Coupling patterns

The long-range coupling of 2.2 Hz which appears in A and B, two quaternary C atoms in the NMR spectrum with appropriate shifts (5c = 76.6 and 83.0) and the two double-bond equivalents (molecular formula C TZ/oO) suggest that a CC triple bond links the two structural fragments. Hence the compound is identified as hex-3-yn-l-ol (C) in accordance with the coupling patterns. 

The most commonly observed coupling patterns and the relative intensities of lines in their multiplets are listed in Table 13.4. Note that it s not possible for a given proton to have five equivalent neighboring protons. (Why not ) A six-line multiplet, or sextet, is therefore found only when a proton has five non-equivalent neighboring protons that coincidentally happen to be coupled with an identical coupling constant /. 

High-resolution H-NMR analysis has recently been employed to ascertain the nature and levels of aldehydes arising from the peroxidation of PUFAs. Indeed, chemical shifts, coupling patterns and coupling constants of the aldehydic (-CHO) and, for a,0-unsaturated... 

A rationale for the exceptionally low reactivity and the unusual reductive coupling pattern, allylation not homoallylation, associated with 1,3-cyclohexadiene is outlined in Scheme 13. In contrast to syn-trans dienes... 

For the parent 2,3-dioxabicyclo[2.2.1]heptane 9 and its 1,4-diphenyl derivative 9 a, the multiplets for the remaining protons do not overlap and have been assigned on the basis of coupling patterns and comparison with the corresponding cw,exo-5,6-dideuterio derivatives 28),... 

As we will see in Chapter 4, g-matrices are often difficult to interpret reliably. The interpretation of isotropic g-values is even less useful and subject to misinterpretation. Thus isotropic ESR spectra should be used to characterize a radical by means of the hyperfine coupling pattern, to study its dynamical properties through line width effects, or to measure its concentration by integration of the spectrum and comparison with an appropriate standard but considerable caution should be exercised in interpreting the g-value or nuclear hyperfine coupling constants. 

The 400 MHz 111 NMR spectrum of 17 (Fig. 1) shows characteristic 3/(H,H) coupling constants for the non-equivalent syn and anti oriented /l-CH2-hydrogens to the x-methine-hydrogen which are useful for the assignment of the stereochemistry. The connectivity and the coupling pattern, in particular the diagnostically valuable AMM X-spin system formed by III H (syn), Ha were analyzed by H,C-COSY and H,H-COSY45 NMR spectra. 

Solid State NMR Spectrum of PNT-N. The attempts to study PNT-F were not successful because the complicated coupling pattern between carbon and fluorine atoms makes the analysis too difficult to accomplish at this time. 

Examining the coupling pattern of Hj in the compounds sufficient to distinguish exo-position of the S-alkyi rl groups. As the dihedral angle between and is close to 90°, the couphng eonstant between H and H is near to 0 Hz. H was... 

Configurational assignments at C-2 and C-4 followed from the spin coupling patterns of the ring protons 2). The configuration of the amino-derivatives (34) and (35) at the branching point was deduced from the chemical shift of the tertiary acetamido resonance in the triacetate ( 55j... 

The coupling patterns of the ring protons clearly established the orientation of substituents at C-1, C-2, C-4 and C-5. 

The stereochemistry at C-1, C-2, C-4 and C-6 of compounds (50)—(53) and the products derived from them, clearly follows from the coupling patterns of the ring protons as well as from the chemical shifts of the acetyl resonances in their acetylated derivatives, taking into consideration the shielding effect of the uracil moiety 27). 

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