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  • 1
    Electronic Resource
    Electronic Resource
    Thermodynamics of vinyl ethers. 31. Isomer equilibria in some six- and seven-membered cyclic dienes (1985)
    s.l. : American Chemical Society
    The @journal of organic chemistry 50 (1985), S. 4844-4847 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00224a038
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  • 2
    Electronic Resource
    Electronic Resource
    Thermodynamics of vinyl ethers. 19. Alkyl-substituted divinyl ethers (1977)
    s.l. : American Chemical Society
    The @journal of organic chemistry 42 (1977), S. 1443-1449 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00428a038
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  • 3
    Electronic Resource
    Electronic Resource
    Carbon-13 nuclear magnetic resonance spectra of divinyl ethers (1978)
    s.l. : American Chemical Society
    The @journal of organic chemistry 43 (1978), S. 2776-2780 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00408a007
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  • 4
    Electronic Resource
    Electronic Resource
    Carbon-13 NMR study of the effect of the polar character of substituents on p-.pi. conjugation in .alpha.,.beta.-unsaturated ethers, acetals, orthoesters, and orthocarbonates (1978)
    s.l. : American Chemical Society
    The @journal of organic chemistry 43 (1978), S. 2773-2776 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00408a006
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  • 5
    Electronic Resource
    Electronic Resource
    Relative thermodynamic stabilities of 2-substituted 4-methylene-1,3-dioxolanes and 4-methyl-1,3-dioxoles (1997)
    Springer
    Structural chemistry 8 (1997), S. 425-433 
    Details
    ISSN: 1572-9001
    Keywords: Thermodynamic stability ; 4-methylene-1,3-dioxolanes ; 4-methyl-1,3-dioxoles ; vinyl ethers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The relative thermodynamic stabilities of 24 pairs of carbon-carbon double-bondexo-endo isomeric 2-substituted 4-methylene-1,3-dioxolanes (a) and 4-methyl-1,3-dioxoles (b) have been determined by base-catalyzed chemical equilibration in DMSO solution. In all cases, theendo isomer (b) is the favored species at thermodynamic equilibrium. A single alkyl substitutent on C-2 gives only a negligible contribution to the relative stability of the isomeric forms, but the presence of two alkyl groups on C-2 increases the relative stability of theendo isomer by 2–3 kL mol−1. A still higher effect in favor of theendo isomer is produced by introduction of a single alkoxy group on C-2; this effect is further slightly accentuated by 2,2-dialkoxy substitution at C-2. The origin of the favorable effect of 2-alkoxy substitution on the relative stability of theendo isomer is not clear, but it seems to arise from an unexpected stability of theendo isomer rather than from an enhanced destabilization of theexo form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311701
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  • 6
    Electronic Resource
    Electronic Resource
    A Thermodynamic, 13C NMR, and 17O NMR Study of Isomeric 4,7-Dihydro-1,3-dioxepins and 4,5-Dihydro-1,3-dioxepins (1999)
    Springer
    Structural chemistry 10 (1999), S. 295-302 
    Details
    ISSN: 1572-9001
    Keywords: Thermodynamic stability ; 4,5-dihydro-1,3-dioxepins ; 4,7-dihydro-1,3-dioxepins ; 13C NMR ; 17O NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The relative thermodynamic stabilities of 4,7-dihydro-1,3-dioxepin (4,6-dioxacycloheptene, 1a) and 4,5-dihydro-1,3-dioxepin (3,5-dioxacycloheptene, 1b), and of a number of their 2-substituted derivatives, have been determined by base-catalyzed chemical equilibration in DMSO solution. Without exception, the 4,5-dihydro isomer is the dominating species at thermodynamic equilibrium. The relative stability of the b form is promoted by the presence of a single alkyl group on C-2, whereas two alkyl groups on C-2 have an opposite effect. In general, the thermodynamic parameters ΔH m Θ and Δ Sm Θ , of isomerization vary unexpectedly with the pattern of substitution at C-2. These trends appear to be derived from significant substituent-induced conformational changes in the b isomer, as suggested by 13C and 17O NMR chemical shift data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022099002667
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  • 7
    Electronic Resource
    Electronic Resource
    An Ab Initio Study of the Relative Stabilities and Molecular Structures of 3-Substituted 2,5-Dihydrofurans and 4-Substituted 2,3-Dihydrofurans (2000)
    Springer
    Structural chemistry 11 (2000), S. 47-53 
    Details
    ISSN: 1572-9001
