Conformational Analysis. XI. The Conformers of 2-Chlorocyclohexanone<sup>1,3</sup>

Allinger, Norman L.; Allinger, J.; Freiberg, Leslie A.; Czaja, Robert F.; LeBel, Norman A.

doi:10.1021/ja01507a026

Cited by 70 publications

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References 2 publications

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“…Given the important role played by hyperconjugative interactions in the Fermi contact (FC) transmission in long-range couplings, hyperconjugative interactions were evaluated using the natural bond orbital (NBO) [13] analyses as implemented in the Gaussian03 program, [14] at the B3LYP/aug-cc-pVTZ level. DFT calculations of all four terms of 4 were carried out using the EPR-III basis set for C and H, [15] which is of a triple-zeta quality and includes diffuse and polarization functions. The s part of this basis set is enhanced to better reproduce the electronic density in the nuclear regions, since this point is particularly important when calculating the FC term.…”

Section: Experimental and Computationmentioning

confidence: 99%

“…[1] The long-range 4 J H2,H6 coupling is expected to operate in the axial conformer, according to the Wcoupling pathway, [9] whilst the corresponding diaxial coupling in the equatorial conformer is usually smaller or even not observed. [10] Long-range 4 J H,H coupling constants were measured in rigid tert-butylcyclohexanes, [11] with W-type coupling constants being significantly larger than diaxial and equatorial -axial couplings. However, 4 J H2,H4 is not observed in 2-bromocyclohexanone, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…[10] Long-range 4 J H,H coupling constants were measured in rigid tert-butylcyclohexanes, [11] with W-type coupling constants being significantly larger than diaxial and equatorial -axial couplings. However, 4 J H2,H4 is not observed in 2-bromocyclohexanone, i.e. only a through-carbonyl long-range coupling has been observed in this compound for H2.…”

Section: Introductionmentioning

confidence: 99%

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On the ⁴J_HH long‐range coupling in 2‐bromocyclohexanone: conformational insights

Coelho

Freitas

Tormena

et al. 2008

Magnetic Reson in Chemistry

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2-Bromocyclohexanone is a model compound in which a 4JH2, H6 coupling constant is observed, whereas the corresponding 4JH2,H4 is absent. The observed long-range coupling is not only a result of the known W-type coupling, in the axial conformation, but also because of the less usual diaxial spin-spin coupling in the equatorial conformer. The carbonyl group plays a determining role in describing the coupling pathway, as concluded by natural bond orbital (NBO) analysis; although the sigma C2-H2-->sigma*C1(O)-C6 and sigma C6-H6 -->sigma*C1(O)-C2 interactions in the axial conformer contribute for transmitting the spin information associated with the W-type coupling, the strong sigma C2-H2-->pi*C=O and sigma C6-H6-->pi*C=O hyperconjugations in the equatorial conformer define an enhanced coupling pathway for 4JH2,H6,despite the inhibition of this coupling because of nO-->sigma*C(O)-C interaction and the large carbonyl angle. These findings provide the experimental evidence that orbital interactions contribute for the conformational isomerism of 2-bromocyclohexanone.

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Section: Experimental and Computationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the ⁴J_HH long‐range coupling in 2‐bromocyclohexanone: conformational insights

Coelho

Freitas

Tormena

et al. 2008

Magnetic Reson in Chemistry

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“…From the resulting difference, the compounded rate constant, Kl,mccpk2,mccp,cp, was calculated, using eq. [7]. Thus a value of 0.39 2 0.17 M-2 s f 1 was obtained at a temDerature of 294 K.…”

Section: Kinetic Modelmentioning

confidence: 75%

Reactions of alicyclic ketones in carbon tetrachloride. II. Kinetics of the chlorination of 2-chlorocyclopentanone and 2-chlorocyclohexanone, catalyzed by hydrogen chloride

Stamhuis¹,

Maatman²,

Joosten³

1986

Can. J. Chem.

