clearly III gives the best set of geometrical parameters.…”

Section: The Acetyl Fragmentmentioning

confidence: 99%

“…Vibrational frequencies, w n (in cm À1 ), and the corresponding normal coordinates Cartesian displacements, w n i,a , are obtained as eigenvalues and eigenvectors of the force-field (F) matrix. Since, to our knowledge, no F has been published for acetophenone, experimental vibrational frequencies were taken from literature [1,42,43] and combined with Cartesian displacements calculated by density functional methods. This mixed approach (i.e.…”

Section: Vibrational Correctionsmentioning

confidence: 99%

“…The cooperative nature of the relative motions of the rigid sub-units composing the molecule, makes, in fact, the investigation of the shape of the internal rotational potential U iso ({f}) (where {f} is the set of internal rotation angles) particularly challenging. [1][2][3][4][5][6][7] For Z = H and R = Ph, the acetophenone molecule, the microwave technique and Hartree-Fock calculations [2,3,6] give strong evidence of a planar structure for the heavy-atom skeleton. [4] Likewise, NMR data from the analysis of the 2 H spectrum of [D 5 ]acetophenone [8] dissolved in a liquid-crystal solvent (LXNMR), and lanthanide-induced shift data [9] indicate an all-planar structure for the heavy-atom skeleton.…”

Section: Introductionmentioning

confidence: 96%

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NMR Spectroscopy Investigation of the Cooperative Nature of the Internal Rotational Motions in Acetophenone

Longeri

Pileio

et al. 2005

ChemPhysChem

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The proton NMR spectrum of the doubly enriched acetophenone-carbonyl,methyl-13C2 isotopomer dissolved in a liquid-crystalline solvent (LXNMR) was analyzed to yield a data set of 19 dipolar couplings. The presence of so many couplings, and in particular the dependence of some of them on the acetyl carbons enabled the investigation of the structure of the acetyl moiety and of possible cooperative motions about the aryl-carbonyl and carbonyl-methyl bonds. Methodological aspects, and approximations relating to the application of the vibrational correction procedure in the presence of large-amplitude torsional motions, are discussed. Results show that it is possible to discriminate between a continuous and a discrete conformer distribution about the angle phi(1) but not among a few proposed continuous shapes of U(iso)({phi}). In this study, the use of dipolar couplings with a non-negligible contribution from the indirect spin-spin coupling tensor J, (D(C8C9) in our case), for structural determination is extended from rigid to flexible molecules. The 1/2J(aniso)(C8C9) contribution was derived theoretically using the density functional theory linear response (DFT-LR) first-principles calculation of the J(C8C9) spin-spin coupling tensor.

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Section: The Acetyl Fragmentmentioning

confidence: 99%

Section: Vibrational Correctionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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NMR Spectroscopy Investigation of the Cooperative Nature of the Internal Rotational Motions in Acetophenone

Longeri

Pileio

et al. 2005

ChemPhysChem

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“…For benzoyl chloride we calculated the entropy from the published frequencies (26), and the rotational barrier (27).…”

Section: Heats Of Formationmentioning

confidence: 99%

Equilibrium constants and heats of formation of methyl esters and N,N-dimethyl amides of substituted benzoic acids

Guthrie¹,

Pike²,

Lee³

1992

Can. J. Chem.

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.Heats of methanolysis and dimethylaminolysis of substituted benzoyl chlorides (4-X-C6H4-COC1, X = H, CH,, 0CH3, C1, NO,) have been measured, as have the heats of hydrolysis of the esters, permitting the calculation of the heats of formation of the benzoyl chlorides (4-X-C6H4-COCl, X, DHf: CH30, -80. 29 of transfer from methanol to water and from gas to water were determined for the esters and amides. Free energies of formation in aqueous solution were calculated for the acids, esters and amides, making use of thermodynamic estimation procedures where necessary. Equilibrium constants were measured for ester formation in water (X, K (M-I): CH30, 0.14; CH,, 0.14; H, 0.12; C1, 0.15; NO,, 0.13) and N,N-dimethylaminolysis in methanol (X, K (M-I): CH30, 8.16; CH,, 17.5; H, 26.5; C1, 22.6; NO,, 41.0). Partition constants for esters and amides were measured for methanol/dodecane and dodecane/water, permitting calculation of the free energy of transfer from methanol to water (4-X-C6H4-COOCH,, X, DG,,: CH30, 3.12; CH,, 3.17; H, 3.01; C1, 3.43; NO,, 2.89; 4-X-C6H4-CON(CH,),, X, DG,,: CH30, 0.96; CH,, 1.48; H, 0.92; Cl, 1.77; NO2, 0.99). These data permit calculation of the equilibrium constants for dimethylaminolysis of substituted methyl benzoates in water, and for amide formation in water (4-X-C6H4-CON(CH,),, X, K(M-', reactants and products as neutral molecules): CH30, 767; CH,, 752; H, 2050; C1, 1020; NO,, 2350). In the course of our calorimetric measurements we derived an improved value for the heat of solution of HC1 in methanol.

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“…Restricted rotation of the formyl group in benzaldehydes has been widely investigated [1][2][3][4][5][6][7][8][9][10][11][12][13]. The activation parameters for the rotational process have been determined using NMR and far-infrared methods [1][2][3][4][5][6] as well as quantum-chemical calculations [9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Solvent influence on the rotational isomerism in terephthalaldehyde

et al. 2006

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Experimental and theoretical studies were carried out in order to investigate the rotational isomerism of terephthalaldehyde. The dipole moment measurements and infrared spectroscopy in Ar matrix and using various solvents were performed experimentally. In order to supplement the experimental study, both static and dynamical theoretical calculations were performed. IR spectra and potential energy distribution (PED) were calculated for both cis and trans isomers of terephthalaldehyde in gas phase using B3LYP/6-31G(d,p) level of theory. Further calculations consisted of conformational analysis were performed in order to estimate the rotational barrier and relative stabilities of isomers. The DFT theory with B3LYP functional and four double-zeta and triple-zeta basis sets served as framework for this part of calculations. Semiempirical AM1 and PM3 methods were also used for gas-phase modeling. Molecular dynamics using MM3 force field was applied to study the preferences of solvent molecules' orientation around the studied molecule. Additionally, the effect of solvent polarity on the Gibbs energy of the trans cis equilibrium was analyzed in terms of the continuum dielectric medium models.

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Far infrared spectra and barriers to internal rotation of benzaldehyde, benzoyl fluoride, benzoyl chloride and acetophenone

Cited by 61 publications

References 20 publications

NMR Spectroscopy Investigation of the Cooperative Nature of the Internal Rotational Motions in Acetophenone

NMR Spectroscopy Investigation of the Cooperative Nature of the Internal Rotational Motions in Acetophenone

Equilibrium constants and heats of formation of methyl esters and N,N-dimethyl amides of substituted benzoic acids

Solvent influence on the rotational isomerism in terephthalaldehyde

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