Conformational Preferences for 1,2- and 1,4-Difluorocyclohexane

Abstract

The conformational preference for 1,2-difluorocyclohexane has been studied experimentally via NMR spectroscopy and computationally using CCSD/6-311+G(2df,p). The results confirm our previous conclusions that the diaxial conformer of trans-1,2-difluorocyclohexane has the lower energy in the gas phase, whereas the diequatorial conformer has the lower energy in solution. SCIPCM reaction field calculations reproduce the observed solvent effects. The 1,4-difluorocyclohexanes have also been reexamined computationally.

Janus all‐cis‐1,2,3,4,5,6‐Hexafluorocyclohexane: A Molecular Motif for Aggregation‐Induced Enhanced Polarization

“…[5][6][7] Due to these unique properties of F, fluorination has already emerged as ap owerful strategy in chemistry and materials cience to design and functionalize systems with interesting electronic, chemical, and mechanical properties, and which have many practical applications. [1,4,[8][9][10][11][12][13] For example, fluoropolymers such as polytetrafluoroethylene (PTFE, popularly knowna sT eflon), ethylene tetrafluoroethylene (ETFE), and polyvinylidene difluoride (PVDF) are among the most widely produced polymers globally.M any fluorinated derivatives are now routinely used in the pharmaceutical industry and continuet ob ea ctively investigated for their pharmacological properties as anticancer, antibacterial, antifungal, antiviral, and antidiabetic drugs. [5,[14][15][16][17][18][19][20][21] Similarly,for nanoscale systems, selective, partial,and complete fluorination methodsa re now available to prepare novel highperformance materials by the fluorination of carbon nanotubes,f ullerenes, graphenes, nanodiamonds, and organic liquid crystals.…”

“…As the van der Waals radius of the F atom is small (1.47 Å) and comparable to that of the H atom (1.20 Å), substitution of F for H can enable significant electronic tunability in a system without introducing additional steric perturbation . Due to these unique properties of F, fluorination has already emerged as a powerful strategy in chemistry and material science to design and functionalize systems with interesting electronic, chemical, and mechanical properties, and which have many practical applications . For example, fluoropolymers such as polytetrafluoroethylene (PTFE, popularly known as Teflon), ethylene tetrafluoroethylene (ETFE), and polyvinylidene difluoride (PVDF) are among the most widely produced polymers globally.…”

On the stereoelectronic effects governing the rotational isomerism of 1,2-di-haloethanes

“…The rotational isomerism of compounds containing the 1,2-difluoroethane fragment has been extensively studied and the synclinal preference often attributed to the gauche effect, the tendency of keeping close certain substituents [1][2][3][4][5]. The origin of this effect for such compounds is assumed to be due to antiperiplanar CAH/ CAF* hyperconjugation, though other recent interpretations have been applied to different systems having vicinal electronegative substituents [6,7].…”

Origin of Diastereocontrol in the Oxy‐Michael Reactions of δ‐Lactol Anions: A Computational and Experimental Study

“…This is consistent with the effect reported by Wiberg for the conformational preference of trans-1,2-difluorocyclohexane in the gas and solution phase. [29] Anion 3 has a long O1ÀC2 bond (1.501 compared to 1.429 in the protonated form minimised under the same conditions and 1.418 found in a crystal structure of the oxy-Michael adduct of 1 with b-methyl-b-nitrostyrene [2b] ) and a short O7 À C2 bond (1.321 ), and the geometry at C2 is distorted considerably from tetrahedral (bond angles: f-…”