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Karplus equation fluorine couplings

C. Thibaudeau, J. Plavec, and J. Chattopadhyaya, A new generalized Karplus-type equation relating vicinal proton-fluorine coupling constants to H-C-C-F torsion angles, J. Org. Chem., 63 (1998) 4967 1984. [Pg.80]

V(F-C3) values in the / -pyranosyl fluorides are 4-10 Hz, while in the a-derivatives they are 0-6 Hz. In the latter the fluorine and C3 atoms have a gauche orientation, while in the former they are trans oriented. On the basis of the results obtained for other three-bond coupling constants in saturated systems, one would expect 3/(F-C) to depend on dihedral angle. However, keeping in mind the results discussed for V(C-C) and 3/(N-C), and the results discussed by Stothers, (1) it is unlikely that one will be able to describe this dependence by a simple Karplus equation. [Pg.282]

Stereochemical dependences of the vicinal fluorine-fluorine coupling have been studied by San Fabian and Westra Hoekzema by the use of MSCF in the restricted active space approach, with the SOPPA and with density functional theory the authors concluded that the through-space interaction is the main reason why /pp couplings do not follow the Karplus equation. [Pg.201]

A Karplus-like equation for 3J(F, H) couplings was empirically determined by Thibaudeau et al.359 and it was applied360 to a study of conformations in fluorinated compounds. [Pg.231]


See other pages where Karplus equation fluorine couplings is mentioned: [Pg.29]    [Pg.26]    [Pg.103]    [Pg.231]   
See also in sourсe #XX -- [ Pg.60 , Pg.61 , Pg.62 ]




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