    Keywords: Dihydrofurans ; relative stabilities ; molecular structures ; ab initio calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The geometry optimized structures and total energies of 3-substituted (R) 2,5-dihydrofurans (a) and their isomers, 4-substituted 2,3-dihydrofurans (b), have been determined by ab initio calculations at the MP2/6-31G*//HF/6-31G* level. The nature of the moiety R has a marked effect on the relative total energies of the isomeric forms: at the calculation level cited, the reaction enthalpies for the a → b isomerization range from +4.7 kJ mol−1 for R = MeO to −30.5 kJ mol−1 for both R = COOMe and R = NO2. The reaction enthalpies appear to be controlled by the electronic effect of R on the strength of p-π conjugation in b. The a isomer has a planar ring, independent of R (excluding NH2), whereas the planarity of b depends on the electronic nature of R: the 2,3-dihydrofuran ring is planar for both R = COOMe and R = NO2, but nonplanar for less conjugation-enhancing substituents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009220406817
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  • 8
    Electronic Resource
    Electronic Resource
    Molecular Structures and Thermodynamic Stabilities of Cycloalkadienes and Their Methoxy Derivatives: An Ab Initio and DFT Study (2000)
    Springer
    Structural chemistry 11 (2000), S. 55-63 
    Details
    ISSN: 1572-9001
    Keywords: Cycloalkadienes ; cycloalkadienyl ethers ; relative stabilities ; molecular structures ; ab initio calculations ; DFT calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The geometry-optimized molecular structures and total energies of 4- to 6-membered cycloalkadienes, and of a number of their monoand dimethoxy derivatives, have been calculated by ab initio (HF/6-31G*, MP2/6-31G*//HF/6-31G*) and DFT (B3LYP/6-31G*) methods. By comparison with available experimental data, the reliability of these computational methods for an estimation of the relative stabilities (enthalpies) of the isomeric forms of the title compounds was tested. The experimental enthalpies of isomerization proved to agree best with the respective theoretical data based on the mean of the HF/6-31G* and B3LYP/6-31G* energies. The theoretical calculations were then extended to several isomeric methoxy-substituted cycloalkadienes, for which no previous thermodynamic data exist. Some structural features of the title dienes were also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009272423655
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  • 9
    Electronic Resource
    Electronic Resource
    Estimation of the Relative Stabilities of the E,Z-Isomers of α,β-Dialkylsubstituted Methyl Vinyl Ethers by Various Computational Methods (2000)
    Springer
    Structural chemistry 11 (2000), S. 185-191 
    Details
    ISSN: 1572-9001
    Keywords: Vinyl ethers ; relative stabilities of geometric isomers ; DFT calculations ; ab initio calculations ; semiempirical calculations ; molecular mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The relative thermodynamic stabilities (relative enthalpies) of the E,Z-isomers of α,β-dialkylsubstituted methyl vinyl ethers MeOC(R1)=CHR2 have been estimated by various computational methods including molecular mechanics, semiempirical, ab initio, and DFT calculations. The best performance, approaching the accuracy of the experimental method of chemical equilibration, is shown by the DFT calculations. Ab initio methods, provided that electron correlation is taken into account, are also satisfactory, but clearly less successful than the DFT calculations. The reliability of the semiempirical methods AM1 and PM3 is considerably less good, and varies in an unpredictable manner from case to case. The poorest general performance is shown by the MM2 and MM3 calculations, which may overestimate the relative stability of the Z isomer by as much as 18 kJ mol−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009274011922
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  • 10
    Electronic Resource
    Electronic Resource
    Relative Stabilities and Molecular Structures of the Geometrical Isomers of α,α′-Dioxasubstituted Cycloalkylidenecycloalkanes. A DFT Study (2000)
    Springer
    Structural chemistry 11 (2000), S. 275-281 
    Details
    ISSN: 1572-9001
    Keywords: Heterocyclic ethers ; olefinic ethers ; 1,2-dialkoxyethenes ; relative stabilities ; DFT calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The relative stabilities and molecular structures of the geometrical isomers of seven α,α′-dioxa derivatives of cycloalkylidenecycloalkanes with 3to 6-membered rings have been studied by DFT calculations at the B3LYP/6-31G* level of theory. In each case, the E form was calculated to have the lower total energy. The relative energy of the Z isomer proved to increase regularly with increasing sizes of the two heterocyclic rings, ranging from 1.1 to 13.8 kJ mol−1 on going from the 3,3to the 6,6-membered rings. Intermediate values of the relative energy were calculated for the Z forms of compounds containing two dissimilar rings. The relative energy of the Z isomer was found to be proportional to d −9.3, where d = the distance separating the two O atoms of the Z compound. The molecular structures, electric dipole moments, and atomic charges on the O atoms are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009274509004
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