NMR and dipole moment studies on dimethyl esters of some simple dicarboxylic acids:  the odd-even characteristics of orientational correlation between the terminal ester groups

Abe, Akihiro; Miura, Ichiro; Furuya, Hidemine

doi:10.1021/j100310a015

Cited by 8 publications

(35 citation statements)

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“…For example, from a critical interpretation of IR, 1 H NMR, and Raman spectra of aliphatic esters and diesters, values ranging from 1 to -1 kcal mol -1 with respect to that of the alternative trans state have been reported for the energy of gauche states about the C R H 2 -C*(O*) bonds. [15][16][17][18][19] Similar disagreement was obtained from both the interpretation of the dipole moments of aliphatic diesters and the temperature coefficient of the unperturbed dimensions of aliphatic polyesters. 17,[20][21][22] As for the energy associated with gauche states about C H 2 -C R H 2 bonds, values of -0.6, 0.3, and 0.8 kcal mol -1 over those of the corresponding trans states were reported, respectively, for dialkyl esters of succinic, glutaric, and adipic acids.…”

Section: Introductionsupporting

confidence: 61%

“…17 Thus the conformational states about the C R H 2 -C*(O*) and C R H 2 -C H 2 bonds were taken to be 0, (123°and 0, (113°, respectively. As for the energy Eσ R of gauche states about C R H 2 -C*(O*), the results at hand are highly controversial.…”

Section: Resultsmentioning

confidence: 99%

“…17,[20][21][22] As for the energy associated with gauche states about C H 2 -C R H 2 bonds, values of -0.6, 0.3, and 0.8 kcal mol -1 over those of the corresponding trans states were reported, respectively, for dialkyl esters of succinic, glutaric, and adipic acids. 17 In this study, these energies were determined by comparing the dipolar correlation coefficient of poly(neopentyl glycol glutarate) (PNG), calculated as a function of these energies, with experimental results.…”

Section: Introductionmentioning

confidence: 99%

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Comparative Study of the Conformational Characteristics of Partially Fluorinated Polyesters and Their Hydrogenated Counterparts

et al. 1996

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From a comparative study of the polarity of poly(neopentyl glycol hexafluoroglutarate) (PNFG) and its hydrogenated counterpart, poly(neopentyl glycol glutarate) (PNG), the influence of the presence of the fluorine atoms on the conformational characteristics of polyesters is investigated. At 30°C, the experimental values of the mean-square dipole moment per repeating unit of PNG and PNFG chains, 〈µ 2 〉/x, are 5.25 and 9.16 D 2 , respectively. A critical interpretation of the experimental results using the rotational isomeric state model suggests that the conformational energies associated with the gauche states about both the C R H2-C*(O*) and C H2-C R H2 bonds of the acid residue of PNG have, respectively, lower and higher energy than the alternative trans states. Similar conclusions are reached for the conformational energies associated with the skeletal bonds of the C F2-C R F2-C*(O*) segment of the acid residue of PNFG chains. This study leads us to conclude that differences in the orientations of the dipoles associated with the ester groups, rather than differences in the rotational populations about the skeletal bonds of the chains, may be responsible for the significant higher polarity of the fluorinated polyesters.

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Section: Introductionsupporting

confidence: 61%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparative Study of the Conformational Characteristics of Partially Fluorinated Polyesters and Their Hydrogenated Counterparts

et al. 1996

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“…The critical interpretation of the 1 H NMR spectra and dipole moments of aliphatic diesters with general formula H 3 CO(*O)-*C(CH 2 ) n C*(O*)OCH 3 led Abe and co-workers 3,4 to conclude that the energy of gauche states about C R -C* bonds, Eσ R , is 1 kcal mol -1 above that of the alternative trans states. According to these authors, however, gauche states about C R -C bonds have an energy E σ which seems to be dependent on the number of methylene groups in the residue acid.…”

Section: Theoretical Calculationsmentioning

confidence: 99%

Conformational Characteristics of Aliphatic Diesters Derived from Fluorinated Diacids

et al. 1996

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A comparative study of the polarity and conformational characteristics of diethyl hexafluoroglutarate (DEFG) and its hydrogenated diester counterpart, diethyl glutarate (DEG), is reported. The value at 30°C of the mean-square dipole moment 〈µ 2 〉 of the latter compound, 5.26 D 2 , is nearly 2 times larger the value of this quantity for the fluorinated diester, which amounts to 12.1 D 2 at the same temperature. Values of the conformational energies associated with the rotational states about the skeletal bonds of the acid residue were calculated by combining molecular mechanics with the critical interpretation of the mean-square dipole moment of these compounds, finding that the rotational populations about the different skeletal bonds are similar in both molecules. The evaluation of 〈µ 2 〉 as a function of the conformational energies indicates that the experimental results are reproduced assuming that the conformation in which the C*dO* group eclipses the C R -C bond in the C C R C*(O*)O residue is less stable than the alternative conformation in which the carbonyl group eclipses the C R sF (or C R sH) bond. The analysis suggests that the high polarity exhibited by DEFG, in comparison with that of DEG, arises from differences in the orientation and the modulus of the dipoles in both compounds rather than from differences in their conformational characteristics.

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“…20 As for the rotational potentials of the terminal phenyl groups, the results of MO calculations and spectroscopic studies are available for relevant model compounds such as methyl benzyl ether 22 and ethylbenzene. 23 The rotational minima -of the phenyl rotation were adjusted in accord with these data for the respective polymers.…”

Section: For the Rotation About The C(o)ca-cpcy(o)mentioning

confidence: 99%

Conformational Analysis of α-Helical Polypeptides in Two Opposite Screw Forms. A Combined Use of 2H NMR and MD Simulation

Okamoto

Furuya

Abe

1995

Polym J

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NMR and dipole moment studies on dimethyl esters of some simple dicarboxylic acids: the odd-even characteristics of orientational correlation between the terminal ester groups

Cited by 8 publications

References 0 publications

Comparative Study of the Conformational Characteristics of Partially Fluorinated Polyesters and Their Hydrogenated Counterparts

Comparative Study of the Conformational Characteristics of Partially Fluorinated Polyesters and Their Hydrogenated Counterparts

Conformational Characteristics of Aliphatic Diesters Derived from Fluorinated Diacids

Conformational Analysis of α-Helical Polypeptides in Two Opposite Screw Forms. A Combined Use of 2H NMR and MD Simulation

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