Coupling constant strong

The coupling constants strongly suggest the half-chair conformation in the 2,3-and 3,4-anhydropyranosides, in which the conformational effect of the oxirane ring is similar to that of a double bond (2,3-unsaturated pyranoside derivatives). The C- H coupling constant can be determined from the C satellites of the proton spectrum and from the C spectrum. ... 

Vicinal coupling constants strongly depend on the dihedral angle, <]) (Karplus equation) ... 

For twice-distilled material infrared (liquid film) cm." 1745 strong, 1565 strong, 1430 medium strong proton magnetic resonance (chloro-form-d) (number of protons, multiplicity, coupling constant J in Hz) 3.14-3.45 (1, multiplet), 3.76 (3, singlet), 3,86 (3, singlet), 5.6 (1, doublet of doublets, J = 6 and 8). 

The spectral properties of pentafluorophenylcopper te-tramer are as follows infrared (Nujol) cm. 1630 medium 1391 medium 1353 medium 1275 medium 1090,1081, and 1071 strong triplet 978 strong 785 medium fluorine magnetic resonance (tetrahydrofuran with trichlorofluoromethane as internal reference) 8 (multiplicity, number of fluorines, assignment, coupling constant J in Hz.) 107.2 (20-line multiple , 2, ortho F), 153.4 (triplet of triplets, 1, para F, J= 1.3 and 20), 162.3 (17-line multiplet, 2, meta F). Absorptions at 820-900, 1100-1125, and 1290 cm.- in the infrared spectrum and at 8 3.05 in the proton magnetic resonance spectrum indicate that dioxane is still present. 

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