✍ Scribed by H.N. Cheng; M.A. Bennett
No coin nor oath required. For personal study only.
A major problem in the use of i3C-NMR spectroscopy for structure identification is to estimate the 13C shifts of compounds known or suspected to be present in the spectrum. The substituent chemical shifts of different functional groups were studied and new, detailed empirical rules are reported. Trends in these shift parameters are noted. It appears that for functional groups containing more than one nucleus, the observed shift parameters (x = a, p, y, 6 shifts) can be approximated by the shift parameters of the component nuclei (x camp) in the functional group, i.e.,
x,bs = x,,,p. The detailed shift behavior and shift additivity rules were computerized.
The resulting program (CSPEC) has many user friendly features, e.g., ease of input , modification of structure, storage and retrieval of known shifts, and rapid computation.
📜 SIMILAR VOLUMES
## Abstract Carbon‐13 chemical shifts of the cyclopropyl carbons of eleven 4‐substituted cyclopropylbenzenes have been measured under conditions effectively corresponding to infinite dilution in DCCI~3~. The substituent‐induced chemical shifts (SCS) of __both__ the α and β carbons of the cyclopropa
## Abstract The Ketonic ^13^C NMR signals of a series of 6‐hydroxy‐5‐oxobicyclo[2.2.2]oct‐7‐ene‐2‐carboxylic acid lactones and of haplophytine and related __N__‐substituted 3‐piperidinones occur at exceptionally high field; the structural factors which are responsible have been elucidated by compar
## Abstract A link between a substructure searching system and a ^13^C NMR data base has been established and permits the retrieval and examination of the chemical shifts associated with specific substructures. The means by which these searches are accomplished is described and the results from the
This study concerns detailed analyses of olefinic carbon shieldings in sterols and related cyclic olefins. Included are detailed considerations of olefinic carbon shieldings in monounsaturated sterols and related compounds and in sterols containing homoannular and heteroannular conjugated diene syst