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13 C n.m.r. spectroscopy of diethyl alkyl‐ and benzyl‐phosphonates. A study of phosphorus–carbon spin–spin coupling constants over one to seven bonds
Author(s) -
Ernst Ludger
Publication year - 1977
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270090108
Subject(s) - chemistry , substituent , coupling constant , alkyl , crystallography , medicinal chemistry , spin (aerodynamics) , stereochemistry , organic chemistry , physics , particle physics , thermodynamics
13 C chemical shifts and 31 P 13 C spin–spin coupling constants are reported for 10 alkyl‐, 20 benzyl‐ and 3 (naphthylmethyl)‐phosphonates. While in saturated aliphatic chains P–C couplings over more than four bonds cannot be resolved, couplings over up to seven bonds are observed in the benzyl type systems. Conformational and substituent effects on J (PC) are studied and discussed. n J (PF) (n = 4, 5, 6) are reported for the isomeric (fluorobenzyl)phosphonates and n J (PP) (n = 5, 6, 7) were obtained from the 13 C satellites in the 31 P n.m.r. spectra of the isomeric diphosphonates, C 6 H 4 [CH 2 P(O)(OEt) 2 ] 2 . Comparison of those 13 C absorptions of the latter, which represent the X parts of ABX or AA′X spin systems, with the spectra of the corresponding (methylbenzyl)phosphonates, CH 3 C 6 H 4 CH 2 P(O)(OEt) 2 , yielded the relative signs of n J (PC) (n = 2–6).