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EIZE J. STAMHUIS, HENK MAATMAN, and GEERT E. H. JOOSTEN. Can. J. Chem. 64, 1690 (1986). The kinetics of the direct chlorination of 2-chlorocyclopentanone (2-mccp) and 2-chlorocyclohexanone (2-mcch) in carbon tetrachloride, catalyzed by hydrogen chloride, were studied. Reaction products are all the possible 2,2-, 2,5-, and 2,6-dichloro compounds. The ratios depend on the concentrations of the monochloro compound and hydrogen chloride. Surprisingly, even at conversions of the monochloro compound as low as 2%, 2,2,5-trichlorocyclopentanone and 2,2,6-trichlorocyclohexanone, respectively, are also formed. The chlorination reaction of both monochloro ketones shows zero order in chlorine. The order in hydrogen chloride is 1.3. The order in 2-mccp and 2-mcch varies somewhat with the concentration of the ketone and was found to be roughly 1.7. The variation in reaction order is explained by a partial self-association of the ketones. The ketones act as substrates as well as basic catalysts in the rate-determining a -or a'-carbon deprotonation. General base catalysis is clearly demonstrated by a strong increase in the rate of chlorination of 2-mccp upon addition of cyclopentanone (cp) to the reaction mixture, which agrees with the mechanism as presented in a previous paper. Kinetic equations derived from the reaction models for the "separate" and "mixed" ketone chlorinations accurately describe the observed rates of the chlorination of 2-mccp and 2-mcch in the concentration range of 0.04-1.0 M. EIZE J. STAMHUIS, HENK MAATMAN et GEERT E. H. JOOSTEN. Can. J. Chem. 64, 1690 (1986). OpCrant dans le tCtrachlorure de carbone, on a CtudiC la cinCtique de la chloration directe, catalysCe par le chlorure d'hydrogkne, des chloro-2 cyclopentanone (2-mccp) et cyclohexanone (2-mcch). Les produits de la reaction correspondent a tous les produits possibles pour les disubstitutions en -2,2, -2,5 et -2,6. Les rapports varient avec les concentrations initiales de composC monochlorC et de chlorure d'hydrogttne. I1 est surprenant de noter, a des taux de transformation du dCrivC monochlorC aussi bas que 2%, qu'il y a aussi formation, selon le cas, de trichloro-2,2,5 cyclopentanone ainsi que de trichloro-2,2,6 cyclohexanone. Par rapport au chlore, l'ordre de la rCaction de chloration des deux cCtones monochlorees est Cgal i zCro. Par rapport au chlorure d'hydroghe, il est Cgal a 1,3. Par rapport aux cCtones 2-mccp et 2-mcch, l'ordre varie en fonction de la concentration des cCtones; il s'Ctablit approximativement 2 1,7. On explique cette variation de I'ordre par rapport aux cCtones en fonction d'une auto-association partielle des cCtones. Les cCtones agissent comme substrats ainsi que comme catalyseurs basiques dans la deprotonation des carbones a et a ' qui dCtermine la vitesse de la rCaction. On a facilement mis en Cvidence une catalyse gCnCrale des bases en notant la grande augmentation de la vitesse de chloration de la 2-mccp par addition de cyclopenta?one (cp) au milieu reactionnel; cette observation est en accord avec le mCcanisme proposC...

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“…En effet, en admettant que la contribution stCrique (interactions de type van der Waals) est sensiblement la mCme quel que soit le solvant, on peut Ccrire que l'knergie Clectronique E de chacune des deux formes dCpend du solvant selon (14,15 CLa largeur W du massif db au proton HI est e x p r i d e en Hz.…”

Section: Discussionunclassified

Alcoxy-2, aryloxy-2, acyloxy-2 cyclohexanones. Synthèse et étude de leur équilibre conformationnel

Cantacuzène¹,

Tordeux²

1976

Can. J. Chem.

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Conformational Analysis. XI. The Conformers of 2-Chlorocyclohexanone^1,3

Cited by 70 publications

References 2 publications

On the ⁴J_HH long‐range coupling in 2‐bromocyclohexanone: conformational insights

On the ⁴J_HH long‐range coupling in 2‐bromocyclohexanone: conformational insights

Reactions of alicyclic ketones in carbon tetrachloride. II. Kinetics of the chlorination of 2-chlorocyclopentanone and 2-chlorocyclohexanone, catalyzed by hydrogen chloride

Alcoxy-2, aryloxy-2, acyloxy-2 cyclohexanones. Synthèse et étude de leur équilibre conformationnel

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Conformational Analysis. XI. The Conformers of 2-Chlorocyclohexanone1,3

Cited by 70 publications

References 2 publications

On the 4JHH long‐range coupling in 2‐bromocyclohexanone: conformational insights

On the 4JHH long‐range coupling in 2‐bromocyclohexanone: conformational insights

Reactions of alicyclic ketones in carbon tetrachloride. II. Kinetics of the chlorination of 2-chlorocyclopentanone and 2-chlorocyclohexanone, catalyzed by hydrogen chloride

Alcoxy-2, aryloxy-2, acyloxy-2 cyclohexanones. Synthèse et étude de leur équilibre conformationnel

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Conformational Analysis. XI. The Conformers of 2-Chlorocyclohexanone^1,3

On the ⁴J_HH long‐range coupling in 2‐bromocyclohexanone: conformational insights

On the ⁴J_HH long‐range coupling in 2‐bromocyclohexanone: conformational insights