13C n.m.r. spectroscopy of diethyl alkyl- and benzyl-phosphonates. A study of phosphorus–carbon spin–spin coupling constants over one to seven bonds
✍ Scribed by Ludger Ernst
- Book ID
- 102950506
- Publisher
- John Wiley and Sons
- Year
- 1977
- Tongue
- English
- Weight
- 876 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
C chemical shifts and 31P-13C spin-spin coupling constants are reported for 10 akyl-, 20 benzyl-and 3 (naphthylmethy1)-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. "J(PF) (n = 4,5,6) are reported for the isomeric (fluorobenzy1)phosphonates and "J(PP) (n = 5,6,7) were obtained from the "C satellites in the 3'P n.m.r. spectra of the isomeric diphosphonates, C,H,[CH,P(O)(OEt),],. Comparison of those l3c absorptions of the latter, which represent the X parts of ABX or AA'X spin systems, with the spectra of the corresponding (methylbenzyl)phosphonates, CHjC6H,CH2P(o)(oEt),, yielded the relative signs of "J(Pc) (n = 2-6).